5 ms·

well, system of black holes would lose some energy via gravity waves, this isn't something that could be reversed, yes?

• Florin_Andrei 7y ago
  In a simulation you would simply flip a sign on that one and it should go back. I've done plenty of simulations myself where waves radiate from a source, and those are perfectly reversible. The article is pointing at a more subtle issue related to a fundamental small-scale fuzziness which affects chaotic systems and breaks reversibility.
  • chrisshroba 7y ago
    Probably a naive question, but why is this a subtle issue? Isn't this basically the well-known butterfly effect?
    • Florin_Andrei 7y ago
      In a nutshell, yes, it kinda is a sort of butterfly effect. But look, you go to school and they drill into you until the cows come home that quantum mechanics is time-reversible, and gravity is time-reversible, and you just assume this is always true. But turns out, all that's needed is a bit of small-scale fuzziness due to QM effects, and then particle ensembles of 3 or more are suddenly not time-reversible anymore, though each of the basic laws still are. For someone like me this was a small shock.
      • perl4ever 7y ago
        Ok, but if you have the idea that "Planck scale" means something, then how can it be a shock then? Often understanding something better makes it less obvious, but at my level, I don't understand what's non-obvious about this.