By the same linearity arguments that apply to the electron-apparatus system, the composite of electron, apparatus, and environment evolves into a superposition: one branch corresponding to the environment coupling to the apparatus registering spin +1/2, and another branch corresponding to the environment coupling to the apparatus registering spin -1/2.
When two things become connected or interact with each other in a way that makes them influence one another.
Electron(as used in quantum physics)
A tiny negatively charged particle that orbits the nucleus of an atom; the basic building block of electricity.
Linearity arguments(as used in quantum mechanics and philosophy of physics)
Reasoning based on the principle that if you combine two things together, the result follows predictable mathematical rules without any weird interactions or surprises.
Spin(as used in quantum physics)
A quantum property of particles (like electrons) that acts similarly to how a spinning top rotates, but exists only in quantum mechanics with no everyday equivalent.
Superposition(as used in quantum mechanics and the measurement problem)
A quantum state where something exists in multiple different conditions at the same time until it's actually measured or observed.
composite(existence-essence distinction)
A pair of existence and essence found in everything that is not simple
Indeed, what happens if we include decoherence in the description? Decoherence tells us, among other things, that plenty of interactions are taking place all the time in which differently localised states of the apparatus registering, say, different \(x\)-spin values of an electron couple to different states of the environment. But now, by the same arguments as above, the composite of electron, apparatus and environment will be a superposition of (i) a state corresponding to the environment coup