4 ms·
You'd see radiation hitting the planet warming the mantel, complex chemicals breaking down & releasing heat, all warming the planet significantly to the point w
by danielsju6 11y ago
You'd see radiation hitting the planet warming the mantel, complex chemicals breaking down & releasing heat, all warming the planet significantly to the point where it was a molten ball, and finally lots of instability where large explosions were throwing pieces of it into space.
Basically take the movie and play it backwards.
- bronson 11y agoI find it very hard to picture a molten ball throwing a giant chunk of cold comet deep into space.
- tbabb 11y agoThat is what is so unsettling about T-symmetry. What you describe is merely improbable, not impossible. With appropriate starting conditions, it is certain. Basically we'd require all the particles in the comet to bounce into each other in such a way that their heat motion cancels and organizes into momentum in one direction, away from the planet. This is physically permitted in either time-direction, but we only see it in one.
- Sharlin 11y agoYes, but that has nothing to do with gravity and everything to do with thermodynamics.
- ajross 11y agoYes, but the reason you do is that it's merely (and extremely) unlikely, not impossible. The third law of thermodynamics has its own arrow of time (the one in which entropy increases), but the basic interactions of the universe don't need to change to make that happen. They work symmetrically (mostly, with some tiny exceptions as detailed in the linked article).