Blog #13: We Come in Peace

The big news for this week is that NASA has discovered running water on Mars. As the liquid water flows across Mars, it absorbs chemicals from Mars's atmosphere, which in turn lower the water's freezing temperature so that it can stay liquid. Understanding the absorbance spectrum of these dissolved chemicals is how NASA was able to determine that the water was there and that it was liquid. As cool as that is, the question that's on everyone's mind is whether this means there could be life on Mars.

This past summer, I read a book called Alone in the Universe, by John Gribbin (not to be confused with the song of the same name). Gribbin asks the same question, but on a larger scale -- are we the only intelligent life in the Galaxy? Before I read the book, I probably would have said no. The Galaxy is a big place, and since we're here, it means that intelligent life isn't impossible. Statistically speaking, then, it should follow that with sheer quantity of stars, some other intelligence should have evolved.

The story that Gribbin presents, however, is much more complicated. He talks about the Drake equation, which I had heard of before, but he investigates factors that I hadn't ever considered before. (Side note: I read the book a while ago, so unfortunately a lot of this is from memory.) For example, he talked about a habitable region in the Galaxy, not only determined by the density of stars, but also by their metallicities. As we've learned so far in Astro 17, the Milky Way has a greater number density of stars towards the center of the Galaxy than it does closer to the outskirts, so this factor alone cuts down pretty heavily on the sheer numbers I had been counting on initially. Among other factors, he also goes on to talk about the set-up of our solar system; I believe he brought up that our planets are spaced out just right and that having a gas giant like Jupiter positioned properly may be vital to protecting rockier planets from constant bombardment from meteors.

He also goes on to talk about Earth's geology (less interesting to me) and the processes that life itself on Earth had to go through to get to the point where I'd be sitting on a futon in the wee hours of the morning writing an increasingly-existential blog post. Gribbin argues (although I don't think it was initially his idea) that there are certain "checkpoints" that life reaches in its evolution, but that at least one of them acts as a bottleneck, restricting the development of intelligent life. The problem is we don't know if we've already gotten lucky and that that bottleneck is behind us, or whether it'll be basically impossible for us to make it to the next stage of our evolution. (Cue suspenseful music.)

Anyway, since this is starting to move away from astronomy and towards biology (I'm a biologist at heart, sorry), I'll wrap up. Basically, Alone in the Universe presented a lot of interesting ideas about the search for extraterrestrial intelligence that I hadn't considered before. Although Gribbin didn't extrapolate for other galaxies, I'm no longer quite so sure what to think about our own Galaxy. I guess being alone in the Galaxy is pretty incredible in that we've made it this far, but definitely sobering to think about just how alone we are. Either way, I think it's safe to bet that the next update on the Mars situation probably won't look like this.