The Anthropic Approach To String Theory

Since I wrote an article about this last year for the non-expert to get some idea of what the discussion was about, let me first point you to it via this link. Since in that article, by way of illustration of the “Landscape” idea, I used a picture of the Maroon Bells and the accompanying valley and lake, let me put here a version that I took today. (The supersymmetric vacua are no longer visible, you’ll notice. I’m hoping that maybe it is time we learned to stop focusing on those for guidance, but….)

Let me next point out a post I did about the panel discussion on “Naturalness” at the SUSY 2006 conference, hosted by UC Irvine, held at Newport Beach. There was a lot said about the Landscape there. Have a read.

Finally, let me point out that Science writer Tom Siegfried (who was also at the conference) has written an article on the science and sociology of the Landscape/Anthropic/String “issue” in the August 11th edition of Science Magazine. He has several quotes and interviews with the key players -such as with Joe Polchinski, particularly discussing his “conversion”- and he also has quotes from the perhaps-not-so-key, such as your friendly neighbourhood host/writer of this blog:

Other physicists, although reluctant to embrace anthropic reasoning, decry the acrimony and seek a middle ground. “It’s unfortunate that it has turned into a situation where you have to choose to be in one camp or the other,” says Clifford Johnson, a string theorist at the University of Southern California in Los Angeles. “It would be nice if we could explore some of those unpalatable ideas just in case that’s the way that nature chooses to go.”

(Hmmm. I could have said that a lot better. For example, “Nature chooses to go” really should have been “Nature chose to go”….or perhaps “Nature is better described”. I was probably a bit tired when I spoke with him…. but this is not so important.)

This “not having to choose” business I try to put forward puts me in mind of a much better quote from commenter Moshe, (not in the article but on my aforementioned Cosmic Variance report on the panel discussion.) He said, in a way that I think is rather good:

I think theorists (and people in general) should have the ability to hold contradictory viewpoints simultaneously, especially in the face of uncertainty.

Overall I think Tom Siegfried does an excellent job of making sense of where the whole business is right now, from a non-expert’s perspective. While I would again (as I often do) caution the unwary reader to not assume from so much press coverage that (as many would have you believe) the entire field is working on Landscape/Anthropic studies and arguing away about this to the exclusion of all else (they are not… there is a lot of other exciting and interesting work going on in the majority of stringy research that has little or nothing to do with this issue) I do recommend having a look at it at this link.

Come back and share with us what you think.

-cvj