To date Susskind has not publicly answered the detailed criticisms of his use of the anthropic principle contained in Smolin’s article. If he has finally read the article and has an answer to Smolin’s criticisms, scientifically his first priority should be to deal with this issue, not to attack Smolin’s more speculative ideas. Doing what he has done gives the strong impression that he has no answer to Smolin’s criticisms, and instead of confessing to this, has decided to go on the attack. Maybe “thuggery” was too strong a term, but I don’t believe this has much to do with trying to get at scientific truth.

By the way, Susskind is famous for not pulling punches, and he does not distinguish `string theorists’ from non-`string theorists’ when he thinks that someone is wrong. Have a look at his hep-th/9405103, `Comment on a Proposal by Strominger,’ and also his contribution hep-th/0204027 to the Hawkingfest. Susskind’s style is not for everyone, but I believe that it is his way of trying to get at the scientific truth, and I am sure that Smolin will take it in this way.

Let me summarize again the facts about what Susskind did in response to Smolin’s 40 page or so paper containing a detailed and serious critique of the anthropic principle and Susskind’s use of it. Without even bothering to read it, within a day of its appearance he wrote a completely incoherent one and a half page defense of the anthropic principle and attack on Smolin, then tried to post it on the arXiv. This was such a ridiculous document that he was told he couldn’t do this, something which is completely unheard of. A couple days later he stripped out the nonsensical defense of his own work, added a more detailed attack on Smolin, and managed to get this posted.

I think this kind of behavior is disgraceful, and it has nothing to do with doing serious science. Susskind clearly just wanted to beat up Smolin for pointing out that what Susskind is doing is not science. I’ve seen all too much of this kind of thuggery, directed at anyone who dares criticize what string theorists are doing.

See my recent comments on “Black Holes at the LHC”. I agree these models are basically silly, and most string theorists I’ve talked to say they don’t believe them. The motivations for this kind of work are not just to get grants, but something more complicated. For one thing there is a desperation among string theorists to do something that can somehow count as an experimentally testable prediction, so the fact that you can cook up models of this kind that would have observable effects at the LHC is a huge motivation, even though the models are highly implausible and cooked up. A second motivation is that this stuff is technically very easy. You don’t have to know any algebraic geometry, conformal field theory, etc. Much of this work just comes down to setting up and solving simple differential equations. It’s a good subject for undergraduate projects.

Either I’m seeing things or asleep, but I recall seeing a comment on this thread about your view on those large TeV scale extra dimensions models.

When those models first appeared, I thought they weren’t much more than somebody working out the consequences of some Kaluza-Klein theory, which didn’t seem much more than a hypothetical exercise. After awhile when more and more folks were cranking out papers on this topic, I got the sense the subject was trying to making predictions that looked too silly to be true or even plausible. (ie. It didn’t even pass the initial “laugh” test.)

After a few years of these large TeV scale extra dimensions models proliferating, I got the impression they seemed fit into the category of “let’s propose these silly models that we know are too outlandish but are nevertheless ‘trendy’, just to get NSF or DOE funding”. On the surface it sure smelled like an excuse for a grant funding grab. At times I wonder what sort of weird things people will propose, just to get grant money from the government, even if they know deep down in their hearts that the work is bogus from the start.

The Susskind article however, does read like a blog/forum rant and not a carefuly thought out scientific article. He even admits he does’nt understand Smolin when he says” the detailed astrophysics that goes into Smolin’s estimate is extremely complicated–too complicated for me–but the basic assumptions that go into the theory can be evaluated in the light of what string theory has taught us about the Landscape and black holes”. How can he evaluate or respond to the article when he admits he doesnt understand the underlying astrophysical arguments?

Also, string theory has not really given any insights into real black holes or cosmology and is not in a sufficiently developed state to do so (many string theorists would actually agree). The Strominger-Vafa paper and other (admittedly interesting )papers in the 90s dealt with extremal black holes in string theory–not real astrophysical black holes. Similarly, string theory simply can’t deal with deSitter space and a very small positive cosmological constant/accelerating universe despite the artifical constructions of the Stanford group.

Basically he seems only interested in promoting his own string-based agenda, even though it can’t actually connect to anything in the observed universe, and any argument that does not conform to his dogma/agenda must be wrong in his eyes. I do find the whole thing somewhat strange. The pro-anthropic camp will have to really do a lot better if they are to maintain credibility. I really wish Susskind would produce one detailed cleary thought-out journal quality article carefully and rigorously promoting his ideas at least. (Papers he wrote years ago I found both interesting and informative, I just don’t get this recent trend of his).

I think the arXiv is a double edged sword:one can instantly access the latest ideas/research in physics from anywhere but at the same time it is filling up with resume padding, career/grant maintaining, ego messaging stuff too. I try and stick to stuff in the Arxiv that at least has a journal acceptance/submission also. Peer review seems to have broken down in hep and string theory especially and I think it is going to be a problem for the field in the long run. I think it is fine for the people like Witten or Weinberg to just post their stuff but I think most others need the conventional journal route. String theorists should actually be the strongest critics of each others work rather than be a mutual admiration society (which is the impression I often get, whether that’s right or wrong). Every other branch of science, engineeering, medicine has to go through the very rigorous “old fashioned” peer-review process via paper journals with subsequent online access. Although it is not perfect I think all scientists (whether students or established professors) still need the discipline/feedback provided by that or else the archive will end up like a ranting open physics forum. If the archive is going to be more rigorous in their acceptance criteria now then that could be a good thing.

But I think the right thing was done in rejecting Susskind’s article. The arXiv shouldn’t become like sci.physics.research, where people post comments of all sorts. It should remain a place where people post scientific articles of the sort that will ultimately appear in a peer-reviewed journal. I can’t believe any such journal will ever publish the kind of thing Susskind has been putting out recently, so arguably others of his articles should also have been rejected. In any case this isn’t an example of censorship of non-mainstream ideas, since Susskind is certainly part of the mainstream. His paper was rejected not because of his ideas, but because of its embarassingly incoherent and unscientific nature.