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As a non physicist, non scientist, I have a question, which may be really stupid.
If quantum mechanics expounds that at an atomic level matter can be in 2 places, at one point in time, does this matter have mass in these 2 different places?
If this matter can have a mass in more than one place, at one point in time, how can we attempt to calculate the mass of matter present in the universe as surely it would depend on what proportion of matter was in what number of places at any point in time? Does that mean its unit of measurement would need to include number of atoms, the proportions of this matter in what numbers of places, at a fixed point in time?
Is there some basic reading that might help me understand this a bit more?
Thank you.

As a non physicist, non scientist, I have a question, which may be really stupid.
If quantum mechanics expounds that at an atomic level matter can be in 2 places, at one point in time, does this matter have mass in these 2 different places?
If this matter can have a mass in more than one place, at one point in time, how can we attempt to calculate the mass of matter present in the universe as surely it would depend on what proportion of matter was in what number of places at any point in time? Does that mean its unit of measurement would need to include number of atoms, the proportions of this matter in what numbers of places, at a fixed point in time?
Is there some basic reading that might help me understand this a bit more?
Thank you.

Response from Allen Stairs on :

It's not a stupid question. The way that popular accounts "explain" quantum mechanics leads naturally to your question. The moral is that those popular accounts are not to be trusted.
Quantum mechanics is unusual in that on the one hand, we understand very well how to apply it and what we should expect to find in experiments if it's correct, but on the other hand there is sharp disagreement over what quantum mechanics is telling us about the nature of the things we use it to predict and explain. The problem you're raising comes from the superposition principle. A quantum system can be in a superposition of being in two different, non-overlapping places, for example. When that happens, there's some probability that if we "look" (make an appropriate measurement) we'll find the system in one of the places, and some probability that we'll find it in the other. However, we can't understand this as a simple case of ignorance --- as a case where the system really is in one place or really is in the other and...