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Comment by Qem | Hacker News Reader

Likely we don't need to replicate. We just need to get a sample of life with completely independent origin to our kind of life here on Earth, to study. This way we would be able to separate what are universal properties for any life from historical contingencies specific to us. To have samples of a single kind of life complicates things.

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Were that to happen it could be the worst news humanity ever receives, since it would greatly increase the chance the "Great Filter" is in front of us, not behind us.

Not if it's just microbial life. Anyway it's just one case or another. We knowing what's the case doesn't change it. If the news never break it would be just as bad, perhaps even slightly worse, as we would not have early warning to prepare.

The Great Filter is only one possible answer to the Fermi Paradox.

The Milky Way is almost 14 billion years old. The Milky Way is perhaps 100K light-years in diameter. If you can travel at 0.1c you could colonize the Milky Way in perhaps around a million years, less than 0.01% of the age of the Milky Way.

So, either there's a filter that's blocked interstellar colonization... or it has occurred already, and we just aren't aware of it (some sort of dark forest thing / we are being secretly watched by an extraterrestrial civilization).

(This is a haunted galaxy either way!)

> If you can travel at 0.1c you could colonize the Milky Way in perhaps around a million years

There's no reason to believe a civilization is capable of million year projects.

You mean there's some filter which prevents civilizations from developing that capability? ;-)

If lack of interest is a filter, sure. Not an especially alarming one though.

There is no need for an organized, unified project for life to spread across the galaxy, any more than there's a need for a unified effort for bacteria and fungi to consume some tasty organic matter, or for humans to have spread across Earth in prehistory.

These sort of calculations are nothing but examples of how a bad model gives bad results. In this case, the model is bad because it's underspecified.

Saying "I have a bad model but there's some unknown Great Factor which would make it a good model" isn't very convincing.

There are myriad factors: the biological challenges of space travel constitute a long list in itself; the economics and politics involved (ROI on any useful timeframe for interstellar travel is zero); the engineering challenges (the vast majority of interstellar travel attempts will result in the death of all crew somewhere in interstellar space); the fact that over million-year timescales, species evolve and change - humans are only around 30% of a million years old.

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