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  • I'm Fraser Cain, the Publisher of Universe Today

  • The Universe is enormous.

  • In the observable Universe, there are more than one-hundred-and-seventy billion galaxies.

  • In our galaxy alone, there are as many as four-hundred billion stars, and most probably

  • have planets.

  • A few of those planets must contain useful minerals for life, and fall within their star's

  • habitable zone, where liquid water is present.

  • Based on this, many believe the conditions for life exist throughout the Universe.

  • So, where are all the aliens?

  • The Universe has been around for thirteen-point-eight *billion* years.

  • Humanity got its start a mere two-hundred-thousand years ago, only zero-point-zero-one-percent

  • of the age of the Universe.

  • There has been plenty of time for an intelligent species to arise on any one of countless worlds,

  • and broadcast their existence to the entire galaxy.

  • Or perhaps, if a species developed interstellar travel, they could completely colonize our

  • galaxy within a few tens of millions of years; that's only a heartbeat in the age of the

  • Universe.

  • We've got the potential for life everywhere, and an incredible span of time for it to migrate

  • itself all around the Universe.

  • Yet, as far as we know, Earth is the only place in the Universe where life has arisen,

  • let alone developed an intelligent civilization.

  • So *where* are all the aliens?

  • This baffling contradiction is known as the Fermi Paradox, first described in nineteen-fifty

  • by the physicist Enrico Fermi.

  • Scientists have been trying to resolve this mystery for decades, listening for radio signals

  • from other worlds.

  • They've sampled only a fraction of the radio spectrum, and to date, haven't detected anything

  • that could be a signal from an intelligent species.

  • So, what are our options?

  • It could be we are the only planet in the entire Universe to develop life.

  • Perhaps, we're the first civilization to reach this level of advancement in the entire Universe.

  • If we're assuming there's life, with so many worlds out there, both seem unlikely.

  • *OR* Civilizations destroy themselves when they reach a certain point.

  • Nuclear weapons, global warming, killer epidemics, and overpopulation could all end humanity.

  • Asteroids could strike the planet and wipe us out.

  • But would this happen to every single civilization? one-hundred-percent of them?

  • Even if ninety-nine-percent of civilizations destroy themselves, we could still have a

  • couple that make it through to fully colonize the galaxy.

  • And if there are actual aliens, why we haven't met them:

  • Perhaps, they're just too far away, and our signals can't reach each other.

  • But why wouldn't they just build self-replicating probes that could traverse those distances

  • and leave a local artifact in every single star system?

  • Maybe we haven't the ability to receive their signals or recognize their artifacts.

  • Sure, but if aliens constructed a series of artifacts on Earth, I think we'd notice them.

  • I'd like to assume if they've mastered space travel, that they'd have experience creating

  • obvious structures.

  • They could be just *too* alien and we can't understand them.

  • Or we're too insignificant, and they don't think we're worth talking to.

  • But we don't need to talk to them to know they exist.

  • If they flew through our Solar System, ignoring us, we'd still know they're around.

  • Perhaps, they're not talking to us on purpose, and we're really in some kind of galactic

  • zoo. Or "aliens" have a Prime Directive, and they're not allowed to talk to us.

  • Maybe some aliens have these rules. But all of them?

  • Not a single sympathetic alien has broken the rules and snuck us some evidence?

  • There are many other potential solutions to the Fermi Paradox, but I find them all lacking.

  • The Universe is big, and old, and if extraterrestrial life is anything like us, it wants to multiply

  • and spread out.

  • The most unsettling idea is that something happens to one-hundred-percent of intelligent

  • civilizations, and that prevents them from exploring and settling the galaxy.

  • Maybe it's something good...

  • Like the discovery of a transportation system to another Universe.

  • Or maybe it's something bad, like a destructive technology, or discovery that has destroyed

  • every single civilization before us.

  • How do you feel about the Fermi Paradox, and how do you propose we resolve the contradictions?

  • Whatever the solution is, it sure is fun to think about.

  • Thanks

  • for watching.

I'm Fraser Cain, the Publisher of Universe Today

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外星人都在哪裡? (Where Are All The Aliens?)

  • 76 5
    Solomon Wolf 發佈於 2021 年 01 月 14 日
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