[belinder]

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)

[kulahan]

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.

[kbelder]

"Need" may be overstating it. Those things certainly all seem to have helped, though.

[kulahan]

I don’t believe it’s an overstatement. We have thousands upon thousands of data points showing life doesn’t appear outside of absolutely perfect conditions. There is not one single piece of proof anywhere which runs against this idea, it’s just the extremely outdated concept that earth isn’t special which makes it seem wrong. That concept hasn’t been valid for probably decades now, but it hangs on due to scientists hoping against all odds that we aren’t alone.