[nordsieck]

>> That wouldn't prevent one off extinction type events like asteroids.

> This is the lamest of all excuses.

> It's a very unlikely for one, we haven't had an extinction asteroid in 65 million years.

He said "like astroids". Quite frankly we don't know how frequent extinction events happen. We've had nuclear weapons for less than 100 years, and have a couple of close calls[1] already.

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1. https://en.wikipedia.org/wiki/1983_Soviet_nuclear_false_alar...

[jonathankoren]

We could just build giant bomb shelters. It’s cheaper, holds more people, and doesn’t require nearly the investment in a completely closed ecosystem. But that ain’t sexy.

If you want something that uniquely requires leaving the planet for somewhere you have truck in literally everything except rocks, you’re pretty much limited to the sun becoming a red giant. That and gamma ray bursts. That’s pretty much it.