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I don’t like the term “observer” because it implies it’s an entirely passive thing.

Why is it that we cannot passively observe quantum states? Why does observation necessarily have to be destructive?

There is no such thing as "passive" observation: something has to change in order for information to become known. Without a transfer of energy, no observation can be made, so either we absorb the particle to register that energy (and then it is literally gone after measurement) or we stimulate the particle into emission (drastically changing its quantum state), or we "poke" the particle by throwing things at it (changing its quantum state in the process).

To “observe” something, you need to interact with it in some way, such as bouncing a photon off it. That interaction changes the quantum state.

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