Re:I Can't Believe it (Score 1)

OK, for once I can post about something I know about. I'm a grad student in the astronomy department at Steward Observatory at the University of Arizona. I build instruments used to measure the millimeter and submillimeter wave emission from molecules, and use these instruments to study the star formation process. I'll try to explain how we can detect molecules in space, and how we can be sure what we're looking at. The molecule people look at the most is carbon monoxide (CO). This is a simple 2 atom molecule shaped like a dumbbell, with a carbon on one end and a oxygen on the other. When the molecule is excited through collisions with other particles or with photons, it can rotate, vibrate like two weights on a spring, or the electrons in each of the atoms can go into more energetic states. The kind of emission we measure with millimeter wave telescopes, like the one that possibly detected glucose, is rotation. Because of quantum mechanical effects, molecules cannot rotate at just any speed they want; they can only have very specific rotational speeds. When a molecule's rotation speeds up or slows down, it has to go from one permitted speed to another one. This makes the molecule emit radiation of a very particular frequency when it makes a fast to slow rotational speed transition. We can predict, with either pencil and paper calculations in the case of CO or with a computer simulation, in the case of glucose, exactly what these frequencies will be (the molecule's spectrum). Since every molecule has a different shape and configuration, every molecule has a unique spectrum. We can also measure a substance in the lab to determine what spectrum it has. A bunch of molecules in space will be composed of individual molecules all with different conditions, so when we look we see lots of different spectral lines corresponding to all the different rotational speed transitions. By looking at the intensity of each of the spectral lines (one of the specific frequencies) in comparison with the others, we can determine things like the gas temperature and density. This is easy with CO. The same telescope used for the glucose experiment was used to detect CO in the late 60s. For a wierd molecule like glucose, the situation is more complicated. The spectrum itself has lots more frequencies than CO, and each one is very weak. In addition, there have been almost 100 molecules discovered in space, which can make for some confusuion. The reason these guys believe they discovered glucose is that they found enough spectral lines in their spectrum in common with the lab spectrum of glucose that they think it couldn't be anything else.

I hope this helps a little. You can learn more by looking at the webpage of my lab, http://soral.as.arizona.edu

note: all of our instruments run using Linux
note: The guys who wrote the paper on Moore's law and slacking which appeared on /. a while ago are my fellow grad students and friends. While I didn't have anything to do with that, I thought it was pretty damn funny, especially that so many people on ./ took it seriously...