Lee Smolin has a radical idea for how to understand an object with no exterior: Imagine it built bit-by-bit from relationships between events.OK, building the Universe from relationships is nothing new let alone radical. To one extent or another, numerous well-established insights as well as numerous proposed extensions of the status quo may be said to match these vague words.
Special relativity says that most quantities, including time, are relative and depend on the chosen reference frame. Only some invariants – such as the relative speed between two observers – are absolute. Because we need two observers to define their relative speed, we may say that it's their relationship that is the "actually real" information according to relativity.
John Wheeler has talked about "It from Bit" which is a similar sequence of words as those above. Phil Gibbs has proposed – much more mathematically concrete – event-symmetric spacetime where the information has to be invariant under all permutations of spacetime points. We could enumerate tons of people who have said various things about "relational" descriptions of the world, starting with Leibniz. The value added by Lee Smolin is non-existent.
Also, he seems to share the misconception that Nature's information is naturally divided to bits, binary digits. It's not. A bit is a very unnatural measure of the information – we could say a man-made or an anthropogenic one. Information comes in continuous quantities in Nature and the natural unit is one nat.
OK, there's nothing intellectually interesting or new to be found in the subtitle. Being [similarly reasonable as Bugs Bunny] doesn't make you radical. What about the first paragraph? It says quite a lot about the "puzzles" and "motivations" behind Smolin's words. Much of the remainder is just repetition and improvisation.
OK, the first paragraph says:
The universe is kind of an impossible object. It has an inside but no outside; it’s a one-sided coin. This Möbius architecture presents a unique challenge for cosmologists, who find themselves in the awkward position of being stuck inside the very system they’re trying to comprehend.These are sentences of a type that resembles some philosophers' talk. People are expected to be impressed and pretend that similar comments are deep. Many people instinctively start to rationalize these words. All these rationalizations are about feelings – some people could think about poor prisoners who can't study much because they've been jailed. But now approach it differently. I mean with a dose of critical thinking. Preserve your common sense and look at the statements above. The Universe is an "impossible object" and terribly hard to study because we're inside.
With some common sense left, you unavoidably conclude: Holy cow, this is so silly. Why should "being inside" make it difficult to study the thing in which you are located? Insiders usually understand the entities better than outsiders; think about the White House insiders. One could argue that this is really a definition of insiders! Why do they understand the thing surrounding them? Because they live in it and interact with it often. That's why. Another example: It's much easier for Russian speakers to become experts in the Russian language and Slavic literature, even at the U.S. universities. I have known several of them.
So the whole thesis that things become hard to study if you're inside them is clearly wrong.
Also, the statement that this "surprising" humans' being inside the Universe has something to do with the Möbius strip is a fantasy. The Möbius strip is an unorientable manifold in which the two sides are continuously identified with each other by a monodromy. Smolin hasn't presented any evidence that the "inside" and "outside" of the Universe may be turned into each other by a monodromy. So what Möbius strip are they talking about? The Möbius strip is a nontrivial manifold while "being inside the Universe" is trivial. These two things are clearly not analogous.
On top of that, the underlying assumption that we – the observers – are inside the Universe is misleading in some sense, too. The best way to imagine the measurement in quantum mechanics does involve a "soul" that may be imagined to exist independently of the Universe and that just "connects" to some wires in the Universe and measures some observables. That's how physicists often proceed in the AdS/CFT, too – they connect the AdS bulk space to some "wires" on the AdS boundary. When they do so, they use a variation of Julian Schwinger's "source theory" and it's the cleanest way to make sure that the observations are operationally meaningful.
The first paragraph therefore says several things that are unoriginal and thousands of people have said almost identical things before. But what's really striking is how uncritically these statements – which are really possibly wrong and the "subtle ways in which they are wrong" may be actually interesting – are being pronounced. You can see that in this case and most others, Smolin just doesn't like to question what he randomly says. He must believe that when he says something, it must be gold. So far, he hasn't really found an idea that could be considered correct and deep or at least promising.
In the next paragraph, we learn that he is a high school dropout. He also wrote some samizdat texts – like I did as a teenager. A difference is that I fought against the totalitarian regime while Smolin clearly fought against the regime that people like me wanted to have. The reasons must have been analogous to Greta Thunberg's but being a high school dropout must have been considered a good reason for him to be accepted to Harvard. I remember four admission committees at Harvard where I have served. About 5% applicants were admitted as undergrads. The idea that a high school dropout could be accepted to Harvard sounds surreal. Nevertheless, some other themes were clearly at play then.
“Perimeter,” in fact, is the perfect word to describe Smolin’s place near the boundary of mainstream physics.That's a very self-confident judgement. I think that most actual experts would say (and, at KITP, have said) that he is behind the boundaries – not only boundaries of "mainstream physics" but really "any physics". The three following sentences convey analogous points:
When most physicists dived headfirst into string theory, Smolin played a key role in working out the competing theory of loop quantum gravity.You see that Amanda Gefter is promoting a man who seems to deliberately say the opposite things than what he hears. Indeed, he seems to be a maverick for the sake of being a maverick. But without any real beef or justification, the scientific value of being a maverick is zero, too. Every imbecile may negate a sentences that he hears – and a huge fraction of imbeciles actually do so.
When most physicists said that the laws of physics are immutable, he said they evolve according to a kind of cosmic Darwinism.
When most physicists said that time is an illusion, Smolin insisted that it’s real.
Negating a thesis isn't a nontrivial contribution to science – or any scholarship that is worth anything – yet. The Academia is constructed in such a way that scholars may say anything they want. They don't risk anything just by experimentally offering an idea. Academic freedoms are the recipe that encourages the scholars to be creative and unlimited. On the other hand, the same Academic freedoms imply that there is no courage proven by saying the negation of a widespread proposition. Scholars still evaluate the quality of other scholars' assertions – and the actual hard work and evidence always matters. Bogus courage doesn't.
(These days, people are being intimidated again and the Academic freedoms are under attack in the West. But it's clearly the people on Smolin's side who are threatening others and it's the others who often need courage to disagree.)
So being a maverick-poser is clearly not useful or valuable from the scientific viewpoint at all. What matters in physics, science, and any decent scholarship is whether you have arguments, evidence, or discoveries that actually support your provoking thesis. Lee Smolin doesn't have those. Unlike string theory which works beautifully and its practitioners had to be truly creative and brilliant to see why, loop quantum gravity isn't a consistent quantum mechanical theory with the general theory of relativity in its long-distance limit. There is no viable framework in which the "laws of physics are mutable" – this hypothesized framework really sounds self-contradictory to sane physicists (because the laws that would govern the change of the "other" laws would become the new immutable laws, anyway) and Smolin has done nothing to cure the contradictions.
Similarly, people have good reasons to say that space and/or time is or isn't emergent or unreal – and Smolin hasn't really presented any equations, evidence, argumentation that would be comparably deep, interesting, innovative, or justified. So he is really just a poser who disagreed with things for the sake of disagreement. He can negate the conclusions of others but he doesn't have any counterpart of the "beef" that has justified the conclusions that he has contradicted. Amanda Gefter may be impressed by that but real scientists are not. That's not how you can do proper science.
Gottfried Leibniz wrote about "Monads" – some units of reality, the details were always vague – and this word has been recycled by computer scientists, graph theorists, and it was even quoted as one of the explanations of "M" in M-theory. Smolin says that he has read something about Monads and he has something to do with them except that we don't learn what he is saying about Monads. So what we are actually told is that by being able to say the word "Monads", Smolin wants to be treated on par with Gottfried Leibniz.
But there is some trouble with this Monad fame. First, Monads were only coined by Leibniz, not by Smolin, so it's ludicrous to say that Leibniz and Smolin have a similar relationship to Monads. Second, Monads were never defined well enough to be useful in natural science and in this sense, even Leibniz should get zero credit for them. Third, there has been no useful connection between Monads and contemporary physics. So there is really absolutely no beef here.
You have a slogan: “The first principle of cosmology must be: There is nothing outside the universe.”Every other physicist who has ever given a talk about cosmology has said an equivalent sentence. I've said it many times. The primary motivation was to clarify a misconception about the curved spacetime. People often imagine that our curved 4D spacetime is embedded into a higher-dimensional, perhaps Euclidean, parent spacetime. Our 4D spacetime behaves like a brane.
But that's exactly how you shouldn't imagine the origin of the curvature. The Universe is everything that exists – and there is nothing outside. So if you imagine our Universe to be a brane within a higher-dimensional flat spacetime, it's still important to realize that the points outside the brane don't physically exist. The embedding is just a method to visualize the curvature of our Universe. But you can describe a curved manifold even without the extra dimensions. No one can ever get there, no one can travel there, no measurement may ever take place outside the brane.
More generally, gravity is defined as the force that is mediated by the dynamical geometry of every piece of spacetime that exists. In other words, gravity may in principle penetrate to all corners of the spacetime that may be said to be physically real. So if we assume that the place outside the brane exists, there would be gravity over there, too. Equivalently, gravity cannot be localized on branes – Randall and Sundrum have come closest to a counter-example because gravity is localized in the vicinity of a brane in one of their scenarios.
So the slogan is true. But it's completely standard. There is nothing new about it. We might say that the slogan is a tautology because the Universe is defined as "everything that exists". So of course nothing can be outside – if it existed, it would have to be included inside, into the Universe. To pretend that the slogan conveys some deep point is silly. Also, there are contexts in which the slogan is incorrect (think about "other Universes" in the "multiverse") – and Smolin doesn't ever want to think about those because he assumes he's infallible. That's a pity because the potential counter-examples to such simple statements tend to be interesting – and after all, even the multiverse is an interesting loophole.
Now, a mandatory assault against the "background":
In different formulations of the laws of physics, like Newtonian mechanics or quantum mechanics, there is background structure — structure which has to be specified and is fixed. It’s not subject to evolution, it’s not influenced by anything that happens.That's not how "background" is understood e.g. in "background-dependent string theory". Background may be time-dependent – so it's simply not true in general that "the background is not subject to evolution". Instead, the property that normally defines the "background" is that it is described by classical fields – \(c\)-numbers whose values are assumed to be close to the expectation values of some quantum fields in an effective quantum field theory.
Once again, what makes the background a background is that it is classical, not that it is independent of time. Smolin's distortion simply shows that he misunderstands some very basic terms that are used in fundamental physics. But listeners such as Amanda Gefter don't have a clue so they are not bothered by the fact that everything he says about the background is wrong.
Physicists don't really use the term "background" in Newtonian mechanics, as Smolin claims, and even if they were using the term, the theories are so conceptually different that it would be a profound fallacy to conflate the "background in Newtonian mechanics" with the "background in quantum field theory". Both of them have some "space" – because "space" is relevant in all of physics – but all the details are different. The space is static, flat, and non-quantum in Newton's theory; and it is time-dependent, curved, and quantum in quantum field theory (effective QFT including GR, in the case we discuss here).
It’s structure outside the system being modeled.No, a background is a collection of auxiliary variables that are, on the contrary, chosen optimally to be useful for the system that is being modeled! The values of background fields are assumed to be close to the actual expectation values of the quantum fields we actually study in a given situation. The statement that the background is "outside the system being studied" is maximally false.
It’s structure outside the system being modeled. It’s the framework on which we hang observables — the observer, a clock and so forth.The first true interpretation of this sentence is that observers and clocks are located in the spacetime. Hardly a surprise. Yes, we live in the spacetime in some basic sense, as he admitted at the beginning, so it's ludicrous to "revolt" against this fact. The second correct interpretation is that the background – the actual expectation values of the quantum fields – aren't refined enough to account for local excitations such as the second hand of a clock. The observers and clocks have to be "added" because the background isn't a complete description of all the physics in the spacetime. Is this fact surprising? Why would one even talk about such trivialities?
I am confident that there is no other valid interpretation of the statement above. The statement is either wrong or completely trivial. Clocks and people live in a spacetime and some simple classical geometry (plus classical values of other fields) isn't enough to fully describe how clocks and observers work. What a shock.
The statement that there’s nothing outside the universe — there’s no observer outside the universe — implies that we need a formulation of physics without background structure.No, there is absolutely no valid implication of this kind. A background may be considered to be just a helpful – and, in some contexts, almost unavoidable – strategy to answer questions within quantum field theory and perhaps other theories.
We just write quantum fields as the background plus a quantum fluctuation (an operator) – the expectation value of the latter is zero. This is a clever and sometimes essential trick to proceed. There is nothing impossible or blasphemous about this trick. Indeed, it's a prerequisite of physics and whoever fails to use this trick fails to be a competent physicist. Whether a Lee Smolin finds the method philosophically pleasing is a question of no importance for science. The conceptual satisfaction that a method brings or doesn't bring to a physicist could be relevant for a physicist who has a good physics intuition but Lee Smolin doesn't belong to this set.
There may be methods to analyze physics "without a background" – but these alternative methods may also be non-existent. There is no "need" to have another way to analyze physical problems if at least one method to analyze them actually works! The argumentation by which Lee Smolin has "eliminated" the background as a tool in physics – or by which he "falsified" the theories where the background is used for solutions – is clearly invalid logically.
And as I wrote many times, dualities offer you to choose the background in very many ways and the excitations upon different backgrounds may end up being completely physically equivalent. So there is a lot of freedom in choosing background, perhaps a "complete freedom", a principle I call the "background indifference". There surely exists no valid argument that backgrounds must be avoided. At some level, it's almost certainly impossible because any system defined mathematically that may be said to be relevant for physics must have some spacetime or its generalization because physics by definition takes place in a spacetime or its generalization. If you erase all connections with a spacetime, you make your ideas unphysical.
In other words, you may have interesting spacetime-free ideas that will become a very important part of physics in the future. But they may only become a part of physics once someone connects them with some known or observed physics in the spacetime!
All the theories of physics we have, in one way or another, apply only to subsystems of the universe. They don’t apply to the universe as a whole, because they require this background structure.This is just a repetition of the incorrect sentences that I have already rebutted.
...we have to avoid what the philosopher Roberto Unger and I called “the cosmological fallacy,” the mistaken belief that we can take theories that apply to subsystems and scale them up to the universe as a whole.It's complete nonsense. All of physics and all of natural science (and also the wisdom of the everyday man) totally depends on this new "blasphemy" – on the extrapolation of experiments performed and patterns observed locally to the whole Universe and to different moments. This assumption is closely linked to the reproducibility of science. A credible scientist really doesn't want to question these principles; science would be impossible without this kind of generalizations. Cosmology is the discipline of science in which this extrapolation – which Unger and Smolin apparently want to ban – is more important than in any other discipline. The cosmological principle is basically the statement that they want to ban – that at the cosmological scales (comparable to the size of the visible Universe), the Universe is uniform and isotropic and has the same laws that apply everywhere.
OK, what can a physicist do with two guys who just say a statement that is the negation of an important principle underlying a whole discipline – in this case cosmology (it really seems that they have just renamed the "cosmological principle" to "cosmological fallacy") – and they don't offer any clarification that could convince others that they're saying something else than a self-evidently wrong statement? A clarification that could imply that they're not simply ignorant about basic undergraduate cosmology? A physicist can't do anything. Amanda Gefter may still be impressed because she doesn't have the slightest clue about physics or cosmology. But that feeling doesn't mean that Unger's and Smolin's propositions have a positive value from the scientific viewpoint. They don't.
We need a formulation of dynamics that doesn’t refer to an observer or measuring instrument or anything outside the system. That means we need a different kind of theory.On the contrary, the whole point of the 1925 quantum revolution is that we need a new theory that does refer to an observer. Werner Heisenberg has repeatedly told Einstein that he could discover this top 3 important insight of the 20th century physics by emulating the philosophy he learned from Einstein, namely that most quantities must be considered "relative" i.e. dependent on the inertial system. It's completely OK for physical descriptions to "demand" the user to choose what is the inertial system or who is the observer. It's completely normal for theories in modern physics to be observer-dependent in both of these meanings – and perhaps others – and the reversal to the physics that is completely observer-independent seems impossible now.
It's particularly ironic for Smolin to demonize the observer dependence of observables in physics given the fact that he's spent so much energy by pointing out the shocking fact that we're confined inside the Universe and the information is hiding in the relations. The need to choose an observer is nothing else than focusing on the subset of the information about the world that is hiding in relationships – an observer is choosing all the information about relationships in which he is one of the sides of the relationship! Both relativity and quantum mechanics say that it's fundamentally wrong to try to "reconcile" the perspectives of different observers. When events are simultaneous according to one observer, they will not be simultaneous according to most other observers. When one observer has observed some observable in quantum mechanics, most other observers have almost certainly observed different observables because they have asked different questions and one can't assume that both measurements have taken place in the same history because generic pairs of observables refuse to commute with one another. That's how modern physics works and there is nothing "wrong" about it.
You’ve recently proposed such a theory — one in which, as you put it, “the history of the universe is constituted of different views of itself.” What does that mean?"Things that happen" is likely to talk about events at some moment, "things that are" is likely to talk about objects that keep on existing at different times. Aside from this self-evident different in focus, there is no difference between the two different "things". Anyone who is willing to believe that one may make a new important physics discovery in 2019 just by recombining the words "things", "that", "happen", "are", and "events" into new sentences is too intellectually handicapped for science. One really can't do physics in this way. Even in Newton's times, it was impossible. There's no conceivable way how these sentences with these basic words could encode some equations that are surely needed to express some new ideas about the Universe.
It’s a theory about processes, about the sequences and causal relations among things that happen, not the inherent properties of things that are. [...]
The quote above adds the causal relations which is potentially interesting but any realistic physical systems contains many causally disconnected (because spacelike-separated) events as well as groups of events that are causally related. The causal structure isn't enough for any complete enough description of a realistic or semi-realistic system and if one could prove otherwise, that would indeed be extremely interesting. But Smolin hasn't proven otherwise. Also, the causal structure of any spacetime is nothing else than a part of the information about that "background".
Physics isn't about words – and elementary words of this type are the most obvious ones to be nothing else than vacuous babbling.
I know from your book that you’re a realist at heart — you believe strongly in a reality independent of our knowledge of it — and therefore, like Einstein, you think quantum mechanics is incomplete. Does this theory of views help complete what you think is missing in quantum theory?You can believe anything you want, starting with a tooth-fairy. But science isn't a machinery to uphold people's beliefs. Science is a machinery to pick promising beliefs and to kill beliefs that are ruled out and the idea that there exists a realist description that is independent of any observers was ruled out over 90 years ago. Anyone who still "believes" in it has been proven to be as wrong as the kids who believe in a tooth-fairy.
But one day, I was sitting in a cafe working and suddenly I thought: What if the ensemble is real? What if, when you have a wave function describing a single water molecule, it’s actually describing the ensemble of every water molecule in the universe?"The ensemble interpretation" is incapable of saying anything meaningful about physics, too. Clump your water molecule with similar water molecules as you wish. But science is ultimately about predicting results of measurements and observers do a measurement with a particular water molecule, not with the ensemble of similar molecules across the world, whatever the definition of such an ensemble would be (there can't be any canonical one).
So the clumping of water molecules into these "ensembles" with other water molecules is a pure fantasy that has nothing to do with the information studied by science. In science, we want to understand or predict particular water molecules (there's no experiment testing "all water molecules of the world" as an ensemble) and once we realize it and study the data, we find out that the fundamental theory – because it is quantum mechanical – may only predict the probabilities of a priori possible outcomes of the measurements. Any talk about ensembles in the context of probabilistic predictions is a pure distraction.
Incidentally, in January, I discussed locality on the configuration space. It may be said to have a similar "spirit" as this ensemble comment by Smolin – or e.g. Sheldrake's morphogenetic field. Things are "close" in a new definition of distance if they have similar "shapes". But unlike the babbling by the two men, I have something specific in mind that may be translated into mathematically unambiguous concepts and statements. Smolin is just talking nonsense. And I generously assume he didn't just try to plagiarize my ideas.
I first read Leibniz at the instigation of Julian Barbour, when I was just out of graduate school. First I read the correspondence between Leibniz and Samuel Clarke, who was a follower of Newton, in which Leibniz criticized Newton’s notion of absolute space and absolute time and argued that observables in physics should be relational. They should describe the relations of one system with another, resulting from their interaction. Later I read the Monadology.How detached from the genuine scientific research as well as common sense one has to be to believe that the order of reading of some letters written in the 17th century is relevant for the advancement of fundamental physics in 2019?
...Leibniz says, "Just as the same city viewed from different directions appears entirely different..."How is it better than e.g. Heraclitus' much older "you never step into the same river twice" or any other random quote that has made it into the mass culture? Why would any sane person believe that such quotes have something to do with physics research? They're at most tools to make a physicist look cultural and poetic but they cannot be foundations on which physics is actually built.
That, to me, evokes why these ideas are very suitable, not just in physics but for a whole range of things from social policy and postmodernism to art to what it feels like to be an individual in a diverse society. But that’s another discussion!Wow. A statement that the city looks different from different direction – which Smolin basically contradicted just a few paragraphs earlier when he said that things mustn't depend on observers – may be used as the basis of not only physics research but also politics? This is just incredible.
The comment about the diverse society is a real gem. Earlier in Gefter's article, Smolin also proposed a law of physics that maximizes the variety – he clearly meant the "diversity" as well. Nature must be a politically correct Human Resources bureaucrat. No justification for these claims was made so I would feel offended if you expected me to respond. Of course I have thought about similar ideas (laws that maximize the diversity etc.) at some moments. But I would never brag about these words if I had no encouraging results – and it is very clear that Smolin has no encouraging results.
Not at all. Many of the leading theorists in foundational physics — where the goal is to deepen our knowledge of the fundamental laws — know philosophy very well.Leading physicists – and even not quite leading but still real physicists – also know that one can't promote random philosophers' quotes into a guide to do physics research. Even if and when philosophers' statements were useful in physics, it was particular statements, not "all of the stuff that philosophers say", and one still needed the hard scientific approach and selection to pick the statements that were valuable for physics.
Then there was this pragmatic turn, where the dominant mode of physics became anti-foundational, anti-philosophy.As discussed elsewhere, the pragmatic turn was unavoidable because physicists were drowning in the data and patterns to explain which looked tangible, down-to-Earth, and sort of analogous to the previously mastered phenomena, and they surely didn't have time to discuss some philosophers' ill-defined, purely verbally formulated, speculations.
Freeman Dyson once said, normally the young people are rebels and the old people are the conservatives, but in his generation it was the reverse.It will be true in coming years, too, as Soph's Generation Z will rebel against the Millennials who have been largely brainwashed by the unfresh postmodern and neo-Marxist stuff by the likes of Lee Smolin.
The young people didn’t want to hear about messy philosophy or foundational issues, they just wanted to get out and apply quantum mechanics.Every modern physicist wants to get out and apply quantum mechanics because this is what the word "physicist" has meant since 1925. Almost all of new physics depends on the principles of quantum mechanics – and quantum mechanics is also sufficiently hard to learn so that it largely defines the physicists' expertise and distinguishes physicists from non-physicists. Whoever doesn't understand that in 2019, "physics research is basically an application of quantum mechanics to different systems" is a non-physicist.
There is still a huge diversity in the "ways to apply quantum mechanics to various problems and disciplines". Contemporary physics is surely more diverse and rich in various ideas than science has ever been before. There is no justification to increase the diversity further.
This was great for the explosion of applications of quantum mechanics from the 1940s into the 1970s, through the establishment of the Standard Model, condensed matter physics and so forth. But then fundamental physics got stuck, ...No, it didn't get stuck at all. Just some people including Lee Smolin would prefer if fundamental physics got stuck and all the progress were banned and delegitimized – and mankind could return to the Middle Ages when people could pretend to be physicists by emitting meaningless, non-quantitative, purely verbal, and often self-contradictory, proverbs.
To achieve this medieval outcome, Lee Smolin denies basically all of science that has been learned in the recent 50 years or so – and he creates the impression of relative adequacy out of the feelings of those people whom he impresses by meaningless slogans and whose intelligence isn't sufficient to figure out that "denying 50 years of science is suspicious". He does many other things that are simply not right according to a scientist's opinion. But science doesn't listen and it's at least those 50 years ahead of Lee Smolin.
The interchange with philosophy is coming back, and I think it’s a good thing.No, it is not. In ancient Greece, physicists and philosophers belonged to the same species. The two disciplines have been generally diverging for 2,000 years, and the harder, more abstract, and more mathematical the fundamental physics became, becomes, or will become, the bigger the gap is guaranteed to be. The gap is basically irreversible, it always grows – it only grows more quickly in some eras and more slowly in others.
What actually explains Smolin's position is that he lives in the world of meaningless would-be philosophical talk and has nothing to do with the discipline that good physicists actually call physics as of 2019. It's a world in which scientifically illiterate journalists are being impressed by monologues and slogans that are partly vacuous, partly wrong, partly self-contradicting but always disconnected from any observations or equations that would actually matter for these observations – and especially from the ideas that make genuine scientists excited. Smolin's world is a world that has nothing to do with science.