Blogocentric Formulations

The Probabilities of the Universe

Prompt ▼

Examine Scientific Mysteries of the Universe. Is there life out there? Can humans thrive on other planets or their moons? These scientific mysteries are still unsolved, so you have an opportunity to analyze them yourself.

When it comes to big questions like "is there extraterrestrial life out there" and "can humans thrive on other planets and/or moons," I tend to take a statistical look at probabilities rather than go with my gut instinct. While there were a number of unlikely conditions and factors that had to take place in order for life to exist here on Earth, one also has to look at the sheer size of the universe and wonder if, statistically, life is possible elsewhere. So let's do a little math...

First, you have to figure out how many planets are out there. This article   does a great job of laying out some basic assumptions, but the main takeaway is this... our galaxy likely has trillions of planets in it, and current best estimates are that there are at least 200 billion other galaxies in the observable universe, so we're talking about 10^25 planets in the universe. If you want to see that number written out, that's 10,000,000,000,000,000,000,000,000 planets in existence in the universe.

But not all of those planets are likely habitable. There's a term in astronomy and astrobiology called the circumstellar habitable zone (CHZ), or "Goldilocks zone" colloquially, which refers to the range of orbits around a star where the planetary surface can support liquid water given sufficient atmospheric pressure. Within our own Milky Way galaxy, it's assumed that there could be as many as 40 billion planets roughly similar to Earth (i.e., in the Goldilocks zone with comparable sizes and geological features to that of Earth.

Multiply that assumption by the 200 billion galaxies out there and out of the 10^25 total planets in the universe, 8^21 (8,000,000,000,000,000,000,000) of them would presumably be in that Goldilocks zone and have the raw setup to be able to support the evolutionary processes that created humans. But let's assume that those unique systems are extremely rare. Maybe 0.000001% (one in every million planets that could support life actually do), and you're still looking at eight quadrillion planets (8,000,000,000,000,000) in the known universe. If you want to factor in time (i.e., assume that only one out of every million of those planets currently has sentient life because the rest either haven't gotten there yet or have since gone extinct, and we're down to eight billion (8,000,000,000) other planets.

Oh, and by the way, these numbers are just for planets. There are also untold number of other moons, asteroids, comets, and other celestial bodies that aren't being counted here.

When viewed like that, it seems almost egotistical to think that we're the only planet that managed to evolve its way to sentient life. That's not to say that sentient life on other planets looks anything like us, communicates like us, or even that conditions are close enough for us to survive on their planet... let alone whether any of them have developed technology possible to traverse the space that separates them, but the question of "whether there is sentient life out there," for me, is a probabilistic "yes." I don't know whether that sentient life has any resemblance to our own, but it just seems likely that some other planet somewhere in our vast universe has figured out how to nurture and sustain intelligent life.

And regarding the other questions of whether humans can thrive on other planets or their moons, I think the answer to that based on our own demonstrated ingenuity, is a resounding yes. As a species who has exponentially advanced its technological capability and understanding in the span of just a few thousand years (and made massive leaps in just the past few decades), I think it's likely that problems of acclimatization are ones that are solvable, whether it's developing technologies that allow us to breathe a new atmosphere, or create structures to insulate ourselves against a hostile (but habitable) atmosphere, I think it's probable that, if we were to find one of those planets similar to our own, whether already inhabited or not, we have the ingenuity and resourcefulness to figure out how to survive in a new environment that has the basic building blocks for sustaining life.

This is one of the reasons why I love reading and writing science fiction so much; figuring out what may or may not have developed elsewhere in the universe at the same time we're finding our way on Earth is a puzzle with endless possibilities and end results.