Comment by ninkendo
13 hours ago
You don’t even need that to understand the tension between QM and GR:
What is the gravitational field of a particle in a superposition of two different locations? What about when the superposition collapses? Does the gravity field instantly change shape, faster than light?
The consensus right now is this is so hard to measure we’ll basically never know the answer from just observations. Maybe having a gravitational influence on something at all, collapses the superposition? Maybe if you put the particles in a large enough configuration it’s impossible to maintain superposition? Maybe there’s enough background noise in our particular universe to make such a measurement permanently impossible, and we get by on a technicality? Nobody knows.
> What is the gravitational field of a particle in a superposition of two different locations? What about when the superposition collapses? Does the gravity field instantly change shape, faster than light?
This is a symptom of the problem of gravity/spacetime being a handled as a classical field, not really the problem itself. The electromagnetic field for example has this exact same problem, but it's handled by the electromagnetic field being quantized. The problem is that nobody is able to fully quantize gravity.
Not all interpretations of QM have collapses, which tend to be underdescribed even in purely QM terms.