Lubos Motl wrote:

"George Chapline just gave the most provoking and most bizarre colloquium we have seen at Harvard for years. (I guess that the talk would not be bizarre enough for Quantoken and perhaps not even for Arun, and I apologize if they will be disappointed by the amount of strangeness.) Chapline used to be a T.A. for Feynman's lectures, he was awarded by various awards, but his goal right now is to revolutionize our understanding of the strong gravitational fields.

...

In other words, Chapline did not like the idea about the horizon being a regular place in space. He did not explain how he wants to modify the laws of physics in such a way that his new critical behavior replacing the horizon suddenly turns on. He also sketched his condensed matter system where the speed of sound goes to zero and asked what happens. Bert Halperin answered but my guess is that during his next lecture, Chapline will repeat his remark that no one at all the famous universities he will have visited knew the answer ...

...

The causal structure is guaranteed by the rules of special relativity that have been tested in detail - and for which there are no good reasons to violate them in a drastical way. And the temperature and the entropy were first calculated by Hawking who followed Bekenstein, but then they were also reproduced by completely independent methods from the microscopic counting of string theory - a calculation that was definitely not guaranteed to give the same results but it did. That is a pretty strong double argument.

Someone asked whether Chapline's new picture of the black hole also requires one to alter the membrane paradigm by Kip Thorne, in which the horizon is viewed as a superconducting membrane, and the answer was that the speaker did not know what the paradigm was.

A particular example of the application of "emergent phenomena" beyond the realm of their validity was the attempt to explain gravity as an emergent phenomenon based on some spin-2 bound states of quasiparticles near the Fermi liquid - the type of work that was done by Zhang and others. In reality, the existence of such bound states was never really justified, and if there were any evidence that such bound states could have existed, such arguments would have allowed not only for the spin-2 "gravitons" but also for higher-spin particles that simply should not exist.

There are many theorems that show that gravity can't be constructed in one way or another, that the interactions are incompatible with higher-spin gauge symmetries, and all things like that. Such no-go theorems are sometimes circumvented by string/M-theory, but it always involves a non-trivial feature of string/M-theory that was not anticipated before and that violates some of the more or less hidden assumptions.

All these vague arguments about gravity being constructed as a solid state system only existed at the level of free particles and there were never hints that the interactions of these particles shall reproduce general relativity. Given the fact that the very reason for introducing gravity is that it is an interaction, the failure to reproduce the interactions is pretty serious.

But even a priori, is there any reason to believe such pictures and pursue them? I think that the primary motivation for such attempts is to satisfy our old instincts that everything, including the most mysterious objects such as those in high-energy physics and quantum gravity, must eventually be "made" of the things we know from the everyday life such as water, wine, bread, and butter.

These objects are macroscopic, slow, low-energy, and with the exception of wine, they are also predictable and deterministic.

In my humble opinion, this approach may be good to entertain ourselves and our non-physics friends, but it is a misguided approach to theoretical physics - and I don't mean just fundamental physics right now but any physics that transcends our everyday lives - simply because theoretical physics has become less intuitive and more mathematically abstract, and it had to be so. And it will be so in the future. And it is one of the symptoms of a true conceptual progress. The humans have been trained to comprehend phenomena associated with classical, non-relativistic, low-energy physics - and it should not be unexpected that the intuition fails if we try to understand quantum, relativistic, high-energy, unusual phenomena that go beyond the realm of validity of our naive approximations."

http://motls.blogspot.com/2005/03/chapline-black-holes-dont-exist.html

Lubos Motl also allegedly wrote in http://motls.blogspot.com/2007/03/steven-weinberg-vs-weird-physicists.html:

The Reference Frame:

Steven Weinberg vs weird physicists: torsion

The most important events in our and your superstringy Universe as seen from a

conservative physicist's viewpoint

Saturday, March 03, 2007 ... /////

"Steven Weinberg vs weird physicists: torsion

A reader has pointed out the following exchange between Steven Weinberg and

Friedrich Hehl in the new issue of Physics Today. If you've never heard about

the latter, you're not the only one. For our purposes, it suffices to know that

this Gentleman has written down many meaningless theories of gravity with an

extra torsion tensor. They have no relevance for experiments and they have

nothing to do with the most important advances in physics of the last 100 years

or so.

Hehl offers some religious, scientifically meaningless statements or loud

screams why the torsion tensor is needed or why it is special, citing some

physically irrelevant sources from the early 1920s. Weinberg of course gives the

only answer that a sane physicist can give: the torsion tensor is just another

tensor field - one that isn't needed for any symmetry, consistency, or beauty -

so if there is no experimental reason why it should be added, and surely there

is no such reason today, it won't be added. Period."

I, Jack Sarfatti rebut Motl: Everything Lubos says here is simply false. Three good references showing Lubos statements to be false are

1. L. O' Raifeartaigh "The Dawning of Gauge Theory", Princeton 1997 Ch. 2, & Ch 10 on Utiyama 1956 locally gauging rigid SO(1,3) to get part of general relativity. Actually what Utiyama got was the torsion-induced curvature beyond Einstein's 1916 theory, but no one realized it at the time.

2. J. C. Taylor "Gauge Theories in the Twentieth Century" 3.1 "Gravity as a gauge theory" T.W.B. Kibble "Lorentz invariance and the gravitational field" J. Math Phys 2 (1061) 212-21 shows that Motl simply does not understand the facts. Kibble showed that when you locally gauge the full RIGID 10 parameter Poincare group of 1905 special relativity you get Einstein's theory generalized by Cartan to include torsion fields as well as curvature fields. Einstein's 1916 torsion-free theory is what you get when you locally gauge only the 4-parameter translation group. This gives the non-trivial part of the 4 tetrad 1-forms as the compensating "Yang-Mills" type compensating gauge potentials (Levi-Civita connection for parallel transport is bilinear in the tetrads and their gradients). When you, in addition, locally gauge the 6-parameter Lorentz group you also get 6 dynamically independent spin-connection 1-forms as compensating potentials giving ultimately the contortion tensor used in theories like Hehl's, Hammond's, Kleinert's et-al. Note 1916 GR T4 only gives curvature-only spin-connections that do not have torsion gaps.

3. Hagen Kleinert's work http://www.physik.fu-berlin.de/~kleinert/kleinert/

"part from the above, the book presents the general differential geometry of defects in spaces with curvature and torsion and establishes contact with the modern theory of gravity with torsion." - Kleinert

Lubos Motl continues

"Weinberg as a relativistic heretic

The origin of this controversy goes back to the 1970s. Weinberg's textbook on

general relativity was very modern - and oriented towards the interpretation of

general relativity as a part of the effective quantum field theory - as it

presented the metric tensor as another field in spacetime whose local symmetry

happens to coincide with the diffeomorphism symmetry but it is just a technical

detail: interacting spin-two fields simply must have gauge symmetries that

reproduce diffeomorphisms. Because of that, we can interpret the whole theory as

a theory of curved space but we don't have to: the metric tensor may also be

viewed as another field living in the Minkowski spacetime or, equivalently - by

symmetries - any other spacetime that you might imagine to be your starting

point. You don't need to know the words "curved space" to calculate the

predictions of general relativity."

(Jack Sarfatti) This is simplistic as can be seen from Feynman's Lectures on Gravitation and Roger Penrose's work on the "nonlinear graviton".

The point is that you do not get the full power of GR for strong fields until you sum an infinity of Feynman diagrams based on the globally flat Minkowski background. This is non-analytic (Ken Wilson) "More is different" (PW Anderson) emergence like in the BCS theory of superconductors. Sure you can do post-Newtonian first order perturbation theory using flat spacetime background, but you will never get horizons.

For example, in SSS solution, the flat background is

g00 ~ 1 - 2GM/c^2r

only in the limit 2GM/c^2r << 1

BTW Puthoff makes a similar error in his PV theory. Dicke never meant his 1961 model to be used beyond the above approximation.

Lubos: "A certain group of people in cosmology has reacted just like religious bigots

and they wanted Weinberg to "retract" these statements whose validity is

completely obvious to anyone who has any idea how field theory - especially

quantum field theory - works."

Jack: Lubos completely misses the point here.

Lubos: "However, the deeper you penetrate into the

community of the loop-quantum-gravity-like pseudoscientists and their fans, the

less clear these things are to them. Weinberg has never retracted but I think

that it is fair to say that these loud irrelevant fourth-class scientists have

intimidated Weinberg into silence which is kind of scary."

Jack: So, Lubos thinks Roger Penrose, Stephen Hawking, Kip Thorne, John Wheeler, Charles Misner are "fourth class"?

Lubos has shifted here from physics to polemics.

Lubos: "Unification vs segregation

Those people think exactly in the opposite way than a theoretical physicist

should. Theoretical physicists want to unify the laws of Nature. They want to

understand an ever greater set of phenomena using theories with an ever smaller

number of independent assumptions and parameters. Gravity is a manifestation of

something that we can call spacetime geometry - but all of physics may be viewed

as a manifestation of some "generalized geometry". There is no fundamental gap

between gravity and other fields. There is only one world whose parts constantly

interact. Any attempt to separate the world into two parts - geometry and matter

- is bound to be an approximation or worse. All of these objects in field theory

are just some tensors that are coupled according to some rules."

Jack: Too vague to be useful. However, the fact that gravity is simply Yang-Mills theory applied to the Poincare group rather than internal groups does do what Lubos yearns for here, but the price is the torsion field that Lubos says is crackpot physics! Lubos is hoisted by his own petard! My own polemics. ;-)

Lubos "In fact, string theory shows that the metric tensor field and the matter fields

arise in the very same way from more fundamental ingredients."

Jack:

ds^2 = e^aea = guvdx^udx^v

e^a is the Einstein-Cartan tetrad 1-form

Lubos "What's important for these interactions is whether they respect some crucial

symmetries and whether they lead to self-consistent predictions that are finite

and whether these predictions can be successfully compared to experiments. We

also want the number of independent parameters - the total number of all

coefficients of terms that can be added without modifying the symmetries - to be

as small as possible so that the theory's predictivity is as large as it can be."

Jack: Cliche. Sure. So what else is new?

Lubos: "Regardless of words, the most general interactions between your tensors must be

considered"

Jack: Cliche. Sure. So what else is new?

Lubos: "Everything else is just religious nonsense. You may try to guess other

principles or ideas how the theory should look like that can lead you to the

right theory if you're lucky. But they don't have to. You can't consider your

own idiosyncratic beliefs to be an argument for your approach before any other

material evidence - either theoretical or experimental - for your theory

appears."

Jack: Polemical ranting.

Lubos: "What about the torsion? Torsion is a hypothetical part of the Christoffel

connection that is antisymmetric in the lower two indices. In conventional

general relativity, the symmetric connection is derived from the metric tensor

and its torsion is simply zero. This is the grand theory that has been

successfully tested. The three-form H-field in many vacua of string theory may

be viewed as some kind of torsion. It's because the conditions for an unbroken

supersymmetry include the term proportional to the H-field in a way that is

analogous to the old papers that discussed torsion together with spinors."

Jack: Obviously Lubos has no knowledge of Kibble's 1961 paper. He is making something simple overly complicated. So like a string theorist! :-)

Lubos: "Other fields in string theory

But if you don't know this "torsion" jargon, you don't lose anything. The

two-form B-field and its exterior derivative, the H-field, are just other

examples of fields in the effective field theory. They have some couplings and

some gauge symmetries and string theory predicts all of them, up to field

redefinitions that can, of course, always be made. It is somewhat misleading to

use the word "torsion" because we can't really say that all objects are affected

universally by the background fields. It is more usual that we interpret the

H-field as a generalization of the electromagnetic field than a kind of a

torsion tensor. And we have good reasons to do so.

For example, charged objects are also influenced by non-gravitational gauge

fields. In the presence of matter, it is no longer true that the geometry knows

everything about the natural motion of objects in a general situation. We need

other fields, too. Once we accept that there are other fields, we must consider

the most general set of rules controlling these degrees of freedom that are

consistent with the given symmetry and consistency principles. In particular,

the torsion is just another tensor and it is not true that its couplings are

completely determined. All contractions of indices etc. are legitimate a priori.

The statements that the dogmatic torsion is necessary because of [some

incoherent principle] are completely dumb."

Jack: An ignorant remark for reasons stated above.

Lubos: "Torsion is not necessary simply

because the theories we have don't include any torsion, they are

self-consistent, and they moreover agree with experiments."

Jack: That 96% of the stuff of the universe is not atoms and photons etc MAY PERHAPS be the smoking gun for torsion fields. Also maybe the Pioneer anomaly. Indeed dark energy and dark matter are the elephant and the 800 gorilla in the room.

Lubos; "It is plausible that

a more complete theory would predict new fields but these fields must be

massive, otherwise they would contradict observations. For example, the

three-form H-field in four-dimensional string-theoretical vacua may be

Hodge-dualized to a one-form which is a gradient of a scalar field called the

universal axion. This particle may or may not exist but it must be massive,

otherwise it would induce new forces that are not observed.

Irrational pressures

At any rate, the idea that there are some additional aesthetic conditions in

field theory that tell you that you should include fields that are otherwise

clearly unnecessary or conditions that tell you that you shouldn't allow some

interactions of some fields just because you want to use some name for these

fields is analogous to astrology. Nothing like that can be used in science. Such

new ideas could only become valid if you showed that they are necessary for some

kind of new symmetry, or that they must arise from an underlying high-energy

theory. At the sociological level, I am flabbergasted how the people who

understand physics and contributed to physics at a rate below 0.1% of Steven

Weinberg are self-confident when they try to intimidate him."

Jack: Again Lubos is obviously not aware that locally gauging the Poincare group in same way as internal groups gives curvature + torsion Einstein-Cartan theory. All we need is the battle-tested local gauge principle applied to the rigid spacetime symmetries of global special relativity and you cannot avoid torsion in addition to curvature.

Lubos: "Einstein's flawed attempts

In the last decades of his life, Einstein used to think about many unified

theories. He thought that only gravity and electromagnetism were real:

everything else was supposed to miraculously emerge from the approach. So he has

tried all the silliest theories you can imagine - for example, an asymmetric

metric tensor whose antisymmetric part describes F_{mu nu}. Torsion was another

example. The greatest mistake of Einstein was his inability to accept the

probabilistic nature and predictions of quantum mechanics. But the unjustified

attempts to "extend" the metric tensor in order to cheaply include

electromagnetism may be viewed as the second greatest blunder of his life.

For example, if we imagine that the metric tensor is not symmetric, we are still

allowed to split it into the symmetric and antisymmetric part. These two parts

can be treated separately: they can have different interactions. If you treat

them separately, you are still able to satisfy all principles of your field

theory. The Lagrangian is locally Lorentz-symmetric and the full action is

diffeomorphism invariant if you do it right. An action written in terms of an

asymmetric tensor could "look" shorter than a general action describing the

action for the symmetric part and the antisymmetric part but Nature never cares

whether something "looks" shorter. For example, the action of eleven-dimensional

supergravity is not really "short" but it is the most symmetric gravitational

low-energy field theory that exists. It is symmetry and rigidity, not the

length, that matters in physics. The crackpots won't ever get this point."

Jack: Note Lubos use of "crackpot" - overkill, too broad a brush - a bad habit he picked up from John Baez who Lubos thinks is a crackpot for pushing L. Smolin's loop theory approach to quantum gravity. Rovelli is also a crackpot in Motl's black book. Lubos accepts 11D supergravity theory as some kind of Holy Revelation. Sir Roger Penrose then becomes a "crackpot" in Lubos's lexicon for his critique of extra dimensions in "The Road to Reality" for example.

Luubos: "The same comment applies to torsion. If you consider an asymmetric Christoffel

connection, you are still allowed to break it into pieces, i.e. irreducible

representations of the Lorentz group or "GL(4)", and to add different

interactions for these pieces. For diffeomorphism invariance, the symmetric part

will be equivalent to what you get from a metric tensor, and the antisymmetric

part is just another tensor field. There can't be any natural unification here."

Jack: Blatantly false as shown by Kibble cited above.

Lubos: "If your action looked simple in terms of an asymmetric metric tensor or an

asymmetric connection, it would be a pure coincidence. You would still have to

consider all possible deformations of this theory - in which the interactions of

the parts differ - to be equally valid candidates to describe reality.

Horizons and the geometric intuition

Is there something in GR that you can't derive by assuming that the metric

tensor is just another tensor field on some background - e.g. the Minkowski

background? Well, GR predicts the existence of spacetime topologies and causal

diagrams that differ from the Minkowski spacetime. Are they possible? Well,

almost certainly. But still, their existence is compatible with the

interpretation of the metric tensor as another field. The geometric intuition

just gives you a good tool to deal with some singularities: for example, you may

find that the black hole horizon is a coordinate singularity and you can

continue your physical laws to the interior of the black hole. You can see that

there is nothing special happening near the black hole event horizon."

Jack: Again false as shown by Feynman for example.

Lubos: "But this conclusion also follows from a careful analysis of field redefinitions

that are helpful to understand physics near the black hole horizon. These field

redefinitions are nothing else than diffeomorphisms,"

Jack: which are simply the local gauge transformations in going from rigid T4 to local T4(x).

Lubos: "and by making the geometry

look smooth near the event horizon, you obtain a natural hypothesis what should

happen when you cross the horizon: namely nothing."

Jack: True in GR, but not true in Chapline's replacement of GR,

Lubos: "Experimentally speaking,

we're not quite sure. We will never be sure unless the whole planet falls into a

black hole which is not the best collective career move.

It can still be true that you die when you hit the black hole horizon. But the

required laws would violate locality and causality - principles whose precise

form is influenced by non-zero values of the spin-two tensor that we happen to

call the metric. These principles are valuable. The dogma about the existence of

torsion is not an independently valuable physical principle and Weinberg has

always been 100% right when he rejected irrational arguments to include such

"principles" into science.

And that's the memo.

Update: Dean of crackpots

I was also told that the dean of crackpots has written about this exchange."

Jack: Who is that pray tell?

Lubos: "The dean himself offers several characteristically absurd comments attempting to

paint Steven Weinberg as the owner of extreme opinions. Steven Weinberg is one

of the people who have defined the mainstream of particle physics for more than

30 years.

In the discussion, some people including Sean Carroll and Moshe Rozali correctly

say that one must include all terms in the Lagrangian that are consistent with

given symmetries. The dean himself argues that "he understands the effective

field theory philosophy", but in order to instantly show that he doesn't, he

says that he is unconvinced because quantum field theories should be valid at

all energies. QCD is and N=8 SUGRA may also be, so why not. Well, he's just too

limited.

Whether or not these theories are well-behaved in the UV can't change the fact

that new physics must surely enter at the conventional 4D Planck scale or

earlier, for example because our world includes gravity. Our world can't be a

pure QCD as the famous apple demonstrates. With gravity, all these theories are

only effective field theories. Even in the case of N=8 SUGRA, the supergravity

description itself is clearly incomplete non-perturbatively because it can't

reproduce poles from the black hole intermediate states.

In the debate with Sean Carroll at the beginning of the debate, the dean shows

that he clearly doesn't understand that the torsion is just another tensor and

its couplings are not determined. It's just amazing how incredibly ignorant this

person is - a person that has been chosen by dozens of journalists to talk big

about physics."

Who is Lubos talking about?

Here Lubos's Polemic/Physics ratio is singular. ;-)

Lubos: "Crackpot Tony Smith tries to spin some - already bizarre - statements by Paul

Ginsparg who has conjectured that Steven Weinberg has "renounced his views". The

similarity of their language with the medieval catholic bigots is clearly

causing them no pain whatsoever. As an argument supporting the opinion that

Weinberg has "renounced" his views, they say that Weinberg likes extra

dimensions in string theory which are geometrical in nature. Well, that's nice

that they are geometrical but the low-energy field theory in 10D is just another

field theory with some tensors, and so is its decomposition in the form of the

four-dimensional effective field theories. In all cases, it is Weinberg's rules

of physics that are important, not pre-conceived opinions about "geometry".

All of string theory may be viewed as a certain generalization of geometry. The

real question is how exactly the right generalization works. ;-) There's no

doubt that string theory has already refined our notions about geometry - by

topology-changing transitions, mirror symmetry, T-duality and so on. If we want

to answer the question what is the right form of geometry in Nature, we must

isolate the right physics arguments and calculations instead of attaching silly

stickers "geometric - good" and "non-geometric - bad" to different ideas. If you

choose any set of axioms or ideas that are called "geometry" at a given moment,

you are never guaranteed that Nature is going to satisfy them. The previous

sentence has been proved many times in the history of physics. It is She who

decides, not you.

Another "wise man" called Eugene Stefanovich argues that Weinberg also has

non-orthodox views on quantum field theory because he starts his derivation of

the theory from particles which makes fields less fundamental. Last semester I

have largely followed Sidney Coleman's QFT I notes that start from particles,

too. What's exactly non-orthodox about it? All these concepts - including fields

and particles - are ultimately parts of the overall picture. There is no

God-given algorithm telling you what you should start with when you learn or

teach these things. Any attempt to pretend that such a God-given algorithm

exists is religious bigotry, not science. Every particle physicist who thinks

that particles are not important in particle physics is deeply confused.

Moreover, even if Coleman and Weinberg were the only two physicists who followed

this approach, which they're not, it would no longer be a fringe pedagogical

direction.

Why do we neglect higher-derivative terms

Peter Woit also completely misunderstands why we neglect higher-derivative terms

in various theories such as the Dirac theory or general relativity. He argues

that we must start with minimal couplings and boldly make predictions to avoid

being not even wrong. But this approach is the obsolete perspective of the

1920s. Today, a physicist who understand her field would certainly not argue in

this way. The reason why the higher-derivative terms (e.g. higher powers of

curvature in general relativity) are not that important is that they are

higher-dimension operators whose effects decrease faster as you go to longer

distances: every derivative adds a 1/L factor to the typical size. The operators

with many additional derivatives are called irrelevant perturbations and it is

the most relevant ones that dominate the long distance physics. You can always

choose sufficiently long distance scale so that the irrelevant operators will

become as unimportant as you wish. There is no other rational justification to

eliminate the higher-derivative terms - in fact, one can't completely eliminate

them at all without contradicting the rules of the renormalization group flow.

Even if the higher-derivative operators were absent at one scale, you generate

them if you flow into another scale. They can't be absent universally.

Because Peter Woit argues that one should study "simple" theories of this kind

because they are "beautiful" proves that his sense of "beauty" is based on ideas

that have been known to be inconsistent with the laws of quantum mechanics for

more than 30 years and he clearly can't understand anything important from the

last 30+ years of particle physics. Beauty can no longer be measured in this

obsolete Woitian way. It is no longer possible to truncate theories in this way.

There is nothing special about the "minimal" theories he likes to think about.

At the quantum level, one can't really define such minimal theories at all.

There's just far too much organized influence terrorizing people in science.

Whenever your results or conclusions of your work disagree with a sufficiently

large group of ignorants, they will attack you personally in the worst possible

ways and hire unwise journalists who do the same in the media. They will present

the fact that your results reject their preconceptions as your moral flaw."

Jack: Let He who is without Sin cast the first stone. Seems like Lubos has a large mote in his own eye? :-)

Lubos: "I think that it has become extremely unpleasant to be a part of

institutionalized science, and I am looking forward to be away from the focus of

these intellectual bottom-feeders who exist not only on Not Even Wrong and who

enjoy a silent approval by many of the leftist officials in the Academia."

Jack: "leftist"?

## Monday, July 30, 2007

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