Will We Know Alien Life When We See It?
In the 1958 science-fiction movie The Blob, an amorphous alien hitchhiked a ride to Earth on a meteorite. Upon landing, the translucent extraterrestrial began to devour humans, growing larger and redder with each meal. While the amoeba-like alien in the cult classic was famous for its insatiable hunger, The Blob managed to articulate something that previous science-fiction movies hadn’t: There’s no guarantee aliens will look anything like the lifeforms that we are familiar with.
Scientists and philosophers have been attempting to define life for ages. In biology class we were taught to define life through the set of features that we, and every other species on the planet share. Things like movement, respiration, growth, and reproduction. Life is made of cells and has DNA. But does biochemistry constitute the whole picture? As far back as 1970, Carl Sagan didn’t think so. Attempts at defining life, he and many others thought, were too constrained by the characteristics of life as we know it. A single example of extraterrestrial life could change everything.
Employing an elegant music metaphor, Sagan , “It is not known whether there is a vast array of biological themes and counterpoints in the universe; whether there are places that have fugues, compared with which our one tune is a bit thin and reedy. Or it may be that our tune is the only tune around. Accordingly, the prospects for life
