String Theory State and History

[Pythagorean]

First off, I've always been under the impression that string theory was crackpot (with absolutely zero reasoning on my part, just from authority) but the way I've seen it discussed here in the last years (and I've heard the LHC has some experiments pertaining to it) maybe my impression was wrong?

I'm curious what the current politi-scientific state of string theory is (is it falsifiable?)

but I'm also curious, in the way of history, why string theory is so appealing to people; how did the idea come up?

 

[MathematicalPhysicist]

Well there's the PBS programme with Michael Green which tells its history, check youtube.

It I remember correctly, it started with Venziano.
http://en.wikipedia.org/wiki/Gabriele_Veneziano

 

[suprised]

First off, I've always been under the impression that string theory was crackpot (with absolutely zero reasoning on my part, just from authority)

What kind of authority might that have been?

 

[revnaknuma]

string theaory is not physics but an ultra high level mathematics.
it is a mathematical success. no physics. it is false.

 

[marcus]

...I'm curious what the current politi-scientific state of string theory is (is it falsifiable?)
...

The best way I know to get a reading on String's current politi-scientific standing is to listen carefully to what Steven Weinberg says in this video:



Drag the time button to around minute 48. He will start commenting on the current state of the String program at around minute 50.

For background, as you may know, Weinberg is a world class physics elder statesman who worked on String back in 1980s but eventually got out of it and is now mainly in Cosmology.
At the beginning of the YouTube video the conference chairperson gives an introduction to him and his work. Central figure in the science Establishment.

It's an especially nice video for several reasons:
He is talking to science writers, a smart non-specialist audience at a level between beginner and expert.
He has a calm balanced view, not partisan, does not take sides in some petty squabble.
He chooses his words carefuly.
He is kind to theorists still working in the String program.
He expresses openness to the idea that the program could still succeed (in arriving at a single explicit testable theory) although he doesn't see how that could happen.
He describes the hopes for String that "some people" have, in a clear understandable way.

 

[marcus]

string theaory is not physics but an ultra high level mathematics...

Hi Revnaknuma and welcome! This is the first time I've seen a post by you. Your profile says you just joined the forum this year. I think you have an interesting point of view as a physics grad student who already has a career in ethnic music (and traditional musical instruments)---someone who is studying physics at graduate level because of pure interest in the subject.

I hope you watch the relevant part of that Steven Weinberg video. He uses much softer language than you---he does not say "crackpot" and "false"---but is perspective has something in common with yours.

The difference is in the words used. Your statement could be taken as an attack. Weinberg's mild carefully chosen words can be heard not as an attack but as measured and sympathetic understanding.

I'm not saying that it is wrong to attack! In some situations it can be the appropriate thing, especially if you want to stimulate a hot debate. But it's interesting to listen to the difference in tone of voice between you and Weinberg.

As an expert in traditional Central Asian musical instruments you undoubtably have a good ear for tone!

 

[marcus]

The best way I know to get a reading on String's current politi-scientific standing is to listen carefully to what Steven Weinberg says in this video:



Drag the time button to around minute 48. He will start commenting on the current state of the String program at around minute 50.

For background, as you may know, Weinberg is a world class physics elder statesman who worked on String back in 1980s but eventually got out of it and is now mainly in Cosmology...

Fzero just transcribed part of what Weinberg said after minute 50 on the video. It looks to me like a faithful accurate transcript and I really appreciate Fzero taking the trouble!

Here is the whole of what Fzero copied:
==quote Weinberg 2009 Science Writers Conference talk on LHC and the state of physics==
It's developed mathematically, but not to the point where there is anyone theory, or to the point where, if we had one theory, we would know how to do calculations to predict things like the mass of the electron or the masses of the quarks. So, I would say, although there has been theoretical progress it's been….I find it disappointing.

One of the hopes would be that the LHC would provide a clue to something we're missing in superstring theory and I think there supersymmetry is the most likely place to look. One of the troubles with superstring theory is that, although in a sense the theorists think there's only one theory, there are an infinite number of approximate solutions of it and we don't know which one corresponds to our world. But at least in a large variety of the solutions of superstring theory there is supersymmetry visible at low energies. And if we see supersymmetry at low energies, the superstring theorists may be able to derive from it some type of clue as to how to try to solve these theories.

But I haven't talked about it in this lecture because I don't see how that would work. But I couldn't say that that was likely with any sincerity and certainly the LHC and any other accelerator that we can imagine being built would not get up to energies which are high enough so that we can directly see the structures that are described by superstring theory: the strings or the D-branes or whatever it is. Those will not be accessible at the LHC, so any clue that we get will be very indirect.

I have myself, well I was working on superstring theory in the 80s and gave it up because I moved into cosmology, which, in the last couple of decades, had the excitement that elementary particle physics had in the 60s and 70s: A wonderful coming together of theory and observation. Cosmology now reminds me of the excitement that I felt when I was younger and doing particle physics.

It's a pity that superstring hasn't developed better. I still think it's the best hope we have. I don't know of anything else. My own work very recently has been trying to develop an alternative to superstring theory as a way of making sense of quantum gravity at high energies. But even though I'm working on this, I still find superstring theory more attractive, but not attractive enough.
==endquote==

If you have time to watch it, you might enjoy the whole 55 minute slide talk. Great sldes, clear non technical explanations of several physics frontiers (particle physics AND cosmology)

 

[negru]

Well, i'd hardly call Weinberg a "Central figure in the science Establishment", when discussing these newer developments. Not even younger people in the field are afraid to call him a crackpot these days. Not that it necessarily means anything, but he certainly hasn't been an authority on strings since the 80's or so.

 

[Pythagorean]

Thank you for your in-depth replies Marcus. I will watch the video later. Shallow response mode.

What kind of authority might that have been?

It was a NOVA show interviewing scientists. I think they were quantum chromodynamicists.

 

[MTd2]

Hi revnaknuma! Is this talented musician you?
http://www.youtube.com/user/revnaknuma#p/a

 

[petergreat]

Well, i'd hardly call Weinberg a "Central figure in the science Establishment", when discussing these newer developments. Not even younger people in the field are afraid to call him a crackpot these days. Not that it necessarily means anything, but he certainly hasn't been an authority on strings since the 80's or so.

Weinberg published two articles last year on pretty modern hep-th topics:
http://arxiv.org/abs/1009.1537"
http://arxiv.org/abs/1006.3480"

 

[marcus]

Another interesting Weinberg talk to transcribe an excerpt from would be his July 7 2009 colloqium talk at CERN.
http://cdsweb.cern.ch/record/1188567/
As I recall the last 10 or 12 minutes were especially enlightening, The first 55 minutes were largely devoted to summarizing the history of quantum field theory.

Weinberg was also one of the invited speakers featured at the annual Strings conference, Strings 2010. (Along with e.g. Strominger, Arkani-Hamed, Witten, Ooguri, Kachru, etc...)
He presented his (non-string) research in "Gravity at High Energy".

 

[negru]

Another interesting Weinberg talk to transcribe an excerpt from would be his July 7 2009 colloqium talk at CERN.
http://cdsweb.cern.ch/record/1188567/
As I recall the last 10 or 12 minutes were especially enlightening, The first 55 minutes were largely devoted to summarizing the history of quantum field theory.

Weinberg was also one of the invited speakers featured at the annual Strings conference, Strings 2010. (Along with e.g. Strominger, Arkani-Hamed, Witten, Ooguri, Kachru, etc...)
He presented his (non-string) research in "Gravity at High Energy".

yeah they also invite Horova to string conferences and everyone makes fun of him and attends his talks like it's the new circus in town.

 

[negru]

It's also difficult to believe he's so central while pushing his pet AS theory, which just completely disregards everything we've learned about gravity in the past decade or so. But I'm sure we've discussed that many times before here.. I don't remember what conclusion we reached however.

Anyway, Weinberg is just one guy, I don't understand why his view is so important, or relevant at all.

 

[marcus]

Well, i'd hardly call Weinberg a "Central figure in the science Establishment", when discussing these newer developments. Not even younger people in the field are afraid to call him a crackpot these days. Not that it necessarily means anything, but he certainly hasn't been an authority on strings since the 80's or so.

yeah they also invite Horova to string conferences and everyone makes fun of him and attends his talks like it's the new circus in town.

It's also difficult to believe he's so central while pushing his pet AS theory, which just completely disregards everything we've learned about gravity in the past decade or so. But I'm sure we've discussed that many times before here.. I don't remember what conclusion we reached however.

Anyway, Weinberg is just one guy, I don't understand why his view is so important, or relevant at all.

Not @ negru---@ others more prepared to understand: Watch the beginning of the 7 July 2009 talk at CERN where he is being introduced by Luis Alvarez-Gaumé, Director of the Theory Division at CERN.
http://cdsweb.cern.ch/record/1188567/
Listen. It's evident that Alvarez-Gaumé is not just "being nice".

 

[martinbn]

string theaory is not physics but an ultra high level mathematics.
it is a mathematical success. no physics. it is false.

I wouldn't say it is mathematics of any level.

 

[petergreat]

Not @ negru---@ others more prepared to understand: Watch the beginning of the 7 July 2009 talk at CERN where he is being introduced by Luis Alvarez-Gaumé, Director of the Theory Division at CERN.
http://cdsweb.cern.ch/record/1188567/
Listen. It's evident that Alvarez-Gaumé is not just "being nice".

He mispronounced "effective" as "composite". What's he thinking about? It sounds like a deliberate joke.

 

[marcus]

It's almost a reflex: If someone says "fundamental or..." what do you think?
theories are either fundamental or effective
but particles are either fundamental or composite.
It could have been a joke (letting the theorist know he was among experimentalists?)
and if so Weinberg took it in urbane good part and was not ruffled.

Luis A-G: "...he's probably one of the deepest physicists we have in the last hundred years..."

 

[Pythagorean]

Ok, so what I gather from the video and the replies here is, "it's complicated". The history of Venziano is interesting.

I don't see myself getting embedded in the formalism anytime soon, though. From where I'm standing, it appears to be a very complicated subject.

 

[atyy]

It was a NOVA show interviewing scientists. I think they were quantum chromodynamicists.

Perhaps they were talking about string theory as applied to QCD?

There are two "uses" of string theory. One is as a theory of quantum gravity, perhaps not of our universe, but of some universe, which will hopefully yield clues about the correct theory of quantum gravity for our universe. I think this part is pretty uncontroversial.

People have also tried to use strings to talk about QCD via the conjectured gauge/string duality. Although it's a conjecture, gauge/string duality is pretty well supported. The problem is that it's unclear if the sorts of gauge theories include QCD. I don't know what the status of AdS/QCD is at the moment.

 

[unusualname]

Who the hell is negru and why is he allowed to post his silly opinions on this forum?

String Theory is a mathematically mature subject that is struggling for a breakthrough idea to make it all work physically. A big mystery is what happened to Matrix String Theory which sounded so promising but controversially predicts a discrete nonlocal microscopic structure - perhaps that's why it's in hiding - until it's perfected.

Anyway, wait for supersymmetry confirmation or no confirmation over the next couple of years to really stir things up, everyone's a bit stuck in all the QG approaches at the moment.

 

[marcus]

I don't think everyone's stuck in all the QG approaches at the moment. There's been a speedup in progress since 2008.

But I like your concise snapshot of the current situation in String (with special mention of matrix theory). Mathematically mature subject in need of a breakthrough idea to make it physically relevant.

 

[negru]

Who the hell is negru and why is he allowed to post his silly opinions on this forum?

Just some guy who doesn't appreciate the fact that people (especially younger students) might get completely wrong impressions about what is going on in the HET field right now. Every time someone asks some stringy question Marcus will show up, post 20 links to LQG papers, as well as his favorite quote from the random string theory skeptic of the month.

You can't expect students who probably barely know any QFT or whatnot to formulate informed opinions on string theory or LQG, yet they will be immediately swamped with papers, quotes from nobel winers and the Pope himself.

I usually find it appropriate that when someone asks about the current state of a field, you also provide some opinions from the people actually still working in the field, preferably of those involved in developments more recent than 1980, since pretty much nothing is the same as it was back then with strings.

That said, I realize that there are probably fewer pro-string people on this forum who would start spamming papers and quotes left and right to balance Marcus, but my hope is that he will balance himself, at least when talking to non-experts.

I mean, I really wouldn't want someone to read his comments on LQG getting big at Berkeley, and then find himself ridiculed by the actual faculty there.(matrix theory isn't hiding, it just turned out not being good enough to answer what needs being answered)

 

[marcus]

... comments on LQG getting big at Berkeley, and then find himself ridiculed by the actual faculty there.
...

:yawn:
You misrepresent what was said. Nobody said "big at Berkeley." Berkeley is now on the LQG map because of Haggard's research with Littlejohn as physics faculty advisor. Evidently you can do a Phd thesis in LQG here now.

 

[suprised]

What negru says is very reasonable. I can judge it since I work more than 20 years in string theory; and never have seen such a silly biased anti-string propaganda anywhere on the planet! This here turned again into a completely unscientific discussion, a complete waste of time. Thank marcus & Co!

 

[marcus]

Here's the thread referred to:
https://www.physicsforums.com/showthread.php?t=477171

It's kind of interesting that Berkeley physics faculty Littlejohn visited at Rovelli's institute at Marseille in 2008 and 2009, and on his second visit he brought his student Haggard along. The thread notes a paper by Haggard and one of the Marseille group (Gene Bianchi).
In a world where PhD students sometimes have narrowly limited options for their thesis research topic it's nice to see a new option take root at Berkeley. I should think most of us would welcome this development.

It does no good to deny simple facts, as happened when I reported this. See thread post #2 and my reply #4.
https://www.physicsforums.com/showthread.php?p=3164318#post3164318
In my experience, Negru's posts tend to be misleading or unreliable (as here) so Unusualname's question makes sense.

Who the hell is negru and why is he allowed to post his silly opinions on this forum?...

From my point of view Negru is a welcome as comic foil but I don't always want to take the time to reply to him.

 

[unusualname]

@surprised &negru

marcus always seems reasonable to me, and posts many relevant links to refer back to professional work backing up what he says. That this can't be done on the pure String Theory side is telling imho, too abstract too difficult and too out of touch with any other mathematical or physical theory. Negru's comment about Matrix String Theory is an example - please post a link to a paper or discussion explaining where Matrix theory was not "good enough" [to give the answers] (hint: there is none, it just drifted into the overly complicated and never came back to an understandable applicable model)

 

[negru]

@surprised &negru

marcus always seems reasonable to me, and posts many relevant links to refer back to professional work backing up what he says. That this can't be done on the pure String Theory side is telling imho, too abstract too difficult and too out of touch with any other mathematical or physical theory. Negru's comment about Matrix String Theory is an example - please post a link to a paper or discussion explaining where Matrix theory was not "good enough" [to give the answers] (hint: there is none, it just drifted into the overly complicated and never came back to an understandable applicable model)

well I don't think there's any paper saying that, I just said why people sort of realized that although useful, it's just not good enough. what sort of paper do you expect? "here we attempt to use matrix theory but show that we fail miserably because we just can't do the calculations?"

 

[marcus]

... I can judge it since I work more than 20 years in string theory...

My goodness! You have quite a substantial career investment in the String approach, not so?

I try to be balanced and objective in reporting QG developments, which may be easier for me than it would be for you because I have no career investment in any of the different approaches.

 

[negru]

You might not have a career investment Marcus, but you quite clearly have an emotional one.

I was just pointing out that the general atmosphere on this forum is way way different from the one in the usual academic settings, and that as a result people will get a totally wrong impression about the current state and future of research in HEP. Which will (fortunately or unfortunately) remain pretty string oriented for quite some time. Saying or suggesting otherwise is simply not a "balanced" view.