Preposterous Universe

 
Interestingness

I wanted to say something about the essay by Robert Laughlin (no relation to this McLaughlin fellow, nor for that matter this one) that was pointed to by 3 quarks daily. Laughlin, of course, is a towering figure in theoretical condensed-matter physics, winner of the 1998 Nobel Prize for his work on the fractional quantum Hall effect. He is also a well-known proponent of "emergence" as a crucial concept in modern physics. This notion of emergence is held up in contrast with reductionism -- the latter attempts to understand things by breaking them down into their component parts, while the former focuses on collective behaviors that only become apparent at the macroscopic level.

This is an interesting distinction, but for some reason people feel compelled to raise it to the status of some sort of competition, arguing that either emergence or reductionism is somehow more important than the other. I don't know why they feel that way. An unfortunate side-effect of this attitude is that it causes very smart people to say very silly things. Laughlin, for example, talks about the current view of string theorists -- the ultimate reductionists -- as represented by Brian Greene's book The Elegant Universe.

The worldview motivating my uncle's attitude toward Yosemite, and arguably also Brian Greene's attitude toward physics, is expressed with great clarity in John Horgan's The End of Science (Addison-Wesley, 1996), in which he argues that all fundamental things are now known and there is nothing left for us to do but fill in details. This pushes my experimental colleagues beyond their already strained limits of patience, for it is both wrong and completely below the belt. The search for new things always looks like a lost cause until one makes a discovery. If it were obvious what was there, one would not have to look for it.

Now, nobody could possibly have read The Elegant Universe and come away characterizing it as saying "all fundamental things are now known and there is nothing left for us to do but fill in details." The book goes into great detail about all of the things that we don't know, even just within the (quite considerable) scope of string theory. It doesn't talk a lot about condensed-matter physics, but that is hardly the same as arguing that condensed-matter physics isn't important. And it clearly does emphasize the need for experiments, even though they are very hard to do at this point.

The reason why such a smart person could say something so obviously wrong becomes clear in the next paragraph:

Unfortunately this view is widely held. I once had a conversation with the late David Schramm, the famous cosmologist at the University of Chicago, about galactic jets. These are thin pencils of plasma that beam out of some galactic cores to fabulous distances, sometimes several galactic radii, powered somehow by mechanical rotation of the core. How they can remain thin over such stupendous distances is not understood, and something I find tremendously interesting. But David dismissed the whole effect as "weather." He was interested only in the early universe and astrophysical observations that could shed light on it, even if only marginally. He categorized the jets as annoying distractions on the grounds that they had nothing in particular to tell him about what was fundamental. I, by contrast, am fascinated by weather and believe that people claiming not to be are fibbing.

Well, sure. There are cosmologists who are not interested in non-cosmological astrophysics. There are particle physicists who are not very interested in superconductivity. Likewise, there are condensed-matter physicists and astrophysicists who are not very interested in relativity or string theory. And there are biologists who are not interested in poetry, and historians who are not interested in number theory. Let's face it -- there are academics of all stripes who are more interested in their own fields of research than in other fields. They're not fibbing, but neither does their attitude translate into an objective statement about the worthiness of other questions.

Interestingness is like beauty -- it is not located out there in the world, it is a function of the relationship between a person and a phenomenon. Things are not intrinsically interesting, they are found to be interesting by people. (In a truly precise language, it wouldn't even be grammatically possible to say "X is interesting"; we'd only be able to say "I find X to be interesting," or "X is found to be interesting by most people.") I personally am interested in the nature of the dark energy that apparently constitutes seventy percent of the universe. But if someone else is not interested, they aren't making a mistake, that's just their honest feeling. If David Schramm wasn't that interested in jets, we can't simply extrapolate that one data point to a general conclusion that those arrogant reductionists are unwilling to appreciate the allure of collective behavior -- some of us think that weather is fascinating, and are more than happy to admit it, even if it's not what we want to do research on. (Not to mention the most likely explanation for the recounted conversation, which is that Schramm was simply yanking his chain.)

Unfortunately, we need to act as if these incommensurable levels of interestingness are somehow real, since we live in a world of finite resources and need to decide how they should be allocated. The good news is that there really is enough to go around, at least at the moment -- we can simultaneously pursue high-energy physics and cosmology, and also contemplate astrophysics and biophysics and condensed matter. Not everyone feels that way, of course, which is why we get unfortunate incidents like Phil Anderson's undercutting of the Superconducting Super Collider. Perhaps someday they will notice that, when funds get cut for massive reductionist experiments, they tend not to flow to research into the fascinating world of emergent phenomena, but rather to simply disappear. Can't we all just get along?

~ posted by Sean Carroll at 5:55 PM ~ link ~ ~ ~