So I’ve recently decided (today) that I’ll try and post a geeky-cool science article once a month. Complete with a physicist of the month, because everyone should know certain physicists in today’s world.
One thing I heard about today that peaked my interest had to do with spy satellites and polarization. Regardless of what the spy satellites may be used for, and whether I do or don’t agree with those uses, this is a pretty cool spy technique. The basic idea is that natural objects like plants and wood and hunks of stone reflect light that is more or less randomly polarized, whereas manmade materials (metals, plastics, aerosols, other funky chemicals) usually have some polarization consistent with their characteristics (Wikipedia has a blurb on this). Using this technique, objects that are as good as invisible in visible-light satellite images stand out severely when you look at their polarizations. So, go ahead and camouflage your tank Osama, we will be able to see it clear as day. (reference of abstracts on the topic, article)
Along the same topic of trying to find things that don’t exist…er, I mean things you can’t see, I was revisiting some of my old dark matter stuff the other day. There are various ideas and explanations for the dark matter problem (which isn’t new, by the way, we’ve known about it since like 1930, what’s surprising is that we haven’t figured it out yet), a lot of which I’ve looked into because I’m interested and most I don’t understand. The main topics of discussion are among:
1. Believers
2. Alternativists
3. Fundamentalists
Group 1: Most physicists believe there to be some kind of dark matter in the universe. This group is looking to find the mystery flavor. (Candidates include axions, axinos, weakly interacting massive particles (WIMPS–go Oxy!), neutrinos, neutralinos, photinos, zinos, Higgsinos—then they get really creative: wimpzillas, Q-balls, and Z-balls. Among others, I’m sure.)
Group 2: This group is smaller, but includes people looking for theoretical alternatives to the dark matter problem. One of these alternatives is Modified Newtonian Dynamics (MOND), which alters our laws of gravitation in the limit of low accelerations in much the same way that Einstein’s special relativity alters Newton’s laws of motion for high velocities. MOND, however, has nothing to say about nucleosynthesis. Another alternative comes from playing with string theories and/or brane theories, which sometimes include dark matter caveats as bonuses. (See physicist of the month, below.)
Group 3: Recently discovered. A paper was published in July by a group of physicists who claim to have solved the dark matter problem solely using the laws of General Relativity (also slashdotted). Seems to me as though somebody ought to have checked that already…but who knows, the thing involves 4 dimensional tensors, and hasn’t actually been solved for many cases.
So there’s dark matter in a nutshell. And that brings us to our physicist of the month: Dr. Lisa Randall who was previously at MIT and is now at Harvard. She is one of the leaders in the field of brane theory. Here is a very understandable and badass interview on the topic with Dr. Randall (2001).