I haven’t posted anything new here in a while, with the holidays and trying to get over a bad cold keeping me otherwise occupied. Partly because of this the comments section has been to some degree taken over by people who want to discuss things I have no interest in. I’ll try and put up something new soon (comments on Penrose’s new book), but I did want to make some remarks about the problem of crackpotism in theoretical physics, something which is especially a problem for open forums on the internet like the comment section here.
When I first started studying particle physics during the 1970s, it was pretty clear to me how to tell the difference between serious people and crackpots. The Standard Model had just recently been formulated and it had started to accumulate an impressive amount of experimental evidence in its favor. So, at least in particle theory, serious people were doing one of a small number of things. The more phenomenologically inclined were analyzing the new experimental results to see if they further validated the Standard Model, or suggesting new experiments that would test different parts of the model. More mathematically inclined sorts were trying to understand the rich structure of the model, trying to get a better grasp of its aspects that were still poorly understood. People inclined to speculation were working on ambitious extensions of the model, hoping to find something compelling that would both explain some of the model’s parameters and make new, testable predictions.
So, to my mind, crackpots were those claiming to have new ideas about particle physics, but refusing to really engage in some way with the Standard Model quantum field theory. There were plenty of them around, including S-matrix die-hards like Fritjof Capra, those who wanted to go on about what happened before the big bang and how that explained all properties of particles, and a wide variety of people with their own private TOE that completely ignored the Standard Model. All you had to do was learn to ignore such people.
During the last 20 years, distinguishing crackpots has become a lot tougher, and it has gotten much more difficult recently. Famous professors from the best research institutions in the world go on about the properties of the universe being determined by colliding branes, or by an anthropically determined point in a multiverse, or any number of similar ideas. The dominant idea in the whole field makes nothing like what would normally be considered a testable scientific prediction, and those pursuing it don’t seem too bothered by the increasing evidence that this situation will never change. Personally I haven’t much changed my criterion for crackpotism in particle physics: if someone is not engaging in a deep way with the Standard Model and/or the kind of mathematical structures it involves, they’re probably a crackpot.
When I first wrote a critical article about string theory and made it public about four years ago, I got quite a lot of reaction. Almost all of it was gratifyingly positive, but I ended up hearing from quite a few people who were convinced that since I didn’t like string theory, surely I would like their alternative. These alternatives spanned a wide range, from very serious work to complete crackpotism, including all shades of in-between. The one thing that caused me to worry that there might be something wrong with my criticisms of string theory was the nature of a small number of my supporters. Some of these people still write to me regularly, and my e-mail is full of crazier things than what appears in the comments on the weblog. It’s embarassing to get cc’d on an e-mail to a long list of very prominent physicists by someone who is quoting my criticisms of string theory to back up their own even sillier ideas.
I’ve gotten very good at hitting the delete key or, in extreme cases, using procmail to automatically filter this stuff out of my inbox. I suggest similar tactics in reading the comment section here. The first line of defense against people who you think are not making any sense is just to ignore them. Do not give in to the temptation to point out to them that they are not making sense, because all this will accomplish is to clutter things up as they respond to your response to them.
I’m not about to start just deleting comments that I think are of a crackpot nature, partly because it is now hard to set up a clear criterion for what is crackpotism (should I delete Lenny Susskind’s comments if he decides to write in some day?). But to the extent that the volume of off-topic comments starts to overwhelm those that are interesting and related to the postings, I will have to take some sort of action. If you are posting large numbers of comments, mostly far off the topic at hand, please stop doing it now. If you are responding to such off-topic comments, please stop doing that too, don’t encourage them!