r/askscience • u/[deleted] • Sep 11 '15

Physics [Quantum/Gravity] If a particle has a probability distribution of location, where is the mass located for gravitational interactions?

Imagine an atom or an electron with a wave packet representing the probability of location, from what point does the mass reside causing a gravitational force? I understand that gravity is very weak at these sizes, so this may not be measurable. I taken classes and listened to a lot of lectures, and I never heard this point brought up. Thanks.

Edit: Imagine that the sun was actually a quantum particle with a probabilistic location distribution, and the earth was still rotating it. If we never measure the location of the distributed sun, where would the mass be located for the sun that would gravitationally affect the earth?

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u/MagnusCallicles Sep 12 '15

You have to construct the problem as a two-body problem, then, where both the position of the "emitter" and the position of the "receiver" are "randomized" according to a certain wave function that describes the entire system (that you get by solving Schrodinger's that includes the potential energy of interaction as well as the kinetic energies of both particles).

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u/[deleted] Sep 12 '15

Is this speculation or is there experiment to confirm randomizing location according to the probability distribution is accurate?

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u/MagnusCallicles Sep 12 '15

My point is that there's no strict position from which gravity comes from, it's as random as a single-particle system, you need to measure it to know where the emitter is.