Causes of loss of interest in String program

negru

And there is any empirical evidence to favor other speculative fields of quantum gravity?

MTd2

As I wrote above, there isn't. The sum of waste of time of all of them together goes to infinite, no matter the theory. The difference, though, it is that they are easier.

negru

Well that's hardly a good reason to change what you're working on. If string theory were easier a lot fewer people would be interested in working on it. People are usually happier knowing that what they're spending time on is making maximum use of their abilities.

Also string theory isn't difficult. I find all the technical and statistical details of high energy experimental talks more difficult than any topic of string theory. The problem is people for some reason are still hoping everyone can know and maybe even be good in everything. But we aren't living in the 1700s anymore. To be good in your field you need to specialize. I find the way physics is taught from highschool up to including grad school incredibly outdated and inefficient. The material is almost the same as 100 years ago. Classical mechanics, EM, stat mech. Then there's some quantum thrown in at the end, and if you're doing qft you're already advanced.
The research i'm doing now everyone could've easily been doing in highschool, with the proper guidance of course.

MTd2

That's a good thing when you are doing it for a constructive feedback. From medicine to art. People are usually not fond of sisyphean tasks. In the case of art, few people can stand being like van Gogh. Although, he was recognized after death...

And those hardly the same as 100 years ago. These things were barely developed back then. On string theory, you've got to fully use them, in the modern sense, for almost no reward. Or at least, in a must more broad sense than in other areas. It's much less specialized. On the contrary, even great advances on science and technology, nowadays, requires just very specialized application of those fields, as you say.

Aidyan

I could mention several technical reasons why SS theory leaves me cold, but am still a layman in QFT and don't dare to go into technical details I'm still learning. But from a simple historical perspective, I'm wondering if there is a single example in the history of physics where hundreds, if not thousands, of top physicists worked on for more than three decades without producing a concrete result, and then turned out to be a correct theory? I can't think of any. People are slowly realizing that if a theory, despite all the efforts, does not produce tangible results after say 15, max. 20 years, then it must be wrong. And I'm afraid that this holds for LQG too.

MTd2

Sure, there are examples of physical theories that fits that criteria. Aristotle's and Ptolemy's theories and biology were considered correct for almost 2 thousand years and several thousand, millions(?), people worked on them.

LQG just became more fashionable from 5 years to now. It was an obscure theory before. It is almost mainstream right now. But it is sort of non predictive too, that annoys me too.

AS gravity is an obscure research up to now, despite of being 35 years old. But it nailed Higg's value precisely! I am more interested in this one now, although one of the saddest possibilities with that is the existence of the large desert up to plank scale.

arivero

Hmm, MTd2, I think that you have misread Aidyan question. He asks for heavy involvement, no results during a long period, and then suddenly it happens to be right. I doubt you are claiming that Aristotle biology happened to be right at the end, nor even a huge involvement of resources (by biologists, aka veterinaries and doctors, not by teologists).

Aidyan

In fact. As everyone knows the aristotelian cosmogony turned out to be dead wrong (and no, between Ptolemy and Copernicus almost nobody was working on it). Would there have not been the church and its inquisition who dogmatically insisted to pursue that path we could perhaps have avoided the 'dark ages'. I hope really that string theoreticians will not take that as an historical reference case. This would only discredit them. And I don't want to wait another 2000 years ....

MTd2

Oh, yeah! I misread! I just noticed that!

MTd2

No! Thousands of people indeed researched the Ptolomaic model! It indeed achieved a great accuracy during the Islamic period. In fact, the accuracy was so great, that the muslim astronomers came up first with the heliocentric model, or close to it:

"Ibn al-Shatir, the Damascene astronomer (1304–1375 AD) working at the Umayyad Mosque, wrote a major book entitled Kitab Nihayat al-Sul fi Tashih al-Usul (A Final Inquiry Concerning the Rectification of Planetary Theory) on a theory which departs largely from the Ptolemaic system known at that time. In his book, "Ibn al-Shatir, an Arab astronomer of the fourteenth century," E.S.Kennedy wrote "what is of most interest, however, is that Ibn al-Shatir's lunar theory, except for trivial differences in parameters, is identical with that of Copernicus (1473–1543 AD)." The discovery that the models of Ibn al-Shatir are mathematically identical to those of Copernicus suggests the possible transmission of these models to Europe.[14] At the Maragha and Samarkand observatories, the Earth's rotation was discussed by al-Tusi and Ali Qushji (b. 1403); the arguments and evidence they used resemble those used by Copernicus to support the Earth's motion.[15][16]"

http://en.wikipedia.org/wiki/Geocent...amic_astronomy

negru

The history of things is irrelevant here. String theory and its alternatives have a minimal amount of external data to work with. This was usually not the case before. People were observing various phenomena then trying to explain them. They were guided by data. Now we're not observing anything new, we're just trying to make the theory we have prettier. Any new predictions we could make will very likely be at unobservable energies anyway (unless we're extremely lucky and there is low energy susy, or dark matter detection says anything). So even if string theory somehow made a prediction around i dunno say 100-1000 Tev, no one would take it seriously anyway for another 50 years or so. Almost everyone working on string theory now would be dead by then.

marcus

In regards testability (mentioned above) some readers might be interested in:
http://arxiv.org/abs/1204.1288
Perturbations in loop quantum cosmology
Ivan Agullo, Abhay Ashtekar, William Nelson
(Submitted on 5 Apr 2012)
The era of precision cosmology has allowed us to accurately determine many important cosmological parameters, in particular via the CMB. Confronting Loop Quantum Cosmology with these observations provides us with a powerful test of the theory. For this to be possible we need a detailed understanding of the generation and evolution of inhomogeneous perturbations during the early, Quantum Gravity, phase of the universe. Here we describe how Loop Quantum Cosmology provides a completion of the inflationary paradigm, that is consistent with the observed power spectra of the CMB.
4 pages, ICGC (2011) Goa Conference proceedings

and in the earlier paper (cited 45 times), simply as an example:
http://inspirehep.net/record/812301?ln=en
Cosmological footprints of loop quantum gravity.
J. Grain (APC, Paris & Paris, Inst. Astrophys.), A. Barrau (LPSC, Grenoble & IHES, Bures-sur-Yvette).
Feb 2009
7 pp. Phys.Rev.Lett. 102 (2009) 081301

You shouldn't lump Loop in with String. Loop is just beginning to get broad attention from researchers, more-than-token representation at major conferences. Even the biennial Loops conference only goes back to 2005. Their arcs of historical development are quite different.
===============

As I mentioned before, 6 or 7 days ago the Munich organizers of Strings 2012 posted the list of 39 invited speakers, but the titles of the talks are all blank except for one. So it has been for nearly a week. The only talk, out of 39, whose title is listed is
Alternative approaches to quantum gravity: a brief survey
http://wwwth.mpp.mpg.de/members/stri...ram/talks.html
It's hard not to conclude that leading string folks and likely participants are interested in hearing about and discussing this. And this, I think, is relativey new. I don't recall much attention to non-string QG, at past conferences.

I'm pointing out a subtle change in climate, or perhaps just a shift in the weather pattern.

Aidyan

MTd2, these are only isolated historical examples (and you surely can find more), but can not in the least be compared with the effort, the people, the machinery and the money spent today on string theory. In string theory there are hundreds of "Ibn al-Shatirs" who produce an amount of papers, books, articles and whatever documents in few month, perhaps even only few weeks, comparable to what humanity did in 20 centuries (just compare what pops into existence daily on arxiv....). Modern organized science in the form we know exists only since three max. four centuries. And since then I can't think of another theory in physics that was so revered, cherished and honored for a so long time without producing concrete results.
I wouldn't call QM, GR, the SM and all the modern particle physics and astrophysical observations "minimal amount of external data to work with". And what "data" had three guys as Copernicus, Kepler or Tycho Brahe to work with? Only those of the extremely limited human senses, and yet they produced something. The "unobservable energies" argument is acceptable provided that a research along the "unobservable energies" line will sooner or later lead to "observable energies" data. Or at least a minimal hint, an allusion, a scratch of evidence. History suggests that "sooner or later" means about a couple of decades, not centuries, and not to say millenniums.

arivero

Hmm perhaps we could have a better example here, with the theory of indivisibles/fluxions... it is a whole lifespan of development, the initial players, such as Kepler or Cavalieri, never see the final physical results (Newtonian Dynamics). Kepler himself -whose treatise is mostly numerical- was never considered a player, except perhaps by Cavalieri, who insisted on showing his work to Galileo (and failing to attract attention). Cavalieri atoms run into all kinds of problems, until Newton and Leibnitz got the final formulation.

negru

Of course not, but the relevant data was already used to give precisely QM, GR and the SM. if you want a bigger theory, you need more data than was already used, that was my point. Just like Newton used all the data he knew to get classical gravity. Even if he saw hints of things beyond classical gravity, the data he had wouldn't have been anywhere near of helping him.

Yes, and the data they had was enough to produce what they did. A bunch of yearly measurements is all that's needed to derive Kepler's laws. A bunch of particles is all that's needed to derive the SM. To derive a TOE, you need data comparable to the scope of that goal.


You might that the combination of all of GR and SM data should be enough. Not necessarily. If Kepler only had data from one of whatever he was measuring, it's very possible that wouldn't have been enough. Or if we had only detected half the particles we did before i dunno EW unification, maybe that wouldn't have happened either. Sure with hindsight a minimal amount of data seems required to derive a new theory, but it doesn't work that way. Same with string theory. Perhaps all that's needed is one low energy susy particle, or missing energy, or who knows, to guide us towards the correct formulation.

MTd2

The scientific method, as we now it was first used by al Haytham, in the X century.

http://en.wikipedia.org/wiki/History...Ibn_al-Haytham

Anyway, I think you are not considering the quantity of data and the works that was not preserved.There was no printing and paper was hard to acquire. So, even important texts were erased, when not destroyed, for random uses. Take a look at this:

"Archimedes lived in the 3rd century BC, but the copy of his work was made in the 10th century AD by an anonymous scribe. In the 12th century the original Archimedes codex was unbound, scraped and washed, along with at least six other parchment manuscripts, including one with works of Hypereides. The parchment leaves had been folded in half and reused for a Christian liturgical text of 177 pages; the older leaves folded so that each became two leaves of the liturgical book. The erasure was incomplete, and Archimedes' work is now readable after scientific and scholarly work from 1998 to 2008 using digital processing of images produced by ultraviolet, infrared, visible and raking light, and X-ray.[1][2]"

http://en.wikipedia.org/wiki/Archimedes_Palimpsest

marcus

Since we've turned a page, I'll remind readers what the basic input data are that we are considering how to explain

The decline itself is clear from the available indices: there has been a downtrend in the rate of first-time faculty hires, starting around 2001. This is visible both in terms of absolute numbers (from average about 9 per year down to around 1 per year) and also in terms of string as a fraction of total Particle Theory. It used to be that around HALF the first-time faculty hires in HEP theory were in string, now it's more like a tenth.

A physicist at the U Toronto (Erich Poppitz) charts first time faculty hires in High Energy Physics Theory (Usa and Canada) by year and keeps track of what fraction of these are in string, which fraction are in lattice field theory, and so on.
http://www.physics.utoronto.ca/~poppitz/Jobs94-08
His chart shows 11 HEP theory hires in 2011 of which one was string.
Here annual rates have been smoothed by averaging over 3 years intervals.The source is http://particle.physics.ucdavis.edu/rumor/doku.php
A new webpage has been started that reports on postdoc fellowships in a broad category (gen. rel. and quantum cosmology) which includes quantum gravity. Also something to keep an eye on:
http://sites.google.com/site/grqcrumourmill/

There has been a decline in annual citations to recent string research by the theorists themselves.
Number of recent string papers making the top fifty in the annual Spires HEP topcite list
Here a paper is counted as recent if it appeared in the previous five years. This gauges the quality/significance of current work by how much other researchers in the field currently refer to it. A kind of community self-evaluation, if you will, concerning the perceived value of current and recent work.

Several ideas have surfaced in this thread regarding possible reasons for the decline in interest. It's conceivable that reasons might be found in the physics of string itself. As an approach to reproducing the Standard Model, say, it might conceivably be fundamentally flawed on physical grounds. Arivero made the point that we should consider it separately as particle model and as a candidate theory of the quantum geometry of the universe.
In that second role, does it offer a promising way to resolve the cosmological singularity and model conditions leading up to the start of expansion? Is it testable by astronomical observation? This seems to be the main thing one wants a QG theory for. So there may or may not be valid physics reasons inherent in the theory.

Or it could simply be that newer approaches to QG and explaining the SM have arisen, and that researchers have some natural tendency to spread out seeking fresh ideas and new areas to work on.

We might get some good out of a special String retrospective issue of the journal Foundations of Physics edited by Gerard 't Hooft. He invited a reputable bunch of string and other theorists to contribute articles for an issue called Forty Years of String Theory.
http://en.wikipedia.org/wiki/Foundations_of_Physics
Some of the articles which 't Hooft invited to be in this special issue of the journal are available online:
http://arxiv.org/find/grp_physics/1/.../0/1/0/all/0/1

Additional help may be found by checking to see what topics interest String researchers these days, as indicated by the titles of invited talks which the the Strings 2012 conference organizers have put online:
http://wwwth.mpp.mpg.de/members/stri...ram/talks.html
One assumes these are the topics which active researchers, the likely participants, are interested in hearing about and having discussed at the main annual conference. So we can get an idea of what they have in mind. For the past six days the list has had only one topic, but we can expect to see more appear shortly.