Symmetry

I spent all morning looking for two pairs of flipflops that are mismatched yet can be worn together (one on each foot) in a matched kind of way. haha. For any of you who remember, I used to have a pair that I loved that had the same pattern on the sole but the strap on one was blue and the other yellow. My friend and I switched them years ago, and wore them down to the cloth, but haven't been able to find a replacement. I've finally decided on one (after weeks of searching)! One is black with white polka dots and a white bow and the other is white with black polka dots and a black bow. Wonderful! I spent my whole way home thinking about why finding symmetrical yet differently colored flip flops is such an interesting idea to me. By the way, if you need a certain type of flip flop, I'm happy to advise as to where you can look.. I've checked at least 30 different shoe stores this week.

I love symmetry. My favorite research question of all time is the question of pattern formation, essentially the study of asymmetry or how forms break out of their uniform mold. You would think that, coming from a single cell, we'd just expand and grow evenly but somehow we get a head that's different than our foot with a spine in between. But even as the uniformity breaks.. the important thing is to find symmetry once again..

Last semester, we had a guest lecturer who was studying asymmetry in the zebrafish brain, that signal A would only stimulate one side and therefore be asymmetric. I asked him where signal A came from and why it only stimulated one side.. and he said well because signal B only signaled to A at that point.. I kept asking him this question until we got to the single cell stage. Now, how does it happen? He said, well, some people studying xenopus showed that there is a directional electrical current.......... sigh, so how did the current choose its direction? What mysteries.

A long time ago (in my previous weblog), I made several entries about twins. I mentioned that as much as 30% of identical twins are also mirror images of each other. I imagine this must happen because the the cells of the embryo are already no longer all equivalent.. they split and divide their asymmetries symetrically and so you get mirror images.

My last reflection on the beauty of symmetries is that they also suggest the idea of inverses. We have them all the time in mathematics: add/subtract, sin/arcsin, even complicated ideas like matrices and fourier have their corresponding opposite. We also know so many examples in biology, in just a slightly different way, i.e. a protein doesn't go backwards in the ribosome to be degrades, but each amino acid undergoes a "decision" process and attaches and unattaches itself by the same/inverse chemical processes before proceeding.

Anyway, this leads to my second favorite question of all time. The question of precision. So if every single thing in the world is fluctuating and deciding, how is it that we get exact patterns and not a funny vague idea of things happening? There's such a balance in fact, and we have absolutely no idea how it happens. There's all sorts of vague ideas of turing stability and etc etc but when it comes down to it, biology does not work "just like turing describes".. there are so many nuts and bolts and possible deterrents in the way.

Funny how you can come to two conclusions with this. I never realized this before. One is, how amazing it is to be alive!! The other is: we should all be dead.