Sigh

I see below that (in what comes as a total surprise) the string thread has already gotten lively. As an experimentalist doing quantum mechanics at the ultra-low-energy end, I don't have a strong opinion on string theory qua theory, and I really don't have a strong opinion on the sociology-of-theory business, beyond saying that I'm not a cynic, and that I find articles in the popular press about Str1ng Warzz a bit tacky.

I'm also not really qualified to weigh in: my only particle theory background was a year of QFT from a phenomenologist out of Peskin & Schroeder, and while I came out of it with a certificate saying I Could Now Calculate Any Cross-Section in QED, which was nice, the last quarter pretty much lost me.

So I think I can summarize my vague feelings on the business as such: theory is hard; experiments are also hard; it would be nice to see more connections to experiment; conspiracy theories are bad; acting like five-year-olds is also bad; and Brian Greene has caused me more grief from my relatives than Hawking ever did. Am I boring or what?

I'm also reminded of Feynman's intro to QED, wherein he says:

What I'd like to talk about is a part of physics that is known, rather than a part that is unknown. People are
always asking for the latest developments in the unification of this theory with that theory, and they don't give us a chance to tell them anything about one of the theories that we know pretty well. They always want to know things that we don't know. So, rather than confound you with a lot of half-cooked, partially analyzed theories, I would like to tell you about a subject that has been very thoroughly analyzed.

As much as I find Feynman invocation distasteful, this made me smile. And I like to think about it whenever my relatives ask me about these crazy little strings.

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Heh, "ultra-low-energy end", I like that, I'll have to start using that in my job description!

But sigh is right, I get this a lot from friends and relatives too - just mention that you do physics and they'll assume you know enough and/or want to talk about whatever latest fad in strings is. Although admittedly, it's still slightly better than someone wanting to know how UFO propulsion worked, and if the government covered it up, etc, etc.

Damn you! I was re-reading QED yesterday and wanted to use that quote as a jumping off point for my own post.

Now I have to wait until it this post is old enough that it isn't stealing, it is reviving as a useful source.

By Paul Schofield (not verified) on 18 Aug 2007 #permalink

That is a good Feynman quote. I personally like Brian Greene, but then, my own field of study is far removed from the little (I instead get waitresses asking me why Pluto isn't a planet anymore), and The Elegant Universe was one of the books that made me realize, "ooooh, physics is soooo much more interesting than chemistry!" (because in high school they are of course at about the same level of Coolness).

If you're looking for a topic to write on, I would be interested in hearing about physicists who work on a human scale. By that I mean things people can see with unaided eyes and hold in their hands, rather than needing microscopes, telescopes, or even more exotic equipment just to get started.

Come to think of it, are there even such physicists anymore, or was that part of the science figured out long ago?

By Johan Larson (not verified) on 19 Aug 2007 #permalink

Soft condensed matter

http://nagelgroup.uchicago.edu/index.htmlh
http://jfi.uchicago.edu/~jaeger/group/granular.html

http://www.physics.upenn.edu/duriangroup/

http://chaos.ph.utexas.edu/

http://www.phys.psu.edu/~schiffer/

http://bigbro.biophys.cornell.edu/index.html (it requires big toys, but look at the shock wave and fuel spray stuff. I can't find a good link quickly, but if you can find the stuff done by Jin Wang at Argonne he is doing a bunch of fluid mechanics) (I work on some of this stuff)

By a cornellian (not verified) on 19 Aug 2007 #permalink

Physics on the human scale is called engineering. (Apologies to anyone from applied math or "materials science" who is reading this.) For example, I know engineers who study how to use carbon fiber to make a better concrete, and want to take nanotubes from the physics lab into the manufacturing sector ASAP. Fluid dynamics research is mostly done by PhD engineers and applied mathematicians even though it is still physics.

However, the "atomic and molecular" folks have made some BEC quantum systems where you can almost see the interference of matter waves with the naked eye. IIRC you still need a magnifying glass or low power microscope, but that is not too different from needing to wear glasses to drive.

By CCPhysicist (not verified) on 19 Aug 2007 #permalink

In response to commenter #4:
So called "complex systems" research contains a lot of physics at the human scale. See here for example.

A few months ago, a fascinating article came out about the low energy application of the Feynman diagrams of QED, namely, applying them to qubits. The advantage over the usual use in QED is that the diagrams are finite at all orders of perturbation theory.

This makes another way of teaching QED. Instead of beginning with a useless scalar theory that has nasty infinity problems, and then generalizing to a spin theory with nasty infinity problems, you begin with a spin-1/2 theory that is finite (and useful), and then generalize to the nasty theory.

I'm very enthusiastic about their elegant little paper, and am a bit surprised that it hasn't gotten a lot more attention.

From the comments, I assume the QED book is the one he wrote for laymen, the one subtitled "strange theory of matter and light" or something like that, and not his QED book for grad students. Applying Feynman diagrams to qubits is mathematically somewhere between that Feynman book and Peskin & Schroeder.

at 4 and 6, I have now tried twice to post a list to links to groups doing some human scale work and twice I have been shown a screen that says "held for moderation"...it must take the list of links as spam, so

Jager and Nagel at University of Chicago

Durian @ University of Pennsylvania

Schifer @ PSU

Swinney @ Utexas

Wang @ argonne

By a cornellian (not verified) on 19 Aug 2007 #permalink

In response to commenter #4:
So called "complex systems" research contains a lot of physics at the human scale. It is a big part of the International Conferences on Complex Systems, sponsorede by the New England Complex Systems Institute, #7 of which will be held 28 October-2 November 2007 in Boston

Also see:

http://necsi.org/events/iccs7/

What exactly does Feynman mean in that quote?

By Dario Scotto (not verified) on 09 Mar 2011 #permalink