“Yes, I sure hope they exist.”
“Yes, and the Loch Ness Monster too.”
“Of course. Why, my uncle Kenny’s been abducted twice in the last year alone.”
Because of this, many people who are sensible (but not particularly knowledgeable) will answer the question with an emphatic no, congratulating themselves on their sensibility. It seems to make sense: You haven’t seen aliens, and their existence seems to be far beyond anything we’ve actually experienced.
But then you’ll get a different answer from someone who is sensible and more knowledgeable. If take someone like myself - who saw Cosmos and now thinks he’s an astronomy expert - and ask them if aliens exist, they’ll tell you that they most certainly do. After all, space is really big. So yes, even though life is surely unlikely to arise on any particular planet, there are so many possibilities, that life must exist somewhere out there. And if you ask the follow-up question, where are they (smartass)? They will refer you back to the “space is really big” principle.
But there’s a problem with that space-is-big, many-possibilities argument. See, space is not only big, it’s also old. It’s about four times older than life on earth, or 70,000 times older than modern humans. On the one hand, that fact adds to the lots-of-chances argument: not only are there lots of planets on which life could have arisen, but there’s been plenty of time for life to arise on them too.
The problem is when it begs that follow-up: Where are they? If the universe is so old, then not only must there be lots of alien races out there, but some of them must have been around for a long time. So even though space is big, they’ve had plenty of time to spread out, explore, and build lots of things. Even if we’re assuming that there’s no way to travel faster than the speed of light, and it will take years just to get to the nearest stars, a race could spread throughout our galaxy in, say, a million years. When you look at it that way, it doesn’t make sense that we haven’t seen any evidence of alien civilizations.
That’s called Fermi’s Paradox. We can’t explain why we can’t find any evidence of aliens, but we also can’t explain how there could not be aliens. There's a long list of interesting explanations for the paradox.
Why rehash this? The Kepler Space Telescope has found a star that appears to have thousands of objects orbiting it. That’s not unusual: a newly created star would have that. Over time, the matter surrounding it would accumulate into bigger and bigger chunks which would turn into planets. Anyone observing our sun five billion years ago would have seen the same thing. But this isn’t a new star, it’s “mature,” like ours. So it should only have a few planets orbiting it. No one has seen anything like this, and we aren’t sure what we’re looking at.
So if science can’t explain it, why not try some wild speculation? People have speculated that a really advanced civilization, with tremendous technology and voracious energy requirements, might build a Dyson Sphere. (Named for physicist Freeman Dyson, not the vacuum cleaner guy.) Essentially the idea is to build a shell around the star to collect all its energy, rather than just settle for the tiny little amount that falls on one planet.
In science fiction, this is often depicted as, literally, a big shell, where your people would live on the inside surface of the shell, with the star essentially above them. Yes, that’s right, there was one on a Star Trek episode once. But there’s a bunch of reasons why that probably wouldn’t work. So if an advanced civilization really wanted to make maximum use of their star’s energy, they’d more likely build something closer to what Dyson actually specified: a “swarm” of small structures of planetlets. They would all orbit the star, absorbing as much of its energy as possible.
So even though there’s probably some rational, boring explanation for this unusual star system, it does seem to resemble what we imagine a Dyson Sphere would look like. And it would provide an answer to Fermi’s Paradox, since this is the sort of thing we would expect to see, given how many really old, presumably advanced civilizations should be out there.
So please allow me to have my moment believing that this really is the sign of intelligent life we’ve always been looking for. Lots of people believe in things just because they want them to be true, and unlike them, at least I’m not voting based on it. And we could all use some good news: just when I was researching this, I found that most astrophysicists on social media were instead complaining about an astronomer given a slap on the wrist for serial sexual harassment. So let’s believe the aliens are there, and we have something better to aspire to.
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