A commenter points out that the Edge web-site has put up John Horgan’s recent New York Times Op-Ed piece about science and common sense, together with some quite hostile responses to it. I’ve already explained what I think about Horgan’s piece, and I agree with some of the points of his critics, but I think their reaction to his quite accurate point that string theory is untestable is pretty remarkable.
John McCarthy, a computer scientists, writes the following bizarre paragraph:
“When Horgan says that string theory is untestable, he is ignoring even the popular science writing about string theory. This literature tells us that the current untestability of string theory is regarded by the string theorists as a blemish they hope to fix.”
Ignoring the peculiar characterization of the untestability of a theory as a “blemish” rather than a serious problem, does this make any sense to anyone? McCarthy seems to be trying to make the argument that one isn’t allowed to point out a problem with a scientific theory if the scientists involved agree it is a problem and say they wish they could do something about it.
McCarthy at least has figured out that string theory is currently untestable, unlike Lenny Susskind, who invokes the heavy artillery of big names to (seem to) claim that it is:
“Finally I must take exception to Horgan’s claim that “no conceivable experiment can confirm the theories [string theory and cosmological eternal inflation] as most proponents reluctantly acknowledge.” Here I speak from first hand knowledge. Many, if not all, of the most distinguished theoretical physicists in the world — Steven Weinberg, Edward Witten, John Schwarz, Joseph Polchinski, Nathan Seiberg, Juan Maldacena, David Gross, Savas Dimopoulos, Andrei Linde, Renata Kallosh, among many others, most certainly acknowledge no such thing. These physicists are full of ideas about how to test modern concepts — from superstrings in the sky to supersymmetry in the lab.”
First of all, his parenthetical elaboration “[string theory and cosmological eternal inflation]” isn’t quite right, Horgan never said anything about “cosmological eternal inflation”, although he did criticize as untestable claims for the existence of “parallel universes”. Susskind attacks Horgan’s claim that string theory is untestable by claiming that he and lots of illustrious physicists have ideas about how to test “superstrings in the sky to supersymmetry in the lab”. Note that Horgan never said anything about supersymmetry not being testable. The “superstrings in the sky” presumably refer to Polchinski’s claims that in some of the infinite variety of possible string theory scenarios there are cosmic strings that might be observable. I fail to see how this counts as a “test” of string theory, since if, as is likely, astronomers don’t see these things, that in no way shows that string theory is wrong.
After this piece of intellectual dishonesty, Susskind ends with the favorite tactic of string theorists on the losing side of an argument, the ad hominem attack:
“Instead of dyspeptically railing against what he plainly does not understand, Horgan would do better to take a few courses in algebra, calculus, quantum mechanics, and string theory.”
I think there is something of a misunderstanding here. Maybe some string theorists claim that we can make testable predictions based on our current understanding of string theory, but some certainly acknowledge that at present we cannot.
Perhaps I can explain why string theorists in the latter class react the way they do when some critics point out that there are currently no testable predictions. The reason is that this is a typical criticism of nonsense theories and religious explanations of phenomena – systems of thought where predictability is not even acknowledged as a virtue. String theorists are not such people, and understandably do not want to be associated with them; who wouldn’t love to find a definite observational consequence of string theory?
One may then decide (as you seem to have done Peter) that this wish is unlikely to be fulfilled, and theorists might better spend their time thinking about other approaches to particle physics if not quantum gravity. Maybe that’s right …
I think Lenny is now practicing what a prominent theorist once described to me as “Hollywood style physics”.
Who cares about what is said on the Edge? I consider the Edge hilariously pompous, elitist trash, because it doesn’t allow readers to post comments. That is THE WAY of the Internet, and any Internet publication that doesn’t understand this, is certainly not on the Edge.
Well Susskind is behaving just like a scholastic philosopher. GSW is their Summa Theologica.
Hi Simon,
In my experience most string theorists are well aware that they don’t know how to make testable predictions, and that this is a big problem. I can understand this, as well as their getting upset if someone seems to be accusing them of not even being interested in having a testable theory. You’re right, I happen to believe that the program they’re pursuing isn’t going to lead to testable predictions, so think people should give up and do other things, but it’s a matter of judgement and reasonable people can disagree.
But I have real trouble understanding the behavior of Susskind, Kaku, and some others, who bald-facedly deny the problem, and/or start twisting the meaning of what it means to make a scientific prediction to evade the problematic position they’re in. Fundamentally I guess I think this is just dishonest, and shouldn’t be tolerated in a scientific community.
Peter, you say that you guess you think that “… the behavior of Susskind, Kaku, and some others … is just dishonest, and shouldn’t be tolerated in a scientific community. …”.
If you are correct (and I agree with you), then:
Does the fact that,
although they may be criticized internally as Lubos criticizes Lenny,
they are NOT disavowed by the conventional superstring community with respect to the general public and the politicians who provide funding,
imply that the conventional superstring community is NOT a scientific community, but is a political club whose purpose is to maintain its status quo of dominance of theoretical physics jobs and funding.
In turn, does that not imply that scientific methods, such as honest intellectual criticism of conventional superstring theory, are doomed to be ineffective in challenging the dominance of conventional superstring theory.
Tony Smith
http://www.valdostamuseum.org/hamsmith/
Tony,
good analysis. indicates an important job for the press
(getting internal criticism out to general public and politicians)
Simon,
I’ll take a guess that you are Simon Ross, welcome.
I hadn’t realized you were posting here at Peter’s blog.
Glad to hear your views.
Nope, not Simon Ross, a different Simon….
Well it’s nice to be confused with a physicist as smart as Simon Ross!
Peter – I haven’t followed Kaku’s or Susskind’s opinions on the future of string theory too closely. But I don’t find Susskind’s response to Horgan objectionable.
String theory is not a theory we understand well enough right now to make a prediction. I believe the physicists he lists are expressing their confidence that one day that will change and their ideas for how it might happen. The string theory they refer to is the hypothetical complete theory, rather than our present glimpse of it. One may not share their confidence in the existence of such a theory, or in our ability to find it.
As for Horgan, his argument against the testability of string theory is essentially that one can’t do accelerator experiments at the relevant energy scales. Well this is really a bad argument. There are many ways even in QFT that observations far below the characteristic scale of the theory can tell you lots.
A spectacular example of this is the electroweak theory. The existence of strong interaction bound states allows one to observe beta decay without building an accelerator. From the kinematics one can deduce the existence of a massless neutral fermion, and then it’s not such a big leap to the Fermi 4-point theory, which describes scattering very well at energies less than 300 Gev. At this energy, the theory violates unitarity, so one can wonder how to alter it so as to conserve probability. One starts adding particles with charges and couplings chosen appropriately. To be consistent with the success of the Fermi theory, one can show that you have to add a massive charged spin 1 particle to mediate the 4-point interaction (W). But then scattering of longitudinally polarized W’s causes new unitarity violations, which require the introduction of at least 2 more particles. If one wants to add only 2, then there are just 2 options. One is a neutral massive spin 1 (Z) and a neutral scalar (Higgs). The other is a neutral fermion, and a neutral scalar. Picking the first option, one then chooses the couplings and masses to avoid unitarity violation in WWZ and vvZ scattering, and amazingly the result is the electroweak theory, with exactly the masses and couplings found from the spontaneously broken gauge symmetry analysis! The other option predicts the W mass to be about 50 GeV, which is ruled out again by experiments well below the electroweak scale.
I left out most of the details, but the argument is spelled out beautifully in a book called ‘Introduction to Electroweak Unification: Standard Model from Tree Unitarity ‘ by J. Horejsi. Of course this isn’t how the electroweak theory was found, but it does show that by thinking hard enough, one can sometimes learn about high energy physics from observations at lower energies. I imagine this is what people have in mind when they suggest that we can learn about string theory by looking at the CMB, or cosmic strings if they are found.
I will be Who then.
(that is not a question)
I liked Simon’s statement very much and I thought that he might be a string theorist I could respect and trust. So I wanted to ask him a question.
for me a kind of test of a QG researcher is the quality of awareness and interest he or she shows in other alternative-QG lines of investigation.
A while back Aaron Bergman ( in spite of the fact that I often dislike and disagree with what he says) impressed me positively because he was volunteering real interest in recent Ambjorn-Loll work in CDT type nonperturbative QG.
the kind of string theorist one wants to listen to is one who is not contemptuous and dismissive of other QG, especially (since string is perturbative) the background independent approaches. so many of them have some stock response.
So I wanted to ask this Simon (whether or not he is a real Simon and doing string, which is merely my guess) what QG alternative(s) to string do you find especially interesting or promising, if any?
Who – I’m sorry to disappoint you, but I’m just a lowly graduate student, and mainly I’m interested in the more mathematical side of string theory. I agree that one shouldn’t be contemptuous or dismissive of other approaches to quantum gravity. But in all honesty I know very little about them. Perhaps someone can clarify for me why background independence is so important?
‘… what QG alternative(s) to string do you find especially interesting or promising, if any? ‘
What if nature turns out to appear boring or unpromising? What do you do then, if your expectations of an elegant or beautiful mathematical structure can’t be fulfilled? If you look back, you see that nature is often unexpected. People didn’t want evolution because it lacked elegance and beauty of creationism. If you don’t know the answer in advance, can you afford to have prejudices?
An approach to QG which is the opposite of string theory, just a fluid Higgs pressure shielding mechanism, offers many testable (tested) predictions and solutions to other issues. It’s amazing that people are so dismissive of alternatives to string theory.
Andrew M Wray, publishing editor of Classical and Quantum Gravity, wrote me a letter dated 14 July 1997 stating: ‘… we do not publish this type of article…’ PRL, Nature, arXiv, and New Scientist didn’t either, but Electronics World (60,000 circulation) and the cern server did 6 years later. Nobody in physics knows about it. The problem is, people were then and still are obsessed by superstrings.
Dr Bob Lambourne of the Open University wrote me on 23 April 1997: ‘… the ultimate “cause” of gravity is an ill-defined concept… Rather the issue should be “what kind of theory is best suited to describing a certain range of phenomena in broad conformity with our current knowledge…” At the present time such a discussion would probably focus on superstrings.’
Strings are therefore the only really rational way to even discuss quantum gravity. If you don’t want to talk strings, you aren’t serious. The physics community is sure about this for some reason. I won’t bore you with my predictive, well tested model.
Hi Simon,
I agree that Horgan’s argument, as stated, is too crude, or incomplete. His two sentences about the lack of testability
“My problem is that no conceivable experiment can confirm the theories, as most proponents reluctantly acknowledge.”
and
“The strings (or membranes, or whatever) are too small to be discerned by any buildable instrument”
are both true, but the implication that the second sentence implies the first isn’t correct. In Horgan’s defense, the true situation here is complex enough that explaining it correctly to a general audience would take up the entire length of his Op-Ed piece. In this kind of very short piece, it’s hard to not sweep a lot of complexity under the table.
Of course, if string theory really were a TOE, it should imply the full range of phenomena we see at low energies and you should be able to calculate them and compare these calculations to experiment. Horgan does ignore this point.
The true situation of course is that there is no well-defined theory, so one really can’t calculate anything, at low energy or high energy. In the approximate versions of a theory that one has, one can do calculations of what the low energy excitations of the theory look like, and, basically, the problem is they come out wrong. I’ll not here go into the long story of attempts to get the standard model out of string theory constructions, but the bottom line is that no one has gotten the full standard model in detail yet, no matter how complicated a construction they use.
Here’s a more detailed version of what I take to be Horgan’s argument, one that would avoid the incorrect implication in his simpler version:
“After more than twenty years of effort, no one has managed to come up with a consistent well-defined version of string theory that reproduces what is known about physics and makes further predictions that can be tested. One of the main reasons for this is that the conjectured fundamental excitations of the theory are too small to ever be directly measured, so we can’t directly check the idea of higher dimensional fundamental excitations by going out and looking for them. String theorists have hoped that the existence of these higher dimensional excitations will have characteristic effects at low, observable energies, but so far this hasn’t worked out at all. The most recent work on the theory implies that these hopes can never be realized, since the theory, if it makes sense at all, seems to have an infinite variety of possible low energy behaviors.”
On the other hand, what Susskind writes is clearly designed to give the impression that a long list of distinguished people are full of ideas for feasible tests of string theory. This is simply untrue and Susskind knows it. You have to parse his words very carefully to see that he’s not quite saying this. Again, I think this is just dishonest.
Simon, thanks for your response. You say:
Who – I’m sorry to disappoint you, but I’m just a lowly graduate student, and mainly I’m interested in the more mathematical side of string theory… Perhaps someone can clarify for me why background independence is so important?
I would be happy if one or more others would discuss background independence. I will take a whack at it from the standpoint of a physics-watcher. There are several ways to respond, some of which you may find less persuasive than others. I won’t try to fit the argument to the listener—I will just lay out several responses.
1. Gen Rel is background independent. So it is likely that any successful QUANTUM spacetime dynamics will also have to be.
2. Go read Smolin’s recent paper “The Case for Background Independence” hep-th/0507235, which argues that it would help string theory resolve the landscape confusion and become more predictive if an effort were made to formulate it in a less background dependent way. I won’t summarize his argument unless you ask. Ignore Motl’s hostile paraphrase. Just read the introduction and conclusion sections of Smolin.
3. There are degrees of background independence. Gen Rel is B.I. in the sense that does not need a prior metric. (By contrast, stringy perturbative calculations require a prior metric to start from.) But Gen Rel is NOT as B.I. as the Triangulations approach that recently became prominent (Ambjorn-Loll, CDT, for instance hep-th/0505154) in the nonperturbative quantum gravity community.
Why? Because CDT does not assume that spacetime is a differentiable manifold, only that it can be APPROXIMATED using a path integral sum involving (triangulated) differentiable manifolds. This means that the continuum does not have to have uniform dimensionality at all scales.
It is not required have to have an atlas of coordinate charts. One can calculate in CDT and there are indications that it reproduces Gen Rel at large scale. But it DOES NOT ASSUME the manifold structure that Gen Rel assumes. Because it assumes less prior structure it is more background independent than General Relativity.
On the other hand, the various Stringy models, seem all to be LESS background independent than General Relativity. Indeed they seem on the whole to be PERTURBATIVE. So, well, maybe that does not interest you Simon but it is a stark contrast and, speaking personally, it gets my attention.
4. As a general rule, theories which assume less prior structure are on that account more predictive. If a theory is having trouble making unambiguous falsifiable predictions, one obvous helpful suggestion is to make it more background independent.
5. There ain’t no absolute spacetime. Newton invented that idea (he called it the sensorium of God) and it prevailed since it is a technical convenience.
As soon as I post this I will think of something I said wrong or left out. But regardless of that, you are asking a good question and some sort of response is needed, so here is one to get started with.
yours truly,
Who
Peter – let me divide your (rather complimentary) paraphrase of Horgan’s argument into two pieces. The first piece ends at “so far this hasn’t worked out at all”. The second piece is just the next sentence.
Imagine if in piece one, the expression “20 years” was changed to “3 months”. I’m guessing you would no longer think the criticism was reasonable. It’s really a judgement as to how long it’s worth working on an approach that hasn’t so far yielded concrete predictions. Presumably this depends on many other things, e.g. whether the theory has interesting mathematical spinoffs, whether other approaches are promising, etc. I don’t want to get into those issues – I honestly have no idea how to decide what is the right amount of time to work on a theory like string theory. And I’m pretty sure Horgan has no sensible idea either. I don’t find 20 years a shockingly long stretch of time.
The second piece concerns the landscape – the apparent plethora of consistent string backgrounds. You are right that it isn’t too encouraging, and I think if it’s correct (i.e. if these are indeed consistent string vacua) it could force us to change our idea of what we hope to get out of string theory. As far as I understand, this is the content of the ‘east coast — west coast’ debate. I don’t understand this subject too well, but I don’t see any reason to rush to the most pessimistic position.
To emphasize just how little is currently understood about the space of string vacua, note the tension between the statement that standard model-like vacua seem to be very difficult to find, and the statement that vastly many of them exist. To me this indicates that it’s premature to ditch string theory because of the landscape.
By the way – I think I understand why Susskind tells Horgan to go take some classes. I suspect that people who say that extra dimensions are ‘preposterous’ would also think quantum mechanics and special relativity were preposterous if they understood them.
Simon, glad to see you are still around! Have to leave (day at the ocean) in a moment, no time to read or respond to posts. However you asked about Background Independence issue earlier and I gave you my response—for contrast or whatever reason you might also like to glance at very different views on this at String Coffee, starting with a post by Robert Helling.
http://golem.ph.utexas.edu/string/archives/000621.html
Different notions of what background independence means arise there, defenses are thought of against Smolin’s urging that string theorists work out a B.I. formulation. Concern is expressed that outsiders will be (naively or mistakenly) critical of string because of its background dependence, and so on. Interesting, if rather intricate, set of reactions to Smolin’s hep-th/0507235.
Simom,
If you noticed Horgan did imply several times that QM and relativity are preposterous but that a wealth of experimental data makes that not matter. That was his main point that common sence reasoning should not be abandoned without good experimental reasons. The reason people started studying string theory was not because of some experimental result like the inability to discover motion throught the ether, the photoelectric effect, and the spectrum of blackbody radiation, but because the mathematical construct of string theory produced an unobserved massless spin 2 particle which previous failed theories to quantize gravity had also predicted to move particles along the geodesinc(or however its spelled) determined by the metric which the mathematical construct of string theory had no mechanicsm to produce. This slim “evidence” that string theory has something to do with nature has led to many “crazy” predictions of particles being one dimmensional loops, then the world having a bunch of extra curled up dimmensions and now that all sorts of branes exist. All of which, while possible, has no basis in the real world other then the fact that some people think the way to reconcile relativity and QM is to quantize gravity and string theory happens to contain a particle similar to the one usualy predicted when someone tries to do this and fails.
Who – thanks for the references. I’ll do some reading!
Simon,
You’re right that if people had only been working on string theory for 3 months no one would be complaining about its present state. Personally I waited about 16 years before starting to publicly complain about what was going on. But, sorry, 20 years (actually 21 and counting since the “First Superstring Revolution”) is a shockingly long time for thousands of the smartest people to work on a speculative idea, given that not only have they not made any progress on using it to come up with a TOE, but they’re much farther from their goal than when they started. I don’t think anything remotely like this has ever happened in the history of physics.
If the landscape is correct it could “force us to change our idea of what we hope to get out of string theory”? How about calling a spade a spade and changing that to “force us to admit this idea has failed completely and we have to do something else”? One of the most annoying things about the way many string theorists express themselves is that they act as if it is completely inconceivable that string theory as a TOE is simply a wrong idea that will need to be completely abandoned.
Susskind’s telling someone who was a senior writer at Scientific American for many years that he should go take a high school algebra class is just a stupid, juvenile insult, one that I recognize all too well from personal experience as a standard kind of thing some string theorists say when challenged about the problems of string theory.
Peter – I don’t think it’s really fair to compare current research to previous research in physics. It’s not the same problem, and it’s not such a surprise to me that as experiments at higher energies become more and more expensive, theoretical progress slows down too. I have a vague recollection that this slow-down of theory was even predicted by Feynman.
I agree with you that it could turn out that when we fully understand the landscape (if it exists), we’ll have to give up on string theory as a TOE, but I have no idea if that’s how things will go. In the meantime, I’m glad some people are trying to figure out if that’s the situation.
I’m sorry you’ve had unpleasant experiences dealing with some string theorists. The reason I defended Susskind a little is that I also found Horgan’s article obnoxious. Not because of anything he said about string theory though. Rather it’s because he rather deviously uses ‘common sense’ as a rhetorical device when lost for a logical argument. As you said above, he makes a couple of statements about string theory which are true if interpreted charitably, but the implied logical links between them are absent. That works for me as a description of the whole article. It’s just not good writing.
It’s also arrogant and self-aggrandizing:
“Needless to say, I reject that position, and not only because I’m a science journalist (who majored in English). I have also found common sense — ordinary, nonspecialized knowledge and judgment — to be indispensable for judging scientists’ pronouncements, even, or especially, in the most esoteric fields.”
Simon I am not sure what you find arrogant and self-aggrandizing in saying that ordinary, nonspecialized knowledge and judgement (which is what he defined common sense as) is indespensible in judging various ideas even in esoteric fields. He goes on tell which parts of ordinary knowledge and judgement(common sense) are usefull, namely that things involving how humans behave are unlikely to be dirrect effects of a single cause and that extroardinary claims should require extraordinary proof(expirmental results).
Hollywood Physics
http://physicsmathforums.com/showthread.php?p=403#post403
FOR IMMEDIATE RELEASE:
ALL TIED UP & STRUNG ALONG, a movie about String Theorists and their expansive theories which extend human ignorance, pomposity, and frailty into higher dimensions, is set to start filming this fall. Jessica Alba, John Cleese, Eugene Levie, Jackie Chan, and David Duchovney of X-files fame have all signed on to the $700 million Hollywood project, which is still cheaper than String Theory itself, and will likely displace less physicists from the academy.
“As contemporary physics is about money, hype, mythology, and chicks,” Ed Witten explained from his offices at the Princeton Institute for Advanced Study, “The next logical step was Hollywood, although I thought Burt Reynolds should play me instead of Eugene Levy.”
Brian Greene, the famous String Theorist who will be played by David “the truth is out there” Duchovney, explained the plot: “String theory’s muddled, contorted theories that lack postulates, laws, and experimentally-verified equations have Einstein spinning so fast in his grave that it creates a black hole. In order to save the world, we String Theorists have to stop reformulating String Theory faster than the speed of light. We are called upon to stop violating the conservation of energy by mining higher dimensions to publish more BS than can accounted for with the Big Bang alone, and I win the Nobel prize for showing that M-Theory is in fact the dark matter it has been searching for.”
Greene continues: “At first my character is reluctant to stop theorizing and start postulating, but when my love interest Jessica Alba is sucked into the black hole, I search my soul and find Paul Davies there, played by John Cleese. I ask him what he’s doing in my soul, and he explains that the answer is contained in the mind of God, which only he is privy too, but for a small fee, some tax and tuition dollars, a couple grants here and there, and an all-expense-paid book tour with stops in Zurich and Honolulu, he can let me in on it. And he shows me God in all her greater glory, as he points out that we can make more money in Hollywood than writing coffee-table books that recycle Einstein, Bohr, Dirac, Feynman, and Wheeler. I am quickly converted, and I agree to turn my back on String Theory’s hoax and save Jessica Alba.”
But it’s not that easy, as standing in Greene’s way is Michio “king of pop-theory-hipster-irony-the-theory-of-everything-or-anything-made-
you-read-this” Kaku, played by Jackie Chan. Kaku beats the crap out of Greene for alomst blowing the “ironic” pretense his salary, benefits, and all-expense paid trips depend on. “WE MUST HOLD BACK THE YOUNG SCIENTISTS WITH OUR NON-THEORIES!! WE MUST FILL THE ACADEMY WITH THE POMO DARK MATTER THAT IS STRING THEORY TO KEEP OUR UNIVERSE FROM FLYING APART, OUR PYRAMID SCHEMES FROM TOPPLING, AND OUR PERPETUAL-MOTION NSF MONEY MACHINE FROM STOPPING!!” Kaku argues as he delivers a flying back-kick, “There can be ony ONE! I WILL be String Theory’s GODFATHER as referenced on my web page!! I have better hair!”
But Greene fights back as he signs his seventeenth book deal to make the hand-waving incoherence of String Theory accessible to the South Park generation, senior citizens, and starving chirldren around the world. “Kaku! Kaku! (pronounced Ka-Kaw! Ka-Kaw! like Owen Wilson did in Bottle Rocket),” Greene shouts. “It is theoretically impossible to build a coffee tables strong enough to support any more coffee-table physics books!!!”
“Time travel is also theoretically impossible, but there’s a helluva lot more money for us in flushing physics down a wormhole. Nobody knows what the #&#%&$ M stands for in M theory ya hand-waving, TV-hogging crank!!! Get it?? Ha Ha Ha! We’re laughing at the public! We’re the insider pomo hipsters! Get with the gangsta-wanksta-pranksta CRANKSTER bling-bling program!!”
How does it all end? Does physics go bankrupt funding theories that have expanded our ignorance from four dimensions into ten, twenty, and thirty dimensions? Do tax payers revolt? Do young physicists overthrow the hand-waving, contortionist bullies and revive physics with a classical renaissance favoring logic, reason, and Truth over meaningless mathematical abstractions? Does Moving Dimensions Theory (MDT) prevail with its simple postulate? We’ll all just have to wait!
But in the meantime, how do you think it will play out?
Will theories with postulates ever be allowed in physics again? Or will the well-funded, tenured pomo String Theory / M-Theory (Maffia-Theory) Priests send their armies of desperate, snarky postdocs and starving graduate students forth to displace and destroy all common sense, logic, reason, and physics in the academy? It must be so–for the greater good of physics, the individual physicist, and thus physics, must be sacrificed.
http://physicsmathforums.com/showthread.php?p=403#post403
If you guys want to talk about quantum gravity please drop by blog (click on my name). I just started the blog recently and learning to keep it steady. (I deleted some comments left by some of you accidently-sorry)