[ExI] The 'Rare Earth' theory might not be rare after all

[Ben Zaiboc]

On 24/10/2025 14:19, Claude Sonnet 4.5 wrote:
> In 1983, physicist Brandon Carter noted a curious coincidence: humans evolved roughly halfway through Earth's habitable lifespan (about 4.6 billion years in, with another 5 billion before the sun dies).

That's not right. Twice.
The earth will become uninhabitable a long long time before the sun 
'dies', and the sun won't 'die' in 5 billion years. It will start to 
turn into a red giant then, and will still have plenty of life left in 
it, depending on what you call 'alive' for a star.

Earth will be uninhabitable long before the red giant phase, though. 
Uninhabitable for complex multicellular life, anyway. Probably somewhere 
between 500 million and 1 billion years.

Humans probably evolved more than four-fifths of the way through earth's 
habitable lifespan, not halfway.

-- 
Ben