The Arcania of Arkani

It is not often you get to disagree with a genius. But if you read enough or attend enough lectures sooner or later some genius is going to say or write something that you can see is evidently false, or perhaps (being a bit more modest) you might think is merely intuitively false. So the other day I see this lecture by Nima Arkani-Hamed with the intriguing title “The Morality of Fundamental Physics”. It is a really good lecture, I recommend every young scientist watch it. (The “Arcane” my title alludes to, by the way, is a good thing, look up the word!) It will give you a wonderful sense of the culture of science and a feeling that science is one of the great ennobling endeavours of humanity. The way Arkani-Hamed describes the pursuit of science also gives you comfort as a scientist if you ever think you are not earning enough money in your job, or feel like you are “not getting ahead” — you should simply not care! — because doing science is a huge privilege, it is a reward unto itself, and little in life can ever be as rewarding as making a truly insightful scientific discovery or observation. No one can pay me enough money to ever take away that sort of excitement and privilege, and no amount of money can purchase you the brain power and wisdom to achieve such accomplishments.  And one of the greatest overwhelming thrills you can get in any field of human endeavour is firstly the hint that you are near to turning arcane knowledge into scientific truth, and secondly when you actually succeed in this.

First, let me be deflationary about my contrariness. There is not a lot about fundamental physics that one can honestly disagree with Arkani-Hamed about on an intellectual level, at least not with violent assertions of falsehood.  Nevertheless, fundamental physics is rife enough with mysteries that you can always find some point of disagreement between theoretical physicists on the foundational questions. Does spacetime really exist or is it an emergent phenomenon? Did the known universe start with a period of inflation? Are quantum fields fundamental or are superstrings real?

When you disagree on such things you are not truly having a physics disagreement, because these are areas where physics currently has no answers, so provided you are not arguing illogically or counter to known experimental facts, then there is a wide open field for healthy debate and genuine friendly disagreement.

Then there are deeper questions that perhaps physics, or science and mathematics in general, will never be able to answer. These are questions like: Is our universe Everettian? Do we live in an eternal inflation scenario Multiverse? Did all reality begin from a quantum fluctuation, and, if so, what the heck was there to fluctuate if there was literally nothing to begin with? Or can equations force themselves into existence from some platonic reality merely by brute force of their compelling beauty or structural coherence? Is pure information enough to instantiate a physical reality (the so-called “It from Bit” meme.

Some people disagree on whether such questions are amenable to experiment and hence science. The Everettian question may some day become scientific. But currently it is not, even though people like David Deutsch seem to think it is (a disagreement I would have with Deutsch). While some of the “deeper ” questions turn out to be stupid, like the “It from Bit” and “Equations bringing themselves to life” ideas. However, they are still wonderful creative ideas anyway, in some sense, since they put our universe into contrast with a dull mechanistic cosmos that looks just like a boring jigsaw puzzle.

The fact our universe is governed (at least approximately) by equations that have an internal consistency, coherence and even elegance and beauty (subjective though those terms may be) is a compelling reason for thinking there is something inevitable about the appearance of a universe like ours. But that is always just an emotion, a feeling of being part of something larger and transcendent, and we should not mistake such emotions for truth. By the same token mystics should not go around mistaking mystical experiences for proof of the existence of God or spirits. That sort of thinking is dangerously naïve and in fact anti-intellectual and incompatible with science. And if there is one truth I have learned over my lifetime, it is that whatever truth science eventually establishes, and whatever truths religions teach us about spiritual reality, wherever these great domains of human thought overlap they must agree, otherwise one or the other is wrong. In other words, whatever truth there is in religion, it must agree with science, at least eventually. If it contradicts known science it must be superstition. And if science contravenes the moral principles of religion it is wrong.

Religion can perhaps be best thought of in this way:  it guides us to knowledge of what is right and wrong, not necessarily what is true and false. For the latter we have science. So these two great systems of human civilization go together like the two wings of a bird, or as in another analogy, like the two pillars of Justice, (1) reward, (2) punishment. For example, nuclear weapons are truths of our reality, but they are wrong. Science gives us the truth about the existence and potential for destruction of nuclear weapons, but it is religion which tells us they are morally wrong to have been fashioned and brought into existence, so it is not that we cannot, but just that we should not.

Back to the questions of fundamental physics: regrettably, people like to think these questions have some grit because they allow one to disbelieve in a God. But that’s not a good excuse for intellectual laziness. You have to have some sort of logical foundation for any argument. This often begins with an unproven assumption about reality. It does not matter where you start, so much, but you have to start somewhere and then be consistent, otherwise as elementary logic shows you would end up being able to prove (and disprove) anything at all. If you start with a world of pure information, then posit that spacetime grows out of it, then (a) you need to supply the mechanism of this “growth”, and (b) you also need some explanation for the existence of the world of pure information in the first place.

Then if you are going to argue for a theory that “all arises from a vacuum quantum fluctuation”, you have a similar scenario, where you have not actually explained the universe at all, you have just pushed back the existence question to something more elemental, the vacuum state. But a quantum vacuum is not a literal “Nothingness”, in fact is is quite a complicated sort of thing, and has to involve a pre-existing spacetime or some other substrate that supports the existence of quantum fields.

Further debate along these lines is for another forum. Today I wanted to get back to Nima Arkani-Hamed’s notions of morality in fundamental physics and then take issue with some private beliefs people like Arkani-Hamed seem to profess, which I think betray a kind of inconsistent (I might even dare say “immoral”) thinking.

Yes, there is a Morality in Science

Arkani-Hamed talks mostly about fundamental physics. But he veers off topic in places and even brings in analogies with morality in music, specifically in lectures by the great composer Leonard Bernstein, there are concepts in the way Bernstein describes the beauty and “inevitability” of passages in great music like Beethoven’s Fifth Symphony. Bernstein even gets close to saying that after the first four notes of the symphony almost the entire composition could be thought of as following as an inevitable consequence of logic and musical harmony and aesthetics. I do not think this is flippant hyperbole either, though it is somewhat exaggerated. The cartoon idea of Beethoven’s music following inevitable laws of aesthetics has an awful lot in common with the equally cartoon notion of the laws of physics having, in some sense, their own beauty and harmony such that it is hard to imagine any other set of laws and principles, once you start from the basic foundations.

I should also mention that some linguists would take umbrage at Arkani-Hamed’s use of the word “moral”.  Really, most of what he lectures about is aesthetics, not morality.  But I am happy to warp the meaning of the word “moral” just to go along with the style of Nima’s lecture.  Still, you do get a sense from his lecture, that the pursuit of scientific truth does have a very close analogy to moral behaviour in other domains of society.  So I think he is not totally talking about aesthetics, even though I think the analogy with Beethoven’s music is almost pure aesthetics and has little to do with morality.   OK, those niggles aside, let’s review some of Arkani’Hamed’s lecture highlights.

The way Arkani-Hamed tells the story, there are ways of thinking about science that are not just “correct”, but more than correct, the best ways of thinking seem somehow “right”, whereby he means “right” in the moral sense. He gives some examples of how one can explain a phenomenon (e.g., the apparent forwards pivoting of a helium balloon suspended inside a boxed car) where there are many good explanations that are all correct (air pressure effects, etc) but where often there is a better deeper more morally correct way of reasoning (Einstein’s principle of equivalence — gravity is indistinguishable from acceleration, so the balloon has to “fall down”).

philsci_immoral_helim_balloon

It really is entertaining, so please try watching the video. And I think Arkani-Hamed makes a good point. There are “right” ways of thinking in science, and “correct but wrong ways”. I guess, unlike human behaviour the scientifically “wrong” ways are not actually spiritually morally “bad”, as in “sinful”. But there is a case to be made that intellectually the “wrong” ways of thinking (read, “lazy thinking ways”) are in a sense kind of “sinful”. Not that we in science always sin in this sense of using correct but not awesomely deep explanations.  I bet most scientists which they always could think in the morally good (deep) ways! Life would be so much better if we could. And no one would probably wish to think otherwise. It is part of the cultural heritage of science that people like Einstein (and at times Feynman, and others) knew of the morally good ways of thinking about physics, and were experts at finding such ways of thinking.

Usually, in brief moments of delight, most scientists will experience fleeting moments of being able to see the morally good ways of scientific thinking and explanation. But the default way of doing science is immoral, by in large, because it takes a tremendous amount of patience and almost mystical insight, to be able to always see the world of physics in the morally correct light — that is, in the deepest most meaningful ways — and it takes great courage too, because, as Arkani-Hamed points out, it takes a lot more time and contemplation to find the deeper morally “better” ways of thinking, and in the rush to advance one’s career and publish research, these morally superior ways of thinking often get by-passed and short-circuited. Einstein was one of the few physicists of the last century who actually managed, a lot of his time, to be patient and courageous enough to at least try to find the morally good explanations.

This leads to two wonderful quotations Arkani-Hamed offers, one from Einstein, and the other from a lesser known figure of twentieth century science, the mathematician Alexander Gröthendieck — who was probably an even deeper thinker than Einstein.

The years of anxious searching in the dark, with their intense longing, their intense alternations of confidence and exhaustion and the final emergence into the light—only those who have experienced it can understand it.
— Albert Einstein, describing some of the intellectual struggle and patience needed to discover the General Theory of Relativity.

“The … analogy that came to my mind is of immersing the nut in some softening liquid, and why not simply water? From time to time you rub so the liquid penetrates better, and otherwise you let time pass. The shell becomes more flexible through weeks and months—when the time is ripe, hand pressure is enough, the shell opens like a perfectly ripened avocado!

“A different image came to me a few weeks ago. The unknown thing to be known appeared to me as some stretch of earth or hard marl, resisting penetration … the sea advances insensibly in silence, nothing seems to happen, nothing moves, the water is so far off you hardly hear it … yet it finally surrounds the resistant substance.”
— Alexander Gröthendieck, describing the process of grasping for mathematical truths.

Beautiful and foreboding — I have never heard of the mathematical unknown likened to a “hard marl” (sandstone) before!

So far all is good. There are many other little highlights in Arkani-Hamed’s lecture, and I should not write about them all, it is much better to hear them explained by the master.

So what is there to disagree with?

The Morally Correct Thinking in Science is Open-Minded

There are a number of characteristics of “morally correct” reasoning in science, or an “intellectually right way of doing things”. Arkani-Hamed seems to list most of the important things:

  • Trust: trust that there is a universal, invariant, human-independent and impersonal (objective) truth to natural laws.
  • Honesty: with others (no fraud) but also more importantly you need to be honest with yourself if you want to do good science.
  • Humility: who you are is irrelevant, only the content of your ideas is important.
  • Wisdom: we never pretend we have the whole truth, there is always uncertainty.
  • Perseverance: lack of certainty is not an excuse for laziness, we have to try our hardest to get to the truth, no matter how difficult the path.
  • Tolerance: it is extremely important to entertain alternative and dissenting ideas and to keep an open mind.
  • Justice: you cannot afford to be tolerant of dishonest or ill-formed ideas. It is indeed vitally important to be harshly judgemental of dishonest and intellectually lazy ideas. Moreover, one of the hallmarks of a great physicist is often said to be the ability to quickly check and to prove one’s own ideas to be wrong as soon as possible.

In this list I have inserted in bold the corresponding spiritual attributes that Professor Nima does not identify. But I think they are important to explicitly state. Because they provide a Rosetta Stone of sorts for translating the narrow scientific modes of behaviour into border domains of human life.

I think that’s a good list. There is, however, one hugely important morally correct way of doing science that Arkani-Hamed misses, and even fails to gloss over or hint at. Can you guess what it is?

Maybe it is telling of the impoverishment in science education, the cold objective dispassionate retelling of facts, in our society that I think not many scientists will even think of his one, but I do not excuse Arkani-Hamed for leaving it off his list, since in many ways it is the most important moral stance in all of science!

It is,

  • Love: the most important driver and motive for doing science, especially in the face of adversity or criticism, is a passion and desire for truth, a true love of science, a love of ideas, an aesthetic appreciation of the beauty and power of morally good ideas and explanations.

Well ok, I will concede this is perhaps implicit in Arkani-Hamed’s lecture, but I still cannot give him 10 out of 10 on his assignment because he should have made it most explicit, and highlighted it in bold colours.

One could point out many instances of scientists failing at these minimal scientific moral imperatives. Most scientists go through periods of denial, believing vainly in a pet theory and failing to be honest to themselves about the weaknesses of their ideas. There is also a vast cult of personality in science that determines a lot of funding allocation, academic appointments, favouritism, and general low level research corruption.

The point of Arkani-Hamed’s remarks is not that the morally good behaviours are how science is actually conducted in the everyday world, but rather it is how good science should be conducted and that from historical experience the “good behaviours” do seem to be rewarded with the best and brightest break-throughs in deep understanding. And I think Arkani-Hamed is right about this. It is amazing (or perhaps, to the point, not so amazing!) how many Nobel Laureates are “humble” in the above sense of putting greater stock in their ideas and not in their personal authority. Ideas win Nobel Prizes, not personalities.

So what’s the problem?

The problem is that while expounding on these simplistic and no-doubt elegant philosophical and aesthetic themes, he manages to intersperse his commentary with the claim, “… by the way, I am an atheist”.

OK, I know what you are probably thinking, “what’s the problem?” Normally I would not care what someone thinks regarding theism, atheism, polytheism, or any other “-ism”. People are entitled to their opinions, and all power to them. But as a scientist I have to believe there are fundamental truths about reality, and about a possible reality beyond what we perceive. There must even be truths about a potential reality beyond what we know, and maybe even beyond what we can possibly ever know.

Now some of these putative “truths” may turn out to be negative results. There may not be anything beyond physical reality. But if so, that’s a truth we should not hereby now and forever commit to believing. We should at least be open-minded to the possibility this outcome is false, and that the truth is rather that there is a reality beyond physical universe.  Remember, open-mindedness was one of Arkani-Hamed’s prime “good behaviours” for doing science.

The discipline of Physics, by the way, has very little to teach us about such truths. Physics deals with physical reality, by definition, and it is an extraordinary disappointment to hear competent, and even “great”, physicists expound their “learned” opinions on theism or atheism and non-existence of anything beyond physical universes. These otherwise great thinkers are guilty of over-reaching hubris, in my humble opinion, and it depresses me somewhat. Even Feynman had such hubris, yet he managed expertly to cloak it in the garment of humility, “who am I to speculate on metaphysics,” is something he might have said (I paraphrase the great man). Yet by clearly and incontrovertibly stating “I do not believe in God” one is in fact making an extremely bold metaphysical statement. It is almost as if these great scientists had never heard of the concept of agnosticism, and somehow seem to be using the word “atheism” as a synonym. But no educated person would make such a gross etymological mistake. So it just leaves me perplexed and dispirited to hear so many claims of “I am atheist” coming from the scientific establishment.

Part of me wants to just dismiss such assertions or pretend that these people are not true scientists. But that’s not my call to make.  Nevertheless, for me, a true scientist almost has to be agnostic. There seems very little other defensible position.

How on earth would any physicist ever know such things (as non-existence of other realms) are true as articles of belief? They cannot! Yet it is astounding how many physicists will commit quite strongly to atheism, and even belittle and laugh at scientists who believe otherwise. It is a strong form of intellectual dishonesty and corruption of moral thinking to have such closed-minded views about the nature of reality.

So I would dare to suggest that people like Nima Arkani-Hamed, who show such remarkable gifts and talents in scientific thinking and such awesome skill in analytical problem solving, can have the intellectual weakness to profess any version of atheism whatsoever. I find it very sad and disheartening to hear such strident claims of atheism among people I would otherwise admire as intellectual giants.

Yet I would never want to overtly act to “convert” anyone to my views. I think the process of independent search for truth is an important principle. People need to learn to find things out on their own, read widely, listen to alternatives, and weigh the evidence and logical arguments in the balance of reason and enlightened belief, and even then, once arriving at a believed truth, one should still question and consider that one’s beliefs can be over-turned in the light of new evidence or new arguments.  Nima’s principle of humility, “we should never pretend we have the certain truth”.

Is Atheism Just Banal Closed-Mindedness?

The scientifically open-mind is really no different to the spiritually open-mind other than in orientation of topics of thought. Having an open-mind does not mean one has to be non-committal about everything. You cannot truly function well in science or in society without some grounded beliefs, even if you regard them all as provisional. Indeed, contrary to the cold-hearted objectivist view of science, I think most real people, whether they admit it or not (or lie to themselves perhaps) they surely practise their science with an idea of a “truth” in mind that they wish to confirm. The fact that they must conduct their science publicly with the Popperrian stances of “we only postulate things that can be falsified” is beside the point. It is perfectly acceptable to conduct publicly Popperian science while privately having a rich metaphysical view of the cosmos that includes all sorts of crazy, and sometimes true, beliefs about the way things are in deep reality.

Here’s the thing I think needs some emphasis: even if you regard your atheism as “merely provisional” this is still an unscientific attitude! Why? Well, because questions of higher reality beyond the physical are not in the province of science, not by any philosophical imperative, but just by plain definition. So science is by definition agnostic as regards the transcendent and metaphysical. Whatever exists beyond physics is neither here nor there for science. Now many self-proclaimed scientists regard this fact about definitions as good enough reason for believing firmly in atheism. My point is that this is nonsense and is a betrayal of scientific morals (morals, that is, in the sense of Arkani-Hamed — the good ways of thinking that lead to deeper insights). The only defensible logical and morally good way of reasoning from a purely scientific world view is that one should be at the basest level of philosophy positive in ontology and minimalist in negativity, and agnostic about God and spiritual reality. It is closed-minded and therefore, I would argue, counter to Arkani-Hamed’s principles of morals in physics, to be a committed atheist.

This is in contrast to being negative about ontology and positively minimalist, which I think is the most mistaken form of philosophy or metaphysics adopted by a majority of scientists, or sceptics, or atheists.  The stance of positive minimalism, or  ontological negativity, adopts, as unproven assumption, a position that whatever is not currently needed, or not currently observed, doe snot in fact exist.  Or to use a crude sound-bite, such philosophy is just plain closed-mindedness.  A harsh cartoon version of which is, “what I cannot understand or comprehend I will assume cannot exist”.   This may be unfair in some instances, but I think it is a fairly reasonable caricature of general atheistic thought.   I think is a lot fairer than the often given argument against religion which points to corruptions in religious practice as a good reason to not believe in God.  There is of course absolutely no causal or logical connection to be made between human corruptions and the existence or non-existence of a putative God.

In my final analysis of Arkani-Hamed’s lecture, I have ended up not worrying too much about the fact he considers himself an atheist. I have to conclude he is a wee bit self-deluded, (like most of his similarly minded colleagues no doubt, yet, of course, they might ultimately be correct, and I might be wrong, my contention is that the way they are thinking is morally wrong, in precisely the sense Arkani-Hamed outlines, even if their conclusions are closer to the truth than mine).

Admittedly, I cannot watch the segments in his lecture where he expresses the beautiful ideas of universality and “correct ways of explaining things” without a profound sense of the divine beyond our reach and understanding. Sure, it is sad that folks like Arkani-Hamed cannot infer from such beauty that there is maybe (even if only possibly) some truth to some small part of the teachings of the great religions. But to me, the ideas expressed in his lecture are so wonderful and awe-inspiring, and yet so simple and obvious, they give me hope that many people, like Professor Nima himself, will someday appreciate the view that maybe there is some Cause behind all things, even if we can hardly ever hope to fully understand it.

My belief has always been that science is our path to such understanding, because through the laws of nature that we, as a civilization, uncover, we can see the wisdom and beauty of creation, and no longer need to think that it was all some gigantic accident or experiment in some mad scientists super-computer. Some think such wishy-washy metaphysics has no place in the modern world. After all, we’ve grown accustomed to the prevalence of evil in our world, and tragedy, and suffering, and surely if any divine Being was responsible then this would be a complete and utter moral paradox. To me though, this is a a profound misunderstanding of the nature of physical reality. The laws of physics give us freedom to grow and evolve. Without the suffering and death there would be no growth, no exercise of moral aesthetics, and arguably no beauty. Beauty only stands out when contrasted with ugliness and tragedy. There is a Yin and Yang to these aspects of aesthetics and misery and bliss. But the other side of this is a moral imperative to do our utmost to relieve suffering, to reduce poverty to nothing, to develop an ever more perfect world. For then greater beauty will stand out against the backdrop of something we create that is quite beautiful in itself.

Besides, it is just as equally wishy-washy to think the universe is basically accidental and has no creative impulse.  People would complain either way.  My positive outlook is that as long as there is suffering and pain in this world, it makes sense to at least imagine there is purpose in it all.  How miserable to adopt Steven Wienberg’s outlook that the noble pursuit of science merely “lifts up above farce to at least the grace of tragedy”.  That’s a terribly pessimistic negative sort of world view.  Again, he might be right that there is no grand purpose or cosmic design, but the way he reasons to that conclusion seems, to me, to be morally poor (again, strictly, if you like, in the Arkani-Hamed morality of physics conception).

There seems, to me, to be no end to the pursuit of perfections. And given that, there will always be relative ugliness and suffering. The suffering of people in the distant future might seem like luxurious paradise to us in the present. That’s how I view things.

The Fine Tuning that Would “Turn You Religious”

Arkani-Hamed mentions another thing that I respectfully take a slight exception to — this is in a separate lecture at a Philosophy of Cosmology conference —  in a talk, “Spacetime, Quantum Mechanics and the Multiverse”.  Referring to the amazing coincidence that our universe has just the right cosmological constant to avoid space being empty and devoid of matter, and just the right Higgs boson mass to allow atoms heavier than hydrogen to form stably, is often, Arkani-Hamed points out, given as a kind of anthropic argument (or quasi-explanation) for our universe.  The idea is that we see (measure) such parameters for our universe precisely, and really only, because if the parameters were not this way then we would not be around to measure them!  Everyone can understand this reasoning.  But it stinks!   And off course it is not an explanation, such anthropic reasoning reduces to mere observation.  Such reasonings are simple banal brute facts about our existence.  But there is a setting in metaphysics where such reasoning might be the only explanation, as awful as it smells.  That is, if our meta-verse is governed by something like Eternal Inflation, (or even by something more ontologically radical like Max Tegmark’s “Mathematical Multiverse”) whereby every possible universe is at some place or some meta-time, actually realised by inflationary big-bangs (or mathematical consequences in Tegmark’s picture) then it is really boring that we exist in this universe, since no matter how infinitesimally unlikely the vacuum state of our universe is, within the combinatorial possibilities of all possible inflationary universe bubbles (or all possible consistent mathematical abstract realities) there is, in these super-cosmic world views, absolutely nothing to prevent our infinitesimally (“zero probability measure”) universe from eventually coming into being from some amazingly unlikely big-bang bubble.

In a true multiverse scenario we thus get no really deep explanations, just observations.  “The universe is this way because if it were not we would not be around to observe it.”  The observation becomes the explanation.  A profoundly unsatisfying end to physics!   Moreover, such infinite possibilities and infinitesimal probabilities make standard probability theory almost impossible to use to compute anything remotely plausible about multiverse scenarios with any confidence (although this has not stopped some from publishing computations about such probabilities).

After discussing these issues, which Arkani-Hamed thinks are the two most glaring fine-tuning or “naturalness” problems facing modern physics, he then says something which at first seems reasonable and straight-forward, yet which to my ears also seemed a little enigmatic.  To avoid getting it wrong let me transcribe what he says verbatim:

We know enough about physics now to be able to figure out what universes would look like if we changed the constants.  … It’s just an interesting fact that the observed value of the cosmological constant and the observed value of the Higgs mass are close to these dangerous places. These are these two fine-tuning problems, and if I make the cosmological constant more natural the universe is empty, if I make the Higgs more natural the universe is devoid of atoms. If there was a unique underlying vacuum, if there was no anthropic explanation at all, these numbers came out of some underlying formula with pi’s and e’s, and golden ratios, and zeta functions and stuff like that in them, then [all this fine tuning] would be just a remarkably curious fact.… just a very interesting  coincidence that the numbers came out this way.  If this happened, by the way, I would start becoming religious.  Because this would be our existence hard-wired into the DNA of the universe, at the level of the mathematical ultimate formulas.

So that’s the thing that clanged in my ears.  Why do people need something “miraculous” in order to justify a sense of religiosity?  I think this is a silly and profound misunderstanding about the true nature of religion.  Unfortunately I cannot allow myself the space to write about this at length, so I will try to condense a little of what I mean in what will follow.  First though, let’s complete the airing,  for in the next breath Arkani-Hamed says,

On the other hand from the point of view of thinking about the multiverse, and thinking that perhaps a component of these things have an anthropic explanation, then of course it is not a coincidence, that’s were you’d expect it to be, and we are vastly less hard-wired into the laws of nature.

So I want to say a couple of things about all this fine-tuning and anthropomorphic explanation stuff.  The first is that it does not really matter, for a sense of religiosity, if we are occupying a tiny infinitesimal region of the multiverse, or a vast space of mathematically determined inevitable universes.  In fact, the Multiverse, in itself, can be considered miraculous.  Just as miraculous as a putative formulaically inevitable cosmos.   Not because we exist to observe it all, since that after-all is the chief banality of anthropic explanations, they are boring!  But miraculous because a multiverse exists in the first place that harbours all of us, including the infinitely many possible doppelgängers of our universe and subtle and wilder variations thereupon.  I think many scientists are careless in such attitudes when they appear to dismiss reality as “inevitable”.  Nothing really, ultimately, is inevitable.  Even a formulaic universe has an origin in the deep underlying mathematical structure that somehow makes it irresistible for the unseen motive forces of metaphysics to have given birth to It’s reality.

No scientific “explanation” can ever push back further than the principles of mathematical inevitability.  Yet, there is always something further to say about origins of reality .  There is always something proto-mathematical beyond.  And probably something even more primeval beyond that, and so on, ad infinitum, or if you prefer a non-infinite causal regression then something un-caused must, in some atemporal sense, pre-exist everything.  Yet scientists routinely dismiss or ignore such metaphysics.  Which is why, I suspect, they fail to see the ever-present miracles about our known state of reality.  Almost any kind of reality where there is a consciousness that can think and imagine the mysteries of it’s own existence, is a reality that has astounding miraculousness to it.  The fact science seeks to slowly pull back the veils that shroud these mysteries does not diminish the beauty and profundity of it all, and in fact, as we have seen science unfold with it’s explanations for phenomena, it almost always seems elegant and simple, yet amazingly complex in consequences, such that if one truly appreciates it all, then there is no need whatsoever to look for fine-tuning coincidences or formulaic inevitabilities to cultivate a natural and deep sense of religiosity.

I should pause and define loosely what I mean by “religiosity”.  I mean nothing too much more than what Einstein often articulated: a sense of our existence, our universe, being only a small part of something beyond our present understanding, a sense that maybe there is something more transcendent than our corner of the cosmos.  No grand design is in mind here, no grand picture or theory of creation, just a sense of wonder and enlightenment at the beauty inherent in the natural world and in our expanding conscious sphere which interprets the great book of nature. (OK, so this is rather more poetic than what you might hope for, but I will not apologise for that.   I think something gets lost if you remove the poetry from definitions of things like spirituality or religion.  I think this is because if there really is meaning in such notions, they must have aspects that do ultimately lie beyond the reach of science, and so poetry is one of the few vehicles of communication that can point to the intended meanings, because differential equations or numerics will not suffice.)

OK, so maybe Arkani-Hamed is not completely nuts in thinking there is this scenario whereby he would contemplate becoming “religious” in the Einsteinian sense.  And really, no where in this essay am I seriously disagreeing with the Professor.  I just think that perhaps if scientists like Arkani-Hamed thought a little deeper about things, and did not have such materialistic lenses shading their inner vision, perhaps they would be able to see that miracles are not necessary for a deep and profound sense of religiosity or spiritual understanding or appreciation of our cosmos.

*      *       *

Just to be clear and “on the record”, my own personal view is that there must surely be something beyond physical reality. I am, for instance, a believer in the platonic view of mathematics: which is that humans, and mathematicians from other sentient civilizations which may exist throughout the cosmos, gain their mathematical understanding through a kind of discovery of eternal truths about realms of axiomatics and principles of numbers and geometry and deeper abstractions, none of which exist in any temporal pre-existing sense within our physical world. Mathematical theorems are thus not brought into being by human minds. They are ideas that exist independently of any physical universe. Furthermore, I happen to believe in something I would call “The Absolute Infinite”. I do not know what this is precisely, I just have an aesthetic sense of It, and It is something that might also be thought of as the source of all things, some kind of universal uncaused cause of all things. But to me, these are not scientific beliefs. They are personal beliefs about a greater reality that I have gleaned from many sources over the years. Yet, amazingly perhaps, physics and mathematics have been one of my prime sources for such beliefs.

The fact I cannot understand such a concept (as the Absolute Infinite) should not give me any pause to wonder if it truly exists or not. And I feel no less mature or more infantile for having such beliefs. If anything I pity the intellectually impoverished souls who cannot be open to such beliefs and speculations. I might point out that speculation is not a bad thing either, without speculative ideas where would science be? Stuck with pre-Copernican Ptolemy cosmology or pre-Eratosthenes physics I imagine, for speculation was needed to invent gizmos like telescopes and to wonder about how to measure the diameter of the Earth using just the shadow of a tall tower in Alexandria.

To imagine something greater than ourselves is always going to be difficult, and to truly understand such a greater reality is perhaps canonically impossible. So we aught not let such smallness of our minds debar us from truth. It is thus a struggle to keep an open-mind about metaphysics, but I think it is morally correct to do so and to resist the weak temptation to give in to philosophical negativism and minimalism about the worlds that potentially exist beyond ours.

Strangely, many self-professing atheists think they can imagine we live in a super Multiverse. I would ask them how they can believe in such a prolific cosmos and yet not also accept the potential existences beyond the physical? And not even “actual existence” just simply “potential existence”. I would then point out that as long as there is admitted potential reality and plausible truth to things beyond the physical, you cannot honestly commit to any brand of atheism. To my mind, even my most open-mind, this form of atheism would seem terribly dishonest and self-deceiving.

Exactly how physics and mathematics could inform my spiritual beliefs is hard to explain in a few words. Maybe sometime later there is an essay to be written on this topic. For now, all I will say is that like Nima Arkani-Hamed, I have a deep sense of the “correctness” of certain ways of thinking about physics, and sometimes mathematics too (although mathematics is less constrained). And similar senses of aesthetics draw me in like the unveiling of a Beethoven symphony to an almost inevitable realisation of some version of truth to the reality of worlds beyond the physical, worlds where infinite numbers reside, where the mind can explore unrestrained by bones and flesh and need for food or water.  In such worlds greater beauty than on Earth resides.


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

Advertisements

Eternal Rediscovery

I have a post prepared to upload in a bit that will announce a possible hiatus from this WordPress blog. The reason is just that I found a cool book I want to try to absorb, The Princeton Companion to Mathematics by Gowers, Barrow-Green and Leader. Doubtless I will not be able to absorb it all in one go, so I will likely return to blogging periodically. But there is also teaching and research to conduct, so this book will slow me down. The rest of this post is a light weight brain-dump of some things that have been floating around in my head.

Recently, while watching a lecture on topology I was reminded that a huge percentage of the writings of Archimedes were lost in the siege of Alexandria. The Archimedean solids were rediscovered by Johannes Kepler, and we all know what he was capable of! Inspiring Isaac Newton is not a bad epitaph to have for one’s life.

The general point about rediscovery is a beautiful thing. Mathematics, more than other sciences, has this quality whereby a young student can take time to investigate previously established mathematics but then take breaks from it to rediscover theorems for themselves. How many children have rediscovered Pythagoras’ theorem, or the Golden Ratio, or Euler’s Formula, or any number of other simple theorems in mathematics?

Most textbooks rely on this quality. It is also why most “Exercises” in science books are largely theoretical. Even in biology and sociology. They are basically all mathematical, because you cannot expect a child to go out and purchase a laboratory set-up to rediscover experimental results. So much textbook teaching is mathematical for this reason.

I am going to digress momentarily, but will get back to the education theme later in this article.

The entire cosmos itself has sometimes been likened to an eternal rediscovery. The theory of Eternal Inflation postulates that our universe is just one bubble in a near endless ocean of baby and grandparent and all manner of other universes. Although, recently, Alexander Vilenkin and Audrey Mithani found that a wide class of inflationary cosmological models are unstable, meaning that could not have arisen from a pre-existing seed. There had to be a concept of an initial seed. This kind of destroys the “eternal” in eternal inflation. Here’s a Discover magazine account: What Came Before the Big Bang? — Cosmologist Alexander Vilenkin believes the Big Bang wasn’t a one-off event”. Or you can click this link to hear Vilenkin explain his ideas himself: FQXi: Did the Universe Have a Beginning? Vilenkin seems to be having a rather golden period of originality over the past decade or so, I regularly come across his work.

If you like the idea of inflationary cosmology you do not have to worry too much though. You still get the result that infinitely many worlds could bubble out of an initial inflationary seed.

Below is my cartoon rendition of eternal inflation in the realm of human thought:
cosmol_primordial_thoughtcloud_field

Oh to be a bubble thoughtoverse of the Wittenesque variety.

Quantum Fluctuations — Nothing Cannot Fluctuate

One thing I really get a bee in my bonnet about are the endless recountings in the popular literature about the beginning of the universe is the naïve idea that no one needs to explain the origin of the Big Bang and inflatons because “vacuum quantum fluctuations can produce a universe out of nothing”. This sort of pseudo-scientific argument is so annoying. It is a cancerous argument that plagues modern cosmology. And even a smart person like Vilenkin suffers from this disease. Here I quote him from a quote in another article on the PBS NOVA website::

Vilenkin has no problem with the universe having a beginning. “I think it’s possible for the universe to spontaneously appear from nothing in a natural way,” he said. The key there lies again in quantum physics—even nothingness fluctuates, a fact seen with so-called virtual particles that scientists have seen pop in and out of existence, and the birth of the universe may have occurred in a similar manner.
Source: http://www.pbs.org/wgbh/nova/blogs/physics/2012/06/in-the-beginning/

At least you have to credit Vilenkin with the brains to have said it is only “possible”. But even that caveat is fairly weaselly. My contention is that out of nothing you cannot get anything, not even a quantum fluctuation. People seem to forget quantum field theory is a background-dependent theory, it requires a pre-existing spacetime. There is no “natural way” to get a quantum fluctuation out of nothing. I just wish people would stop insisting on this sort of non-explanation for the Big Bang. If you start with not even spacetime then you really cannot get anything, especially not something as loaded with stuff as an inflaton field. So one day in the future I hope we will live in a universe where such stupid arguments are nonexistent nothingness, or maybe only vacuum fluctuations inside the mouths of idiots.

There are other types of fundamental theories, background-free theories, where spacetime is an emergent phenomenon. And proponents of those theories can get kind of proud about having a model inside their theories for a type of eternal inflation. Since their spacetimes are not necessarily pre-existing, they can say they can get quantum fluctuations in the pre-spacetime stuff, which can seed a Big Bang. That would fit with Vilenkin’s ideas, but without the silly illogical need to postulate a fluctuation out of nothingness. But this sort of pseudo-science is even more insidious. Just because they do not start with a presumption of a spacetime does not mean they can posit quantum fluctuations in the structure they start with. I mean they can posit this, but it is still not an explanation for the origins of the universe. They still are using some kind of structure to get things started.

Probably still worse are folks who go around flippantly saying that the laws of physics (the correct ones, when or if we discover them) “will be so compelling they will assert their own existence”. This is basically an argument saying, “This thing here is so beautiful it would be a crime if it did not exist, in fact it must exist since it is so beautiful, if no one had created it then it would have created itself.” There really is nothing different about those two statements. It is so unscientific it makes me sick when I hear such statements touted as scientific philosophy. These ideas go beyond thought mutation and into a realm of lunacy.

I think the cause of these thought cancers is the immature fight in society between science and religion. These are tensions in society that need not exist, yet we all understand why they exist. Because people are idiots. People are idiots where their own beliefs are concerned, by in large, even myself. But you can train yourself to be less of an idiot by studying both sciences and religions and appreciating what each mode of human thought can bring to the benefit of society. These are not competing belief systems. They are compatible. But so many believers in religion are falsely following corrupted teachings, they veer into the domain of science blindly, thinking their beliefs are the trump cards. That is such a wrong and foolish view, because everyone with a fair and balanced mind knows the essence of spirituality is a subjective view-point about the world, one deals with one’s inner consciousness. And so there is no room in such a belief system for imposing one’s own beliefs onto others, and especially not imposing them on an entire domain of objective investigation like science. And, on the other hand, many scientists are irrationally anti-religious and go out of their way to try and show a “God” idea is not needed in philosophy. But in doing so they are also stepping outside their domain of expertise. If there is some kind of omnipotent creator of all things, It certainly could not be comprehended by finite minds. It is also probably not going to be amenable to empirical measurement and analysis. I do not know why so many scientists are so virulently anti-religious. Sure, I can understand why they oppose current religious institutions, we all should, they are mostly thoroughly corrupt. But the pure abstract idea of religion and ethics and spirituality is totally 100% compatible with a scientific worldview. Anyone who thinks otherwise is wrong! (Joke!)

Also, I do not favour inflationary theory for other reasons. There is no good theoretical justification for the inflaton field other than the theory of inflation prediction of the homogeneity and isotropy of the CMB. You’d like a good theory to have more than one trick! You know. Like how gravity explains both the orbits of planets and the way an apple falls to the Earth from a tree. With inflatons you have this quantum field that is theorised to exist for one and only one reason, to explain homogeneity and isotropy in the Big Bang. And don’t forget, the theory of inflation does not explain the reason the Big Bang happened, it does not explain its own existence. If the inflaton had observable consequences in other areas of physics I would be a lot more predisposed to taking it seriously. And to be fair, maybe the inflaton will show up in future experiments. Most fundamental particles and theoretical constructs began life as a one-trick sort of necessity. Most develop to be a touch more universal and will eventually arise in many aspects of physics. So I hope, for the sake of the fans of cosmic inflation, that the inflaton field does have other testable consequences in physics.

In case you think that is an unreasonable criticism, there are precedents for fundamental theories having a kind of mathematically built-in explanation. String theorists, for instance, often appeal to the internal consistency of string theory as a rationale for its claim as a fundamental theory of physics. I do not know if this really flies with mathematicians, but the string physicists seem convinced. In any case, to my knowledge the inflation does not have this sort of quality, it is not a necessary ingredient for explaining observed phenomena in our universe. It does have a massive head start on being a candidate sole explanation for the isotropy and homogeneity of the CMB, but so far that race has not yet been completely run. (Or if it has then I am writing out of ignorance, but … you know … you can forgive me for that.)

Anyway, back to mathematics and education.

You have to love the eternal rediscovery built-in to mathematics. It is what makes mathematics eternally interesting to each generation of students. But as a teacher you have to train the nerdy children to not bother reading everything. Apart from the fact there is too much to read, they should be given the opportunity to read a little then investigate a lot, and try to deduce old results for themselves as if they were fresh seeds and buds on a plant. Giving students a chance to catch old water as if it were fresh dewdrops of rain is a beautiful thing. The mind that sees a problem afresh is blessed, even if the problem has been solved centuries ago. The new mind encountering the ancient problem is potentially rediscovering grains of truth in the cosmos, and is connecting spiritually to past and future intellectual civilisations. And for students of science, the theoretical studies offer exactly the same eternal rediscovery opportunities. Do not deny them a chance to rediscover theory in your science classes. Do not teach them theory. Teach them some theoretical underpinnings, but then let them explore before giving the game away.
With so much emphasis these days on educational accountability and standardised tests there is a danger of not giving children these opportunities to learn and discover things for themselves. I recently heard an Intelligence2 “Intelligence Squared” debate on academic testing. One crazy women from the UK government was arguing that testing, testing, and more testing — “relentless testing” were her words — was vital and necessary and provably increased student achievement.

Yes, practising tests will improve test scores, but it is not the only way to improve test scores. And relentless testing will improve student gains in all manner of mindless jobs out there is society that are drill-like and amount to going through routine work, like tests. But there is less evidence that relentless testing improves imagination and creativity.

Let’s face it though. Some jobs and areas of life require mindlessly repetitive tasks. Even computer programming has modes where for hours the normally creative programmer will be doing repetitive but possibly intellectually demanding chores. So we should not agitate and jump up and down wildly proclaiming tests and exams are evil. (I have done that in the past.)

Yet I am far more inclined towards the educational philosophy of the likes of Sir Ken Robinson, Neil Postman, and Alfie Kohn.

My current attitude towards tests and exams is the following:

  1. Tests are incredibly useful for me with large class sizes (120+ students), because I get a good overview of how effective the course is for most students, as well as a good look at the tails. Here I am using the fact test scores (for well designed tests) do correlate well with student academic aptitudes.
  2. My use of tests is mostly formative, not summative. Tests give me a valuable way of improving the course resources and learning styles.
  3. Tests and exams suck as tools for assessing students because they do not assess everything there is to know about a student’s learning. Tests and exams correlate well with academic aptitudes, but not well with other soft skills.
  4. Grading in general is a bad practise. Students know when they have done well or not. They do not need to be told. At schools if parents want to know they should learn to ask their children how school is going, and students should be trained to be honest, since life tends to work out better that way.
  5. Relentless testing is deleterious to the less academically gifted students. There is a long tail in academic aptitude, and the students in this tail will often benefit from a kinder and more caring mode of learning. You do not have to be soft and woolly about this, it is a hard core educational psychology result: if you want the best for all students you need to treat them all as individuals. For some tests are great, terrific! For others tests and exams are positively harmful. You want to try and figure out who is who, at least if you are lucky to have small class sizes.
  6. For large class sizes, like at a university, do still treat all students individually. You can easily do this by offering a buffet of learning resources and modes. Do not, whatever you do, provide a single-mode style of lecture+homework+exam course. That is ancient technology, medieval. You have the Internet, use it! Gather vast numbers of resources of all different manners of approach to your subject you are teaching, then do not teach it! Let your students find their own way through all the material. This will slow down a lot of students — the ones who have been indoctrinated and trained to do only what they are told — but if you persist and insist they navigate your course themselves then they should learn deeper as a result.

Solving the “do what I am told” problem is in fact the very first job of an educator in my opinion. (For a long time I suffered from lack of a good teacher in this regard myself. I wanted to please, so I did what I was told, it seemed simple enough. But … Oh crap, … the day I found out this was holding me back, I was furious. I was about 18 at the time. Still hopelessly naïve and ill-informed about real learning.) If you achieve nothing else with a student, transitioning them from being an unquestioning sponge (or oily duck — take your pick) to being self-motivated and self-directed in their learning is the most valuable lesson you can ever give them. So give them it.

So I use a lot of tests. But not for grading. For grading I rely more on student journal portfolios. All the weekly homework sets are quizzes though, so you could criticise the fact I still use these for grading. As a percentage though, the Journals are more heavily weighted (usually 40% of the course grade). There are some downsides to all this.

  • It is fairly well established in research that grading using journals or subjective criteria is prone to bias. So unless you anonymise student work, you have a bias you need to deal with somehow before handing out final grades.
  • Grading weekly journals, even anonymously, takes a lot of time, about 15 to 20 times the hours that grading summative exams takes. So that’s a huge time commitment. So you have to use it wisely by giving very good quality early feedback to students on their journals.
  • I still haven’t found out how to test the methods easily. I would like to know quantitatively how much more effective journal portfolios are compared to exam based assessments. I am not a specialist education researcher, and I research and write a about a lot of other things, so this is taking me time to get around to answering.

I have not solved the grading problem, for now it is required by the university, so legally I have to assign grades. One subversive thing I am following up on is to refuse to submit singular grades. As a person with a physicists world-view I believe strongly in the role of sound measurement practice, and we all know a single letter grade is not a fair reflection on a student’s attainment. At a minimum a spread of grades should be given to each student, or better, a three-point summary, LQ, Median, UQ. Numerical scaled grades can then be converted into a fairer letter grade range. And GPA scores can also be given as a central measure and a spread measure.

I can imagine many students will have a large to moderate assessment spread, and so it is important to give them this measure, one in a few hundred students might statistically get very low grades by pure chance, when their potential is a lot higher. I am currently looking into research on this.

OK, so in summary: even though institutions require a lot of tests you can go around the tests and still given students a fair grade while not sacrificing the true learning opportunities that come from the principle of eternal rediscovery. Eternal rediscovery is such an important idea that I want to write an academic paper about it and present at a few conferences to get people thinking about the idea. No one will disagree with it. Some may want to refine and adjust the ideas. Some may want concrete realizations and examples. The real question is, will they go away and truly inculcate it into their teaching practices?

CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

*      *       *

Coupling to the Universe — or “You Are You Because You Are You”

Carlo Rovelli can sure talk up a blizzard (I’m reviewing his conference talk: (The preferred time direction in the dynamics of the full universe). For an Italian native he can really weave a blinding spell in English.

He has my confused when he tries to explain the apparent low entropy Big Bang cosmology. He uses his own brand of relational quantum mechanics I think, but it comes out sounding a bit circular or anthropomorphic. Yet earlier in his lectures he often takes pains to deny anthropomorphic views.

So it is quite perplexing when he tries to explain our perception of an arrow of time by claiming that, “it is what makes us us.” Let me quote him, so you can see for yourself. He starts out by claiming the universe starts in a low entropy state only form our relative point of view. Entropy is an observer dependent concept. It depends on how you coarse grain your physics. OK, I buy that. We couple to the physical external fields in a particular way, and this is what determines how we perceive or coarse grain our slices of the universe. So how we couple to the universe supposedly explains way wee see the apparent entropy we perceive. If by some miracle we coupled more like antiparticles effectively travelling in the reverse time direction then we’d see entropy quite differently, one imagines. So anyway, Rovelli then summarizes:

[On slides: Entropy increase (passage of time) depend on the coarse graining, hence the subsystem, not the microstate of the world.] … “Those depend on the way we couple to the rest of the universe. Why do we couple to the rest of the universe in this way? Because if we didn’t couple to the rest of the universe this way we wouldn’t be us. Us as things, as biological entities that very much live in time coupled in a manner such that the past moves towards the future in a precise sense … which sense? … the one described by the Second Law of Thermodynamics.”

You see what I mean?

Maybe I am unfairly pulling this out of a rushed conference presentation, and to be more balanced and fair I should read his paper instead. If I have time I will. But I think a good idea deserves a clear presentation, not a rush job with a lot of vague wishy-washy babble, or obscuring in a blizzard of words and jargon.

OK, so here’s an abstract from an arxiv paper where Rovelli states things in written English:

” Phenomenological arrows of time can be traced to a past low-entropy state. Does this imply the universe was in an improbable state in the past? I suggest a different possibility: past low-entropy depends on the coarse-graining implicit in our definition of entropy. This, in turn depends on our physical coupling to the rest of the world. I conjecture that any generic motion of a sufficiently rich system satisfies the second law of thermodynamics, in either direction of time, for some choice of macroscopic observables. The low entropy of the past could then be due to the way we couple to the universe (a way needed for us doing what we do), hence to our natural macroscopic variables, rather than to a strange past microstate of the world at large.”

That’s a little more precise, but still no clearer on import. He is still really just giving an anthropocentric argument.

I’ve always thought science was at it’s best when removing the human from the picture. The problem for our universe should not be framed as one of “why do we see an arrow of time?” because, as Rovelli points out, for complex biological systems like ourselves there really is no other alternative. If we did not perceive an arrow of time we would be defined out of existence!

The problem for our universe should be simply, “why did our universe begin (from any arbitrary sentient observer’s point of view) with such low entropy?”

But even that version has the whiff of observer about it. Also, you just define the “beginning” as the end that has the low entropy, then you are done, no debate. So I think there is a more crystalline version of what cosmology should be seeking an explanation for, which is simply, “how can any universe ever get started (from either end of a singularity) in a low entropy state?”

But even there you have a notion of time, which we should remove, since “start” is not a proper concept unless one already is talking about a universe. So the barest question of all perhaps, (at least the barest that I can summon) is, “how do physics universes come to exist?”

This does not even explicitly mention thermodynamics or an arrow of time. But within the question those concepts are embedded. One needs to carefully define “physics” and “physics universes”. But once that is done then you have a slightly better philosophy of physics project.

More hard core physicists however will never stoop to tackle such a question. They will tend to drift towards something where a universe is already posited to exist and has had a Big Bang, and then they will fret and worry about how it could have a low entropy singularity.

It is then tempting to take the cosmic Darwinist route. But although I love the idea, it is another one of those insidious memes that is so alluring but in the cold dead hours of night, when the vampires of popular physics come to devour your life blood seeking converts, seems totally unsatisfying and anaemic. The Many Worlds Interpretation has it’s fangs sunk into a similar vein, which I’ve written about before.

cosmo_OnceUponATimeInRovellisUniverse

*      *       *

Going back to Rovelli’s project, I have this problem for him to ponder. What if there is no way for any life, not even in principle, to couple to the universe other than via the way we humans do, through interaction with strings (or whatever they are) via Hamiltonians and mass-energy? If this is true, and I suspect it is, then is not Rovelli’s “solution” to the low entropy Big Bang a bit meaningless?

I have a pithy way of summarising my critique of Rovelli. I would just point out:

The low entropy past is not caused by us. We are the consequence.

So I think it is a little weak for Rovelli to conjecture that the low entropy past is “due to the way we couple to the universe.” It’s like saying, “I conjecture that before death one has to be born.” Well, … duuuuhhh!

The reason my photo is no longer on Facebook is due to the way I coupled to my camera.

I am an X-gener due to the way my parents coupled to the universe.

You see what I’m getting at? I might be over-reaching into excessive sarcasm, but my point is just that none of this is good science. They are not explanations. It is just story-telling. Still, Rovelli does give an entertaining story if you are a physics geek.

So I had a read of Rovelli’s paper and saw the more precise statement of his conjecture:

Rovelli’s Conjecture: “Any generic microscopic motion of a sufficiently rich system satisfies the second law (in either time direction) for a suitable choice of macroscopic observables.

That’s the sort of conjecture that says nothing. The problem is the “sufficiently rich” clause together with the “suitable choice” clause. You can generate screeds of conjectures with such a pair of clauses. The conjecture only has “teeth” if you define what you mean by “sufficiently rich” and if a “suitable choice” can be identified or motivated as plausible. Because otherwise you are not saying anything useful. For example, “Any sufficiently large molecule will be heavier than a suitably chosen bowling ball.”

*      *       *

Rovelli does provide a toy example to illustrate his notions in classical mechanics. He has yellow balls and red balls. The yellow balls have an attractor which gives them a natural second law of thermodynamic arrow of time. The same box also has red balls with a different attractor which gives them the opposite arrow of time according to the second law. (Watching the conference video for this is better than reading the arxiv paper.) But “so what?”

Rovelli has constructed a toy universe that has entities that would experience opposite time directions if they were conscious. But there are so many things wrong with this example it cannot be seriously considered as a bulwark for Rovelli’s grander project. For starters, what is the nature of his Red and Yellow attractors? If they are going to act complicated enough to imbue the toy universe with anything resembling conscious life then the question of how the arrow of time arises is not answered, it just gets pushed back to the properties of these mysterious Yellow and Red attractors.

And if you have only such a toy universe without any noticeable observers then what is the point of discussing an arrow of time? It is only a concept that a mind external to that world can contemplate. So I do not see the relevance of Rovelli’s toy model for our much more complicated universe which has internal minds that perceive time.

You could say, in principle the toy model tells us there could be conscious observers in our universe who are experiencing life but in the reverse time direction to ourselves, they remember our future but not our past, we remember their future but not their past. Such dual time life forms would find it incredibly hard to communicate, due to this opposite wiring of memory.

But I would argue that Rovelli’s model does not motivate such a possibility, for the same reason as before. Constructing explicit models of different categories of billiard balls each obeying a second law of thermodynamics in opposite time directions in the same system is one thing, but not much can be inferred from this unless you add in a whole lot of further assumptions about what Life is, metabolism, self-replication, and all that. But if you do this the toy model becomes a lot less toy-like and in fact terribly hard to explicitly construct. Maybe Stephen Wolfram’s cellular automata can do the trick? But I doubt it.

I should stop harping on this. Let me just record my profound dissatisfaction with Rovelli’s attempt to demystify the arrow of time.

*      *       *

If you ask me, we are not at a sufficiently mature enough juncture in the history of cosmology and physics to be able to provide a suitable explanation for the arrow of time.

So I have Smith’s Conjecture:

At any sufficiently advanced enough juncture in the history of science, enough knowledge will have accumulated to enable physicists to provide a suitable explanation for the arrow of time.

Facetiousness aside, I really do think that trying to explain the low entropy big bang is a bit premature. It would be much better to be patient and wait for more information about our universe before attempting to launch into the arrow of time project. The reason I believe so is because I think the ultimate answers about such cosmological questions are external to our observable universe.

But even whether they are external or internal there is a wider problem to do with the nature of time and our universe. We do not know if our universe actually had a beginning, a true genesis, or whether it has always existed.

If the universe had a beginning then the arrow of time problem is the usually low entropy puzzle problem. But if the universe had no beginning then the arrow of time problem becomes a totally different question. There is even a kind of intermediate problem that occurs if our universe had a start but within some sort of wider meta-cosmos. Then the problem is much harder, that of figuring out the laws of this putative metaverse. Imagine the hair-pulling of cosmologists who discover this latter possibility as a fact about their universe (but I would envy them the shear ability to discover the fact, it’d be amazing).

So until we know such a fundamental question I do not see a lot of fruitfulness in pursuing the arrow of time puzzle. It’s a counting your chickens before they hatch situation. Or should I say, counting your microstates before they batch.

*      *       *


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

A Plain Simple Lecture — Non-ergodic , but … satisfying

There is another talk from the Philosophy of Cosmology Conference in Tenerife 2014 that is in a similar league to Joel Primack’s awesome display of the Bolshoi Simulations of dark matter structure. Only this one I will write about tonight is pretty much words and equations only. No pretty pictures. But don’t let that dissuade you from enjoying the talk by Bob Wald on Gravity and Thermodynamics.

Most physics students might only know Robert Wald from his famous textbook on General Relativity.

Aside: While searching for a nice picture to illuminate this post I came across a nice freehand SVG sketch of Shaun Maguire’s. He’s a postdoc at Caltech and writes nicely in a blog there: Quantum Frontiers. If you are more a physics/math geek than a philosophy/physics geek then you will enjoy his blog. I found it very readable, not stunning poetic prose, but easy-going and sufficiently high on technical content to hold my interest.

blackhole_thermodynamics_RindlerQuest2

Says Maguire, “I’ve been trying to understand why the picture on the left is correct, even though my intuition said the middle picture should be (intuition should never be trusted when thinking about quantum gravity.)” Source: http://quantumfrontiers.com/2014/06/20/ten-reasons-why-black-holes-exist/

That has to do with black hole firewalls, which digresses away from Wald’s talk.

It is not true to say Wald’s talk is plain and simple, since the topic is advanced, only a second course on general relativity would cover the details. And you need to get through a lot of mathematical physics in a first course of general relativity. But what I mean is that Wald is such a knowledgeable and clear thinker that he explains everything crisply and understandably, like a classic old-school teacher would. It is not flashy, but damn! It is tremendously satisfying and enjoyable to listen to. I could hit the pause button and read his slides then rewind and listen to his explanation and it just goes together so sweetly. He neither repeats his slides verbatim, not deviates from them confusingly. However, I think if I were in the audience I would be begging for a few pauses of silence to read the slides. So the advantage is definitely with the at-home Internet viewer.

Now if you are still reading this post you should be ashamed! Why did you not go and download the talk and watch it?

I loved Wald’s lucid discussion of the Generalised Second Law (which is basically a redefinition of entropy, which is that generalised entropy should be the sum of thermodyanmics entropy plus black hole entropy or black hole surface area.)

Then he gives a few clear arguments that provide strong reasons for regarding the black hole area formula as equivalent to an entropy, one of which is that in general relativity dynamic instability is equivalent to thermodynamic instability, hence the link between the dynamic process of black hole area increase is directly connected to black hole entropy. (This is in classical general relativity.)

But then he puts the case that the origin of black hole entropy is not perfectly clear, because black hole entropy does not arise out of the usual ergodicity in statistical mechanics systems, whereby a system in an initial special state relaxes via statistical processes towards thermal equilibrium. Black holes are non-ergodic. They are fairly simple beasts that evolve deterministically. “The entropy for a black hole arises because it has a future horizon but no past horizon,” is how Wald explains it. In other words, black holes do not really “equilibrate” like classical statistical mechanics gases. Or at least, they do not equilibrate to a thermal temperature ergodically like a gas, they equilibrate dynamically and deterministically.

Wald’s take on this is that, maybe, in a quantum gravity theory, the detailed microscopic features of gravity (foamy spacetime?) will imply some kind of ergodic process underlying the dynamical evolution of black holes, which will then heal the analogy with statistical mechanics gas entropy.

This is a bit mysterious to me. I get the idea, but I do not see why it is a problem. Entropy arises in statistical mechanics, but you do not need statistically ergodic processes to define entropy. So I did not see why Wald is worried about the different equilibration processes viz. black holes versus classical gases. They are just different ways of defining an entropy and a Second Law, and it seems quite natural to me that they therefore might arise from qualitatively different processes.

But hold onto you hats. Wald next throws me a real curve ball.

Smaller then the Planck Scale … What?

Wald’s next concern about a breakdown of the analogy between statistical gas entropy and dynamic black hole entropy is a doozie. He worries about the fact the vacuum fluctuations in a conventional quantum field theory are basically ignored in statistical mechanics, yet they cannot (or should not?) be ignored in general relativity, since, for instance, the ultra-ultra-high energy vacuum fluctuations in the early universe get red-shifted by the expansion of the universe into observable features we can now measure.

Wald is talking here about fluctuations on a scale smaller than the Planck length!

To someone with my limited education you begin by thinking, “Oh, that’s ok, we all know (one says knowingly not really knowing) that stuff beyond the Plank scale is not very clearly defined and has this sort of ‘all bets are off’ quality about it. So we do not need to worry about it yet until there is a theory covering the Planck scale.”

But if I understand it correctly, what Wald is saying is that what we see in the cosmic background radiation, or maybe in some other observations (Wald is not clear on this), corresponds to such red shifted modes, so we literally might be seeing fluctuations that were originated on a scale smaller than the Planck length if we probe the cosmic background radiation to highly ultra-red shifted wavelengths.

That was a bit of an eye-opener for me. I was previously not aware of any physics that potentially probed beyond the Planck scale. I wonder if anyone else thought this is surprising? Maybe if I updated my physics education I’d find out that it is not so surprising.

In any case, Wald does not discuss this, since his point is about the black hole case where at the black hole horizon a similar shifting of modes occurs with ultra-high energy vacuum fluctuations near the horizon getting red shifted far from the black hole into “real” observable degrees of freedom.

Wald talks about this as a kind of “creation of new degrees of freedom”. And of course this does not occur in statistical gas mechanics where there are a fixed number of degrees of freedom, so again the analogy he wants between black hole thermodynamics and classical statistical mechanics seems to break down.

There is some cool questioning going on here though. The main problem with the vacuum fluctuations Wald points out is that one does not know how to count the states in the vacuum. So the implicit idea there, which Wald does not mention, is that maybe there is a way to count states of the vacuum, which might then heal the thermodynamics analogy Wald is pursuing. My own (highly philosophical, and therefore probably madly wrong) speculation would be that quantum field theory is only an effective theory, and that a more fundamental theory of physics with spacetime as the only real field and particle physics states counted in a background-free theory kind of way, might, might yield some way of calculating vacuum states.

Certainly, I would imagine that if field theory is not the ultimate theory, then the whole idea of vacuum field fluctuations gets called into suspicion. The whole notion of a zero-point background field vacuum energy becomes pretty dubious altogether if you no longer have a field theory as the fundamental framework for physics. But of course I am just barking into the wind hoping to see a beautiful background-free framework for physics.

Like the previous conundrum of ergodicity and equilibration, I do not see why this degree of freedom issue is a big problem. It is a qualitative difference which breaks the strong analogy, but so what? Why is that a pressing problem? Black holes are black holes, gases are gases, they ought to be qualitatively distinct in their respective thermodynamics. The fact there is the strong analogy revealed by Bekenstein, Hawking, Carter, and others is beautiful and does reveal general universality properties, but I do not see it as an area of physics where a complete unification is either necessary or desired.

What I do think would be awesome, and super-interesting, would be to understand the universality better. This would be to ask further (firstly) why there is a strong analogy, and (secondly) explain why and how it breaks down.

*      *       *

This post was interrupted by an apartment moving operation, so I ran out of steam on my consciousness stream, so will wrap it up here.

*      *       *


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

Primacks’ Premium Simulations

After spending a week debating with myself about various Many Worlds philosophy issues  and other quantum cosmology questions, today I saw Joel Primack’s presentation at the Philosophy of Cosmology International Conference, on the topic of Cosmological Structure Formation. And so for a change I was speechless.

Thus I doubt I can write much that illumines Primack’s talk better than if I tell you just to go and watch it.

He, and colleagues, have run supercomputer simulations of gravitating dark matter in our universe. From their public website Bolshoi Cosmological Simulations they note: “The simulations took 6 million cpu hours to run on the Pleiades supercomputer — recently ranked as seventh fastest of the world’s top 500 supercomputers — at NASA Ames Research Center.”

To get straight to all the videos from the Bolshoi simulation go here (hipacc.ucsc.edu/Bolshoi/Movies.html).

cosmos_BolshoiSim_MD_cluster01_gas_sn320

MD4 Gas density distribution of the most massive galaxy cluster (cluster 001) in a high resolution resimulation, x-y-projection. (Kristin Riebe, from the Bolshoi Cosmological Simulations.)

The filamentous structure formation is awesome to behold. At times they look like living cellular structures in the movies that Primack has produced. Only the time steps in his simulations are probably about 1 million year steps. for example, on simulation is called the Bolshio-Planck Cosmological Simulation — Merger Tree of a Large Halo. If I am reading this page correctly these simulations visualize 10 billion Sun sized halos.  The unit they say they resolve is “1010 Msun halos”. Astronomers will often use a symbol M to represent a unit of one solar mass (equal to our Sun’s mass). But I have never seen that unit “M halo” used before, so I’m just guessing it means the finest structure resolvable in their movie still images would be maybe a Sun-sized object, or a solar system sized bunch of stuff. This is dark matter they are visualizing, so the stars and planets we can see just get completely obscured in these simulations (since the star-like matter is less than a few percent of the mass).

True to my word, that’s all I will write for now about this piece of beauty. I need to get my speech back.

*      *       *

Oh, but I do just want to hasten to say the image above I pasted in there is NOTHING compared to the movies of the simulations. You gotta watch the Bolshoi Cosmology movies to see the beauty!

*       *       *


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

“I’d Like Some Decoherence Sauce with that Please”

OK, last post I was a bit hasty saying Simon Saunders undermined Max Tegmark. Saunders eventually finds his way to recover a theory of probability from his favoured Many Worlds Interpretation. But I do think he over-analyses the theory of probability. Maybe he is under-analysing it too in some ways.

What the head-scratchers seem to want is a Unified Theory of Probability. Something that gives what we intuitively know is a probability but cannot mathematically formalise in a way that deals with all reality. Well, I think this is a bit of a chimera. Sure, I’d like a unified theory too. But sometimes you have to admit reality, even abstract mathematical Platonic reality, does not always present us with a unified framework for everything we can intuit.

What’s more, I think probability theorists have come pretty close to a unified framework for probability. It might seem patchwork, it might merge frequentist ideas with Bayesian ideas, but if you require consistency across domains then apply the patchwork so that on overlaps you have agreement, then I suspect (I cannot be sure) that probability theory as experts understand it today, if fairly comprehensive. Arguing that frequentism should always work is a bit like arguing that Archimedean calculus should always work. Pointing out deficiencies in Bayesian probability does not mean there is no overarching framework for probability, since where Bayesianism does not work probably frequentism, or some other combinatorics, will.

Suppose you even have to deal with a space of transfinite cardinality and there is ignorance about where you are, then I think in the future someone will come up with measures on infinite spaces of various cardinality. They might end up with something that is a bit trivial (all probabilities become 0 or 1 for transfinite measures, perhaps?), but I think someone will do it. All I’m saying is that it is way too early in the history of mathematics to say we need to throw up our hands and appeal to physics and Many Worlds.

*      *       *

That was along intro. I really meant to kick off this post with a few remarks about Max Tegmark’s second lecture at the Oxford conference series on Cosmology and Quantum Foundations. He claims to be a physicist, but puts on a philosophers hat when he claims, “I am only my atoms”. Meaning he believes consciousness arises or emerges merely from some “super-complex processes” in brains.

I like Max Tegmark, he seems like a genuinely nice guy, and is super smart. But here he is plain stupid. (I’m hyperbolising naturally, but I still think it’s dopey what he believes.)

It is one thing to say your totality is your atoms, but quite another to take consciousness as a phenomenon seriously and claim it is just physics. Especially, I think, if your interpretation of quantum reality is the MWI. Why is that? Because MWI has no subjectivity. But, if you are honest, or if you have thought seriously about consciousness at all, and what the human mind is capable of, then without being arrogant or anthropocentric, you have to admit that whatever consciousness is, (and I do not know what it is just let me say, but whatever it is) it is an intrinsically subjective phenomenon.

You can find philosophers who deny this, but most of them are just denying the subjectiveness of consciousness in order to support their pet theory of consciousness (which is often grounded in physics). So those folks have very little credibility. I am not saying consciousness cannot be explained by physics. All I am saying is that if consciousness is explained by physics then our notion of physics needs to expand to include subjective phenomena. No known theories of physics have such ingredients.

It is not like you need a Secret Sauce to explain consciousness. But whatever it is that explains consciousness, it will have subjective sauce in it.

OK, I know I can come up with a MWI rebuff. In a MWI ontology all consistent realities exist due to Everettian branching. So I get behaviour that is arbitrarily complex in some universes. In those universes am I not bound to feel conscious? In other branches of the Everett multiverse I (not me actually, but my doppelgänger really, one who branched from a former “me”) do too many dumb things to be considered consciously sentient in the end, even though up to a point they seemed pretty intelligent.

The problem with this sort of “anything goes” so that in some universe consciousness will arise, is that it is naïve or ignorant. It commits the category error of assuming behaviour equates to inner subjective states. Well, that’s wrong. Maybe in some universes behaviour maps perfectly onto subjective states, and so there is no way to prove the independent reality of subjective phenomenon. But even that is no argument against the irreducibility of consciousness. Because any conscious agent who knows of (at least) their own subjective reality, they will know their universes branch is either not all explained by physics, or physics must admit some sort of subjective phenomenon into it’s ontology.

Future philosophers might describe it as merely a matter of taste, one of definitions. But for me, I like to keep my physics objective. Ergo, for me, consciousness (at least the sort I know I have, I cannot speak for you or Max Tegmark) is subjective, at least in some aspects. It sure manifests in objective physics thanks to my brain and senses, but there is something irreducibly subjective about my sort of consciousness. And that is something objectively real physics cannot fully explain.

What irks me most though, are folks like Tegmark who claim folks like me are arrogant in thinking we have some kind of secret sauce (by this presumably he means a “soul” or “spirit” that guides conscious thought).  I think quite the converse. It is arrogant to think you can get consciousness explained by conventional physics and objective processes in brains. Height of physicalist arrogance really.

For sure, there are people who take the view human beings are special in some way, and a lot of such sentiments arise from religiosity.

But people like me come to the view that consciousness is not special, but it is irreducibly subjective.  We come to this believing in science.   But we also come without prejudices.  So, in my humble view, if consciousness involves only physics you can say it must be some kind of special physics. That’s not human arrogance. Rather, it is an honest assessment of our personal knowledge about consciousness and more importantly about what consciousness allows us to do.

To be even more stark.  When folks like Tegmark wave their hands and claim consciousness is probably just some “super complex brain process”, then I think it is fair to say that they are the ones using implicit secret sauce.  Their secret sauce is of the garden variety atoms and molecules variety of course. You can say, “well, we are ignorant and so we cannot know how consciousness can be explained using just physics”.  And that’s true.  But (a) it does not avoid the problem of subjectivity, and (b) you can be just as ignorant about whether physics is all their is to reality. Over the years I have developed sense that it is far more arrogant to think physical reality is the only reality. I’ve tried to figure out how sentient subjective consciousness, and mathematical insight, and ideal Platonic forms in my mind can be explained by pure physics. I am still ignorant. But I do strongly postulate that there has to be some element of subjective reality involved in at least my form of consciousness. I say that in all sincerity and humility. And I claim it is a lot more humble than the position of philosophers who echo Tegmark’s view on human arrogance.

Thing is, you can argue no one understands consciousness, so no one can be certain what it is, but we can be fairly certain about what it isn’t. What it is not is a purely objectively specifiable process.

A philosophical materialist can then argue that consciousness is an illusion, it is a story the brain replays to itself. I’ve heard such ideas a lot, and they seem to be very popular at preset even though Daniel Dennett and others wrote about them more than 20 years ago. And the roots of the meme “consciousness is an illusion” is probably even centuries older than that, which you can confirm if you scour the literature.

The problem is you can then clearly discern a difference in definitions. The consciousness is an illusion folks use quite a different definition of consciousness compared to more onologically open-minded philosophers.

*      *       *

On to other topics …

*      *       *

Is Decoherence Faster than Light? (… yep, probably)

There is a great sequence in Max Tegmark’s talk where he explains why decoherence of superpositions and entanglement is just about, “the fastest process in nature!” He presents an illustration with a sugar cube dissolving in a cup of coffee. The characteristic times for relevant physical processes go as follows,

  1. Fluctuations — changes in correlations between clusters of molecules.
  2. Dissipation — time for about half the energy added by the sugar to be turned into heat. Scales by roughly the number of molecules in the sugar, so it takes on the order of N collisions on average.
  3. Dynamics — changes in energy.
  4. Information — changes in entropy.
  5. Decoherence — takes only one collision. So about 1025 times faster than dissipation.

(I’m just repeating this with no independent checks, but this seems about right.)

This also gives a nice characterisation of classical versus quantum regimes:

  1. Mostly Classical — when τdeco≪τdyn≤τdyn.
  2. Mostly Quantum — when τdyn≪τdeco, τdiss.

See if you can figure out why this is a good characterisation of regimes?

Here’s a screenshot of Tegmark’s characterisations:

quanta_decoherencetimes_vs_dissipationtime

The explanation is that in a quantum regime you have entanglement and superposition, uncertainty is high, dynamics evolves without any change in information, and hence also with essentially no dissipation. Classically you get a disturbance in the quantum and all coherence is lost almost instantaneously, and yeah, it goes faster than light because with decoherence nothing physical is “going” it is a not a process, rather decoherence refers to a state of possible knowledge, and that can change instantaneously without any signal transfer, at least according to some theories like MWI or Copenhagen.

I should say that in some models decoherence is a physically mediated process, and in such theories it would take a finite time, but it is still fast. Such environmental decoherence is a feature of gravitational collapse theories for example. Also, the ER=EPR mechanism of entanglement would have decoherence mediated by wormhole destruction, which is probably something that can appear to happen instantaneously from the point of view of certain observers. But the actual snapping of a wormhole bridge is not a faster than light process.

I also liked Tegmark’s remark that,

“We realise the reason that big things tend to look classical isn’t because they are big, it’s just because big things tend to be harder to isolate.”

*      *       *

And in case you got the wrong impression earlier, I really do like Tegmark. In his sugar cube in coffee example his faint Swedish accent gives way for a second to a Feynmanesque “cawffee”. It’s funny. Until you here it you don’t realise that very few physicists actually have a Feynman accent. It’s cool Tegmark has a little bit of it, and maybe not surprising as he often cites Feynman as one of his heroes (ah, yeah, what physicist wouldn’t? Well, actually I do know a couple who think Feynman was a terrible influence on physics teaching, believe it or not! They mean well, but are misguided of course! ☻).

*      *       *

The Mind’s Role Play

Next up: Tegmark’s take on explaining the low entropy of our early universe. This is good stuff.

Background: Penrose and Carroll have critiqued Inflationary Big Bang cosmology for not providing an account for why there is an arrow of time, i.e., why did the universe start in an extremely low entropy state.

(I have not seen Carroll’s talk, but I think it is on my playlist. So maybe I’ll write about it later.) But I am familiar with Penrose’s ideas. Penrose takes a fairly conservative position. He takes the Second Law of Thermodynamics seriously. He cannot see how even the Weyl Curvature Hypothesis explains the low entropy Big Bang. (I think WCH is just a description, not an explanation.)

Penrose does have a few ideas abut how to explain things with his Conformal Cyclic Cosmology ideas. I find them hugely appealing. But I will not discuss them here. Just go read his book.

What I want to write about here is Tegmark and his Subject-Object-Environment troika. In particular, why does he need to bring the mind and observation into the picture? I think he could give his talk and get across all the essentials without mentioning the mind.

But here is my problem. I just do not quite understand how Tegmark goes from the correct position on entropy, which is that is is a coarse graining concept, to his observer-measurement dependence. I must be missing something in his chain of reasoning.

So first: entropy is classically a measure of the multiplicity of a system, i.e., how many microstates in an ensemble are compatible with a given macroscopic state. And there is a suitable generalisation to quantum physics given by von Neumann.

If you fine grain enough then most possible states of the universe are unique and so entropy measured on such scales is extremely low. Basically, you only pick up contributions from degenerate states. Classically this entropy never really changes, because classically an observer is irrelevant. Now, substitute for “Observer” the more general “any process that results in decoherence”. Then you get a reason why quantum mechanically entropy can decrease. To whit: in a superposition there are many states compatible with prior history. When a measurement is made (for “measurement” read, “any process resulting in decoherence”) then entropy naturally will decrease on average (except for perhaps some unusual highly atypical cases).

Here’s what I am missing. All that I just said previously is local. Whereas, for the universe as a whole, globally, what is decoherence? It is not defined. and so what is global entropy then? There is no “observer” (read: “measurement process”) that collapses or decohere’s our whole universe. At least none we know of. So it all seems nonsense to talk about entropy on a cosmological scale.

To me, perhaps terribly naïvely, there is a meaning for entropy within a universe in localised sub-systems where observations can in principle be made on the system. “Counting states” to put it crudely. But for the universe (or Multiverse if you prefer) taken as a whole, what meaning is there to the concept of entropy? I would submit there is no meaning to entropy globally. The Second Law triumphs right? I mean, for a closed isolated system you cannot collapse states and get decoherence, at least not from without, so it just evolves unitarily with constant entropy as far as external observers can tell, or if you coarse grain into ensembles then the Second Law emerges, on average, even for unitary time evolution.

Perhaps what Tegmark was on about was that if you have external observer disruptions then entropy reduces (you get information about the state). But does this not globally just increase entropy since globally now the observer’s system is entangled with the previously closed and isolated system. But who ever bothers to compute this global entropy? My guess is it would obey the Second Law. I have no proof, just my guess.

Of course, with such thoughts in my head it was hard to focus on what Tegmark was really saying, but in the end his lecture seems fairly simple. Inflation introduces decoherence and hences lowers quantum mechanical entropy. So if you do not worry about classical entropy, just focus on the quantum states, then apparently inflationary cosmology can “explain” the low entropy Big Bang.

Only, if you ask me, this is no explanation. It is just “yet another” push-back. Because Inflationary cosmology is incomplete, it does not deal with the pre-inflationary universe. In other words, the pre-inflationary universe has to also have some entropy if you are going to be consistent with taking Tegmarks’ side. So however much inflation reduces entropy, you still have the initial pre-inflationary entropy to account for, which now becomes the new “ultimate source” of or arrow of time. Maybe it has helped to push the unexplained entropy a lot higher? But then you get into the realm of, “what is ‘low’ entropy in cosmological terms?” What does it mean to say the unexplained pre-inflationary entropy is high enough to not worry about? I dunno’. Maybe Tegmark is right? Maybe pre-inflation entropy (disorder) is so high by some sort of objectively observer independent measure (is that possible?) that you literally no longer have to fret about the origin of the arrow of time? Maybe inflation just wipes out all disorder and gives us a proverbial blank slate?

But then I do fret about it. Doesn’t Penrose come in at this point and give baby Tegmark a lesson in what inflation can and cannot do to entropy? Good gosh! It’s just about enough confusion to drive one towards the cosmological anthropic principle out of desperation for closure.

So despite Tegmark’s entertaining and informative lecture, I still don’t think anyone other than Penrose has ever given a no-push-back argument for the arrow of time. I guess I’ll have to watch Tegmark’s talk again, or read a paper on it for greater clarity and brevity.


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

Oil Pilots and Many World Probability

Continuing my ad hoc review of Cosmology and Quantum Foundations, I come to Max Tegmark and Simon Saunders, who were the two main champions of Many Worlds Interpretations present at this conference. But before discussing ideas arising from their talks, I want to mention an addendum to the Hidden Variables and de Broglie-Bohm pilot wave theory that I totally coincidentally came across the night after writing the previous post (“Gaddamit! Where’d You Put My Variables”).

Fluid Dynamics and Oil Droplets Model de Broglie-Bohm Pilot Waves

This is some seriously recent and immature research, but it is fascinating. And really simple to explain so it’s cool. Here’s the link: Fluid Tests Hint at Concrete Quantum Reality.

quanta_OilDropletPilotwaves

Oil droplets surfing ripples on a fluid surface exhibit two-slit interference. Actually not! They follow chaotic trajectories that reproduce interference patterns only statistically, but there is no superposition at all for the oil droplet, only for the wave ripples. Remarkably similar qualitatively to de Broglie-Bohm pilot wave theory.

You delicately place oil droplets on an immiscible fluid surface (water I suppose) and the droplets bounce around creating waves in the fluid surface. Then, lo and behold! Send an oil droplet through a double slit barrier and it goes through one slit right! Shocking! But then hold on to your skull … after traversing the slit the oil droplet then chaotically meanders around surfing on the wave ripples spreading out from the double slit that the oil droplet was actually responsible for generating before it got to the slits.

Do this for many oil droplets and you will see the famous statistical build-up of interference pattern at a distance radius, but here with classical oil droplets that can be observed to smithereens without destroying superposition of the fluid waves, so you get purely classical double slit interference. Just like the de Broglie-Bohm pilot wave theory predicts for the Bohmian mechanics view of quantum mechanics. I say, “jut like” because clearly this is macroscopic in scale and the mechanism of pilot waves is totally different to the quantum regime. Nonetheless, it is a clear condensed matter physics model for pilot wave Bohmian quantum mechanics.

(There is a recent decades trend in condensed matter physics where phenomenon qualitatively similar to quantum mechanics or black hole phenomenology, or even string theory, can be modelled in solid state or condensed matter systems. It’s a fascinating thing. No one really has an explanation for such quasi-universality in physics. I guess, when different systems of underlying equations give similar asymptotic behaviour then you have a chance of observing such universality in disparate and seemingly unrelated physical systems. One example Susskind mentions in his theoretical Minimum lectures is the condensed matter systems that model Majorana fermions. It’s just brilliantly fascinating stuff. I was going to write separate article about this. Maybe later. I’ll just mention that although such condensed matter models have to be taken with a grain of salt, to whatever extent they can recapitulate the physics of quantum systems you have this tantalising possibility of being able to construct low energy desktop experiments that might, might, be able to explore extreme physics such as superstring regimes and black hole phenomenology, only with safe and relatively affordable experiments. I’m no futurist, but as protein biology promises to be the biology of the 21st century, maybe condensed matter physics is poised to take over from particle accelerators as the main physics laboratory for the 1st century? It’d be kinda’ cool wouldn’t it?)

The oil droplet experiments are not a perfect model for Bohmian mechanics since these pilot waves do not carry other quantum degrees of freedom like spin or charge.

Normally I would scoff at this and say, “nice, but so what?” Physics, and science in general, is rife with examples of disparate systems that display similarity or universality. It does not mean the fundamental physics is the same. And in the oil droplet pilot wave experiments we clearly have a hell of a lot of quantum mechanics phenomenology absent.

But I did not scoff at this one.

The awesome thing about this oil droplet interference experiment is that there is a clear mechanism that can recapitulate a lot of the same phenomenology at the Planck scale, and hence offers an intriguing and tantalising alternative explanation for quantum mechanics as an effective theory that emerges from a more fundamental of Plank scale spacetime dynamics (geometrodynamics to borrow the terminology of Wheeler and Misner). Hell, I will not even mention “quantum gravity”, since that’d take me too fa afield, but dropping that phrase in here is entirely appropriate.

The clear Planck scale phenomenology I am speaking of is the model of spacetime as a superfluid. It will support non-dissipative pilot waves, which are therefore nothing less than subatomic gravitational waves of a sort. Given the weakness of gravity you can imagine how fragile are the superpositions of these spacetime or gravitational pilot waves. Not hard to destroy coherent states.

Then, of course, we already have the emerging theory of ER=EPR which explains entanglement using a type of geometrodynamics. If you start to package together everything that you can get out of geometrodynamics then you being to see a jigsaw puzzle filling in that hints maybe the whole gamut of quantum physics phenomenology at the Planck scale can be largely adequately explained using spacetime geometry and topology.

One big gap in geometrodynamics is the phenomenology of particle physics. Gauge symmetries, charges, and the rest. It will take a brave and fortified physicist to tackle all these problems. If you read my blog you will realise I am a total fan of such approaches. Even if they are wrong, I think they are huge fun to contemplate and play with, even if only as mathematical diversions. So I encourage any young mathematically talented physicists to dare to go in to active research on geometrodynamics.

The Many Worlds Guys

So what about Tegmark and Saunders? Well, by this point I kind of exhausted myself today and forgot what I was going to write about. Saunders mentioned something about frequentist probability having serious issues and that Frequentism could not be a philosophical basis for probability theory. I think that’s a bit unfair. Frequentism works in many practical cases. I don’t think it has to be an over-arching theory of probability. It works when it works.

Same in lots of science. Fourier transforms work on periodic signals, and FT’s can compress non-periodic signals too, but not perfectly. Newtonian physics works bloody well in many circumstances, but is not an all-encompassing theory of mechanics. Natural selection works to explain variation and speciation in living systems, but it is not the whole story, it cannot happen without some supporting mechanism like DNA replication and protein synthesis. You cannot explain speciation using Natural selection alone, it’s just not possible, Natural selection is too general and weak to be a full explanatory theory.

It’s funny too. Saunders seems to undermine a lot of what Tegmark was trying to argue in the previous talk at the conference. Tegmark was explicitly using frequentist counting in his arguments that Copenhagen is no better or worse than Many Worlds from a probabilistic perspective. I admit I do not really know what Saunders was on about. If you can engineer a proper measure than you can do probability. I think maybe Tegmark can justify some sort of MWI space measures. Again, I do not really know much about measure theory for MWI space. Maybe it is an open problem and Tegmark is stretching credibility a bit?

*      *       *


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

var MyStupidStr = “Gadammit! Where’d You Put My Variables!?”;

This WordPress blog keeps morphing from Superheros and SciFi back to philosophy of physics and other topics. So sorry to readers expecting some sort of consistency. This week I’m back with the Oxford University series, Cosmology and Quantum Foundations lectures. Anthony Valentini gives a talk about Hidden Variables in Cosmology.

The basic idea Valentini proposes is that we could be living in a deterministic cosmos, but we are somehow trapped in a region of phase space where quantum indeterminism reigns. In the our present epoch region there are hidden variables but they cannot be observed, not even indirectly, so they have no observable consequences, and so Bell’s Theorem and Kochen-Specker and the rest of the “no-go” theorems associated with quantum logic hold true. Fine, you say, then really you’re saying there effectively are no Hidden Variables (HV) theories that describe our reality? No, says Valetini. The Hidden Variables would be observable if the universe was in a different state, the other phase. How might this happen? And what are the consequences? And is this even remotely plausible?

Last question first: Valentini thinks it is testable using the microwave cosmic background radiation. Which I am highly sceptical about. But more on this later.

cosmol_Valentin_all.dof.have.relaxed

The idea of non-equilibrium Hidden Variable theory in cosmology. The early universe violates the Born Rule and hidden variables are not hidden. But the violent history of the universe has erased all pilot wave details and so now we only see non-local hidden variables which is no different from conventional QM. (Apologies for low res image, it was a screenshot.)

How Does it Work?

How it might have happened is that the universe as a whole might have two (at least, maybe more) sorts of regimes, one of which is highly non-equilibrium, extremely low entropy. In this region or phase the Hidden Variables would be apparent and Bell’s Theorems would be violated. In the other type of phase the universe is in equilibrium, high entropy, and Hidden Variables cannot be detected and Bell’s Theorem’s remain true (for QM). Valentini claims early during the Big Bang the universe may have been in the non-equilibrium phase, and so some remnants of this HV physics should exist in the primordial CMB radiation. But you cannot just say this and get hidden variables to be unhidden. There has to be some plausible mechanism behind the phase transition or the “relaxation” process as Valentini describes it.

The idea being that the truly fundamental physics of our universe is not fully observable because the universe has relaxed from non-equilibrium to equilibrium. The statistics in the equilibrium phase get all messed up and HV’s cannot be seen. (You understand that in the hypothetical non-equilibrium phase the HV’s are no longer hidden, they’d be manifest ordinary variables.)

Further Details from de Broglie-Bohm Pilot Wave Theory

Perhaps the most respectable HV theory is the (more or less original) de Broglie-Bohm pilot wave theory. It treats Schrödinger’s wave function as a real potential in a configuration space which somehow guides particles along deterministic trajectories. Sometimes people postulate Schrödinger time evolution plus an additional pilot wave potential. (I’m a bit vague about it since it’s a long time since I read any pilot wave theory.) But to explain all manner of EPR experiments you have to go to extremes and imagine this putative pilot Wave as really an all-pervading information storage device. It has to guide not only trajectories but also orientations of spin and units of electric charge and so forth, basically any quantity that can get entangled between relativistically isolated systems.

This seems like unnecessary ontology to me. Be that as it may, the Valentini proposal is cute and something worth playing around with I think.

So anyway, Valentini shows that if there is indeed an equilibrium ensemble of states for the universe then details of particle trajectories cannot be observed and so the pilot wave is essentially unobservable, and hence a non-local HV theory applies which is compatible with QM and the Bell inequalities.

It’s a neat idea.

My bet would be that more conventional spacetime physics which uses non-trivial topology can do a better job of explaining non-locality than the pilot wave. In particular, I suspect requiring a pilot wave to carry all relevant information about all observables is just too much ontological baggage. Like a lot of speculative physics thought up to try to solve foundational problems, I think the pilot wave is a nice explanatory construct, but it is still a construct, and I think something still more fundamental and elementary can be found to yield the same physics without so many ad hoc assumptions.

To relate this with very different ideas, what the de Broglie-Bohm pilot wave reminds me of is the inflaton field postulated in inflationary Big Bang models. I think the inflaton is a fictional construct. Yet it’s predictive power has been very successful.   My understanding is that instead of an inflaton field you can use fairly conventional and uncontroversial physics to explain inflationary cosmology, for example the Penrose CCC (Conformal Cyclic Cosmology) idea. This is not popular. But it is conservative physics and requires no new assumptions. As far as I can tell CCC “only” requires a long but finite lifetime for electrons, which should eventually decay by very weak processes.  (If I recall correctly,  in the Standard Model the electron does not decay.)  The Borexino experiment in Italy has measured the lower limit on the electron lifetime as longer than 66,000—yottayears, but currently there is no upper limit.

And for the de Broglie-Bohm pilot wave I think the idea can be replaced by spacetime with non-trivial topology, which again is not very trendy or politically correct physics, but it is conservative and conventional and requires no drastic new assumptions.

What Are the Consequences?

I’m not sure what the consequences of cosmic HV’s are for current physics. The main consequence seems to be an altered understanding of the early universe, but nothing dramatic for our current and future condition. In other words, I do not think there is much use for cosmic HV theory.

Philosophically I think there is some importance, since the truth of cosmic HV’s could fill in a lot of gaps in our civilisations understanding of quantum mechanics. It might not be practically useful, but it would be intellectually very satisfying.

Is Their Any Evidence for these Cosmic HV’s?

According to Valentini, supposing at some time in the early Big Bang there was non-equilibrium, hence classical physics more or less, then there should be classical perturbations frozen in the cosmic microwave radiation background from this period. This is due to a well-known result in astrophysics where perturbations on so-called “super Hubble” length scales tend to be frozen — i.e., they will still exist in the CMB.

Technically what Valentini et al., predict is a low-power anomaly at large angles in the spectrum of the CMB. That’s fine and good, but (contrary to what Valentini might hope) it is not evidence of non-equilibrium quantum mechanics with pilot waves. Why not? Simply because a hell of a lot of other things can account for observed low-power anomalies. Still, it’s not all bad — any such evidence would count as Bayesian inference support for pilot wave theory. Such weak evidence abounds in science, and would not count as a major breakthrough, unfortunately (because who doesn’t enjoy a good breakthrough?) I’m sure researchers like Valentini, in any sciences, in such positions of lacking solid evidence for a theory will admit behind closed doors the desultory status of such evidence, but they do not often advertise it as such.

It seems to me so many things can be “explained” by statistical features in the CMB data. I think a lot of theorist might be conveniently ignoring the uncertainties in the CMB data. You cannot just take this data raw and look for patterns and correlations and then claim they support your pet theory. At a minimum you need to use the uncertainties in the CMB data and allow for the fact that your theory is not truly supported by the CMB when alternatives to your pet theory are also compatible with the CMB.

I cannot prove it, but I suspect a lot of researchers are using the CMB data in this way. That is, they can get the correlations they need to support their favourite theory, but if they include uncertainties then the same data would support no correlations. So you get a null inconclusive result overall. I do not believe in HV theories, but I do sincerely wish Valentini well in his search for hard evidence. Getting good support for non-mainstream theories in physics is damn exciting.

*      *       *

Epilogue — Why HV? Why not MWI? Why not …

At the same conference Max Texmark polls the audience on their favoured interpretations of QM. The very fact people can conduct such polls among smart people is evidence of areal science of scientific anthropology. It’s interesting, right?! The most popular was Undecided=24. Many Worlds=15. Copenhagen=2. Modified dynamics (GRW)=0. Consistent Histories=0. Bohm (HV)=5. Relational=2. Modal=0.

This made me pretty happy. To me, undecidability is the only respectable position one can take at this present juncture in the history of physics. I do understand of course that many physicists are just voting for their favourites. Hardly any would stake their life on the fact that their view is correct. still, it was heart-warming to see so many taking the sane option seriously.

I will sign off for now by noting a similarity between HV and MWI. There’s not really all that much they have in common. But they both ask us to accept some realities well beyond what conservative standard interpretation-free quantum mechanics begs. What I mean by interpretation-free is just minimalism, which in turn is simply whatever modeling you need to actually do quantum mechanics predictions for experiments, that is the minimal stuff you need to explain or account for in any metaphysics interpretations sitting on top of QM. There is, of course, no such interpretation, which is why I can call it interpretation-free. You just go around supposing (or actually not “supposing” but merely “admitting the possibility”) the universe IS this Hilbert space and that our reality IS a cloud of vectors in this space that periodically expands and contracts in consistency with observed measurement data and unitary evolution, so that it all hangs together consistently and a consistent story can be told about the evolution of vectors in this state space that we take as representing our (possibly shared) reality (no need for solipsism).

I will say one nice thing about MWI: it is a clean theory! It requires a hell of a lot more ontology, but in some sense nothing new is added either. The writer who most convinces me I could believe in MWI is David Deutsch. Perhaps logically his ideas are the most coherent. But what holds me back and forces me to be continually agnostic for now (and yes, interpretations of QM debates are a bit quasi-religious, in the bad meaning of religious, not the good) is that I still think people simply have not explored enough normal physics to be able to unequivocally rule out a very ordinary explanation for quantum logic in our universe.

I guess there is something about being human that desires an interpretation more than this minimalism. I am certainly prey to this desire. But I cannot force myself to swallow either HV(Bohm) or MWI. They ask me to accept more ontology than I am prepared to admit into my mind space for now. I do prefer to seek a minimalist leaning theory, but not wholly interpretation-free. Not for the sake of minimalism, but because I think there is some beauty in minimalism akin to the mathematical idea of a Proof from the Book.


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

Collapsitude of the Physicists

The series of Oxford lectures I am enjoying in my lunch hours is prompting a few blog ideas. The latest is the business of the collapse of the wavefunction. So much has been written about the measurement problem in quantum mechanics that I surely do not need to write a boring introduction to it all. So I will just assume you can jump in cold and use Wikipedia or whatever to warm up when needed.

quanta_decoherance_awyoumademecollapse

There were no simple cartoons capturing the essence of the “collapse of the wavefunction”, so I made up this one.

By the way, the idea behind my little cartoon there is that making a measurement need not catastrophically collapse a system into a definite eigenstate as most textbooks routinely describe.  This (non-total collapse) is depicted as the residual pale pink region which entertains states in phase space that still have finite probability amplitudes.  We never really notice them subsequently because the amplitudes for these regions are too darn small to detect in any feasible future measurements.   Every measurement has finite precision, so you cannot completely use an actual real messy brains and wheetbix and jelly experiments to form a pure state.  Textbooks on QM are like this, they take so many liberties with the reality of an experimental situation that the theoreticians tend to lose touch with reality, especially when indulging in philosophy while calling it physics.

The issue is rife in many lectures I am watching, one is Simon Saunders’ talk on “The Case for Many Worlds“. He poses a sequence of questions for his audience:

  • Why does the collapse of the state happen?
  • When does it happen?
  • To what state does the state collapse?

He presages this by polling his audience on whether they believe the proverbial Schrödinger’s Cat is exclusively either alive or dead before the observer looks inside the diabolical box with the vial of radioactively triggered nerve gas. Some half of the audience believe the Cat was either alive or dead (i.e., not in a superposition). He then asks what about if the box was not an isolated box but a broom cupboard? Not many people change their mind! But the point was that the cupboard is, surely, in no way or form now isolated from the external universe, and surely has enough perturbations to destroy any delicate entangled superposed states.  But I guess some lovers of cats are hard to budge.

Then he asks, “well, what about if the experiment is being done up on a branch of a tree in a forest with no observer anywhere around?” (The clear unspoken implication is to think about the proverbial tree falling …). He cites a quantum information theoretic conference audience 80% of whom believed the Cat would then still not be in an exclusive XOR state, i.e., would still be in a superposition. Which is quite remarkable. Maybe they never heard of the phenomenon of environmental decoherence?

It’s at such times I wonder if Murray Gell-Mann has had an unhealthy influence on how physicists take their philosophy? In much of his popular style writing Gell-Mann has argued for environmental decoherence. The idea though is that there is no collapse, not ever. The universe remains mixed in a superposition of a giant cosmic wavefunctional state. Gell-Mann is not the sole culprit of course, but he’s the head honcho by fame if nothing else. And boy! You don’t want to go up head-to-head arguing against Gell-Mann! You’ll get your ears pulverised by pressure waves of unrelenting egg-headedness.

To be fair and balanced here’s a book cover that looks like it would be a juicy read if you really want to tangle with environmental decoherence as the explanation for classical physics appearances.

quanta_Joos_bookcover_EnvironmentalDecoherance

Looks like a good read. the lead author is Erich Joos.

I just want to warn you, if you ever feel like you are in a superposition of states then there are some medications that can recover classical physics if you find it too nauseous.

You do not have to take wavefunctions literally. They are just computational devices. The mathematical tool used to model quantum mechanics is not the thing itself that we are trying to describe and model. The point is, the idea is, that whatever the universe is, it must be described by a wavefunction or some equivalent modelling that enjoys a superposition of classical states. That’s what makes the world quantum mechanical, there are classical-like states that get all tensored up in a superposition of some form, and whether you choose to describe this mathematically by a wavefunction, or by matrices, or by Dirac bra and ket vectors in a Hilbert space is largely immaterial.

Many Worlds theorists have a fairly similar outlook to the decoherence folks. Although at some root level their interpretations differ, or are even perhaps empirically incompatible in principle (I’m not sure about that?) I think both views have the germ of the idea that there really is no collapse of state space. In environmental decoherence a measurement merely entangles the system with more stuff, and so gazillions of new things are now entangled, and the whole lot only appears to behave more classically as a result. But there is still superposition, only so many of the coefficients in the linear superposition have shrunk to near zero the overall effect is classical-like collapse. Then of course Schrodinger evolution picks up after the measurement is done, and isolation can gradually be reestablished around some experiment, … and so on and so forth.

Here’s my penny take on this. I’ve become a firm proponent of ER=EPR.  So I figure entanglement is as near to wormhole formation as you wanna get. You can take this literally or merely computationally convenient. For the time being I’m a literalist on it, which means I’ll change my mind if evidence mounts contrarily, but I think it is fruitful to take ER=EPR at more or less face value to see where it leads us.

ERrrr … who just collapsed me? You fiend!

I am also favouring something like gravitational collapse ideas. These seem to have a lot of promise, including (and this is a big selling point for me) the possibility of a link with ER=EPR. For one: if entanglement is established via ER bridges, then probably collapse of superposition can be effected by break-up of the wormholes. It seems a no-brainer to me. Technical issues aside. There might be some bugger of mathematical devilishness that renders this all nonsense. But I’m in like with the ideas and the connections.

Ergo I do not subscribe to environmental decoherence and the eternal superposition of the cosmos. Ergo again I do not subscribe to Many Worlds interpretations. Not that physics foundations is about popularity contests. But I think, when/if experimental approaches to these questions become possible I would be wanting to put research money into rigorously testing gravitational collapse and (if you deign to be a bit simplistic) also ER=Superposition, and therefore “NoER=Collapse”.

Well, that’s a smidgen of my thoughts for now on record. I think there are so many vast unexplored riches in fundamental theories and ideas of spacetime and particle physics that we do not yet need to reach out to bizarre outlandish interpretations of quantum mechanics. Bohr was the original sinner here. But pretty much every physicist who has dabbled in metaphysics and sought a valid interpretation of quantum mechanics has collapsed to the siren of the absurd ever since. This includes all those who followed Feynman’s dictum of forget about an interpretation. I think such non-interpretations are just as silly as the others.

Actually I’m not sure why I’ve characterised this as Feynman’s dictum. To be fair he did not say anything so extreme. He just marvelled at nature and warned physicists not to get into the mode of trying to tell nature what to do:

“We are not to tell nature what she’s gotta be. … She’s always got better imagination than we have.”

— R.P. Feynman, in the Sir Douglas Robb Lectures, University of Auckland (1979).

Man, I LOVED those lectures. My high school physics teacher John Hannah exposed our class to Feynman. Those were some of the best days of my life. The opening up of the beauty of the universe to my inner eyes. Here’s another favourite passage from those lectures:

“There’s a kind of saying that you don’t understand its meaning, ‘I don’t believe it. It’s too crazy. I’m not going to accept it.’ … You’ll have to accept it. It’s the way nature works. If you want to know how nature works, we looked at it, carefully. Looking at it, that’s the way it looks. You don’t like it? Go somewhere else, to another universe where the rules are simpler, philosophically more pleasing, more psychologically easy. I can’t help it, okay? If I’m going to tell you honestly what the world looks like to the human beings who have struggled as hard as they can to understand it, I can only tell you what it looks like.”
— R.P. Feynman (b.1918–d.1988).

Feynman actually said, “It’s the woy nature woiks.”

*      *       *


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)

Rovelli’s Roll

In a highly watchable talk in the Oxford University lecture mini-series on Cosmology and quantum Foundations Carlo Rovelli gives a lot of persuasive arguments about why the Many Worlds Interpretation is suspect. But he goes fast and furious sometimes. Sometimes constructing strawman arguments (I do not think anyone seriously thinks just literally interpreting mathematics in a given model of physics leads to necessarily great ontological truths, apart from the likes of characters like Tegmark perhaps) but I think generally even these points are well made and interesting to ponder. Rovelli describes his own current opinion as “Everettian” — which means not a traditional Many Worlds interpretation but rather Relative State interpretation.

relativestateQM_screenshot_Rovelli_lecture_twoobservers

One observer observing another, screenshot from Carlo Rovelli’s lecture.

There are many key slides in his presentation that I thought worthy of mentioning and which inspired this current post of mine.

In another slide Rovelli puts up a couple of threads, one is,

    • “Why don’t we see superpositions?” — what a silly question! Because in textbook QM we do not see the state, we see eigenvalues. We see where is the position o the electron or it’s momentum, never it’s wavefunction.
    • These (facts) are described by the position in phase space in classical physics; and by points in the spectra of elements of the observable algebra in quantum physics.

Which is cool, but then he riles the zen masters by writing:

  • They can be taken as primary elements, and the quantum formalism built up from them.

First, I should point out this is not erroneous. You can build up a theory from elements that are such primitives as “points in the spectra of elements of the observable algebra”.

But I think this is misleading for purists and philosophers of physics. Just because one approach to calculating expectation values works does not make it’s mathematical elements isomorphic in some sense to elements of physical reality. So I think Rovelli un-does some of his good arguments with such statements. (I’m not the expert Rovelli is, I’m just sayin’ ya know …)

You might counter: “Well, if you are not willing to take your theoretical elements of reality direct from the best mathematical model’s primitives, then where are you going to define your ontology (granting you are wishing to construct a realist interpretation)?”

I would concede, “ok, for now, you can have a favoured realist interpretation based on the primitives of your observables algebra.” But I think you are always going to have to admit this will be temporary, only an “effective interpretation” that is current to our present understandings.

My point is that while this makes for great contemporary physics it does not make for good philosophy (love of both knowledge and truth). The reason is blatant. If all you have is a model for computing amplitudes then there is really only a small probability for hoping this is a dead accurate and “True” picture of the real ontology in our universal physics. You can certainly freely pin your hopes on this chance and see where it leads.

I, for one, think that such an abstraction as an “observable algebra” although nice and concrete and clean, is just too abstract to be wisely taken literally as the basis for a realist interpretation. Again, I’m “just sayin’…”.

There are many more good discussion points in Rovelli’s lecture.

The Wavefunction is a Computational Tool

This meme has always gelled with me. You can map a wavefunction over time, for example, you can visualize an atomic electron’s orbital. But at no single moment in time is the electron ever seen to be smeared out over it’s orbital. To me, as a realist, this means the electron is probably not a wave. But it’s temporal behaviour manifests aspects of wave-like properties. Or to be bold: over time the (non-relativistic) constant energy electron’s state is completely coded as a wave. I will admit in future we might find hard evidence that electron’s truly are waves of some weird spacetime foamy medium, not waves in an abstract mathematical space, but I do not think we are there yet, and I think we will not find this to be so. My guess would be electrons are extended topological geons, perhaps a little more gnarly than superstrings, but less “super”. I think more like solitons of spacetime than embedded strings.

The keyword there for philosophy is “coded”. The wave picture, or if you prefer, the Heisenberg state matrix representation, (either the Schrödinger or Heisenberg mathematical tool will do) is a code for the time evolution of the electron. But in no realist sense can it be identified as the electron.  Moreover, if you are willing to accept the Schrödinger and Heisenberg pictures are equivalent then you have a doubled-up ontology.  To me that’s nonsense if you are also a realist.

Believe it or not though, I’ve read books where this is flatly denied and authors have claimed the electron is the wavefunction. I really cannot subscribe to this. It violates the principle of separation of ontology from theory (let me coin that principle if no one has before!). A model is not the thing being modelled, is another way to put it.

On a related aside note: John Wheeler was being very cheeky or highly provocative in suggesting the “It from Bit” meme. It sounds like a great explanatory concept, but it seems (to me) to lack some unknown extra structure needed to motivate sound belief. Wheeler also talked about “equations written on paper cannot bring themselves into existence” (or something to that effect). But I think “It from Bit” is not very far removed from equations writing themselves into a universe.

EPR is Entanglement with the Future?

That’s not quite an accurate way to encapsulate Rovelli’s take on EPR, but I think it captures the flavour. Rovelli is saying that in a Relational QM interpretation you do not worry about non-locality, because from each observers (the proverbial Alice and Bob at each end of an EPR experiment, or non-human apparatus if you prefer to drop the anthropomorphisms) point of view there is a simple measurement, nothing more. The realisation entanglement was happening only occurs later in the future when the two observers get back together and compare data.

I’m not quite with Rovelli fully on this. And I guess this makes me a non-Everettian. There might be something I’m missing about all this, but I think there is something to explain about the two observers from a “Gods eye” view of the universe at the time each makes their measurements. (Whether God exists is irrelevant, this is pure gedankenexperiment.)  If you are God then you witness effects of entanglement in the measurement outcomes of Alice and Bob.

The recent research surrounding the ER=EPR meme seem to give a fairly sound geometric or geometrodynamic interpretation of EPR as a wormhole connection. So I think Rovelli does not need to invoke anything fancy to explain away EPR entanglment. ER=EPR has, I believe, put the matter of the realist interpretation mechanism of entanglement to rest.

No matter how many professors shout out, “do not attempt to make mental mechanical models of QM, they will fail!” I think ER=EPR defies them at least on it’s own ground. (Ironically, Susskind says just such things in his popular Theoretical Minimum lectures, and yet he was one of the original ER=EPR co-authors!)

What About Superposition: Is Superposition=ER?

I am now going beyond what Rovelli was entertaining.

If you can explain entanglement using wormholes, how about superposition?

ERequalsEPR_NingBao_etal_PenroseCompressed

ER=EPR depiction from a  nice article by “Splitting Spacetime” Bao, Pollack, and Remmen (2015) http://inspirehep.net/record/1380145

 

I have not read any good papers about this yet. But I predict someone will put something on the arxiv soon (probably have already since I just haven’t gotten around to searching.) In a hand-waving manner, superpositions are bit like self-entanglement. A slightly harder interpretation might be that at the ends of a wormhole you could get particle duplication or mirror-effects of a sort.

One might even get quite literal and play with the idea that when an electron slips down a minimal wormhole it’s properties get mirrored at each end. Although, “mirror” is not the correct symmetry. I think perhaps just “copied at each end” is better. Cloned at each end? Whatever.

Maybe the electron continually oscillates back and forth between the mouths in some way? Who knows. It does require some kind of traversable ER bridge, or maybe just that when the bridge evaporates in a finite time the electron’s information snaps but to one end, but not both ends. Susskind and Hawking both concur now that there is no black hole information loss right? So surely a little ol’ electron’s information is not going to get lost if it wanders into a minimal ER bridge.

Then measurement or “wave function collapse” is likely a process of collapse of the wormhole. But in snapping the ER bridge the particle property can (somehow) only get restored at one end. Voila! You solve Schrodinger’s Cat’s dilemma.

Oh man! Would I not love t0 write a detailed technical mathematical exposition of all this. Sigh! Someone will probably beat me to it. Meehhh … what do I care, I’m not doing physics for fame or fortune.

Someone will have to eventually worry about stability of minimal ER bridges and the like. Then there are Lorentzian wormholes and closed time-like curves to consider. That Bao, Pollack, Remmen (2015) paper I cited above talks about “no-go” theorems arising from admitting ER bridges, no-go for causality violation and no-go for topology change.  I think what theoretical physics needs is an injecting of going past such no-go theorems.  They have to be “goes”.  Especially topology change.  If topology change implies violation of causality then all the better.  It only needs to have direct consequences at the Planck scale, then it’s not so scary to admit into theory, whatever the mess it might cause for modelling.  The upshot is that at the macroscopic scale I think allowing the “go” for these theorems rather than the “no-go” will reveal a lot of explanatory power, maybe even most of the explanation for the core phenomenon of quantum mechanics.  They mention concerns about violation of causality All of which I think is brilliant. I can see this sort of deep space structure explaining a lot of the current mystery about quantum mechanics, and in a realist interpretation. Awesome! And that I am not “just sayin” — it truly would be justifiably awesome.

*      *       *

Hmmm … had a lot more to say about Rovelli’s talk. Maybe another day.

*      *       *


CCL_BY-NC-SA(https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode)