Martin

If you would like to see the String-related research papers available online at arXiv, listed by year, here are links to the arXiv search engine (papers whose abstract summary has the keywords string OR brane OR braneworld OR D-brane OR M-theory OR p-brane.) Year 2000: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2000/0/1 Year 2001: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2001/0/1 Year 2002: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2002/0/1 Year 2003: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2003/0/1 Last twelve months (e.g. 1 June 2003 to 1 June 2004): http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/past/0/1

In looking over the Spires Citation Database for physics papers I've noticed a remarkable drop in citations of recent string theory papers. this is for all kinds (string, brane, braneworld cosmology, M-theory) of stringy research. citations by other papers are one possible measure of the quality of research and there has been a surprisingly sharp decline for definiteness I take 'recent' to mean the preprint appeared in the past 4 years so at end 2000 papers appearing in years 1997-2000 are recent. In year 2000 there were 9 stringy research papers that garnered 125+ citations. In year 2003 there were only 4 such papers! And the numbers are telling In 2003 the 4 recent highly cited papers got: 198,135,134, 125 citations. In 2000 the 9 recent highly cited papers got: 498, 446,397, 347, 316 268,191,164,131 citations Caveat: you cant tell anything for sure about the longterm validity of a research line. But if you go by appearances you might think that in the Good Old Days when string theorists were really string theorists there were a lot more landmark breakthrough by more active innovative people who got a lot more citations from their colleagues. Now the raw output rate and also the citability quality of research seems to be dwindling. In terms of raw quantity (not citation quality) there were a lot fewer stringy research papers written in 2003 than in 2000 or 2001. Again this covers all the categories across the board (string, brane, braneworld, M-theory etc.) The decline in raw numbers of papers could have other reasons (from the quality decline) so I will segregate discussion of it in a separate thread of its own I will get some Spires links so anyone interested can check this out for themselves. Spires HEP database is maintained by Stanford/SLAC. It's a real useful resource. Meanwhile, what to make of this sharper-than-expected drop-off? Is it going to bounce back or is the field in enough trouble that one would expect the decline to continue next year? (so far 2004 output has been lower even than in the same timeperiod in 2003, but we dont have any data on citations)

Trend in raw output of papers, arxiv count Non-string quantum gravity, and string-related year Non-string QG String 2000 81 1481 2001 92 1487 2002 113 1362 2003 128 1062 LTM 134 729 this is as of today Friday 4 June 2004 the search engine at arxiv is a bit cranky so results vary some from day to day I got these counts by clicking on these links, which do keyword searches for papers with those keywords in the summary these are for the non-string QG papers: Year 2000: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/2000/0/1 Year 2001: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/2001/0/1 Year 2002: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/2002/0/1 Year 2003: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/2003/0/1 Last Twelve Months: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/past/0/1 these are for the String-related: ( abstract summary has the keywords string OR brane OR braneworld OR D-brane OR M-theory OR p-brane) Year 2000: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2000/0/1 Year 2001: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2001/0/1 Year 2002: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2002/0/1 Year 2003: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2003/0/1 Last twelve months (e.g. 1 June 2003 to 1 June 2004): http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/past/0/1 For Non-string QG the keyword boolean used is: ((abs=((loop AND quantum) AND (cosmology OR gravity)) OR abs=((quantum AND gravity) AND ((discrete OR phenomenology) OR (canonical OR nonperturbative)))) OR abs=((spin AND foam) OR (doubly AND special))) which covers topics like: loop quantum gravity loop quantum cosmology discrete quantum gravity canonical quantum gravity nonperturbative quantum gravity quantum gravity phenomenology spin foam doubly special relativity a slightly different search picks up some this one misses: 2001: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+OR+spinfoam+AND+spin+foam+AND+doubly+special/0/1/0/2001/0/1 2002: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+OR+spinfoam+AND+spin+foam+AND+doubly+special/0/1/0/2002/0/1 2003: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+OR+spinfoam+AND+spin+foam+AND+doubly+special/0/1/0/2003/0/1 Last Twelve Months: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+OR+spinfoam+AND+spin+foam+AND+doubly+special/0/1/0/past/0/1 ------------------ http://arxiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+simplicial+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+dynamical+triangulation/0/1/0/past/0/1

the Stanford/SLAC Spires database has come out with their list of most-cited GRQC (General Relativity-Quantum Cosmology) papers http://www.slac.stanford.edu/library/topcites/2003/eprints/index.shtml a week earlier, when the HEP topcite list appeared, I sifted out the "hit" papers that had appeared recently (in the last 4 years, 2000 thru 2003) to get an idea of what recent research garners comparatively many citations. High energy physics (HEP) is a much larger field with more researchers and more publication, so the numbers are much larger. But by comparing this year's GRQC numbers and hot topics with those of past years one can get an impression of the trends in various lines of research. with a 4 year window defining "recent" here is the Spires list of highly cited GRQC papers----showing only recent papers: eg a preprint with number gr-qc/9910076 would be excluded as not recent because it appeared in 1999. change from 2002 is noted ----------quote, non-recent removed------ 2003 highly cited gr-qc papers 0058 up from zero QUASINORMAL MODES, THE AREA SPECTRUM, AND BLACK HOLE ENTROPY By Olaf Dreyer (Perimeter Inst. Theor. Phys.). Published in Phys.Rev.Lett.90:081301,2003 [PS file for arXiv: gr-qc/0211076] 0057 up from 27 AN ALTERNATIVE TO QUINTESSENCE By Alexander Yu. Kamenshchik (Landau Inst. & Landau Network Centro Volta), Ugo Moschella (Insubria U., Como & INFN, Milan), Vincent Pasquier (Saclay). Published in Phys.Lett.B511:265-268,2001 [PS file for arXiv: gr-qc/0103004] 0055 up from 31 THE CONFRONTATION BETWEEN GENERAL RELATIVITY AND EXPERIMENT By Clifford M. Will (Washington U., St. Louis). Published in Living Rev.Rel.4:4,2001 [PS file for arXiv: gr-qc/0103036] 0052 up from zero AN ANALYTICAL COMPUTATION OF ASYMPTOTIC SCHWARZSCHILD QUASINORMAL FREQUENCIES By Lubos Motl (Harvard U., Phys. Dept.). Published in Adv.Theor.Math.Phys.6:1135-1162,2003 [PS file for arXiv: gr-qc/0212096] 0052 down from 57 RELATIVITY IN SPACE-TIMES WITH SHORT DISTANCE STRUCTURE GOVERNED BY AN OBSERVER INDEPENDENT (PLANCKIAN) LENGTH SCALE By Giovanni Amelino-Camelia (Rome U.). Published in Int.J.Mod.Phys.D11:35-60,2002 [PS file for arXiv: gr-qc/0012051] 0049 up from 36 INTRODUCTION TO MODERN CANONICAL QUANTUM GENERAL RELATIVITY By Thomas Thiemann (Potsdam, Max Planck Inst.). [PS file for arXiv: gr-qc/0110034] 0043 up from 16 GENERALIZED CHAPLYGIN GAS, ACCELERATED EXPANSION AND DARK ENERGY MATTER UNIFICATION By M.C. Bento, O. Bertolami, A.A. Sen (Lisbon, IST). Published in Phys.Rev.D66:043507,2002 [PS file for arXiv: gr-qc/0202064] 0038 up from zero QUASINORMAL MODES OF THE NEAR EXTREMAL SCHWARZSCHILD-DE SITTER BLACK HOLE By Vitor Cardoso, Jose P.S. Lemos (Lisbon, IST). Published in Phys.Rev.D67:084020,2003 [PS file for arXiv: gr-qc/0301078] 0036 up from 19 GENERALIZED LORENTZ INVARIANCE WITH AN INVARIANT ENERGY SCALE By Joao Magueijo (Imperial Coll., London), Lee Smolin (Perimeter Inst. Theor. Phys. & Waterloo U.). Published in Phys.Rev.D67:044017,2003 [PS file for arXiv: gr-qc/0207085] 0033 up from 21 QUANTUM GEOMETRY OF ISOLATED HORIZONS AND BLACK HOLE ENTROPY By A. Ashtekar (Penn State U. & Santa Barbara, KITP), John C. Baez (UC, Riverside & Penn State U.), Kiriil Krasnov (UC, Santa Barbara & Santa Barbara, KITP). Published in Adv.Theor.Math.Phys.4:1-94,2000 [PS file for arXiv: gr-qc/0005126] 0030 down from 54 CLASSICAL BLACK HOLE PRODUCTION IN HIGH-ENERGY COLLISIONS By Douglas M. Eardley, Steven B. Giddings (UC, Santa Barbara). Published in Phys.Rev.D66:044011,2002 [PS file for arXiv: gr-qc/0201034] 0029 up from zero D-DIMENSIONAL BLACK HOLE ENTROPY SPECTRUM FROM QUASINORMAL MODES By Gabor Kunstatter (Winnipeg U.). Published in Phys.Rev.Lett.90:161301,2003 [PS file for arXiv: gr-qc/0212014] 0027 up from zero ON QUASINORMAL MODES, BLACK HOLE ENTROPY, AND QUANTUM GEOMETRY By Alejandro Corichi (Mexico U., ICN). Published in Phys.Rev.D67:087502,2003 [PS file for arXiv: gr-qc/0212126] 0026 up from zero QUASINORMAL BEHAVIOR OF THE D-DIMENSIONAL SCHWARZSCHILD BLACK HOLE AND HIGHER ORDER WKB APPROACH By R.A. Konoplya (Dnepropetrovsk Natl. U.). Published in Phys.Rev.D68:024018,2003 [PS file for arXiv: gr-qc/0303052] 0026 SCALAR, ELECTROMAGNETIC AND WEYL PERTURBATIONS OF BTZ BLACK HOLES: QUASINORMAL MODES By Vitor Cardoso, Jose P.S. Lemos (Lisbon, IST). Published in Phys.Rev.D63:124015,2001 [PS file for arXiv: gr-qc/0101052] ... ... -------I dropped off the tail of the list, those with less than 25 citations-----

Bad news! The actual witten article in Nature is only available for subscribers but Woit's blog is of course free and the latest issue of Nature is at the nearest public library

New paper of Edward Witten in latest issue of Nature link to online copy (for subscribers) is in the 3 June post of Woit's blog http://www.math.columbia.edu/~woit/blog/ paper involves dark energy (which is an astronomy/cosmology topic!) and concerns dark energy, the Higgs mass, and electroweak symmetry breaking

You are in luck! Today's N.E.W. blog comments on Witten's latest paper and gives a link to it. Check out http://www.math.columbia.edu/~woit/blog/ the 3 June post has a link to an article by Witten on electroweak symmetry breaking ( and dark energy and the Higgs mass) that is in the latest issue of the journal Nature.

several ways you can find out (besides someone here at SFN who follows his work telling you) go to http://arxiv.org/ press search and get http://arxiv.org/multi?group=physics&%2Ffind=Search type "Witten" in for the author that will find you his recent papers I see 11 papers that appeared in 2003 or 2004. "string theory in twistor space is a recent theme" for more recent news: he gave a talk just two weeks ago at UC Davis at a conference of other HEP theorists including Leonard Susskind and other famous string folk and Witten's slides are available online along with the other speakers at the conference there is a link to the UC Davis conf lecture slides at Peter Woit's blog called "Not Even Wrong"---Woit is a close watcher of the string scene, and an alert critic as well so go to Woit's blog and check out what Witten said to his theorist colleagues on 15 May just two weeks ago, no substitute for firsthand info. http://www.math.columbia.edu/~woit/blog/ link to slides is in the 29 May blog "Slides from the Davis Conference" summary of Witten's talk is in 15 May blog "The Landscape at Davis" if you have any trouble getting to the slides, please ask again and i will get the precise link

there is plenty of anecdotal evidence of a string theory decline statements from a leading figure such as Leonard Susskind, worrisome reports from Michael Douglas, objections raised by Tom Banks---(all three of them eminent string gurus)---but also there is a simple bit of numerical evidence as well which I recently came across at the Stanford/SLAC Spires database. there has been a recent 6-fold decline in highly cited string papers, in the following sense: suppose one takes as "recent" the papers in a 4-year window and one looks at the year 1999 In that year there were 18 recent string papers which, in 1999, were each cited by 125+ other papers. these are the blockbuster or highly influential papers which initiate lines of investigation with landmark results and potentially valuable new ideas. In 1999 many of the highly cited papers were by Witten, Maldacena, Vafa, etc. etc. big names. but if one looks at the year 2003 the Spires citebase shows that only 3 recent string papers were, in 2003, cited by 125+ other papers the big names were more quiet. the blockbuster papers were fewer. the heavily cited recent papers in the Spires HEP database tended to be in other fields: neutrinos, astroparticle theory, whatever. by recent in 2003 I mean the paper appeared in 2000, 2001, 2002, 2003 by recent in 1999 I mean the paper appeared in 1996,1997, 1998, 1999 a decline in high-quality papers from 18 to 3 is a pretty sharp decline it corresponds to the subjective impression of collapse in the string research enterprise that one gets from anecdotal evidence maybe even not too interesting because the dwindling of string is already old news---still, it is a numerical result which may count for something

here a similar 5 links to those a couple of posts back but where abstract summary has the words string OR brane OR braneworld OR D-brane OR M-theory OR p-brane it is very unselective, if one wants to sift for quality then you look for papers by famous people with interesting titles or for papers which have been cited as references by a lot of others, this is just the raw output for each 12-month period Year 2000: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2000/0/1 Year 2001: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2001/0/1 Year 2002: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2002/0/1 Year 2003: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2003/0/1 Last twelve months (e.g. 1 June 2003 to 1 June 2004): http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/past/0/1

Peter Woit's blog http://math.columbia.edu/~woit/blog/ reinforces the point that string research should be curtailed because it doesn't qualify as empirical science. The case for cutting funds for string research (until some definite testable predictions can be derived from the theory) was made in Woit's article in the journal "American Scientist", available online, and the earlier article "String Theory: an Evaluation". http://arxiv.org/physics/0102051 It is argued that after a considerable period of waiting (it's been 40 years since the original papers) the theory's many variants still make no definite testable predictions, and therefore one may conclude that no experiment could, by contradicting it, cause the theory to be rejected, in which case such theorizing is logically vacuous. To borrow Pauli's phrase, string theory is "not even wrong."

you said it! rarity is right! why should an academic even bother with SPR much less SFN but they have stray impulses to browse around, teach random people, explain things, watch streetfights, whatever just like normal folks so Ive seen academics come in and post at a rather similar venue to this one and in fact I believe it was the quantum gravity/string theory controversy that brought them in, for whatever reason. I forget who brought up the issue in this thread of attracting more qualified people-----I sense some ambiguity, should one even bother? who needs them?-----I can sympathize with that viewpoint too.

you want to boost the number of academics participating in SFN then debate an issue that bears on research funding Peter Woit of the math department at Columbia (see his blog and homepage) maintains that string theory is bogus science and should be cut back in the research budget until (if ever) there are some testable results Rudy Vaas a prominent German science-journalist has published some popularizations of the discontent with string theory on the other hand any criticism of string research is a hot button issue with string-academics and they can get vituperative and highly defensive so it is potentially a fun debate and, since it ultimately involves public image and funding, is apt to bring in some academics ---------------- another potentially lively discussion concerns the various ("background independent") approaches to making a quantum theory of general relativity, since these have seen growing research activity recently and string-loyalists tend to want to badmouth them, perhaps perceiving them as rivals. Lubos Motl (harvard) has been attacking John Baez (UC riverside) on SPR (sci.physics.research) recently apparently because Baez "this weeks finds in mathematical physics #206 has some good words about one of these alternative quantum gravity approaches----a recent paper by Jan Ambjorn and Renate Loll which seems to some people to presage a breakthrough "Emergence of a 4D world from causal quantum gravity" online at arxiv ----------- in larger scheme these things may not matter a great deal (or they could, its hard to tell) but they are hot controversial issues for academics because they influence the allocation of research grants, fulltime positions, access to NAS/NRC advisory committees, and also plain old status and sense of importance --------- I will get a link to Peter Woit's homepage and blog, and to a Rudy Vaas article from something in Germany analogous to Scientific American so you can sample how this discussion is going at present (it may already be completely familiar to anyone reading this post! so there may be no need for the links, but just in case) http://www.math.columbia.edu/~woit/blog/'>http://www.math.columbia.edu/~woit/blog/ http://www.math.columbia.edu/~woit/ (has links to an article published in American Scientist in 2002, and an earlier article "String Theory--an Evaluation") http://www.arxiv.org/abs/physics/0102051 also some interesting reactions from readers of Woit's articles http://www.math.columbia.edu/%7Ewoit/reaction.html the blog has a lot of reactions from readers too, so if you look at the entries that have to do with string theory you get some idea of the controversy then there is some pretty vitreolic stuff from Lubos Motl on SPR and the new SPS (sci.physics.strings) which he co-moderates I will get the Rudy Vaas link---an example of popular as opposed to technical writing, but nevertheless with bearing on the controversy "The Duel: Strings versus loops" http://arxiv.org/abs/physics/0403112 A translation of Rudy Vaas' article in the German science magazine "Bild der Wissenschaft"

a paper on quantum gravity testing QG is hard to test, some theories may get tested by Glast (gammaray burst orbiting observatory scheduled for 2007) very slight effects accumulating over astronomical distances but these people in this paper, just out, talk about testing some features of QG theories with experimental apparatus on the ground. dont know if it is reasonable, they consulted with Jorge pullin, who is broadly knowledgeable, maybe their ideas are good, anyway here is the link http://arxiv.org/quant-ph/0406007 Could Energy Decoherence due to Quantum Gravity be observed? Christoph Simon, Dieter Jaksch 7 pages, no figures "It has recently been proposed that quantum gravity might lead to the decoherence of superpositions in energy, corresponding to a discretization of time at the Planck scale.... ... We also show how local energy decoherence, which acts separately on system and phase reference, could be detected with remarkable sensitivity and over a wide range of length scales by long-distance Ramsey interferometry with metastable atomic states. The sensitivity of the experiments can be further enhanced using multi-atom entanglement." --------------- today a new paper on loop quantum cosmology appeared http://arxiv.org/gr-qc/0406008 it is by J. Velhinho

At the moment when I try these links I get this many papers for the various years 2000 81 2001 92 2002 113 2003 128 LTM 132 the boolean search isnt perfect, it misses some and gets some it shouldnt but it seems useful for turning up new research related to quantum gravity (background independent non-stringy approaches) and getting an idea of how the various lines of research are going

this could be kind of interesting arxiv search for four years, 2000, 2001, up to the last 12-month period (currently 1 June 2003 to 1 June 2004) basically for Loop Quantum Gravity-related papers keywords in the abstract are listed below Year 2000: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/2000/0/1 Year 2001: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/2001/0/1 Year 2002: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/2002/0/1 Year 2003: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/2003/0/1 Last Twelve Months: http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/past/0/1 the keyword boolean is: ((abs=((loop AND quantum) AND (cosmology OR gravity)) OR abs=((quantum AND gravity) AND ((discrete OR phenomenology) OR (canonical OR nonperturbative)))) OR abs=((spin AND foam) OR (doubly AND special))) which covers topics like: loop quantum gravity loop quantum cosmology discrete quantum gravity canonical quantum gravity nonperturbative quantum gravity quantum gravity phenomenology spin foam doubly special relativity

Niel Cornish is an Australian who has a monkey for a pet http://www.physics.montana.edu/faculty/cornish/ and he studied at Cambridge with StephenHawking and at Princeton and is now in the physics department at Montana State U. and he and co-authors have a paper in Phys Rev. Lett. 21 May 2004 saying that whereas cosmologists generally allow the U might be infinite because it looks spatially flat nevertheless there is enough uncertainty about the curvature that it might be just slightly positive in which case the U would be finite but very very large Cornish et al have determined that it could be no smaller than 78 billion LY (halfway round as I understand them) they do this with a statistical measure they invented, applied to the bumps in the CMB that are seen by WMAP, that thing orbiting the sun at a lagrange point a million miles or so out from earth. WMAP is mapping the CMB with exquisite precision and so it is not too incredible that people like Cornish (ozzies with monkeys) can derive estimates for the smallest possible size of the universe. Since this is a tourdeforce we should get the original article and look at it. Here it is in arxiv http://arxiv.org/abs/astro-ph/0310233 And it looks like the hardcopy version in PhysRevLett has been scanned and posted at Niel Cornish website (presumably by the monkey) Here is the abstract: "The first year data from the Wilkinson Microwave Anisotropy Probe are used to place stringent constraints on the topology of the Universe. We search for pairs of circles on the sky with similar temperature patterns along each circle. We restrict the search to back-to-back circle pairs, and to nearly back-to-back circle pairs, as this covers the majority of the topologies that one might hope to detect in a nearly flat universe. We do not find any matched circles with radius greater than 25 degrees. For a wide class of models, the non-detection rules out the possibility that we live in a universe with topology scale smaller than 24 Gpc."

Whoah! the BBC journalist mistook it. I looked at Niel cornish original paper in Phys Rev. Lett. 21 May 2004 which did NOT say that particle horizon was 78 billion LY it was talking about the smallest possible size the U could be if it was finite. its either infinite in extent, and flat, or flat and toroidal or it has a slight positive curvature and is finite, but then, because the curvature is so near zero it has to be very big. so cornish and spergel etc estimated how big and they said there could be an antipodalpoint (which we would not be observing now because the light wouldnt have reached us) which is 24 Gpc a parsec is 3.0857 LY so multiply 24 by that and get 70-some so that is OK, close enough to 78 so its infinite flat (toroidal doesnt seem likely) or else if its finite S3 and slightly positive curved then it cant be any smaller than this Cornish/Spergel distance of 78 billion LY well this took me completely by surprise. and had me fooled for a while, I am used to the flat infinite model with a particle horizon (the present distance of something whose light we imagine getting after 13.7 billion years, rather idealized) of say 46 billion LY or around 50 should start a thread about the Cornish article

Well, I went to the online calculator http://www.earth.uni.edu/~morgan/ajjar/Cosmology/cosmos.html and put in z = 10,000 and got a distance of 46 billion LY. So my first reaction was wrong. this number 78 is kind of revolutionarily big. With Morgan's calculator you put in 0.73 for lambda and 0.27 for omega and 71 for H (which are pretty widely accepted values for dark energy, matter(ordinary and dark) and hubble parameter. Then you say z = 10,000 and it tells you the present distance of an object whose light you observe today with a redshift of 10,000. It says the light has been traveling for 13.7 billion years and it shows the distance to be 46 billion LY (because of space stretching out during travel) Something has changed, for them to be saying 78 instead of 46 (or anyway something around 50 since there is a fair bit of uncertainty it should be plus or minus some confidence interval but lets not worry about that) So I am a little troubled by the 78. Maybe someone will offer some new information.

having LaTex is great! whether or not to tidy up the subforum menu categories depends on whether you have time for it---and how pressured you feel by competition from the larger more established board. I think its great to be smaller, younger, looser, less crowded. I think SFN is great---I just found it or re-discovered it after some format changes gave it a new look. From a strictly personal perspective, I'm interested in research news in astronomy cosmology and quantum gravity (the newer background independent approaches). what I would like to see is other people here who watch for research news and arxiv preprints in those areas and who have an interest in those things and tell me about it or give me a link when they find something. Are you in London? There is a great conference on Quantum Gravity scheduled for around the 6 or 7 of September at London's Imperial College. Leading people will be there, john baez, carlo rovelli, renate loll, lee smolin, chris isham, laurent freidel, abhay ashtekar, (names in no particular order). would you like the Imperial College website that has the announcement describing the conference? A lot is happening, including mathematics, in quantum gravity. you should go.

the links in the preceding two posts give a pulse check on the string research output. Quantity has been level or declining: 1491 in year 2000 under 1200 (depending on the day) in the past 12 months Quality as measured by number of citations garnered by recent papers has also been declining In 2003 there were only 4 recent (since 1999) papers which were cited 125 or more times, whereas in 1999 there were 18 recent (since 1995) papers which were cited 125 or more times. This is a drop by a factor of between four and five in the production of highly-cited influential research papers. It appears that less stringy research is being done overall and what is being done is less influential, distinguished, ground-breaking or whatever it is that being cited by a lot of other research measures. As it happens this does not interest me personally since I'm much more excited by some newer approaches to quantum gravity-----dynamical triangulations, spin foams, LQG. Essentially what intrigues me are those approaches which are background independent (dont require prior choice of a rigid geometry on which to base the model). But it seems to get other people concerned. At least in the USA the string research establishment has been highly publicized and accustomed to a fat slice of the funding pie. And now it seems to be (at least temporarily) in decline. so some are upset and some in denial and soforth. It has no cosmic significance but it seems worth knowing the underlying figures.

I want to try this link as a way of keeping track of current research http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,hep-ex,math-ph,hep-lat,cond-mat,physics,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/past/0/1 I wonder if it will copy right and become clickable WOW! It works. It does a search of arxiv for every paper posted in the last 12 months which had, in its abstract summary, the key words string OR brane OR braneworld OR D-brane OR M-theory OR p-brane Let me try to install a link for the same search but of papers dated in year 2000. http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+OR+string+brane+abs:+OR+braneworld+D-brane+abs:+OR+M-theory+p-brane/0/1/0/2000/0/1 that works too! You can see that in year 2000 there were posted 1491 research papers (with those keywords in the summary) and in the past 12 months, essentially June 2003 to June 2004, there were posted (according to this search engine) 1177. When you go to arxiv you may not always get the same database or search engine. Results seem to vary by the day of the week. The variation is not too great. I dont mind the jitter, but if you want more consistency always do your searches on some fixed day of the week. [edit: here is another link I want to try---arxiv search for LQG related papers] http://arXiv.org/find/nucl-ex,astro-ph,nucl-th,math-ph,hep-ex,physics,cond-mat,hep-lat,quant-ph,gr-qc,hep-ph,hep-th/1/OR+OR+abs:+AND+AND+loop+quantum+OR+cosmology+gravity+abs:+AND+AND+quantum+gravity+OR+OR+discrete+phenomenology+OR+canonical+nonperturbative+abs:+OR+AND+spin+foam+AND+doubly+special/0/1/0/past/0/1

I think you are right! the simplest version of dark energy is an energy density that just corresponds to Einstein's cosmological constant Einstein himself is supposed to have toyed with the idea of a positive cosmological constant with just this inflationary (or accelerative) effect. I believe he thought of it as a way of keeping a static universe from collapsing so Lambda has been waiting in the wings all this time and finally in 1998 there were the supernovae observations so that at last it, as you say, "tallied with observation." wonderful story---human discoveries walk a crooked path to unimagined destinations

the "most users ever online" thing is broken it would be nice to have some gauge of activity I would expect the view-rate and post-rate to grow now that LaTex is working and with the format, which is attractive and usable I cant think why more people, including knowledgeable ones, shouldnt keep showing up moderation keeps down the sheer foolishness and also can, if applied, prevent personal attacks, insulting arrogance, etc to some extent. there is a real need for places like this to discuss new research so much of which is online at arxiv. I go to bull. boards to a large degree because there I can learn of new work, new observational results, etc. and get other peoples take on it. I get news I wouldnt find on my own and I get links to stuff. if this board doesnt take a growth spurt in the next month or two, let me know and i will personally do something-----that is why I would like the "most ever" gadget to work, so I can tell whether or not I should be a booster or whether things are just naturally improving on their own. BTW the main physical science menu could use a little slight tweaking or editing. for some reason there seems no place for classical EM to go (like rail guns and coil guns) and so they wander into "modern physics" which should really be more particles, standard model, and that. Personally a slight awkwardness of categories in the menu doesnt put me off---am quite comfortable with little disorder!