LogFAQs > #964773266

Hejiru posted...

It's pretty much a statistical certainty that life exists elsewhere in the galaxy.

It's really not. And people who assume this generally don't understand how statistics work.

This line of thinking usually boils down to "There are so many planets in the universe, therefore there has to be life out there", but that doesn't take into account just how likely (or unlikely) life is. Which is something we generally can't answer with our current level of understanding. Almost every attempt to guess (like the Drake Equation) is mostly just making up bullshit to argue a hypothetical.

If the formation of life is statistically likely, then yes, lots of planets would theoretically imply lots of life. But if the initial creative spark of life is infinitesimally small, then even a near infinite number of planets wouldn't necessarily be enough to result in multiple life-bearing planets. If the odds of life forming are small enough, then even our existence could be utterly unlikely, let alone anyone else's.

And that's because we even start factoring in things like:

*) Questions of scale - is it just life alone that matters, or specifically sentient life? Sapient life? Life intelligent enough to develop technology? Actual space-faring civilizations? Each successive step in development will by definition have its own statistical likelihood, so it's possible we live in a universe where there are millions of planets that could develop microbes but almost none where those microbes will ever evolve beyond single-cellular forms. Discussing the likelihood of life existing elsewhere is not the same thing as the likelihood of intelligent life, or life that has the capacity to actually travel through space.

*) The limiting factors of time - humans have existed for a fraction of an eyeblink in the timeline of the universe. When you take into account the full timeline of universal existence, it's possible that you could have multiple intelligent alien species form yet never exist at the same time, thus making each species functionally "alone". If the last species died out millions of years ago and the next one won't crawl out of the primordial ooze for millions of years to come, they essentially don't really exist from our narrow perspective.

*) The "primacy" argument - even in a universe that has millions of sapient species, one of them has to be the first one. From the perspective of that species, they will be alone in the universe (at least until the second species manages to spawn). This could easily be us because the universe is actually very young in cosmic terms - in the vast cosmic timeline, humans would probably come very early in universal history. It's entirely possible we ARE the first, even if we won't be the last.

*) The Great Barrier - there's been lots of discussion about whether or not the universe acts as a filter in some way that prevents civilizations from reaching obvious galaxy-spanning existence. This is usually in regards to talk about the Fermi Paradox and why, if there are tons of alien species out there, why we never find any real evidence of them. If there is some step in development that is nearly impossible to pass without going extinct, then any potential civilization is essentially doomed from the start. While it's possible that such a thing exists and we've already passed the threshold, it's also possible that we're already in the process of inevitably destroying ourselves.

When it comes down to it, us being alone in the universe (for whatever reason) isn't necessarily any more or less statistically likely than there being tons of life out there. Because we don't really know the objective odds of any of this shit. It's hard to calculate odds when you're dealing with a single system. Which is part of what gives us the mistaken assumption that life is likely (after all, it's happened 100% of the time in the single case we've examined!).

The most we can really say with any degree of accuracy is that it's possible we're not alone. But it's also possible that we are.



Hejiru posted...

People really underestimate how BIG space is. You may think it's a long way down the road to the chemist, but that's just peanuts to space.

That's why it's always vitally important to know where your towel is.