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Dynamical origin of Theia, the last giant impactor on Earth

(arxiv.org)
92 points bikenaga | 3 comments | 08 Jul 25 18:10 UTC | HN request time: 0.84s | source
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echelon ◴[08 Jul 25 19:36 UTC] No.44503282[source]▶
Imagine if life had evolved on Earth or Theia prior to impact. Imagine if it was intelligent and played witness to the giant cataclysm.

Given that intelligence took an awfully long time to emerge from LUCA, that seems implausible. But it's fun to imagine pre-Theia "Silurians". That sort of impact would have scorched earth of any trace or remnant of their existence. It feels as though there must be sufficiently advanced civilizations out there witnessing this exact scenario play out without the necessary technology to stop it. Though that fate would be horrifying.

Another thing to think about is that shortly after the Big Bang (if there was one, Lamda-CDM or similar models holding up), was that shortly after the Big Bang the temperature of the early universe was uniformly 0-100 degrees Celsius. It may have been possible for life to originated in this primordial interstellar medium without even so much as needing a host planet or star! Just life coalescing in space itself.

That early primordial soup, if it existed, could have seeded the whole universe. Most aliens might have matching molecules and chirality if those decisions predate our galaxy.

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1. belinder ◴[08 Jul 25 21:29 UTC] No.44504221[source]▶
Temperature on its own wouldn't be enough for life would it? Isn't everything moving around way too fast after the Big bang and therefore too far apart for whatever life there would be to find food (or whatever equivalent source of energy)
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2. kulahan ◴[08 Jul 25 23:47 UTC] No.44505039[source]▶
Temperature isn’t even close to being enough. If we didn’t have a moon, despite everything else being so good for life, we may have been stuck at the bacterial phase if we didn’t have tides, or life may have never formed at all due to minerals not being recycled, tide pools not concentrating amino acids, and constant wet-dry phases driving evolutionary pushes.

Edit: beyond that, there’s the need for a stable orbit, a stable axial tilt, a stable star (few mega flares), some kind of galactic shield a la Jupiter, and more.

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3. kbelder ◴[09 Jul 25 04:26 UTC] No.44506346[source]▶
"Need" may be overstating it. Those things certainly all seem to have helped, though.