A video on loop quantum gravity

Sabine Hossenfelder watched a 43-minute video on loop quantum gravity that was posted two days ago. She wasn't too impressed.

Well, I am always impressed by low-budget or no-budget teams that manage to shoot a semiprofessional video of this size but it's hard to avoid some criticisms. Most of them are really criticisms of the topic they chose to cover, loop quantum gravity, so they shouldn't be used against the creators of the video. And I will avoid detailed criticisms of the imperfect sound quality (noise filters were used too much at some places), the subtitles (and whether it makes sense to have a video if there exists a written form of it), and the speakers' limited rhetorical abilities.



00:00 It's strange that loop quantum gravity is being connected with the birth of stars etc. because it isn't really capable of explaining the particle spectrum and other parts of physics that are crucial for our understanding of the early Universe.




00:40 Loop quantum gravity is said to be "treating gravity quantum mechanically". While this phrase is omnipresent and seems like an innocent one, and it can even be interpreted innocently, in the strict form – which is probably one chosen by most of the speakers – it is a seed of lots of confusion. A theory of quantum gravity isn't just the same classical physics "treated" differently. It is new physics, a brand new theory that leads to different conclusions and predictions. The procedures needed to find a quantum theory with certain properties are, in general, more complicated and different than just "placing hats on the heads of all objects in classical physics". Loop quantum gravitists sort of understand that a quantum theory differs from a classical theory. But they live in the misconception that the transition from a classical theory to a quantum theory is straightforward and one-to-one. It's surely not. The space of quantum theories with certain properties is completely different from its classical counterpart. Their consistency conditions are different, and so on.




00:50 LQG is said to tell us that space has discrete units. Well, it pretty much assumes it so it's misleading to say that it's a prediction. And this assumption has indeed far-reaching consequences – far-reaching destructive consequences, to be precise. It makes the theory incompatible with the Lorentz invariance, other continuous symmetries, and it is a property that guarantees that the infinite indeterminacy seen in the non-renormalizable Einstein's theory can't be cured by this attempted theory. It's unfortunate to hype this property of LQG without asking whether it's actually a good thing or a bad thing and without making a credible attempt to answer this question. But this hyping is being done not only by filmmakers but also by most LQG proponents.

01:00 Ivan Agullo is said to be a "rising star" of the field. I've never heard of the name and INSPIRE seems to confirm it's not my fault. I don't quite get the concept of a "rising star" whose most famous paper has 52 citations shared by 5 authors. It's surely an inflation of words. What about an average young researcher in this subpar discipline?

01:10 Abhay Ashtekar is a pleasant guy. In some of his features of the smile, he resembles Cumrun Vafa (Vafa is Iranian while Ashtekar is Indian by his roots). He read a book by George Gamow as a kid. So did I. Agullo loved algebra and calculus. I don't quite understand why we're told these stories about the childhood of someone whose contribution to physics still remains completely unknown to me – and all other viewers.

02:20 Are you afraid that Einstein failed and you're trying to solve it? Agullo says Yes but it's OK because many people are working on it. Well, many people with much lower capabilities couldn't replace the genius of one individual. What allows modern physicists to go beyond Einstein is their much better mastery or quantum mechanics and related portions of physics. Unfortunately, this can't be said about the LQG researchers which is another reason why they should be afraid of their inevitable failure.

02:50 Ashtekar: Einstein's GR is geometric and predictive, QM is different, probabilistic and algebraic. There should be a unifying theory. These sound like innocent words for every "unifier" of gravity and QM. However, the vague formulation about the two limits – which are completely different and which impose very different restrictions on the unified theory – is a seed of confusion within LQG. In particular, the postulates of QM have to be exact and they affect every dynamical degree of freedom and interaction in physics. On the contrary, the foundations of GR are about one particular field only, the metric tensor or the field communicating gravity, and its interactions with other fields while most of the other degrees of freedom remain unconstrained. Moreover, the original equations of GR don't have a reason to be exact and aren't exact. LQG folks don't understand these differences.

04:05 Ashtekar: Gravity is encoded in the very geometry of spacetime. Well, the same is true for every theory that respects the equivalence principle, e.g. string theory. However, in string theory, one may derive such conclusions from a more fundamental starting point. Ashtekar says things like "there is no background and everything is interacting with everything else". These two statements aren't equivalent. The background is just a condensate that must be allowed to develop and exist. So if you can't get background from your theory, it's doomed. You can't mask this doom by demagogic identifications of the lethal flaw "there is no background" (bad) with the principle that "everything is interacting with everything else" (true, it does in pretty much every theory).

05:44 Comparison with string theory. LQG folks from the GR background, ST came from particle physics. So we're told by Ashtekar that string theorists are focused on the unification of forces and not the peculiar properties of the spacetime itself. That's just untrue. String theory has discovered and still studies lots of new remarkable properties of the quantum spacetime – T-duality, mirror symmetry, other dualities, holography, entanglement is a glue or wormhole, emergence of spacetime from other degrees of freedom, topology change – flops, conifolds, others. It's just a lie that string theory isn't fascinated and fascinating us with new insights about the peculiar properties of the spacetime in the quantum theory.

06:20 In string theory, SUSY and extra dimensions are essential, in LQG, they're not. Friendly speculations about the cooperation of LQG and ST. Not really realistic but OK.

07:30 Agullo about the Big Bang singularity. GR fails over there. He uses "loop quantum gravity" and "loop quantum cosmology" in the same sentence. It's pretty bad that they don't even explain enough to explain the viewer that these are two things and what the relationship between them is. Sabine has already complained about it. LQC isn't really a limit or special case of LQG; it is a simplified toy model of it. It suffers from all the problems of LQG and more. The "cure" of the singularity is presented as an extra quantum-caused repulsive force that creates a bounce. I find this 1) a wishful thinking, 2) a naive strategy to deal with the problem. Such a bounce only moves all the problems to (even more serious problems with) the pre-big-bang cosmology and it doesn't seem one has made any progress at all.

08:50 Sponge has a maximum capacity to hold water, and space has similarly a maximum density. That's just stupid. Even semiclassical GR is enough to see that the density is maximized for the minimum-size i.e. Planckian black hole when it's Planckian, too. But this is really just a transitory regime, not an extreme one. Lighter black holes are like elementary particles and their density isn't too well-defined or isn't finite because they're pointlike in some very specific sense. Larger black holes have a much lower than the Planckian density, and so do all other celestial bodies. There's really no way to make a whole "filled sponge", a macroscopic piece of the maximum-density "material" of space, and if a theory predicts otherwise, it's immediately dead. It's dead because the final stage of the collapse of localized matter is a large black hole whose density (mass/volume) is much lower.

09:50 Big bounce instead of Big Bang. Agullo says the naive things about the bounce, without really solving anything. One could really embed this "solution" even to classical GR as long as one adds some (non-local) interaction. But we really do know there was a Big Bang and by the second law, the entropy "before it" if there was any "before" couldn't have been higher than during the Big Bang. Agullo explains terms in a high-school-level equation but it's both incomprehensible and inadequate for analyses of extreme physical conditions such as the Big Bang.

12:00 Ashtekar says that this bounce force comes out automatically blah blah blah. He's happy about it. It's hard to see where this satisfaction comes from. Every new theory predicts some new effects. A generic effect is bound to get corrections from the new physics. This is not yet a reason to be happy. It is not a consistency check analogous to those in string theory. There are no successful consistency checks in LQG.

13:00 The female narrator starts to talk about cosmic inflation. What does LQG say? Ashtekar says confusing things about the probability of inflation that is small at some moments and so on. Bizarre. Inflation is a generic process that arises in theories with scalar fields and viable enough potentials that are surely not "infinitely unlikely". It arises whenever a region of space sees a scalar field sitting near the maximum of the slow-roll potential. It even arises without the slow-roll potential. Once the small region obeys this condition, which must be clearly allowed because it's an allowed configuration, exponentially large volumes of inflating space will be created. All the "inflation is unlikely" criticism trying to argue otherwise is complete unscientific gibberish, and so is Ashtekar's story about this topic.

14:40 Ashtekar also praises LQC for giving us a preferred instant, the bounce, while the Planck time after the Big Bang isn't special. Those comments are extremely special, too. The Planck scale surely is special in a theory of quantum gravity. Special things tend to occur there or its vicinity by dimensional analysis. On the other hand, the bounce in LQC isn't special, at least not the exact moment, because the evolution isn't time-reversal-symmetric (e.g. because the second law of thermodynamics) so the volume-minimizing instant is just a convention to choose a moment in the middle, and not the only convention. So the situations are equally special or non-special.

16:00 She asks a surprisingly sensible question – doesn't the observed positive cosmological constant rule out the recollapse, namely the bounce? Agullo says that LQC doesn't predict that there will be a recollapse. That's nice but it does say t – or at least they do say - that there was a bounce so it was a collapse of an earlier Universe. One has problems with this in a positive C.C. world, too, especially because the pre-big-bang universe had to be more or less maximally symmetric due to its low entropy.

17:40 Why was the entropy low at the beginning – which is not the beginning in the bounce models? A good question. Agullo says that the entropy was "reset". Wow. I suppose he means that an agent reduced a high positive value to zero. Jesus Christ? This is a flagrant violation of the second law and it is enough to kill any model with this feature. He talks this rubbish to a laywoman for many minutes and she has no way to learn that it is rubbish contradicting basic physics, even physics taught to undergraduates.

19:30 Ashtekar correctly says that we usually count matter entropy and not horizon entropy. But he doesn't elaborate upon this good point. One has to be a bit careful about double-counting here. Well, the matter entropy is always parameterically lower than the horizon entropy so if we count the horizon entropy, it beats the matter entropy, anyway. Ashtekar is trying to solve the same problem as Agullo by equally if not more childish comments. The entropy is "infinite" at the bounce and it drops to zero because the horizon disappears. But this is just an oxymoron. The event horizon is always defined relatively to the causal structure of the whole future spacetime. So if it's somewhere, it just can't disappear. Ashtekar's comments about the disappearance make no sense and they're added on top of Agullo's nonsense about the "reset entropy". Moreover, the idea that one may just ignore the decreasing matter entropy is also wrong. One may only ignore the disappearing matter entropy in GR if the matter ends in a singularity. But if it doesn't, the matter density separately can't decrease, either. Those folks are a community of sloppy folks who just support each other when they talk vague physical nonsense.

21:50 Resolution of black hole singularities. There are no precise calculations, we hear. They hype a Pullin-Gambini paper that happens to be about a similar question. The singularity is replaced by a new large spacetime. You know, that's a big problem, something that would revive all the information loss puzzles after they were solved.

22:50 She asks about Alan Guth who dared to publish a paper that bounces are prohibited. Agullo says that Guth assumed classical GR near the bounce while LQG violates it. Ashtekar agrees. She also asks about other problems of contracting universes. Agullo just says that there are "papers" and they imply that singularities don't appear. But this really means that the theory disagrees with GR in rather mundane contexts, a point that isn't noticed at all.

25:00 Ashtekar is worshiping the repulsive force. I can't get rid of the feeling that these people still live somewhere in the 17th century and they're adding terms to Newton's equations. Physics no longer operates like that and similar extra terms aren't considered fundamental or interesting. Ashtekar says that unlike previous attempts, LQC has a way to make a "cube of size 10 Planck lengths" uniform. I suppose that the mechanism he refers to is the Jesus Christ who resets the entropy and flattens the region. That's nice but the Jesuits already had the same mechanism (Jesus Christ) many centuries ago. All this stuff is ludicrous. Inflation and things equivalent to it is the only known actually operational mechanism to produce flattened, nearly empty large regions of space out of a different environment.

25:45 Ashtekar is asked about the proposal by Smolin – whom he doesn't like – and a physicist with a Polish name that black hole singularities are big bangs of other universes. Asthtekar thinks that this can't be the case because the singularities are different.

26:50 Ashtekar is asked whether inflation may be eternal according to LQC. He doesn't seem to have an answer. He has no intuition, we hear, and asks others to do a strange calculation.

28:35 Agullo is asked why the previous Universe contracted. He says we don't have observational access to this question. That's a fun excuse because if you claim to have a theory replacing the Big Bang singularity, it should give you a mechanism for that process, too. After all, we don't have the observational access to the Big Bang singularity which doesn't mean that we can sweep it under the rug. He's using different standards for his pet theories and the (more viable) conventional theories. Agullo says that quantum effects wash out the information about the previous phase. Great. But the theory should have the information about the overall evolution, otherwise it says nothing about the early Universe.

29:10 The female narrator complains that a paper by Guth et al. (Borde, Vilenkin, Guth) didn't refer to LQG. Well, Alan Guth rarely cites crackpots in general. Agullo meaningfully explains the paper, saying that it claims that inflation can't be eternal in the past. At the end, he says that the theorem may be ignored but there is no justification except for foggy claims that we don't have the final theory yet. A great power of the theorem is that they may prove many things even before we know everything else, a point that Agullo clearly fails to grasp. Ashtekar says that the theorem doesn't apply to LQC because LQC has a contracting phase, something assumed to be absent in the theorem.

32:25 It's hard to test quantum gravity experimentally; interesting that no one dares to criticize these folks for this fact of Nature. Random wrong papers about the Lorentz violation by gamma-ray bursts, wrong ways in which black holes should evaporate, and so on are hyped. The CMB is most promising for Agullo except that his LQG has nothing to say about it.

34:00 Ashtekar says that everything we observe is compatible with LQC. Wow. An unexpected conclusion after half-an-hour of hyping the difference between LQC and the theories that actually do agree with the data.

35:40 Violations of Lorentz invariance due to the discreteness space were experimentally falsified "while other experiments have confirmed it" (the latter is bullshit, all these positive signals have been debunked or explained as being due to a more mundane effect). Ashtekar says that this violation of relativity is a robust prediction of LQG, in analogy with crystals in condensed matter physics. Very true: LQG imagines that the world literally is a sort of a crystal. So why doesn't he see that LQG has been ruled out? He wants to believe that the correction only contribute at the second order. But even the (experimentally falsified) first-order correction is a wild underestimate of the huge violations of relativity that a fundamentally Lorentz-violating theory predicts!

37:10 Detection of gravitational waves, polarization of CMB, etc. What does LQG have to say about these matters? The only honest answer, nothing, isn't heard.

38:50 Small black holes at the LHC. They would be great, Agullo says. All this stuff is incompatible with the LHC because black holes may only appear at the LHC with the extra Randall-Sundrum warped dimensions which aren't a part of LQG. Agullo doesn't explain this fundamental thing – either he doesn't understand it or he finds it beneficial to hide the fact.

39:50 The narrator talks about a Planck press conference, anomalies, differences from WMAP. The video doesn't look honest concerning the question who authored these comments. They're not hers, are they? Agullo talks about some perturbations from the pre-big-bang cosmology and while the gap between the conventional physics and LQC is deep, he blurs the boundaries so that it is often completely unclear whether he is talking about the LQC research or proper physics. Ashtekar admits he doesn't understand these anomalies so he offers general wishful thinking about learning things about the initial state instead. We're told that Planck data are compatible with LQC except that LQC predicts nothing that looks like the real world, and talking about details of Planck data in this context is way over the edge.

The narrator wraps the video by comments about an entirely new vista that the bounce may open.

I don't plan to proofread this text.

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Shmoits face a German competitor

Book market flooded with garden-variety cranks

In 2010, a German conspiracy theorist and high school teacher named Alexander Unzicker released his anti-physics tirade that was reformatted as a book. The title was "Vom Urknall zum Durchknall" which I would translate as "From the Big Bang to Their Big Butts' Being Banged" but that was translated as "Bankrupting Physics" by the unimaginative translator. The English translation will appear tomorrow. You may pre-order it.

Most of the 21 chapters have titles saying things like "something is rotten in the state of physics", "why cosmology is going the wrong way", "how physics became a junk drawer", "branes, multiverses, and other supersicknesses: physics goes nuts", "string theory: how the elite became a sect and mafia", "what's wrong with the physics business", "get ready for the crash". You get the point.

I haven't read and I won't read the book because I consider the table of contents to be fully sufficient to know what's inside the book. It's surely not the first time when most of the 20th century physics is being trashed by an aggressive stupid asshole who has no clue about science. But a review of the book written by a TRF reader may be published later.




Alexander Unzicker is undoubtedly the most accurate German counterpart of his U.S.-based "colleagues", especially Lee Smolin and Peter Woit. I am totally confident that well over 95% of the readers of these two hacks agree with this assessment. That's why the readers of the U.S. crackpot – the one who is the grandson of a top Nazi official in a European country – had to be stunned when they saw this review of Unzicker's book.




We learn that Unzicker is a garden-variety crank and his book is depressing, tedious, nonsense, worth ignoring, unpublishable, and (which is most damning) parroting Woit's crackpot blog and book. Well, yes, it is parroting it very well, indeed. The only problem with Woit's criticism is that he is attacking his intellectual twin brother. We learn that Woit is sometimes aware of this fact:

Well, maybe he does get something right… I have to admit that one of the things that every so often makes me wonder if I’m completely misguided, and maybe there is a lot more value to strings/SUSY/branes/extra dimensions etc. than I think, is reading rants like Unzicker’s.

However, Woit always forgets that he's the same dull pile of feces as his fellow garden-variety crank from Germany and continues to do what he is best at – polluting the intellectual landscape by hateful lies and demagogy.

A difference between Unzicker and Woit is that Unzicker rejects about 20-30 more years of modern theoretical physics than Woit does. However, if I compared Unzicker and Smolin, even this possible difference would largely disappear because Smolin hates much of the 1900-1950 physics as well while Unzicker has a positive attitude to some of it, too. They're more or less exact equivalents in this respect.

Concerning the Woit-Unzicker difference, I have mixed feelings about the question which of these two crackpots is worse. On one hand, Unzicker must be even more stupid than Woit because he misunderstands – and slings mud at – old and therefore more elementary physics insights than Woit. On the other hand, Unzicker is more internally consistent than Woit. He distributes the "initial moment" when physics allegedly began to move in a wrong direction over much of the 20th century. On the contrary, Woit loves to create the picture that theoretical physics took the wrong direction exactly at one moment in the early 1980s, just when the physics job market determined that Peter Woit, incapable of even learning string theory, is – diplomatically speaking – a worthless pile of stinky shit who hasn't contribute anything and who probably won't contribute anything (this prediction remains as rock-solid today as it was 30 years ago).

Such an abrupt change of the direction of physics research, moreover one that is so exactly correlated with the events in Woit's life, is a remarkable claim. Everyone who actually understands physics knows that there has been no "existential" discontinuity or conceptual change in the 1970s, 1980s, or 1990s. Modern physics has been steadily marching and doing remarkable technical progress but it has continued to build on the spirit and philosophical foundations that have been around for a century or so. Moreover, the AdS/CFT and other developments have taught us that string theory as the only consistent theory of quantum gravity is really physically equivalent to gauge theories, the key addition to theoretical particle physics from the 1960s (at least when both sides of the equivalence are applied to some specific classes of problems), so it is utterly ludicrous to say that one of them is right and one of them is wrong.

It means that Peter Woit is displaying some shocking inconsistency when he tries to talk positively about the physics of the 1960s but negatively about physics of the following decades. The actual facts don't allow any such inconsistency.

Moreover, Woit hasn't sold a single copy of his own rant by his occasionally positive words about gauge theories etc. The hardcore crackpots who read his book and blog – and yes, all these people are just stupid scum – tolerated and suffered through the positive words about gauge theories. These positive words – something that could have been copied from every relevant undergraduate course or a popular presentation of the physics developed 50 years ago – were the "necessary evil" for them. What they bought the book for were the hostile dishonest rants against physics from the 1970s through the present. And when it comes to any of these topics that really matter for the ability of the books to be sold – and influence imbeciles, including those employed in the media – Woit and Smolin are exactly equivalent to Unzicker. That's also why Unzicker's book was praised by German counterparts of those who have praised the two American Shmoits' books, e.g. by the incompetent journalists in the German edition of Scientific Americans and maverick astronomers such as the Czech-German anti-dark-matter warrior Pavel Kroupa (Kroupa is surely in a much higher league than Unzicker but he just agreed to endorse the Unzicker jerk).



So I urge Mr Woit to stop his breathtaking hypocrisy. If he admits that Mr Unzicker and his "work" are dirty garbage, then it is completely obvious that the very same statement applies to Mr Woit, Mr Smolin, and their "work". All the readers of "Not Even Wrong" know this much as well as I do. Germany is able to compete in most industries and as we can see, the industry of hardcore anti-physics demagogues and populist crackpots addressing their "work" to the ultimate bottom of the human society is undoubtedly among those in which Germany is competitive.

And that's the memo.

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The "Past Hypothesis" nonsense is alive and kicking

I can't believe how dense certain people are. After many years that Sean Carroll had to localize the elementary, childish mistakes in his reasoning, he is still walking around and talking about the "arrow of time mystery" and the "Past Hypothesis":

Cosmology and the Past Hypothesis

His Santa Cruz, California talk about this non-problem took no less than 3.5 hours. Imagine actual people sitting and listening to this utter junk for such a long time. I can't even imagine that. He has even coined some new phrases that describe the very same misconception of yours.

If there is one central idea, it’s the concept of a “cosmological realization measure” for statistical mechanics. Ordinarily, when we have some statistical system, we know some macroscopic facts about it but only have a probability distribution over the microscopic details. If our goal is to predict the future, it suffices to choose a distribution that is uniform in the Liouville measure given to us by classical mechanics (or its quantum analogue). If we want to reconstruct the past, in contrast, we need to conditionalize over trajectories that also started in a low-entropy past state — that the “Past Hypothesis” that is required to get stat mech off the ground in a world governed by time-symmetric fundamental laws.

As talented enough students learn when they are college juniors or earlier, statistical mechanics explains thermodynamic phenomena by statistically analyzing large collections of atoms (or other large collections of degrees of freedom) and doesn't depend on cosmology (or anything that is larger than the matter whose behavior we want to understand) in any way whatsoever. It's the atoms, short-distance physics, that determines the behavior of larger objects (including the whole Universe), not the other way around!



Reverse Times Square 2013. In the real world, objects moving forward and backward in time can't co-exist, a well-defined logical arrow of time indicating what evolves from what has to exist everywhere. That's also why none of the clowns above managed to unbreak an egg. Exercise for you: Can the video above be authentic or was it inevitably computer-reversed afterwords? You should be able to decide by looking at details of the video. For the advanced viewers: Which parts were edited?

Moreover, since its very birth, statistical physics was a set of methods to deal with the laws of physics that were time-reversal- (or CPT-) symmetric and it always "got off the ground" beautifully. There is absolutely nothing new about these matters in 2013. In fact, nothing really qualitative has changed about statistical physics for a century or so.




At least, you see some progress in Carroll's talk about these matters because in the quote above, he at least seems to admit that to reconstruct the past, you need to use somewhat different methods than to predict the future. For years, we would hear him saying the – completely wrong – statement that the retrodictions follow the very same procedure as predictions.

However, his ideas about the way how retrodictions work are still completely wrong.




He thinks that to retrodict the past, "we need to conditionalize over trajectories that also started in a low-entropy past state". But that's not true. In fact, the correct method to retrodict the past – one based on the Bayesian inference – automatically implies that the entropy was lower in the past than it is now.

I have already explained this thing about 20 times on this blog but the reason why I keep on repeating the simple argument is that I want to be absolutely certain that I am accurate when I say that every physicist who still fails to understand these issues is either a fraudster or a complete moron avoiding fundamental knowledge whatever it costs.

To predict the future, you take the initial state – either a point in the classical phase space or the pure state vector in quantum mechanics; or (if you deal with incomplete knowledge) the probability distribution on the phase space or the density matrix in quantum mechanics – and evolve them in the future direction. In general, this tells you the probabilities of different final states whose interpretation is straightforward (frequentism is good enough).

However, to retrodict the past, you need to follow a reverse procedure. The possible initial states are different hypotheses \(H_i\) as understood by Bayesian inference. These hypotheses – initial states – predict (i.e. imply) different observations (observed in the present). The actual observations are evidence that may be used to adjust the probabilities of different hypotheses (initial states).

It's important to realize that just like we can't predict the exact state in the future – only probabilities may be reconstructed – we can't retrodict the exact microstate in the past. We may only retrodict probabilities of different states but we have to do it right. When we do it right, we automatically see that the entropy of the state in the past had to be lower, just like the second law of thermodynamics always said.

I borrow the proof that the entropy of the initial state was lower from the December 2012 article, Information and Heat. Let's consider the evolution from the ensemble \(A\) to ensemble \(B\). By ensembles, I mean some states roughly given by their macroscopic properties which may be represented by one of many "practically indistinguishable" microstates. Only when we consider statistically large collections of atoms or other degrees of freedom, we may derive some non-probabilistic statements such as "one entropy is higher than the other".

The probability of the evolution from \(A\) to \(B\) is\[

P(A\to B) = \sum_{a\in A}\sum_{b\in B} P(a)\cdot P(a\to b)

\] where \(a,b\) go over microstates included in the ensembles \(A,B\), respectively. This notation is valid both for classical physics and quantum mechanics (where the microstates refer to basis vectors in an orthonormal basis of the ensemble subspace); in quantum mechanics, we could write the expression in a more basis-independent way using traces, too. If we compute the probabilities for ensembles, we must sum the probabilities over all possible final microstates \(b\) because we're calculating the probability of "one possible \(b\)" or "another possible \(b\)" and the word "OR" corresponds to the addition of probabilities.

On the other hand, we have included \(P(a)\) which denotes the probability that the initial microstate is a particular \(a\), because the probability of evolution \(P_{a\to b}\) is only relevant when the initial state actually is the particular \(a\). Now, we will simplify our life and assume that all microstates \(a\) are equally likely so \(P(a)=1/N(A)\), the inverse number of microstates in the ensemble \(A\). This "egalitarian" assumption could be modified and different microstates in the ensemble could be given diifferent prior probabilities but nothing would qualitatively change.

It's also possible to calculate the probability of the time-reversed process \(B^*\to A^*\). The stars mean that the signs of the velocities get inverted as well; in quantum field theory, the star would represent the complete CPT conjugate of the original ensemble because CPT is the only reliably universal symmetry involving the time reversal (but the star may also mean T whenever it is a symmetry). Clearly, the probability is\[

P(B^*\to A^*) = \sum_{a^*\in A^*} \sum_{b^*\in B^*} P(b^*) P(a\to b)

\] where I used that \(P(a\to b)=P(b^*\to a^*)\) from the time-reversal symmetry (or, more safely, CPT symmetry) of the evolution followed by the microstates. Note that the two probabilities are almost given by the same formula but in the latter one, we see the factor \(P(b^*)=1/N(B^*)=1/N(B)\) in our simplified "equal odds" setup. At any rate, the ratio is\[

\frac{P(A\to B)}{P(B^*\to A^*)} = \frac{P_a}{P_b} = \frac{1/N(A)}{1/N(B)} = \exp\left(\frac{S_B-S_A}{k}\right)

\] where I used \(N(A)=\exp(S_A/k)\) – the inverted formula from Boltzmann's tomb – and similarly for \(B\). But now realize that \(k\) is extremely tiny in the macroscopic SI-like units while \(S_B-S_A\), the entropy change, is finite. So the ratio \((S_B-S_A)/k\) is equal either to plus infinity or minus infinity. It follows that one of the probabilities, \(P(A\to B)\) or \(P(B^*\to A^*)\), is infinitely (even exponential of infinity) times greater (i.e. more likely) than the other one which means that only one of the processes may occur with a nonzero probability (just like probabilities in general, both are less than or equal to one which means that the larger one equals at most one and the smaller one is infinitely smaller than that, i.e. zero).

If you look at the sign, the only possible (nonzero probability) transition between ensembles is one for which the final entropy is greater than the initial one. If \(S_B-S_A\gt 0\), the numerator \(P(A\to B)\) is infinitely greater than the denominator \(P(B^*\to A^*)\) which means that only the numerator is allowed to be nonzero. In other words, \(A\to B\) may occur while \(B^*\to A^*\) is prohibited.

Again, I have proven that the evolution in which the entropy increases is hugely more likely than the reverse process – the ratio of their probabilities is \(\exp(\Delta S/k)\) where \(\Delta S\) is the entropy difference between the initial and final state. To prove such a thing, I didn't have to assume anything about the Earth, the Solar System, the Universe, or cosmology because these – totally universal – calculations in statistical physics and their conclusions (that were already known to thermodynamics) have nothing to do with these large objects. If we were talking about the entropy change in a closed lab, we have only discussed the degrees of freedom (atoms...) inside the lab. Whatever the rest of the Universe was doing had no impact whatsoever on the calculation (and the resulting odds).

The calculation above is not hard but you may say that this particular general derivation above – presented in a way optimized by your humble correspondent, to say the least – is a bit unfamiliar to students who don't go through clear enough courses. Perhaps it is a bit ingenious. It may be OK if people happen to be ignorant about it.

However, what I find amazing is that people like Carroll are clearly ignorant about certain facts indicating that they must completely misunderstand the scientific method. Why? Sean Carroll is clearly convinced that the laws of physics as he knows them imply that the entropy of the young Universe had to be higher than the current entropy. So this is a prediction of those laws of physics and those methods to calculate that he is proposing. Because he also agrees that the entropy of the young Universe was actually lower, it must mean that his laws of physics or methods or both have been falsified. They're dead because they have made a wrong prediction (in this case, infinitely many exponentially bad predictions about pretty much everything!). Once they're dead, they can't be made "undead" again. This is a trivial observation that everyone who uses the scientific method in any context simply has to realize. Because Sean Carroll doesn't realize that, he can't possibly understand what the scientific method is.

If there is a contradiction between the empirical data – low entropy of the Universe in the past – and your theory, your theory has to be abandoned. You have to throw at least pieces of it and, perhaps, replace them with other pieces. Just adding "extra stuff" to your theory can't possibly help. If the theory was able to produce a wrong prediction (at least with a high enough confidence, like 99.9999%), then it has been falsified and making the theory more extensive (by the supposedly helpful additions such as "the cosmological realization measure" or the "Past Hypothesis") just can't solve the problem.

I am also amazed by the brutal distortion of the history below – Sean Carroll must know very well that it is a distortion:

That would stand in marked contrast to the straightforward Boltzmannian expectation that any particular low-entropy state is both preceded by and followed by higher-entropy configurations.

Ludwig Boltzmann has never believed that the entropy was higher in the past than it is today. In fact, he was the history's most important man who has demonstrated just the opposite – that the increase of the entropy is a universal property of any system with many degrees of freedom. He has proven this second law of thermodynamics using the tools of statistical physics – where the second law is represented by the H-theorem, a more waterproof and transparent demonstration of why the second law has to be right.

It's important to realize that this second law or H-theorem apply to any moment of the history and any state. It doesn't matter whether the year "now" is 2013 or less or more. The proof of the H-theorem doesn't depend on "now" or the current year at all. It always implies that the entropy increases. It will increase between 2013 and 2014 and it was increasing between 2012 and 2013, too. If \(t_1\lt t_2\), then \(S(t_1)\lt S(t_2)\). One may have different emotional attachments to these two periods of time (perhaps we were not yet born at time \(t_1\) while we fell in love at \(t_2\)) but physics – and the proof of the H-theorem – just isn't about emotions. It is about facts and the laws of physics and about mathematically valid propositions and implications – and those are (perhaps except for the facts that may be interpreted as time-dependent things) independent of the time, independent of the current year.

I am also stunned by the fact that among the hundreds of readers who were probably going through the blog entry at Sean Carroll's blog, there was not a single person who would understand these basic issues about statistical physics and who would kindly explain to Sean Carroll how utterly stupid he was being and how superfluous all his concepts and proposed hypotheses are.

Incidentally, some news related to time: Strontium lattice clocks may improve the accuracy of the state-of-the-art atomic clocks by a stunning factor of 100! See BBC, Nature.

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Eric Weinstein's invisible theory of nothing

On Friday, I received an irritated message from Mel B. who had read articles in the Guardian claiming that Eric Weinstein found a theory of everything or something close:

Roll over Einstein: meet Weinstein (by Alok Jha)

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Eric Weinstein may have found the answer to physics' biggest problems (by Marcus du Sautoy)

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Geometric Unity (a lecture at Oxford that no physicist attended)

First, the puns involving names emulating Einstein are extremely far from being new to me because as the most successful Czechoslovak debunker of these new Einsteins (I mean anti-relativity cranks in this particular case), I've spent quite some time with the Slovak crackpot originally named Arthur Bolčo who also wrote the book Arthur Bolstein: An Ordinary Collapse of an Extraordinary Theory (which had both Einstein's and Bolstein's photographs on the cover, cute).

Now, Weinstein is a smart guy, a likable figure, a hedge fund speculator, the father of the MathWorld encyclopedia later run on Wolfram's domain (mistake! A different man, see the comments), and a discrete physicist close to folks like Edward Frenkel, a mathematician at Berkeley.

But the stories in the Guardian are just completely insane because they have absolute no basis.




This aspect of the story was nicely discussed by Jennifer Ouellette's blog entry "Dear Guardian: You’ve Been Played". Her blog, Cocktail Party Physics, has been incorporated into the website of a once nice American science magazine.




Eric Weinstein doesn't seem to have written a physics paper in his whole life (if we don't count his bizarre 0-citation PhD thesis) and this particular new theory of everything isn't described in any paper – not even an informal preprint – that anyone has seen. He was just invited by a buddy to give a seminar that no one attended and no one who knows similar things was invited to, in fact.

So it seems like another self-evident case of nepotism, self-promotion, unprofessionality of the journalists in the Guardian, and "science" run by press conferences. Even Nude Socialist's Andrew Pontzen concluded that Weinstein's theory of everything is probably nothing; see also a similar criticism by Spinor Info. I am not gonna speculate on whether or not Eric Weinstein has paid for the self-promotion but I think that it would be legitimate to speculate because there's quite some case for this hypothesis. It's comparably conceivable that the whole effect may be explained by the journalists' gullibility and stupidity and nothing else.

I don't know the content of the Oxford seminar, I haven't seen any paper, and I don't even know whether a paper will ever exist at all but building on some rumors, it seems that his work is another episode in the widespread confusion about the "graviweak unification". Papers by authors by Garrett Lisi – and in the case of the "TOE" papers, even papers by folks like Fabrizio Nesti (who wrote the JHEP \(\rm\LaTeX\) macro and added even some papers on matrix string theory, among others; despite his "priority", Nesti is less famous than Lisi because he's a sailor, not surfer) – are mixed sequences of mistakes, blunders, errors, misunderstandings, and – in the best passages – unjustified hopes.



I guess that Rammstein is a relative of Einstein, too. It's cool music I only began to like less than 10 years ago under the influence of friends JB and OK.

There are lots of lethal flaws in these papers each of which is sufficient to kill the idea. But the most general theme, the "graviweak unification" i.e. the unification of the electroweak and gravitational interactions at the level of spacetime fields, is just totally hopelessly wrong. There can't be any "graviweak unification".

It seems rather clear to me that all these authors are confused by the apparent similarity between the local Yang-Mills groups of gauge theories such as \(SU(2)_W\times U(1)_Y\) for the electroweak theory on one hand; and the local Lorentz group such as \(SO(3,1)\) acting on vielbeins \(e_\mu^a\) in the tetrad formalism describing the general theory of relativity i.e. gravity on the other hand.

These groups enter the dynamics differently but these differences could perhaps be due to some symmetry breaking (and even the difference between one group that is compact and another group that is not could turn out to be harmless, perhaps).

But the key fact that those people completely miss is that the \(SO(3,1)\) local Lorentz group is in no way the key local symmetry principle underlying general relativity in its "covariant" description. Instead, it's the diffeomorphisms that are the key symmetry. And diffeomorphisms are completely different transformations than the local Lorentz symmetries! Diffeomorphisms act like\[

\phi(x,y,z,t)\to\phi'(x,y,z,t) = \phi(x',y',z',t')

\] on the scalars and I want to avoid descriptions how tensors transform because you should know it. At any rate, the new value of a field at a point after the action of a diffeomorphism depends on the value(s) of the field at another point before the diffeomorphism acted. On the other hand, the local Lorentz symmetries – much like the Yang-Mills symmetries – only transform the fields at the same spacetime points into each other. The counterpart of the transformation above would need no primed coordinates \(x',y',z',t'\).

These are completely different transformations and the local Lorentz transformations are really unnecessary, optional. We may do general relativity without them. On the other hand, the tetrad formalism of general relativity requires both the local Lorentz symmetry and diffeomorphisms. What's essential for gravity are the diffeomorphisms which are completely different beasts than the local Lorentz transformations. Their generators are given by the stress energy tensor \(T_{\mu\nu}\) which has two vector indices (spin 2), unlike the generators of Yang-Mills-like symmetries \(J_\mu\) which are currents with one index (spin 1 of the gauge bosons).

There can't exist any purely field-theoretical unification of spin-1 fields and spin-2 fields (and of the corresponding symmetries) in the same spacetime that would be described by field theory. Only string theory and its diverse descriptions may achieve such a unification. They do so by attributing an internal structure of a sort to the particles including the messengers – for example, it's the string that may have internal vibrations and those may change the spin of the resulting particle, too. In this unification, one immediately generates an infinite tower of new states with arbitrarily high spins aside from \(J=1\), \(J=2\), too. And if we're "lucky", the excitations of the extended objects interact consistently, avoid divergences and anomalies, agree with the physics of gauge theories and general relativity. Only string theory in its different manifestations has been "lucky" so far and it seems likely that no other theory will ever join this "lucky" club.

The reasons why gravity can't be unified with the Yang-Mills forces in the naive, field-theoretical way is no string theory. In fact, it's not even rocket science. I find it strange that these men can't understand the reasons. I find it shocking that they still can't penetrate these simple things and isolate the simple mistakes they've been doing for years.

You may perhaps define some equations of motion that unify the (compact) Yang-Mills groups of the Standard Model (or similar ones) with the (noncompact) local Lorentz symmetry but the resulting theory will still have nothing whatsoever to do with gravity because the natural local transformations that allow us to write gravity covariantly are diffeomorphisms, not local Yang-Mills-like symmetries. Moreover, actual physicists have known for quite some time that in the real world, the unification of gravity with other forces critically depends on quantum mechanics which is why arbitrary games with the classical Lagrangians are no good.

Eric, Fabrizio, Garrett, please try to wake up and stop with this immensely stupid crackpottery and the embarrassing promotion of this crackpottery in the media!

14-dimensional fiber bundle

Incidentally, some sources suggest that Weinstein wants to construct his "theory of everything" out of a 14-dimensional bundle obtained by placing the 10-dimensional space of possible values of the 10-component metric tensor \(g_{\mu\nu}\) at each point of the 4-dimensional spacetime. That's a fun thing to present the identity \(10+4=14\) but it's otherwise completely empty. If you specify how many dimensions a theory should have, it is extremely far from actually having a theory – knowing a consistent description of the interactions of some particle, fields, or other objects in a given spacetime. Moreover, in some reasonable clarifications of the 14-dimensional theory, the 10 dimensions are spurious and the theory is still the same 4-dimensional theory with 10 fields we have known as general relativity.

Independently of that, there can't be any natural theories with a stable enough spacetime in 14 dimensions.

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Tommaso Dorigo impressed by a cold fusion paper

...but the paper is 100% crackpottery...

In his text "Is Cold Fusion For Real?", Tommaso Dorigo seems highly impressed by the following new Italian-Swedish preprint about cold fusion:

Indication of anomalous heat energy production in a reactor device

They claim that an Andrea-Rossi-style tube with nickel and hydrogen produced 10+ times more energy per liter of fuel than any known chemical reaction, as measured by thermal imaging cameras during 96- and 116-hour experimental runs.



Image credit: Rossi, Kullander, Essén and the e-Cat, retrieved from energydigital.com.

Dorigo says that "the conclusions of the tests are at the very least startling". He "continue[s] to believe in the scam hypothesis, but [he] must admit that this study impressed [him] for its reported result." Also, he must say that "[he] will from now on follow more closely the developing story of Rossi's E-CAT...".




Congratulations, Mr Rossi. You have clearly earned a fan who thinks that cold fusion is more realistic than supersymmetry! If you really believe so, Mr Dorigo, then you are an unhinged lunatic.

First, let's discuss the sociology. What I find remarkable is how easy it is for the authors to make folks like Dorigo repeat some self-congratulatory words such as the "third-party [investigation]" that appears in the first sentence of Dorigo's article.

If you look for a rather detailed, enlightened, entertaining, and completely reasonable criticism of the new paper (with discussions of mistakes, possible ways to do such an experiment to be convincing, and differences between science and pseudoscience, not to mention some useful links), see The E-Cat is back, and people are still falling for it! by Ethan Siegel (Starts With a Bang).




If you look at the previous publication record of the seven authors via the arXiv (click at the author names here), you will see that only two of them have previously published something. Bo Höistad appeared among dozens of authors in an (unknown) technical design report on a tracker in the KLOE-2 experiment. Hanno Essén of KTH Mechanics, Stockholm has published a dozen or two dozens of preprints on magnetism and fluid dynamics, none of which is really well-known and all of which look like papers by an engineer attempting to "do" physics as his hobby – which is what they are, after all.

Given the large amount of money that is circulating in the cold fusion business today, one must say that all the data are consistent with the seven authors' being inserted just as puppets who don't have to be afraid of their scientific credibility because they don't have much to lose (relatively to what they can be promised from the Rossi industry). So I have a problem with the adjective "third-party" in Dorigo's article. There doesn't seem to be solid evidence that this is independent from Rossi's organizations; the presence of the Italian co-authors makes the independence even less likely.

Update: Hours after this blog entry was written, Steven Krivit explained that this paper doesn't describe any independent test; instead, the authors were just witnesses of a Rossi demonstration. Essén, the only co-author with at least 2 other papers, admitted he didn't replicate the experiment. On the picture at the top of this blog entry, he is shown together with Rossi, in a position clearly indicating that Rossi is a teacher and Essén is an obedient disciple.



Dorigo himself may be rather positive because all the Italians form a family of a sort. A trailer for Mafia II, an amazingly realistic but too linear PC game.

A technical or sociological detail that doesn't prove that the preprint is rubbish but it's always a brightly shining and blinking "red light" for me is that the physics.gen-ph preprint was delivered as PDF only and it wasn't written in \(\rm \TeX\) but rather in Microsoft Word (on a Mac). That makes it very likely that the authors don't actually know \(\rm \TeX\) and most of such authors don't really know physics well, either.

Tommaso Dorigo often likes to paint himself as a person who is willing to think independently except that the extent to which he simply copied the self-congratulatory decoration that was added to this paper suggests that he isn't really thinking critically.

Now, somewhat more technically.

The authors are clearly ignorant not just about \(\rm \TeX\); they seem to be unfamiliar with the basics of the scientific notation and the rudimentary methodologies that are needed in experiments. For example, the units of dimensionful quantities are always written as \([\rm W]\) including the square brackets. No, if we perform dimensional analysis and want to say something about the units of a quantity, we may use the symbol \([l]\) or \([{\rm length}]\) to describe the units of length. But we never actually write meters – the particular units themselves – into the square brackets! This is a detail but a strong indication that the authors haven't really gone through some relevant undergraduate freshman courses of physics.

Perhaps more importantly, the paper never discusses the error margins properly. You may easily check that they never talk about anything such a "systematic error" and when they talk about errors at all, they're just "optional". Sometimes they add them to the results, sometimes they don't, and if they do add them, it seems that they just make the numbers up. For example, on pages 22-23, they say that the effective power consumption has error of 10% because "errors of this extent are commonly accepted in calorimetric measurements". Wow. There's surely no "one-size-fits-all" error for calorimetric measurements. The error depends on what you measure, how you measure it, and almost all the details in your experiment. The magnitude of a systematic error of your apparatus actually has to be measured and calculated for your case specifically; you can't copy a "general figure" from completely different papers describing different apparatuses. This sentence by itself shows that they don't know how to do experiments well.

But on page 22, you see an example of the "key calculation" meant to show that the "reactor" produces lots of energy. Over the 116 hours of the experiment discussed here, the gadget was consuming 283.5 watts from the grid and producing 810 watts (much more), we hear. An anomalous production of heat, they happily announce. Those 810 watts are claimed to be determined from the thermal radiation that the reactor was emitting; the 283.5 watts are calculated as 35% of 810 watts.

Where does the figure 35% come from? The resistors (electric heaters of a sort) were on for "about" 35% of the time and off for "about" 65% of the time. Couldn't one just measure the precise time during which something was turned on and off? Are we supposed to think that they used a gadget to measure time that uses "one percent" as the unit of time? Don't you agree that this claim about "65% off" is just a potential lie to mask that the energy was coming in all the time? See also this comment for a convincing indication that they measured the incoming energy completely incorrectly (even though this should be a very easy task!).

OK, let's not think about details. It's plausible that the average consumption in those 116 hours was close to 283.5 watts. The produced average power 816 watts is much higher and it would be enough for a proof that some very strong anomalous production of energy is taking place. Where does the figure 816 watts come from?

It comes from equation (24); the power was calculated from the emitted thermal radiation. The numerical value 816 watts whose error is estimated as just 2% is the sum 741.3+17+58 watts. Clearly, the only large contribution that affects the overall qualitative result is the term 741.3 watts. Where does this come from?

It comes from Table 8 on page 21 where it's calculated as the sum of radiated 459.8 watts and 281.5 watts participating in convection. The latter figure, 281.5 watts, contradicts some calculation resulting in equation (17) on page 12 where convection was claimed to give about 466 watts. I was trying to check where various numbers were coming from but almost nothing seems to be consistent with anything else. The paper looks like an incoherent pile of rubbish to me.

Moreover, the gadget seems to depend on the power outlet and has a nonzero consumption. So you could expect that its power production will also depend on whether or not the resistor coils are turned on or turned off. However, this dependence of the produced power on time isn't discussed anywhere in the paper.

Let's ignore the differences between 281.5 and 466 watts. They still see lots of radiating energy that is produced, don't they? Well, they surely claim so. In equation (8) on page 10, they boast to have produced 1568 watts (during the other, 96-hour experiment) which is 1609 watts minus the small contribution from the room. The numerical value 1609 watts is computed in equation (5) and nearby equations as the Stefan-Boltzmann power corresponding to the (fourth-power-based) mean temperature around 723 kelvins (450 Celsius degrees) multiplied by the area of the Rossi cylindrical "black box" (whose bases are overlooked).

The emissivity is set to one i.e. they assume the "reactor" to be a black body. This choice is labeled "conservative". Except that the truth seems to be going exactly in the opposite direction. The actual emissivity is lower than one and it's the coefficient multiplying the fourth power of the absolute temperature to get the power. Because they seem to calculate the power from the measured temperature (the infrared camera is claimed to give the right temperature and automatically adjust the observed radiation for emissivity etc.; see page 7 of the paper), the actual power is actually much lower than [the calculated figure] 1609 watts. The emissivity of metals at similar reasonable temperatures seems to be 0.2 or so – something of this order – which reduces 1609 watts to something like 300 watts, pretty much equal to the consumption.

Pretty much every hint that I have looked at in the paper suggesting that they produce some energy that exceeds the electricity consumption from the power outlet seems to be plagued by similarly basic errors.

Recall that I believe that the error in virtually all Rossi's presentations is that he assumes that the boiling point of water is always 100 °C, regardless of the pressure, and he "takes credit" for the evaporation of lots of water that actually stays mostly liquid because it's below the boiling point which is above 100 °C if the pressure is elevated (and it is elevated in his setup); even visually, it's clear that liters of water can't be getting vaporized because the steam would look much more intense than the feeble traces of vapor coming from his "miracle gadget". All these errors seem completely elementary to me. It's hard to say whether the authors see them or not. I guess that they're training themselves to overlook them because they are afraid that by admitting they have believed and promoted something that so silly that clearly doesn't work, they would look like complete idiots – and indeed, they look like complete idiots even if they try to obscure the evidence.

To summarize, the preprint is complete rubbish and the authors are probably linked to Andrea Rossi personally but that doesn't prevent the loudest blogger of the LHC's CMS Collaboration to partially endorse this preprint – without even attempting to read it because "this is not [his] field of research" – and suggest even though he hasn't looked at this paper at least to see that it's pure trash (and it's very easy to see), he will more closely follow cold fusion because of that. It's so easy to propagate lies and stupidity in this world especially because most people are even more stupid, mindless sheep than Tommaso Dorigo.

At any rate, I am amazed by Dorigo's claim "not to be an expert" itself. He is an experimental subnuclear physicist and this is a claimed groundbreaking paper in experimental nuclear physics. I have not been an experimenter at all but I see nothing in the paper that I could be misunderstanding because of an insufficient background. You see that even people claiming to be "scientists" often don't behave as scientists. Without even trying to study something, they just uncritically endorse some ambitious claims. And in many cases, their "being a scientist" is exploited in the promotion of a nonsense even though they clearly failed to evaluate the issue scientifically. Note that it's enough to find a few dozens of such "scientists" who haven't performed even the basic checks and the media often claim a "scientific consensus" even though the strength of the scientific evidence behind the claim is exactly zero.

With this extremely sloppy attitude, you can't be surprised that Mr Dorigo and others have no problem to deny string theory or other basic pillars of modern science. This particular chap denies completely basic insights into nuclear physics as well – and never hesitates to use a paper not knowing how numbers with units are written as evidence that nuclear physics fails.

See also a dozen of previous articles on this blog that mention Rossi and fusion.

Concerning somewhat more realistic sources of energy, see this new wind turbine with funnels (via Joseph S.). They claim to concentrate the wind so that 1 kWh only costs $0.20 or so – almost competitive with coal etc. at the Czech prices. The gadget looks silly but I do think that the concentration of wind energy (and similarly, possibly, concentration of solar energy with mirrors) is a largely unused way to make these "renewable" sources cheaper and more productive.

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Lee Smolin: Time Reborn

An incredible pile of unscientific gibberish

There's one aspect in which Lee Smolin's newest book is less irritating than his previous book, The Trouble With Physics: the main purpose of the new book isn't to mindless attack and lie about the best results of the contemporary theoretical physics research. Instead, if we ignore the mega-arrogant and super-dishonest subtitle "From the Crisis of Physics to the Future of the Universe", "Time Reborn" tries to attack physics from the times of Newton and "constructively" present Smolin's own ideas about physics – or something he apparently calls "physics" – and it's a stinky junk of the most despicable kind, indeed.




You may read some reviews before you decide whether you want to buy this tome or not. But let me summarize some basic points and some characteristic elementary mistakes that may serve as examples of what this pile of paper is all about.




If one suppresses the actual atrocious content of the book, its main thesis may be summarized by the slogan "time is real". What does it mean? Smolin opposes the idea that time may be emergent or the spacetime is doomed – without offering a tiniest glimpse of evidence for his prejudices. Everything must be a slave of time. You may recall his delusions about time-dependent laws of physics – this preposterous and ill-defined concept is given some attention, too.

You might think that the book is therefore a sequence of inconsequential quasi-philosophical babbling that is entirely disconnected not only from the advances in physics of the last 40 years – which was the case of "The Trouble With Physics" – but it is also unrelated to the physics research of the 20th century and probably physics as we have known it for 300+ years. And you would be mostly right. Most of the book is composed of scientifically meaningless words of the author who knows nothing about science but who can't resist to preach about his medieval philosophical prejudices.

But it would be just a part of the truth.

In fact, he does mention some things related to modern physics but almost always negatively so. He makes it very clear that he wants physics, science, and Nature to obey the prejudices of this super-arrogant would-be thinker and he wants to pay no attention whatsoever to what Nature and science research are actually telling us. He is clearly the polar opposite of a good physicist – or an honest human being, for that matter.

Off-topic – surely unrelated to Smolin because related to experiments: LHCb published its paper on the first observation of CP-violation in the decay of \(B_s\) mesons. Via Joseph S.

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Dark matter: Some new papers incorporate the three highly persuasive events from CDMS. Frandsen et al. use a Kundera-inspired title to make the remarkable claim that this light dark matter is not ruled out by XENON, thus strengthening the "dark matter is seen" alliance in the dark matter wars. Del Nobile et al. are more negative in their halo-independent analysis. See also an older 2010 paper by Fox, Liu, Weiner. Via Neal Weiner's tweets.

How does it influence his proclamations about physics? For example, he predecides that time has to be fundamental but he also predecides that space is not. He seems to think that he is being told such insights directly from Heaven. However, we've known since the 1905 discovery of the special theory of relativity by Einstein that space and time are related by a symmetry – the Lorentz symmetry – so when it comes to certain properties such as their being "real" or "fundamental", they must have the same properties. How does Smolin deal with this fact?

He simply ignores (and spits on) all the evidence in favor of relativity. The scientific evidence – empirical facts and/or credible observations – never play a role in decisions about his portrait of the world. Well, more precisely, they do play a role – a negative one because Smolin seems to be obsessed with writing gibberish that contradicts the maximal possible number of scientific results.

It's not just relativity that gets spitted upon in this way. All these negative statements are being extrapolated to downright pathological dimensions. So you will find an almost literally endless tirade attacking the concept of symmetries in physics. Symmetries has to be destroyed, Smolin preaches. Every theory that has too many symmetries in it has to be banned. Given the importance that symmetries have played in physics for a century, we can only say one thing: What an amazing imbecile!

Needless to say, Smolin – who has no clue why relativity is not only right but an important finding about Nature – has no chance to understand quantum mechanics which is arguably much more inaccessible to the eternally hopeless laymen such as himself. So there's another endless tirade in which we "learn" that quantum mechanics has to be wrong as well and it will surely be replaced by a hidden variable theory. There isn't a glimpse of evidence supporting this bold claim, either. And all the evidence proving that this statement by Smolin is demonstrable bullshit are completely suppressed.

Even this theme isn't enough for Smolin so it gets generalized. Everything about physics has to be wrong. Moreover, he seems to assume that as soon as he convinces you to agree that something about the current picture of physics will be modified in the future (which is conceivable), you will have to accept his delusions instead (which is not conceivable). No suggestion that his delusions could be wrong as well can ever be found in the book. He behaves like a fungal cell that conspires to eliminate the good bacteria from your guts and instantly wants to occupy their place. Fungi may be hard to fight with but at least some imperfect fungicides and fungistats exist. I am not sure whether there exist efficient enough Smolinocides. At least in the institutions that are supposed to do science, they're badly needed.

The diversity of "obviously right and important" insights of science that Smolin can't resist to attack because they contradict his medieval dogmas is unbelievable. For example, he tells you – without any apologies – that electrons in the Universe are not indistinguishable. To "prove" this point, he says that one electron may be on Earth and another electron may be on the Moon so they're distinguishable.

He both misunderstands what the identical nature of particles means; and why it's true. Or he at least pretends to misunderstand both of these things. Location may effectively distinguish two or several electrons but the point is that if two or several electrons share the same region or come to occupy "states" that are not separated from each other by a "gap", e.g. during a collision or in the atom, we can't say "which one is which one" and connect the electrons in the initial state with those in the final state. For example, in terms of Feynman diagrams, we must sum over all the histories including the possible permutations of all the electrons to get the right result (the right probability amplitude). He can't possibly understand any of this basic undergraduate physics about (anti)symmetric wave functions. Or he understands it but finds it OK to hide all the evidence known to him that unequivocally implies that this whole book is a pile of shit.

If someone writes hundreds of pages of an incoherent text that dismisses not only the Lorentz symmetry, quantum mechanics, and (of course) quantum field theory and string theory (the only other known framework that is capable to reproduce and surpass the successes of QFTs: all these essential facts are totally censored in the book) but also any symmetry and probabilities and almost every other important result of the 20th century physics – such as the indistinguishability of particles – don't you agree that a "hardcore crackpot" is a very accurate description of the person? I don't believe that there exists a competent physicist who doesn't agree that Lee Smolin is a hardcore crackpot – although there may be folks who, probably for egotist reasons, try to hide this understanding of theirs.

The last three chapters resemble a speech of an Islamic fundamentalist preaching before the execution of a heretic who is being stoned to death. There isn't a trace of science in those chapters. It's pure religion and screaming that everyone must act to agree with Smolin's unscientific delusions. Lots of the book is dedicated to would-be arguments that physics shouldn't be studied using mathematics which is apparently "limited" for him.

I originally forgot but Phil Gibbs reminded me about an unbelievable claim in the book – that the best studied approach to quantum gravity is... loop quantum gravity. A somewhat honest crackpot might think various bizarre things, e.g. that loop quantum gravity is more correct, but the fact that string theory is more studied than loop quantum gravity by orders of magnitude is undoubtedly well-known to Mr Smolin so this proclamation has to be a deliberate lie.

The book is so terrible that it got a very negative review from Smolin's other most notorious fellow sourball, too.

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Speed of light is variable: only in junk media

Francis the Emule (Spanish) diplomatically agrees with me...

If you open Google Science News at this very moment, the #1 story is saying things like

new research shows that the speed of light is variable in real space.

The only problem is that the "research" is pure crackpottery. Those stories build upon the following two papers in a journal called European Physical Journal D I have never heard of in the context of fundamental physics:

A sum rule for charged elementary particles by Gerd Leuchs, Luis L. Sánchez-Soto (free: arXiv)

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The quantum vacuum as the origin of the speed of light by Marcel Urban, François Couchot, Xavier Sarazin, Arache Djannati-Atai (free: arXiv)

The abstracts are enough to see that the authors aren't just making one or two serious technical errors. Instead, they misunderstand the very logic of science - how arguments in favor of some claims may or may not be phrased.




The first, German-Spanish paper tries to claim that the sum of squared electric charges over all elementary particle species (regardless of their mass) is \[

\sum_i Q_i^2 \sim 100.

\] This is quite a bold statement. You may try to look what is the quantum field theoretical (or stringy?) calculation leading to this condition. What you will find is that there isn't any quantum field theory in the paper at all!




Instead, the paper misinterprets virtual particles etc. in the way you expect from a 10-year-old schoolkid. For them, the virtual particles are real and they're connected by springs of some sort. Some physically meaningless calculations lead them to the sum of the squared charges. If you try to find out where the number \(100\) came from, you will find out that it was calculated as a function of three more real parameters whose values were chosen arbitrarily.

It would be a terribly stupid paper even for a 10-year-old boy. But the authors must believe that it's possible to learn things about physics in this way even if they don't know anything about the way how modern physics describes particle species and their interactions with the electromagnetic field – about quantum field theory. So one sentence in the paper refers to quantum field theory, after all. It's the last sentence before acknowledgements that says:

We hope that this result will stimulate more rigorous quantum field theoretical calculations.

Wow: they leave the details for their assistants whose task is to convert the ingenious findings that contradict everything that a quantum field theory could say about these matters to a proof in quantum field theory.

Needless to say, it's totally impossible in \(d=4\) to have a similar constraint for the sum of squared charges. At most, the sum of cubed charges is what enters the gauge anomalies in \(d=4\). But summed squared charges over particle species can't occur in physically meaningful formulae. Moreover, the number of particle species is really infinite – although most of them may have masses near the string scale or higher – so the sum is either ill-defined or divergent. In other words, it's implausible for an important physical formula to deal with particle species regardless of their mass.



Via Gene, off-topic: Lots of music for a buck.

The other paper, the French one, is a similar nonsense about the variable speed of light. These papers are being clumped together because the authors of both of them are clearly pals and they coordinated their invasion into the journals and the media. Let me repost the abstract here:

We show that the vacuum permeability and permittivity may originate from the magnetization and the polarization of continuously appearing and disappearing fermion pairs. We then show that if we simply model the propagation of the photon in vacuum as a series of transient captures within these ephemeral pairs, we can derive a finite photon velocity. Requiring that this velocity is equal to the speed of light constrains our model of vacuum. Within this approach, the propagation of a photon is a statistical process at scales much larger than the Planck scale. Therefore we expect its time of flight to fluctuate. We propose an experimental test of this prediction.

Unbelievable. Look at the first sentence. They think that they "show" that the vacuum permeability and permittivity "may" originate from the magnetization and the polarization of continuously appearing and disappearing fermion pairs. (Needless to say, there's no quantum field theory in this paper, either.) How do they achieve this ambitious task?

It's easy. They forget and ignore everything we know about physics and everything they should have learned about physics, even at the high school. In this state of perfect oblivion, one isn't constrained by any knowledge at all – because there isn't any knowledge – so anything goes and an arbitrarily stupid pile of crackpottery "may" be true and one thus "shows" that it's possible.

Except that a person who knows something about physics may show that pretty much every sentence in this paper is pure rubbish. Their particular nonsense that "may" be true as they "show" is that the vacuum is chaotic for photons so the light propagation is chaotic and the speed is variable. By saying these things, they prove that they don't have the slightest clue about the actual explanation of the existence of light that we have known since the late 19th century.

The actual explanation of light is that it's a type of electromagnetic waves. And electromagnetic waves are simple solutions to Maxwell's equations, the equations that describe all electromagnetic phenomena. These equations are particularly simple in the vacuum. Maxwell's equations in the vacuum are actually the more fundamental ones; the propagation of electromagnetic waves in other mediums requires some extra work.

But in the vacuum, the permittivity \(\varepsilon_0\) and permeability \(\mu_0\) simply enter Maxwell's equations as conversion factors that disappear – that are replaced by \(1\) – if we use more natural units. The reason why I say these things is that \(\mu_0,\varepsilon_0\) are not supposed to be "derived" from any complicated mechanism involving lots of charged particles etc. On the contrary, they're players in the most fundamental equations of electromagnetism and it's the behavior of lots of charged particles that is "derived" and that can be reduced to fundamental Maxwell's equations.

Hendrik Lorentz was the first man who showed that Maxwell's equations in general materials may be derived from the vacuum Maxwell's equations combined with some behavior of the charged and magnetized particles that exist inside the materials. It was an important insight (it helped Einstein to think in the right way when he was marching towards relativity) and people could have been unfamiliar with this insight at some point – except that Lorentz found those things more than 100 years ago so they shouldn't be unknown to authors of a journal called European Physical Journal D in 2013.

The authors are trying to derive the light propagation in the vacuum from light propagation in some fictitious complex material – which is exactly the opposite strategy than physics chooses (and it's obvious why it chooses the opposite one): complicated materials are more complicated than the vacuum. In other words, the authors suggest that if their contrived "additional" effects didn't exist, the permittivity and permeability would vanish in the vacuum. But they couldn't vanish. Even when all the chaos is removed, physics must be described by non-singular equations which essentially means – among many other things – that the permittivity and permeability would still have to be finite nonzero constant in the vacuum. We know what these constants are: they are \(\varepsilon_0,\mu_0\).

But what is even more important is that the authors don't understand what is primary in science: unrestricted speculations about the ways how the world "may" work, or constraints from observations and experiments? They clearly think that it's the former. They "may" write kilobytes about nonsensical models that have nothing whatsoever to do with the Universe around us and they claim that this "shows" something.

But science doesn't work like that. We actually know that the speed of light has to be completely constant and free of any fundamental "noise". In fact, our definition of one meter is such that the speed of light in the vacuum is tautologically \(299,792,458\,{\rm m/s}\). So it's obviously constant. The constancy of the vacuum speed of light follows directly from special relativity and special relativity is what we actually know to be true from the observations. So all the speculations must adjust to this knowledge – and all other empirical knowledge we have. The authors' approach is just the opposite: they want the empirical knowledge to be adjusted to their unconstrained fantasies. They simply don't understand the basic point of science that the self-consistency of a hypothesis isn't enough for such a hypothesis to be a good scientific theory. Empirical knowledge actually matters and kills most of the conceivable guesses.

I can't resist to compare their approach with the following question that a user named John Smith asked on Physics Stack Exchange two days ago:

Why perpetual motion wouldn't be possible if we are so technological advanced?

You see some kind of a fundamental misunderstanding about the inner workings of the Universe and the humanity. John Smith – and similarly the authors of the papers discussed in this blog entry – doesn't get the point that regardless of the technological sophistication, every civilization much like every object in Nature is "obliged" to obey the laws of physics and the non-existence of the perpetual motion machines are among these laws (the so-called first two laws of thermodynamics).

John Smith's – and the authors' – opinion about this basic issue (about the very existence of the laws of Nature) is the opposite one. He believes – and they believe – that there are no permanent laws, there are just limitations that we're constantly breaking as we're getting more technologically advanced and more self-confident. The non-existence of the perpetual motion machines (or similarly the constancy of the speed of light in the vacuum) must be just due to some limitations of technology we can surely transcend in 2013 if we want! ;-)

It doesn't make sense to spend too much time with these silly papers. So I will stop and finish this blog entry with the complaint that the adjective European in the name of the journal could be replaced by Idiots' if we wanted the name of the journal to be more accurate. And that's not a good result for the old continent of ours! At the same moment, these idiotic crackpot papers are widely quoted in the U.S. and other media so Europe is not the unique continent on which similar junk flourishes.

And that's the memo.

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