Does your reality collapse or branch every time you look away?
In short: Quantum mechanics predicts that particles exist in multiple states simultaneously, yet we only ever see one. This creates a profound mystery: how does the fuzzy world of atoms become the solid world we inhabit? Two competing theories offer radically different answers about the nature of existence.
The standard framework taught in universities is the Copenhagen interpretation, established by Niels Bohr and Werner Heisenberg. It relies on the Schrödinger equation—developed in 1926—which uses a wave function (psi) to describe quantum behavior. According to Max Born's interpretation of this equation, the square of the norm of psi represents the probability of finding a particle in a specific state. The core of this view is 'wave function collapse': the moment an external observer or apparatus interacts with a quantum system, the superposition of possibilities vanishes, and one single outcome becomes reality.
The primary flaw in the Copenhagen model is the 'measurement problem.' It fails to explain the actual physical mechanism that causes this collapse to happen. As the text notes, Bohr essentially argued that the collapse simply fits the observed data, but it doesn't explain the 'how.' This leaves a gap between the quantum rules we use to calculate results and the classical reality we actually experience.
The Many Worlds Interpretation, formulated by Hugh Everett in 1957, removes the need for collapse entirely. It suggests that every possible outcome of a quantum event actually occurs, creating branching realities. In the famous Schrödinger’s cat thought experiment, instead of the cat being either dead or alive, the observer becomes entangled with the cat. Both the living cat and the dead cat exist in separate, simultaneous worlds.
Everettians explain why we only perceive one branch through 'decoherence.' This is the process where a quantum system becomes entangled with its surrounding environment. Because the environment for a living cat differs from that of a dead one, the states become separated. In this view, you aren't choosing a reality; you are simply inhabiting one of the many branches that the universe constantly produces.
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- Summary by Intellect · source: Copenhagen vs Many Worlds Interpretation of Quantum Mechanics - Explained simply
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