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Our Quiet Galaxy

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This is a blog on why we believe and do what we do, why we pretend otherwise, how we might do better, and what our descendants might do, if they don't all die.
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Our Quiet Galaxy

Robin Hanson
Mar 31, 2012
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Our Quiet Galaxy

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Part of our surviving the great filter was our galaxy having especially few collisions with other galaxies:

The Milky Way and Andromeda are siblings, … we used to think they were near-twins. .. [But] the black hole at [Andromeda’s] heart is more than a hundred times as massive as ours. And while our galaxy is strewn with about 150 of the bright galactic baubles known as globular clusters, Andromeda boasts more than 400. … Whereas Andromeda is a pretty well-adjusted spiral, the Milky Way is an oddball – dimmer and quieter than all but a few per cent of its peers. That is probably because typical spirals such as Andromeda are transformed by collisions with other galaxies over their lifetimes. …

The Milky Way must have lived relatively undisturbed. Except for encounters with a few little galaxies such as the Sagittarius dwarf, which the Milky Way is slowly devouring, we wouldn’t have seen much action for 10 billion years. Perhaps that is why we are here to note the difference. More disturbed spirals would have suffered more supernova explosions and other upheavals, possibly making the Milky Way’s rare serenity especially hospitable for complex life. (more)

So alien life is more likely to be found in our galaxy than in random galaxies. More generally, the more steps in the filter that are spatially correlated like this, the more likely that if life is anywhere out there, it is especially near to us.

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Our Quiet Galaxy

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Our Quiet Galaxy

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Overcoming Bias Commenter
May 15

I kind of think the fact that NASA gives 10 million y age to the near by nova that disrupted our local gas field, or created it, or added to it is more significant. Over there by Centauri A & B and Proxima and the Coal Sack. Science has said our sun may be pulled out of M something on a pass, and our planets aren't even supposed to be Sol's. So this is more indicative of the creation of life I think. Otherwise we would be salps swimming under the ice whose only purpose is to consume carbon and die.

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gwern
May 15

How much of the Great Filter does this defuse? The calculations I usually see are for within this galaxy, so this wouldn't affect Drake equations...

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