Anyone There?

Paul Davies’ The Eerie Silence was an eye-opener on the topic of extra-terrestrial life. Would we even recognize a life form that is totally different from “life as we know it”? After all, our techniques to identify microbes today are “customized and targeted to life as we know it”.

1)      One idea is based on the term ‘chirality’ from chemistry. It means that the mirror image of the molecule is different from the molecule. Notice the similarity with your hands? Ergo, chirality is called the “handedness” of a molecule (right-handed or left-handed). Ok, so what’s that got to do with life? Well, known life always uses right-handed sugars and left-handed amino acids. If we found things different in a life form, it may be a sign of life from elsewhere.

2)     All known life on earth is based on DNA. And DNA disintegrates at temperatures above 120˚C. If we found a life form that can live even at, say, 170˚C, it means it isn’t DNA based, and might be alien. Till date, no “extremophile” found on earth (like life found in 90˚C hot springs or the salty Dead Sea or deep, deep underground while boring holes) has passed this test.

3)     But just because all life on earth seems to be DNA-based (so far), does it mean that that non-DNA life (if found on earth) found must be alien? Or could it mean that life evolved on earth via two separate branches (DNA and the other thing)? Or would we eventually discover that the two different branches originated from a common root?!

 

Moving on, if we found life on Mars, does that mean life is common across the universe? Not necessarily! Why not? Because:

“(Earth and Mars) are not quarantined. They regularly exchange material in the form of ejected rocks (some of which could carry life).”

Then there’s the problem that biology isn’t a mathematical science. Huh?

“(Theoretical physics) means establishing an elaborate interlocking system of specific mathematical equations to capture aspects of physical reality that on casual inspection we would never guess are related… No other science possesses this underpinning. There is no ‘theoretical biology’.”

Put differently, while (theoretical) physics could predict all kinds of unseen things about the universe that were eventually found much later, biology doesn’t have that ability to give us a list of possible ways that alien life might be.

Assuming advanced life does exist elsewhere in the universe, could we infer its presence in any way? That’s a possibility, because any advanced life form would need one thing for sure: energy. Theoretical physics predicts the existence of magnetic monopoles, i.e., a magnet that only has a North (or South) pole, not both. Nobody has ever found one. If such monopoles exist, they could be used to generate enormous energy: bring a North monopole in contact with a South monopole, and boom! They’d annihilate releasing a huge amount of energy based on that famous equation, E=mc². Ok, but didn’t we just say no such monopoles have ever been found? Aha, but is that because they don’t exist? Or because aliens swept them up in our region of the universe to use as fuel for their energy needs?

Davies admits that astrobiology (study of life beyond earth) is a hard field because there is no theoretical biology to make predictions or tell what to look for or where to look at. Until then, we end up using the only other astro- field that exists, astrophysics. That’s probably why this blog read as much like a physics blog as a biology one!