Wigner's friend and continuous time evolution of the state of a closed system and the probabilistic, discontinuous collapse of the state of a system upon measurement. Wigner's friend is therefore directly linked to the measurement problem in quantum mechanics with its famous Schrödinger's cat paradox. The thought experiment posits a friend of Wigner in a laboratory and lets him perform a quantum measurement on a physical system (this could be a spin system or also Schrödinger's cat). This system is assumed to be in a superposition of two distinct states, say, state 0 and state 1 (or "dead" and "alive", in the
Cosmological interpretation of quantum mechanics Cosmological interpretation of quantum mechanics The cosmological interpretation of quantum mechanics, proposed by Anthony Aguirre and Max Tegmark, is an interpretation of quantum mechanics that applies in the context of eternal inflation, which arguably predicts an infinite three-dimensional space with infinitely many planets and infinitely many copies of any quantum system. According to this interpretation, the wavefunction for a quantum system describes not some imaginary ensemble of possibilities for what the system might be doing, but rather the actual spatial collection of identical copies of the system that exist in our infinite space. Its collapse can be avoided. Moreover, the