This week’s press release trumpeting a bogus “test of string theory” comes from the University of Illinois at Urbana-Champaign, which is headlined Scientists propose test of string theory based on neutral hydrogen absorption, and informs us that
Ancient light absorbed by neutral hydrogen atoms could be used to test certain predictions of string theory, say cosmologists at the University of Illinois. Making the measurements, however, would require a gigantic array of radio telescopes to be built on Earth, in space or on the moon.
String theory – a theory whose fundamental building blocks are tiny one-dimensional filaments called strings – is the leading contender for a “theory of everything.” Such a theory would unify all four fundamental forces of nature (the strong and weak nuclear forces, electromagnetism, and gravity). But finding ways to test string theory has been difficult.
Now, cosmologists at the U. of I. say absorption features in the 21-centimeter spectrum of neutral hydrogen atoms could be used for such a test.
One peculiar aspect of this press release is that it seems that the relevant paper is not yet publicly available. Supposedly it has been submitted to PRL and accepted, but it has not yet appeared in PRL, and I don’t see a preprint on the arXiv (the authors do have a PRL paper with an arXiv preprint from last year on a different topic, one that also came with a press release, but this one didn’t mention string theory).
As far as I can tell from the press release the idea behind this “test of string theory” is the same as lots of other similar ones that invoke cosmic strings. Among the huge variety of string theory backgrounds and the many possible ways to try and use such backgrounds to model the big bang, some will (just like some non-string theory GUT models) produce macroscopic “cosmic strings”. Astronomers have looked hard for evidence of such things and found none, but one can always imagine that, miraculously, such things exist, with characteristics exactly such that they wouldn’t have shown up so far, but would in some new, improved astronomical observations. In this case, I guess to come up with some new possible observation not already ruled out, the authors of the paper invoke a possible radio telescope with an area of a thousand km2.
There seem to be at least a couple reasons for the recent flood of bogus “we’ve found a test of string theory” press releases. One is that PRL evidently encourages authors to issue press releases whenever they have a paper appearing in PRL. Another reason is that string theorists are on the defensive, and some of them have decided that finding some way to claim that string theory really is testable, no matter how dubious, is the way to fight back. Earlier this month, one such claim hyped in New Scientist carried the headline “slammed for their failure to explain how our particular universe came to exist, string theorists are fighting back.” In an interview with string theorist Thibault Damour in today’s edition of the Swiss paper le Temps, he promotes three possible tests of string theory. One is the possibility (which he describes as “very speculative”) that one might observe extra dimensions at the LHC, another is cosmic strings, and finally there are his claims that string theory leads to violations of the equivalence principle. Lubos Motl strongly disagrees. Lubos also has a posting about this latest hype, where he comments:
Such possibilities highlight that creative people may often solve questions that look too difficult at the beginning. They also emphasize how incredibly idiotic are the aggressive crackpots’ proclamations that modern theoretical physics in general and string theory in particular is untestable.
Not clear who it is who believes that “modern theoretical physics” is untestable. While at Lubos’s blog, you might want to see what you can make of his posting on his new book The Bogdanov Equation: the secret of the universe?
Update: This story is appearing lots of places, including the UPI newswire, and at Wired, where the writer seems to realize that the bogosity level here may be problematic, including the unusual disclaimer:
Disclosure: I have no idea whether this makes sense.
Update: A correspondent points me to another recent “test of string theory”, one where for some reason the authors don’t seem to have issued a press release. The article is Toward a test of string theory using Rydberg atoms, and it begins by referencing my book and then claiming that
… measurable effects are predicted by String Theory on normal quantum scales, which the current criticisms have apparently overlooked.
What is discussed in the paper is actually not string theory, but just the idea of adding spatially non-commuting terms to the Heisenberg commutation relations. Certainly such terms should have experimentally observable effects. I suppose you can claim that such terms, of any size you want, come from a “string theory background”, but, as with all these “tests of string theory”, what is going on here just reflects the fact that you can pretty much get anything you want out of string theory, which is why it’s not testable…
Not related to this post, but have you seen the article about someone’s “prediction” of a different set of Higgs masses such that the W/Z-binding Higgs is far above current accelerator limits but that other Higgs (that haven’t been being searched for) could be detected with current hardware.
Slashdot pointed to this link:
http://sciencenow.sciencemag.org/cgi/content/full/2008/123/3
But I haven’t looked at it, not being qualified to tell BS from science…
Glenn,
There’s no prediction of Higgs masses there. The minimal supersymmetric extension of the standard model has lots and lots of extra parameters, and extra Higgs particles. For some values of these parameters, one of these could be relatively light, but still not have been seen at LEP. I assume the Tevatron experiments have looked for these sorts of things, don’t know what the limits are. It’s not just a matter of having enough energy to produce Higgs particles, you also need a large enough event rate to distinguish them from background. The Tevatron presumably has already produced Higgs particles, just not enough to distinguish them.
In other words, it’s yet another example of the billion-knobs problem.
I expected that, but like I said, I’m not savvy enough to tell the hype from the hope.
That’s *your* job.
Thanks for the info.
Astronomers have looked hard for evidence of [Cosmic Strings] and found none, but one can always imagine that, miraculously, such things exist, with characteristics exactly such that they wouldn’t have shown up so far, but would in some new, improved astronomical observations. In this case, I guess to come up with some new possible observation not already ruled out, the authors of the paper invoke a possible radio telescope with an area of a thousand km2.
Would the information the authors want to gather with this hypothetical telescope (the “absorption features in the 21-centimeter spectrum of neutral hydrogen atoms”?) be for any particular reason useful data to have even in a universe where no cosmic strings exist?
Also: Is there any difference between the phrases “cosmic string” and “one-dimensional topological defect”? Or in other words, would a detection of cosmic strings actually prove string theory, or would any cosmological theory with one-dimensional topological defects predict cosmic strings too?
Coin,
Since there’s no paper, I don’t even know exactly what the signal is they are saying one should look for, or whether it could come from other sources or tell us anything about them.
“Cosmic strings” are topological defects of 1d of astrophysical dimensions. They also occur in simple GUTs. There’s an industry of papers out there on the question of how to try and tell the difference between GUT cosmic strings and ones coming from a fundamental superstring. I gather you need a network of the strings and consider their interactions.
I know that this is off-topic, but cannot of think where else to ask. How has Simon’s Renaissance Technology been getting along recently? Is his crew truly a band of financial magicians, or has the whole thing been revealed as hype?
”Astronomers have looked hard for evidence of such things and found none”
Actually Bevis’ group at Imperial College, London are claiming to have detected traces of cosmic strings in the WMAP data which maps the afterglow of the Big Bang. Bennet, the head of WMAP isn’t buying it and calls it a statistical fluke.
I’ll you just one guess as to where this report appeared. What? New Scientist? How on earth did you guess that?
http://tinyurl.com/3xkrbm
PW – you are either a megalomaniac or cynically trying to shift a few more copies of your book (maybe even both). Physicists have been trying to come up with ways to test string theory long before you started your little crusade. Perhaps you have been too busy with your blog to notice the huge advances in observational cosmology that have been made in the last few years, for example. To think that theorists are suddenly “fighting back” (against what exactly – a popular book written by somebody who has made zero impact in theoretical physics?) is to misunderstand how science makes progress. But like I said, I guess that’s not what interests you.
Not Even Woit,
Sure, BS claims to have a “test of string theory” are not new, but I’ve been following them for years and they’re a lot more common now than they used to be.
“slammed for their failure… string theorists are fighting back” are not my words, but those of the headline writer for New Scientist. Take it up with them…
Your words, PW: “string theorists are on the defensive, and some of them have decided that finding some way to claim that string theory really is testable … is the way to fight back.”
I will ask again, PW: what/who are they fighting? Your argument is circular. You start with the unsubstantiated (and therefore quite possibly bogus) claim that string theorists are on the defensive, and then try to fit everything they do around that claim.
Unless your blog is just a blatant PR blurb for your book, one can only conclude that you are living in a fantasy world.
Not Even Woit,
I seem to be repeating myself, but the substantiation of my claim is that it comes from a New Scientist headline. They may not be reliable about science, but I do think they accurately reflect popular perception.
As for doing PR for my book, the only person who has mentioned it at all here is you. Thanks!
Your book appears as a prominent thumbnail on your homepage, PW.
So let me get this straight: you are claiming that theorists are publishing (where there’s a press release there’s usually a peer-reviewed paper) potential tests of string theory in response to the negative public perception of their field.
What is your evidence? Surely there is more to it than a single headline written by someone trying to sell a magazine story last summer?
How can you be sure that the increase in the number of papers reporting potential tests of string theory is not the result of genuine progress in science (both theory and observation)?
Shouldn’t you be more rigorous in your reasoning, given that you claim string theory is a failed research program based on its lack of falsification criteria? Or is that one of the luxuries of living in a fantasy world?
Hi Peter,
Please do not argue with Not Even Woit. Just delete his comments.
Thanks,
Peter O.
Not Even Woit,
The headline is not from last summer, but from earlier this month. I suppose I could waste a lot of time gathering together similar quotes from news stories, but I doubt that would convince you. OK, here’s one more, since I just ran across it this morning. The opening lines of a story at Wired:
“The apparent inability of physics’ string theory to be proved right or wrong is one of the stickiest – and argument-generating – problems in modern science.”
followed by
“But because none of these descriptions of the universe offered any obvious way to be tested or proven, skeptics have called string theory “not even wrong” – meaning that it doesn’t fulfill the most basic requirement of a proper scientific theory, the ability to be be proven wrong.
Now Illinois cosmologist Benjamin Wandelt, along with graduate student Rishi Khatri, say that some of these predictions can be tested, or at least addressed…”
The reason I’m sure that the papers reporting tests of string theory don’t represent genuine progress is that I’ve read them.
Just saw Peter Orland’s comment and he has a point. Unless you’ve got something new to say, or are at least willing to hiding behind anonymity and tell us who you are, explaining your qualifications on this issue, enough is enough…
So what if this detection device was built according to the specifications outlined in the article, and NO evidence for the cosmic strings in the form of hydrogen spectra lines were observed (as described in the popular press article), what aspects of string theory would now be falsified?
dan,
No aspect of string theory would be falsified, that’s the problem.
The only thing going for String theory seems to be that it is a finite theory. As far as I know, in it calculations beyond 3 loops are unsurmountably hard. So has the finiteness been substantiated consensually? Or is it that what still exists is only wishful thinking with regard to strings interacting over an extended region as opposed to a point? And even that argument is a bit dubious owing to the fact that there would be regions of the moduli space where the string length (it can be looked upon as one of the moduli) goes to zero, signaling the possibility of a field theory like divergence here as well (from that part of the moduli space). So one really needs to check order by order in perturbation theory. Supergravity theories have been shown to be finite to a high loop order, but they fail beyond a certain order.
My point is, even apart from the fact that they are non-falsifiable, can they ever live up to their other more radical promises?
Somdatta Bhattacharya,
The topic of the finiteness of superstring amplitudes beyond 3 loops is a highly technical one that has been the subject of fierce arguments here and elsewhere, and I’d rather not reopen those here unless there’s something new about the subject to discuss. As far as I know a fair summary of the situation is that two-loop amplitudes can be explicitly written down and are definitely finite (work of d’Hoker and Phong). At higher loops there are some proposals for explicit amplitudes, and plausibility arguments for finiteness, but no rigorous proofs of finiteness.
Again, this is quite off-topic, and the kind of thing that attracts heated comments about a very technical issue that spread more heat than light. Unless you have accurate and relevant new information about this, please avoid trying to discuss it here.
Not even Woit, I do know that many people who used to work on string theory
have moved on to different fields (long before Peter’s book). Also I do agree with Peter that something is weird with a theory which predicts BOTH violation of
equivalence principle as well as its sanctity
Peter,
I just wanted to be apprised of the current understanding on the issue. As I had suspected, there exist only plausibility arguments and no rigorous proofs. I am aware of the “heat and light” that you mentioned. I have nothing new to offer except what I said in the previous post which is that even the heuristic argument that is usually offered seems to be dubious.
I think that the idea of testing a theory means something quite different to physicists than it appears to mean in science reporting and press releases. I just stumbled onto this blog today and I’ve enjoyed reading it, and feel maybe I can contribute to a discussion here. It seems to me that a press release is in order defining exactly a “test of a theory” means.
I’m going to shoot for a definition here, with some preamble, that I think most physicists could agree on, though its probably more likely that in trying to please most it could end up pleasing none. Here goes.
Physics is a rigorous, skeptical, and ultimately empirical science. A claim for evidence or observation of new phenomena must be held to stringent standards. A true “test of a theory” first involves the postdiction of known physics where feasible, because if a theory explicitly contradicts observed phenomena, it must be discarded. This at least establishes the viability of a theory. The second, and more rigorous aspect of a test, is the observation of phenomena uniquely predicted by that theory (to separate it from other preciously viable theories which do not predict the same observations) and generically predicted by that theory, so that the observation represents a true test of the theory as a whole and not a constraint of parameter space.
By this definition, or by any other real definition of what a scientific test should be, press releases and science journalism too often use the words “test of a theory” to generate buzz about a project that, while it could provide interesting and new experimental data, doesn’t really test a particular theory.
On another phrase that seems to pop up in every article about string theory, what truly establishes it as “the leading contender for the theory of everything”? (besides more public awareness of its existence and a large community of people working on it). Reading back, I realize that sounds a bit sarcastic or condescending, I’m not trying to make people angry, but its a legitimate question of mine. In the absence of observational evidence, what separates string theory from any other theory that could also claim to reduce to QFT and GR in appropriate limits?
Kevin,
The “leading contender” business is a phrase designed to emphasize the sociological fact that string theory remains a dominant research program for finding a TOE, even though the scientific case for this has weakened dramatically in recent years.
As far as the “test of string theory” business goes, I don’t think the problem is that of science journalists understanding this in a different way than scientists. I see two sources of the bogus “test of string theory” claims, one being non-string theorists who don’t really understand what the state of string theory is, but hope that some very different sort of physics they know about is somehow relevant. The other is string theorists who are well aware that string theory has not been able to make the kind of predictions necessary for a legitimate test, but have chosen to try and muddy this issue and mislead people when speaking to the public. In such cases you often find quite different claims in the scientific papers and in the press releases.
Kevin,
The main reason for string theory being considered the ‘leading’ (really, the only) contender for a theory of everything is that it is presently the only known way to consistently combine gravity with quantum mechanics. String theory only works because of number of nearly miraculous anomaly cancellations. It is because of this that it is studied, despite the fact that it has not yet been possible to make definitive experimental predictions.
Eric,
If you have something substantive to say, please do so. But your repetition of stale, nearly 25 year old hype is off-topic. If Kevin cares about the science here, I’d suggest he read Brian Greene and Lee Smolin’s books to see both sides of this argument.
Peter,
There is no need for you to be testy or defensive, and certainly the point that I made is not insubstantive or a ‘repetition of 25 year old hype’. You may not like to admit it, but the anomaly cancellation is in fact an extremely important test of any potential quantum theory of gravity. It is perhaps useful for you to ponder why string theory is still taken seriously when there is very little hope of it making any experimental predictions in the near future. Well, here’s your answer, and it is not hype. It is cold, hard fact.
Peter the paper by Khatri and Wandelt is now posted on the preprint
archive
Eric,
I believe the anomaly cancellation in superstring is a meaningful condition only if the corresponding QFT has gravitational anomaly. The existence of gravitational anomaly in QFT was claimed by Alvarez-Gaume and Witten (Nucl. Phys. B 234 (1984) 269), but their reasoning contained a serious mistake: They were not aware of the fundamental difference between T-product quantities and T*-product ones. Both coincide for chiral current but not for energy-momentum tensor, because the expression for the latter contains time differentiation. The genuine anomaly must be considered for T-product quantities, but what they considered are T*-product ones,
because only T*-product quantities can be calculated by Feynman integrals and path integrals. I have explicitly shown in the 2dimensional case that what they called gravitational anomaly arises from the difference between T-product and T*-product. Thus,
at least in the 2-dimensional case, the gravitational anomaly in the genuine sense is non-existent in QFT. It is quite likely that the same is true in the 10-dimensional case.
B. Schroer completely agreed with me.
For details, see Abe and Nakanishi, Prog. Theor. Phys. 115 (2006) 1151 or arXiv hep-th/0503172 v2.
eric,
there is absolutely no problem formulating a quantum theory of gravity without any speculative ingredients. and there is extremely strong evidence, that it is consistent. see e.g. arXiv:0708.1317
Eric,
1) Peter W. was not being testy or defensive (though he did seem
somewhat irritated). I am not reading his mind, just reading what he wrote.
2) More seriously, how does the gravitational-anomaly cancellation test (your word) string theory? It just provides a constraint on matter multiplets. 10-dimensional String theory, with the gauge group SO(32) or E(8)XE(8), satisfies this constraint. So what?
A bit of history: gauge-anomaly cancellation was regarded as
good evidence for SU(5) or SO(10) GUTS back in the late 70’s
(when I started grad school). But really any model with the right
charge assignments is fine – so it really provides no evidence at all.
More history: anomaly cancellation wasn’t regarded as evidence
for string theory even in 1984. It simply removed the main reason
why theorists weren’t considering string theory before then. I
remember this quite clearly. As a postdoc, I was reading Schwarz’s
1982 Physics Reports. People were trying to talk me out spending
time on it because of the problem with gravitational anomalies.
Hello Peter,
Since GUT and SUSY-GUT’s presumably can be emdedded in some string framework, is as you say, and I quote “macroscopic “cosmic strings”. Astronomers have looked hard for evidence of such things and found none” constitute a falsifiable prediction of GUT and SUSY-GUT’s (i.e do GUT’s generically predict observable cosmic strings arising form the Big Bang – as the Big Bang does predict other observations such as nucleosynthesis and CMB — that have, thus far, been failed to confirmed)
Peter O:
“More seriously, how does the gravitational-anomaly cancellation test (your word) string theory? It just provides a constraint on matter multiplets. 10-dimensional String theory, with the gauge group SO(32) or E(8)XE(8), satisfies this constraint. So what?”
Are you joking? Since any putative theory of quantum gravity must be completely free of both gravitational and gauge anomalies, this provides a stringent theoretical test. String theory is the only theory known that passes this test.
Eric,
“Are you joking? Since any putative theory of quantum gravity must be completely free of both gravitational and gauge anomalies, this provides a stringent theoretical test. String theory is the only theory known that passes this test.”
No, any theory with the same matter content passes this test in 10 dimensions.
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dan,
Some GUTs have stable cosmic string solutions, some don’t. The standard model doesn’t. The existence of such solutions depends on the structure of the Higgs sector of the theory.
Problem is, it’s not just a matter of whether such solutions exist. To predict whether you’ll see them, you need a model of what happened during the big-bang, i.e of the inflationary period and how the universe emerged from it. So, even if your GUT has cosmic string solutions, whether or not you expect to see such things depends on something different, your model of inflation.
I quoted Nakanishi at Lubos Motl’s blog, and he replied:
[material copied from Lubos’s blog deleted]
First of all, this topic has nothing at all to do with the posting. Secondly, please do not copy material wholesale from other people’s blogs here, trying to drag them into the discussion at this site. If a discussion about an off-topic comment here is going on at another blog and you think people should be aware of this, just give the link here, and discussion of the issue should take place on the other blog, not here.
Peter O,
Are you sure you aren’t forgetting about conformal invariance of the world-sheet?
hi PW,
thanks for replying. I understand that string theory dosn’t offer a falsifiable prediction regarding an (non)observation of cosmic strings (through gravitational lensing, hydrogren spectra, or othersie,) and, to quote “that’s the problem” but isn’t any worse than “GUTs have stable cosmic string solutions” which don’t offer a falsifiable prediction b/c if what you say is true “So, even if your GUT has cosmic string solutions, whether or not you expect to see such things depends on something different, your model of inflation” would you regard this class of GUT physics research to be as hoplessly misguided as string theory, for consistency sake? If you’d like me to clafiy I’d be happy to do so but I wonder whether you regard GUT physics research as much a failed idea of unification as stringy unification research.
regards,
Dan
eric,
are you joking? how can a sane person argue like this?
let me reming you that
a) there is no gravitational anomaly with SM matter content in 4D
b) there is very strong evidence, that gravity in 4D is consistent
c) experimentally, D=4 to a very high accuracy
d) some bizarre model that lives only in 10D has some restrictions of its mater content that excludes SM alone
and this you call evidence for the bizarre model? excuse me.
Eric,
Nothing inherently stringy is required for gravitational-anomaly
cancellation. It just provides a condition on the matter content.
Peter O,
I presume by ‘matter content’ you mean the number of bosons and fermions on the world-sheet, described by a CFT on the world-sheet?
Eric,
No, I mean the number of Fermions and Bosons in space-time
(target space to the string theorists). Green and Schwarz’s 1984
paper just started from the classification of gravitational anomalies of
Alvarez-Gaume’ and Witten; who did not use any
string theory.
dan,
The situation of research into GUTs is a complicated topic. One difference with string theory is at least for GUTs it is clear what one is talking about. GUT models are well-defined and one can calculate exactly what they imply and see if the simplest ones can be used to make testable predictions. As string theorists love to point out, if you start looking at arbitrarily complicated GUT models, as with string theory, you’re not going to get any testable predictions.
There are two implications of simple GUT models that show a non-trivial agreement with experiment, but they’re both kind of marginal and not completely convincing. One is the fact that a single generation of SM particles fits nicely into one SO(10) spinor representation. The other is that the ratio of observed gauge couplings you expect in SO(10) supersymmetric GUTs comes out close.
On the other hand, many initial hopes for GUTs have failed. The biggest failure was the prediction by non-supersymmetric SU(5) and SO(10) models of observable levels of proton decay, which were not seen. I think it is also fair to say that initial hopes that GUTs would make distinctive, testable predictions about the early universe have not worked out. Here the situation actually is much like that of string theory, with people going on about how cosmology will be used to test the theory, just the way they used to with GUTs, despite the lack of plausible ideas for how this is going to happen. The best hopes there are that somehow we’ll observe cosmic strings or something similar, but the fact of the matter is that there is no evidence for such things, and both string and GUT models don’t at all require them to be there.
“First of all, this topic has nothing at all to do with the posting. Secondly, please do not copy material wholesale from other people’s blogs here, trying to drag them into the discussion at this site.”
Please accept my apologies.
Peter O.
“No, I mean the number of Fermions and Bosons in space-time
(target space to the string theorists). Green and Schwarz’s 1984
paper just started from the classification of gravitational anomalies of
Alvarez-Gaume’ and Witten; who did not use any
string theory.”
The hexagon anomaly which arises at ONE LOOP is cancelled by the TREE LEVEL diagram coming from the B-field exchange. Clearly, one has to go beyond the supergravity approximation to demonstrate the cancellation.
I don’t think this kind of discussion of anomaly cancellation is enlightening anyone about anything, and it’s off topic anyway. Enough already.
In any case, the “miraculous cancellations” occur for d=10, and for E8 or SO(32) gauge groups from what I remember, which would be pretty exciting if we lived in d=10 or observed those gauge groups, but…
Peter,
Sorry, but I can’t resist. I won’t object if you delete this response.
Otto, using the B-field is clever duality trick to turn a loop
diagram into a tree diagram. The anomalies cancel in the
field-theory limit. No string theory is required.
OK, I misbehaved and will shut up about this matter.
Dear PW,
Thanks for replying, I think we agree that GUT research is similar to string research. The simplest GUT models (i.e SU(5) have been ruled out, and to evade experimental falsification, both research programs have been made more complicated.
From the press release:
” “If we embed brane inflation into string theory, a network of cosmic strings is predicted to form,” Wandelt said.”
This seems to be at odds with what Woit wrote:
“Among the huge variety of string theory backgrounds and the many possible ways to try and use such backgrounds to model the big bang, some will […] produce macroscopic “cosmic strings” ”
Can the experts out there clarify: is formation of a cosmic string network a generic prediction of brane inflation embedded in string theory, or isn’t it? Are there other known viable ways to model the big bang using string theory besides this?
amused,
To get an idea of the range of models “string cosmologists” are investigating, you might want to take a look at any one of a number of summary talks on the subject. One example would be Renata Kallosh’s talk at PASCOS 2007
http://www.pascos07.org/programme/talks/Kallosh.pdf
On pages 15-6 and 17 of her slides she describes two classes of models with no cosmic strings.
Restricting to “brane inflation” models, as far as I know, you can get a huge range of possible “predictions”, depending on the specific model and parameters you choose, ranging from far too many, already falsified by experiment, to so few you have no hope of observing their effects. Wandelt for some reason doesn’t mention this…
Ok, so brane inflation is one of several scenarios that the string cosmologists have come up with. But within that scenario they say that cosmic string networks are indeed generic for the various specific models. E.g., from the abstract of Tye’s review paper hep-th/0610221:
“Another generic consequence of brane inflation is the production of cosmic strings towards the end of inflation. These cosmic strings are nothing but superstrings stretched to cosmological sizes. The properties of these cosmic superstrings and their subsequent cosmological evolution into a scaling network open up their possible detections in the near future, via cosmological, astronomical and/or gravitational wave measurements. At the moment, cosmological data is already imposing strong constraints on the details of the scenario….”
Tye goes on to claim on page 2 of the review that the various parameters in the brane inflation models can be overconstrained by observational data (presumably in the future). In that case the scenario will either be falsified or lead to a predictive cosmological model.
Well, clearly it is misleading for a press release to describe a paper about an observable imprint of cosmic strings as a way to “test string theory” (rather than a way to test one of the main string-inspired cosmological scenarios). But it seems just as misleading to give the impression that there is nothing interesting or worthwhile about this paper or the other ones mentioned in these “hype!” posts. (Working out an imprint that cosmic strings would leave in the hydrogen absorbtion spectrum, and how it would constrain various cosmological models, sounds pretty neat, as does working out collider signatures for distinguishing between different geometries in braneworld models.) I wouldn’t want to work on any of this kind of speculative stuff myself, but people who want to disparage it should first come up with something more promising themselves. It’s a lot easier to disparage the work of others that to find something interesting yourself.