This is essentially the standard argument for why we have to quantize gravity. If the sources of the gravitational field can be in superposition, then it must be possible to superpose two different gravitational fields. But (as I think you acknowledge) this doesn’t mean that quantum mechanical deviations from GR have to be detectable at low energies.
This is essentially the standard argument for why we have to quantize gravity.
Sort of. The problem first appears because the LHS of the EFE is a classical tensor, while the RHS is an operator, two different beasts. And using expectation value of the stress energy tensor does not work that well. The cosmological constant problem does not help, either. The MWI ontology just makes the issues starker. That’s why I am surprised that Carroll completely avoids discussing it even though GR is his specialty.
This is essentially the standard argument for why we have to quantize gravity. If the sources of the gravitational field can be in superposition, then it must be possible to superpose two different gravitational fields. But (as I think you acknowledge) this doesn’t mean that quantum mechanical deviations from GR have to be detectable at low energies.
Sort of. The problem first appears because the LHS of the EFE is a classical tensor, while the RHS is an operator, two different beasts. And using expectation value of the stress energy tensor does not work that well. The cosmological constant problem does not help, either. The MWI ontology just makes the issues starker. That’s why I am surprised that Carroll completely avoids discussing it even though GR is his specialty.