4 ms·

I don't quite get it they say relativity and Quantum Mechanics are incompatible. Does that mean they give different predictions?

• computerfriend 6y ago
  No. They cover different domains, so their predictions within those domains are consistent (and non-overlapping). It is combining them that is the problem.
• lazyjones 6y ago
  GR assumes reality is continuous, QM assumes it’s discrete.
  • drdeca 6y ago
    QM doesn’t assume space is discrete. It does deal with a number of discrete quantities though. Are you sure that’s where the conflict is? I think people have done QM with a given curved spacetime, just, where the spacetime manifold isn’t decided based on the distribution of matter and whatnot? Like, I think that’s where the ideas of Hawking radiation come from?
  • mhh__ 6y ago
    Quantum mechanics is not inherently discrete. We don't know whether the planck length is fundamental or not, but current models are in terms of continuous spatial and rotational degrees of freedom (in general). The eigenvalues often are quantized, however.
• T-A 6y ago
  It means we don't know how to quantize GR. Unlike the standard model of particle physics, it's a classical theory, i.e. a set of equations which tell you deterministically, without any of the inherent uncertainty of QM, how a given initial configuration will evolve. This becomes a problem when you try to include GR in even simple experimental setups which expose QM's non-classical behavior, like the Stern-Gerlach experiment [1]. What does gravity do before the path chosen by the particle (which is gravitationally attractive) is measured? [1] https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experiment https://en.wikipedia.org/wiki/Stern%E2%80%93Gerlach_experime...