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Is QM really trying very hard to tell us that spacetime is emergent? Space is emergent because: spooky action at a distance. Time is emergent because: delayed

• tim333 6y ago
  I've thought that before now, with respect to spooky action. There's an interesting seeming bit in the Feynman Lectures on Gravitation where he kind of demonstrates you can get Einstein type spacetime from the maths of a spin-2 particle though it's remained a bit beyond me to understand it. I even thought at one point I'd try to write a summary of his argument for Wikipedia but failed. It's not the most simple of things. The end bit I was thinking was "the fact is that a spin-two field has this geometrical interpretation; this is not something readily explainable--it is just marvelous." In section 8-4. But the math leading up to that is tricky.
  • captainmuon 6y ago
    As far as I understand it, you can decide which part of the dynamics you put into the spacetime, and which part into the fields. So a spin-2 field on a flat spacetime is equivalent to general relativity. (And you can't tell the difference because you can't detect individual gravitons, among other reasons.) A smiliar cool idea that I encountered in a string theory course, is when you have tachyons. They seem pretty bad because you can gain energy by creating more tachyons, and your spacetime would decay. But what it really means is that you have chosen a "wrong" spacetime, and you can transform the tachyons away by choosing a different background. (Handwaving here since I'm just an experimentalist ;-))
    • tim333 6y ago
      Thanks. I think handwavy is ok for this stuff as no one has really cracked the quantum gravity thing.