Complex Numbers

It Came From Outer Space

Today's article, from Popular Mechanics, is a few years old, but I'm not aware of any related developments since then.

    Some Scientists Believe All Life Started on Mars  
Maybe it's not as crazy as it sounds.

Let me state right off the bat that I have multiple issues with the way the headline is phrased. I'll give it a pass for now, though, because what's really important is the actual article.

Could life as we know it have begun on Mars instead of Earth?

Could it? Sure. Now, how about some evidence?

A handful of scientists believe so, and even more think we should at least consider the possibility.

One of my issues with the headline, and this sentence, is the use of the word "believe." It's as out of place in science as a clown at a black-tie ball.

This special case of the overall theory of panspermia, where life on Earth began somewhere else and traveled or was planted here, has some prominent supporters.

"Traveled or was planted" could imply that some sentience or conscious guidance was involved, so I don't like that in science either. As I've said before, if aliens planted life on Earth, where did said aliens come from? There are some good hypotheses as to how life emerged from non-life (though the distinction isn't a bright bold line) right here on Earth; where are the competing hypotheses for extraterrestrial origin?

I've described it before as "kicking the can down the road," and I suspect the underlying impetus for wanting to "believe" this is either a) an attempt to bring religious beliefs into science, or b) a conviction that life on Earth is not "special." Or maybe both.

In a new Salon article, these proponents say the theory makes intuitive sense based on what the two planets are like.

If there's one thing you need to know about science, it's this: the whole point is to question intuition. Lots of solid scientific theories and discoveries very much contradict intuition.

On the other talon, there's some evidence (as the article later points out) that Mars cooled off to the point where it had liquid water—essential for life as we know it—way before Earth did, so, okay, perhaps the chemical reactions that turned non-life into life took place there and not in our own oceans, only getting kicked off that planet by asteroid impacts. There's also some evidence that simple life can survive such a journey. So I can accept the possibility. But again: evidence? "Can" isn't the same thing as "did."

There is, of course, at least one other possibility: life started on Mars, and also started on Earth, perhaps later, but separately.

BUT. If you're going to assert that sentient aliens did it, then you also have to ask when and how said aliens got their start. Or, of course, you can hand-wave it and say "God did it," but then it's not science, but religion.

And I have one more quibble with the article:

Either way, Mars’s once-molten core slowed and solidified, reducing the planet’s gravity and atmosphere to nearly nothing and removing essential protections for any life form of which we know.

Solidifying a molten core would do exactly jack and squat to the planet's gravity, which is correlated to its mass. I guess maybe a tiny fraction of a bit, due to energy/mass equivalence, but come on. I think they meant "magnetic field," not gravity. It's the magnetic field (which on Earth is probably generated by processes in the molten interior) that keeps the worst of the dangerous emanations of the accursed daystar from knocking complex molecules (like proteins and DNA) apart.

Now, don't get me wrong, here; I'd be as excited as anyone to hear that real evidence for life, now or in the past, on Mars has been confirmed (by which I mean microbes or their equivalent, not pop-fiction sentient Martians). And maybe then we can compare it to Earth life and have a better idea if the one came from the other. But right now, it's all speculation, and, again, we have some very compelling, evidence-based ideas for how inert molecules might have come together to initiate the self-replicating process we call life, right here on this planet.