Is Information Theory the Key to Quantum Gravity? A Rant from an Angry Physicist

[marcus]

this new blog (that Peter Woit flagged) is potentially very interesting and
has an uninhibited style

http://angryphysicist.wordpress.com/about/
==quote==

Rantings of an Angry Physicist

An angry Physicist ranting about Quantum Gravity, foundational Quantum Mechanics, the gross incompotency of Economists, and other fun issues!
About

I’m a undergrad at UC Davis, I have been studying physics for two or three years. I started studying from the library at CalTech with a retired rocket scientist and have been fascinated by theoretical physics since. I have a few more years to go until they kick me out with a degree or two; next year I am going to be taking 13 to 15 math courses, so I don’t know how much I can keep up with this blog then. But for now, I read everything I get my hands on and try to read up on every technical paper I can (truth be told: Dr. Carlip is very intimidating with his demigod-like powers to mystically cite sources like one would recite one’s phone number! So that is something to aspire to!) and as a bad habit from my earlier years I tend to think critically (I’m a baaaad man!).

Consequently I reject String theory as it stands now (yes, I am a heathen heretic whatever). Hmmm…I think that if we had strings that are one Planck length long, all we could really know about these strings are their relative position perhaps desribable by a graph? The various graph-states would be superpositioned and we easily recover quantum mechanics via a sum over histories method, etc. But that’s not what bothers me about string theory the most. What bothers me the most is that they propose the existence of the graviton, which I see as cartoonish. I’m certain that String theorists will have a host of insults to hurl at me about this, but it doesn’t change the fact that it makes no sense to have a graviton. Saying “Well quantum field theory demands the existence of a mediating boson” is no better than saying “Well, the bible demands that evolution be false”; it’s a simple appeal to authority.

Anyways, I thought about being an economist a while back (since fifth grade!). I must confess that I have a soft spot in my heart for economics…well, criticisms of Neoclassical and marginalist economics now. I’m an “old school” Neo-Ricardian type of fellow. I might actually post some stuff criticizing Neoclassical economics later on, keep your eyes peeled for it!

Back to my history, uh well, that’s it I guess for now.
==endquote==

 

[Ratzinger]

This is great indeed!

He is really an undergraduate student?

 

[Angryphysicist]

This is great indeed!

He is really an undergraduate student?

Yep, I am a first year freshman at UC Davis; I am taking physics 250 (special topics taught by Steve Carlip - as you imagine by my blog and who the professor is, it is on quantum gravity), physics 9D ("modern physics" - basic quantum theory and relativity), Linear Algebra, and English.

 

[marcus]

High A.P,

Davis could be becoming a strong place, or even more of one.
Did you see Derek Wise's paper?
He should be part of Carlip's (and your) group soon:

http://arxiv.org/abs/gr-qc/0611154
MacDowell-Mansouri Gravity and Cartan Geometry.

 

[Angryphysicist]

Davis could be becoming a strong place, or even more of one.

Perhaps...Dr. Carlip's being at Davis was the reason I chose to go to UCD.

Did you see Derek Wise's paper?
He should be part of Carlip's (and your) group soon:

http://arxiv.org/abs/gr-qc/0611154
MacDowell-Mansouri Gravity and Cartan Geometry.

If I am not mistaken, he is a rather pleasant chap with a British accent.

If that's him, I haven't spoken to him very much. I was not aware of his paper before, it looks interesting. Thanks for the link :)

A number of physics grad students here (except for a handful that I've met) don't believe in a lot of the stuff they write though. Very disappointing to say the least; perhaps, hopefully, he'll be one of the handful exceptions.

 

[ensabah6]

this new blog (that Peter Woit flagged) is potentially very interesting and
has an uninhibited style

http://angryphysicist.wordpress.com/about/
==quote==

Rantings of an Angry Physicist

An angry Physicist ranting about Quantum Gravity, foundational Quantum Mechanics, the gross incompotency of Economists, and other fun issues!
About

I’m a undergrad at UC Davis, I have been studying physics for two or three years. I started studying from the library at CalTech with a retired rocket scientist and have been fascinated by theoretical physics since. I have a few more years to go until they kick me out with a degree or two; next year I am going to be taking 13 to 15 math courses, so I don’t know how much I can keep up with this blog then. But for now, I read everything I get my hands on and try to read up on every technical paper I can (truth be told: Dr. Carlip is very intimidating with his demigod-like powers to mystically cite sources like one would recite one’s phone number! So that is something to aspire to!) and as a bad habit from my earlier years I tend to think critically (I’m a baaaad man!).

Consequently I reject String theory as it stands now (yes, I am a heathen heretic whatever). Hmmm…I think that if we had strings that are one Planck length long, all we could really know about these strings are their relative position perhaps desribable by a graph? The various graph-states would be superpositioned and we easily recover quantum mechanics via a sum over histories method, etc. But that’s not what bothers me about string theory the most. What bothers me the most is that they propose the existence of the graviton, which I see as cartoonish. I’m certain that String theorists will have a host of insults to hurl at me about this, but it doesn’t change the fact that it makes no sense to have a graviton. Saying “Well quantum field theory demands the existence of a mediating boson” is no better than saying “Well, the bible demands that evolution be false”; it’s a simple appeal to authority.

Anyways, I thought about being an economist a while back (since fifth grade!). I must confess that I have a soft spot in my heart for economics…well, criticisms of Neoclassical and marginalist economics now. I’m an “old school” Neo-Ricardian type of fellow. I might actually post some stuff criticizing Neoclassical economics later on, keep your eyes peeled for it!

Back to my history, uh well, that’s it I guess for now.
==endquote==

So if you reject string theory, are you a LQG fanboy then? Or a fan of some other approach like CDT, noncommuntive geometry, twistor theory, supergravity, induced gravity etc.

Personally I'll suspend judgment on string theory until LHC goes live and hopefully finds Higgs bosons and SUSY-partners and possibly evidence of higher dimensions as a result of microblack hole production.

If LHC does not find Susy-partners, and no other evidence for strings, such as cosmic strings, is forthcoming, then I will be intensely skeptical of string theory, and in-the-closet LQG'er :)

BTW which approach to QG does Steve Carlip favor? I recall he, John Baez, and Lubos Motl debating it out over at Sci.physics.research

 

[Haelfix]

Carlip is known more as a GR guru. He wrote the book on 2+1 gravity, has done some LQG work and done some work on BHs. Hes open to new ideas, and tackled various problems of QG that are sort of pushed to the wayside in traditional mainstream research but important nonetheless.

 

[ensabah6]

Carlip is known more as a GR guru. He wrote the book on 2+1 gravity, has done some LQG work and done some work on BHs. Hes open to new ideas, and tackled various problems of QG that are sort of pushed to the wayside in traditional mainstream research but important nonetheless.

Interesting. It appears to me that String theorists feel that since their closed lowest vibration mode of a string is a graviton, and they believe it is renormalizable, that therefore, string theory is the only consistent and only candidate theory of quantum gravity.

 

[marcus]

If I am not mistaken, he is a rather pleasant chap with a British accent.

I have no idea---can't help guess. Derek will officially be in the math department at davis. Might not be around there regularly yet: his postdoc contract begins in the Fall. Here's a picture of John Baez students taken summer 2004
http://math.ucr.edu/home/baez/students.html

 

[Kea]

...since their closed lowest vibration mode of a string is a graviton...

You know, string theory isn't so bad once you get rid of the graviton and other silly things.

 

[ensabah6]

You know, string theory isn't so bad once you get rid of the graviton and other silly things.

If, as angry physicst rant says, you disbelieve in the graviton, then there's no basis for calling string theory a theory of quantum gravity.

 

[Angryphysicist]

So if you reject string theory, are you a LQG fanboy then? Or a fan of some other approach like CDT, noncommuntive geometry, twistor theory, supergravity, induced gravity etc.

I don't really favor any of the current approaches right now, to be honest. I was impressed with Loop Quantum Gravity until we got to the math behind it in Carlip's class, and then I got rather disappointed with some of the choices made (e.g. the SU(2) gauge group being used, etc.).

I'm intrigued by noncommutative geometry, but despite having read Connes book several times I must confess I still don't fully understand the math.

Supergravity I don't understand one bit.

Twistor theory actually has been appealing to me on occasions, but I do not know whether to look into it any further than I all ready have.

I've actually been entertaining the idea of general relativity and quantum theory both being approximations to some underlying theory, but I would have no clue how to approach that.

So all in all I don't really subscribe to any school of thought; as Goethe once said:
Somebody says: "Of no school I am part,
Never to living master lost my heart,
Nor any more can I be said
To have learned anything from the dead."
That statement - subject to appeal -
Means "I'm a self-made imbecile."

I have no idea---can't help guess. Derek will officially be in the math department at davis. Might not be around there regularly yet: his postdoc contract begins in the Fall. Here's a picture of John Baez students taken summer 2004
http://math.ucr.edu/home/baez/students.html

After looking at the picture, I can say that I haven't noticed him too much. He looks like a rather cool fellow though.

 

[Kea]

If ... you disbelieve in the graviton, then there's no basis for calling string theory a theory of quantum gravity.

Who did?

 

[ensabah6]

Who did?

well there's Lubos Motl :0

 

[f-h]

At least as perturbation theory gravitons should make sense.

That is: pick a semiclassical state and study thepropagation of gravitationaldisturbations with respect to it. (e.g. Rovellis work)

Angry Physicist, feel free todo it with a non compact gauge group, you are assured to become quite famous in the QG community if you succeed. In the mean time we'll have to make do with the maths we can handle, not the maths we wish we could handle, and try to do physics within this constraint. Otherwise we're not doing physics but just annoyingly whinning about.

 

[Thomas Larsson]

I was impressed with Loop Quantum Gravity until we got to the math behind it ...
having read Connes book several times ...
Supergravity ...
Twistor theory actually has been appealing to me on occasions...
general relativity and quantum theory...

I am a first year freshman.

Either you are an extreme child prodigy, or you are quite old for a first year undergraduate :!)

 

[marcus]

Either... child prodigy, or ... quite old for a first year undergraduate ...

if it were me I think I'd choose both, that is: to be a former brainy kid who went into economics first (self-educated) and made a bunch of money or anyway somehow had fun being a finance whiz, and then decided on a second career. I would be about 35 years old and have already gone thru around 5 years of sporadic physics self-education reading at the CalTech library

but it is really not worth speculating.
the main thing is it looks like a package of unusual past experience and decisions that led to a good preparation for addressing the problems in QG

they are interesting problems and call for interesting people (like yourself Thomas) to address them

which random combination of accidents prepares you does not matter as long as you can do original research that bears on the problem---ultimately what counts.

 

[josh1]

Either you are an extreme child prodigy, or you are quite old for a first year undergraduate :!)

It appears that he doesn't have a UC Davis email address either.

 

[Angryphysicist]

It appears that he doesn't have a UC Davis email address either.

My ucdavis email is the same as my gmail address, just change the "@gmail.com" to "@ucdavis.edu", I'm just overly paranoid about spam getting into my ucdavis email account as there is an extremely poor spam detector.

Go ahead and email me at my uc davis email account, I'd be delighted to talk with you.

[edit]: out of my sheer love for you, I have changed my email account here to be my ucdavis email account.

Either you are an extreme child prodigy, or you are quite old for a first year undergraduate

I'm told I look old...but not old enough to not get carded

 

[ensabah6]

My ucdavis email is the same as my gmail address, just change the "@gmail.com" to "@ucdavis.edu", I'm just overly paranoid about spam getting into my ucdavis email account as there is an extremely poor spam detector.

Go ahead and email me at my uc davis email account, I'd be delighted to talk with you.

[edit]: out of my sheer love for you, I have changed my email account here to be my ucdavis email account.

I'm told I look old...but not old enough to not get carded

Hey Anger,
Do you know that Josh1 is our angry pro-string theorists here? He aggressively promotes string theory. He's made remarks that offended Peter Woit

Not that there's anything wrong, but when LHC comes online and fails to find SUSY or higher dimensions, and maybe only a single higgs, I think that will set the tone for future string theory research, and give non-string approaches breathing room.

 

[Demystifier]

An angry Physicist ranting about ... foundational Quantum Mechanics ...

I could not found what exactly he said about foundational QM?

 

[josh1]

Hey Anger,
Do you know that Josh1 is our angry pro-string theorists here? He aggressively promotes string theory. He's made remarks that offended Peter Woit...Not that there's anything wrong...

If I’m annoyed, it’s not because of other approaches. It’s because some PF members misrepresent the amount of interest in other approaches shown by researchers in general as a way of preventing other members who don’t know any better from learning why string theory is still the theory of choice for researchers and that this is not a result of stringy people having a "bad attitude".

...but when LHC comes online and fails to find SUSY or higher dimensions, and maybe only a single higgs, I think that will set the tone for future string theory research, and give non-string approaches breathing room.

Actually, although there are strong arguments independent of string theory (in particular, the higgs naturalness argument) that if supersymmetry exists in nature, evidence for it is likely to be found at the electro-weak scale, this need not be the case for supersymmetry to exist. In fact, even string theory can be correct without supersymmetry existing. It’s just that we’ve stuck with supersymmetric solutions since the theory is more tractable mathematically there. So even if evidence for supersymmetry is not found, strings will continue to dominate until a better idea is found since all of the reasons we believe that the current alternatives are hopeless will still apply.

On the other hand, if evidence for supersymmetry is found, all other research programs will be greatly effected because it would become much harder to believe that the correct theory doesn't treat gravity along with the other forces in a way that is much more unified than in all the other approaches.

 

[ensabah6]

If I’m annoyed, it’s not because of other approaches. It’s because some PF members misrepresent the amount of interest in other approaches shown by researchers in general as a way of preventing other members who don’t know any better from learning why string theory is still the theory of choice for researchers and that this is not a result of stringy people having a "bad attitude".



Actually, although there are strong arguments independent of string theory (in particular, the higgs naturalness argument) that if supersymmetry exists in nature, evidence for it is likely to be found at the electro-weak scale, this need not be the case for supersymmetry to exist. In fact, even string theory can be correct without supersymmetry existing. It’s just that we’ve stuck with supersymmetric solutions since the theory is more tractable mathematically there. So even if evidence for supersymmetry is not found, strings will continue to dominate until a better idea is found since all of the reasons we believe that the current alternatives are hopeless will still apply.

On the other hand, if evidence for supersymmetry is found, all other research programs will be greatly effected because it would become much harder to believe that the correct theory doesn't treat gravity along with the other forces in a way that is much more unified than in all the other approaches.

I agree with you 100% if evidence of SUSY is found all other programs will dry up. In fact, I might even do graduate-level work in strings (though I'm more leaning to solid state physics) as I know the job prospects of string theorists are very good (though I might want to work for industry rather than academia).

But if LHC does not find SUSY, one argument for SUSY, that it stabilizes the electro-weak scale against radiative corrections, is undermined. If LHC does not find evidence of higher dimensions, for example, in an unexpected rate of microblackhole production, and no other observational evidence, such as cosmic strings in astronomy, is forthcoming, it's not clear to me that continuing to pursue string theory is rational. ONe argument against string theory is that it is monopolizing theoretical physics and taking away the best and brightest young students away from developing other approaches, such as non-SUSY 4D LQG, toward working on string theory problems. A same situation exist in the software industry where the vast majority of programmers are working on microsoft windows rather than say linux or mac os x. All researchers have worked on string theory, much like computer programers, so it is much better developed than competing approaches like LQG, and this fact then draws in more researchers in a feedback loop completely independant of experimental evidence.

I am well aware that SUSY could exist on any breaking scale, from energies accessible to LHC all the way to the Planck breaking scale. But usually the way science works is that would like to see positive evidence for a theory, not reasons for non-observance.

Tevatron hasn't found evidence of SUSY which puts tight bounds on it.
I'll suspend judgment until LHC goes online but my intuition tells me the world is 4D and non-supersymmetric.

 

[Angryphysicist]

I could not found what exactly he said about foundational QM?

Nothing...yet. I am a busy undergrad, mind you, I have stuff to do, people to see, women to try and date; all of these endeavors failures mind you!

Still, one has to quixotically tilt the windmills now and again

Besides, if I spent all my time writing about what I wanted to on my blog, and researching, and so forth, I would have no time for my studies, and end up not getting into a grad school. Then where would I be?

 

[LukeD]

A same situation exist in the software industry where the vast majority of programmers are working on microsoft windows rather than say linux or mac os x.

Horrible comparison by the way. Microsoft hires a very limited amount of software developers. The rest of people go to work at other companies where they are hired. Apple also hires a good deal of people to work on Mac OS X, but few of the programmers work on the kernel; the majority work on applications that go along with the OS. Few people work on Linux because few companies hire anyone to work on Linux, and the companies that do have poor control over the code because they need to open source all of it due to Linux's license. There's just not much money in developing Linux for the individual programmers because Linux itself is free, so there are a few people who get paid to work on it, but the majority just do it in their free time.

This is completely different than the state of theoretical physics where pretty much every solution is just like Linux. To get anywhere, you need to publish your work to the public domain, and you're not getting paid by the owners of the theory (whoever that would be), you're getting paid by interested parties. Since you're getting paid by interested parties, only people who work on things that people deem promising get paid. This is like the state of Linux where no one who works on "side projects" like Enlightenment gets anything at all, but a few people who are working on projects like KDE and Gnome are actually getting paid for it. Of course there are few people working on Linux who are getting paid at all, so that's not the only reason there are a lot more people working on projects like KDE and Gnome than Enlightenment. More people are currently using KDE and Gnome and view it as a stable solution even though Enlightenment may be extremely promising and "the solution" to get people to actually switch to Linux.

Anyway... didn't actually mean to rant about that for a while, sorry.

-------------

Josh: I just found it extremely interesting that you doubted the idea that he could be a first year undergrad simply because you didn't see his university email address. What benefit would someone actually have of presenting himself as a first year student if he were not? If someone were a grad student but presented himself as a first year, that would just completely destroy his credibility.
You just seem to be doubting quite literally everything that you hear from anyone here. Doubting people so entirely like that can set you back as a theoretical physicist.

 

[ensabah6]

Horrible comparison by the way. Microsoft hires a very limited amount of software developers. The rest of people go to work at other companies where they are hired. Apple also hires a good deal of people to work on Mac OS X, but few of the programmers work on the kernel; the majority work on applications that go along with the OS. Few people work on Linux because few companies hire anyone to work on Linux, and the companies that do have poor control over the code because they need to open source all of it due to Linux's license. There's just not much money in developing Linux for the individual programmers because Linux itself is free, so there are a few people who get paid to work on it, but the majority just do it in their free time.

This is completely different than the state of theoretical physics where pretty much every solution is just like Linux. To get anywhere, you need to publish your work to the public domain, and you're not getting paid by the owners of the theory (whoever that would be), you're getting paid by interested parties. Since you're getting paid by interested parties, only people who work on things that people deem promising get paid. This is like the state of Linux where no one who works on "side projects" like Enlightenment gets anything at all, but a few people who are working on projects like KDE and Gnome are actually getting paid for it. Of course there are few people working on Linux who are getting paid at all, so that's not the only reason there are a lot more people working on projects like KDE and Gnome than Enlightenment. More people are currently using KDE and Gnome and view it as a stable solution even though Enlightenment may be extremely promising and "the solution" to get people to actually switch to Linux.

Anyway... didn't actually mean to rant about that for a while, sorry.

-------------

Josh: I just found it extremely interesting that you doubted the idea that he could be a first year undergrad simply because you didn't see his university email address. What benefit would someone actually have of presenting himself as a first year student if he were not? If someone were a grad student but presented himself as a first year, that would just completely destroy his credibility.
You just seem to be doubting quite literally everything that you hear from anyone here. Doubting people so entirely like that can set you back as a theoretical physicist.

My point is that without any physical results, like SUSY-partners at Tevatron or LHC, researchers are like programmers, most programmers work on Microsoft Windows due to its dominate position and most QG researchers work on string theory due to its dominate position. Faculty hiring and H-index reinforce the status quo -- if in a gedenaken thought experiment we lived in a world where Witten, Susskind and everyone else worked on LQG rather than strings, then Witten would still have the highest H-index as his papers would be cited by other entrenched LQG'er theorists, and such a position would put pressure on young physicists to go into LQG rather than strings.

The TWP is that the string position is self-reinforcing due to economies of scale -- there's the slick marketing of string theory to the public, there are universities wanting to improve their reputation by hiring string theorists, there are string theorists who cite Witten's and fellow string theorists work, improving string theory's H-index, string theorists who decide who get hired and often that is fellow string theorists, undergrad physics majors only hearing of string theory and wanting to go into that, etc. In a gedenken thought experiment everyone was LQG in academia, then academics publishing LQG papers would be highly cited by other LQG'ers, improving those H-index, and of course, faculty hiring and positions, and even marketing to the public, would reinforce LQG dominance.

i.e Maldacena may be the most cited paper on AdS/CFT correspondence, but that does not mean nature actually respects AdS/CFT correspondence. Observational evidence is that nature is DS, not ADS. Witten's paper on supersymmetric Yang mills paper, the KKLT papers, Randall-Sundram models are all highly cited by other string theorists, and they enjoy a higher h-index as a result, but there's no emperical evidence any of this - KKLT constructions, supersymmetry, p-branes, etc., are physics.

 

[f-h]

I don't see how SUSY/no SUSY at CERN should influence the rationale or need for Background Independent approaches.
We're trying to generalize the class of QFTs we know how to build, whether or not TeV scale SUSY is a feature of them is not crucial.

 

[Chris Hillman]

High A.P,

Davis could be becoming a strong place, or even more of one.
Did you see Derek Wise's paper?
He should be part of Carlip's (and your) group soon:

http://arxiv.org/abs/gr-qc/0611154
MacDowell-Mansouri Gravity and Cartan Geometry.

This paper is remarkable for offering a clear explanation of rolling without sliding via a term new to physics, "hamsterball". Highly recommended for the rodent characters alone.

 

[Kea]

Chris

Haven't seen you around here much before. Attempts to block threads on CarlB's (quantum gravity) work might be a little more difficult in this forum.

 

[marcus]

This paper is remarkable for offering a clear explanation of rolling without sliding via a term new to physics, "hamsterball". Highly recommended for the rodent characters alone.

Chris, what happens to GR when you remodel it based on deSitter instead of Minkowski? I ask because you are the web's GuRu, so your hunch about it could be really interesting.

 

[Kea]

Chris, what happens to GR when you remodel it based on deSitter instead of Minkowski?

Yes, Chris, that's the same deSitter that can be interpreted in a varying speed of light framework, such as that arising in the flat space GA formalism.

 

[Haelfix]

Eh? Desitter is a solution to Einstein's field equations (much to Einstein's chagrin). What do you mean exactly by remodeling it?

 

[marcus]

Eh? Desitter is a solution to Einstein's field equations (much to Einstein's chagrin). What do you mean exactly by remodeling it?

See Hillman's post (#28 on this thread)
https://www.physicsforums.com/showthread.php?p=1331501#post1331501

Cartan geometry using deSitter space as the local model

in Cartan geometry the tangent space at a point does not have to be a vectorspace

Haelfix you are talking about GLOBAL deSitter as a possible solution to Einst. eqn. That is not what I am talking about. I mean have the manifold be locally deSitter instead of locally Minkowski.

Maybe it is impractical. Chris Hillman might have an idea

he referred to the paper "MacDowell-Mansouri Gravity and Cartan Geometry" so he knows about Cartan geometry and so he knows that the tangent space does not have to be flat (momentum space can be curved, as in DSR). So I wonder has he thought about rebuilding GR and the Einstein eqn. on a Cartan manifold.

 

[marcus]

I don't see how SUSY/no SUSY at CERN should influence the rationale or need for Background Independent approaches.
We're trying to generalize the class of QFTs we know how to build, whether or not TeV scale SUSY is a feature of them is not crucial.

This is clear. I suppose (Background Independent) non-string QG research will continue to grow and get interesting results regardless anything you can reasonably expect to see or not see at CERN

 

[Fra]

Angry physicist, keep up your attitude and think for yourself at all cost. I sometimes wonder what the probability is that someone that has invested 30 years will want change direction and walk back. I can feel the pain and resistance.

The triggering reason why I as a student didn't decide continue with my original plan to try to get a research position somewhere is that I was sincerely disgusted by the attitude I faced that put the off from the academic world with the political and granting issues it contains. Maybe I was just unfortunate to end up having a string theorist as as supervisor during my undergraduate studies but I realized that going that route would imply a lot of politics and compromising and I that is not what I wanted to spend my time on, and to get into string theory wasn't on the map, no matter what the supposed "experts" tried to induce in a innocent student. Maybe time is changing though. Anyway, at this point the only thing thay annoys me is that I think they feed on my tax money. But I'll let that pass, because politics is not my cup of tea :)

/Fredrik