eCosmology

How does the many-worlds interpretation of quantum mechanics treat radioactive decay?

Examples of Everett's many-worlds theory of quantum mechanics invariably give an example of a one-time measurement, rather than a continuous process like detecting radioactive decay with a geiger counter. The theory would seem to say that at every moment there is a division into a decay world and a non-decay world, which would lead to an infinity of worlds in every time period, however short, and offer no way to deal with half-life and the probability of decay. (Probability seems like a problem with the theory even in the ordinary measurement case.)

Public Comments

1. For a given uranium atom, there would be a quantum division only at the point of decay. Measurement of probability and half-life are meaningful and possible in each and every such parallel universe. What does seem implausible is that the decay of a single uranium atom has the power to spawn a complete parallel universe. I'm also anxious to see some evidence or a plausible prediction based on that theory.
2. Everett's many-worlds theory is similar to quantum field theory in that if a virtual particle interaction can happen, it has happened "in a virtual world". All virtual interactions that can happen has happened, but what we see is decided probabilistically after all the complex probability amplitudes have been added up. Likewise, in the example of radioactive decay, one way to look at this is that ALL possible ways a radioactive sample can decay "has happened", and that what we see is one probabilistically decided outcome, all the others which "have happened in other Everett's many worlds". In other words, every time a nucleus has decayed, there is a branch point where there would be an additional world. What most laymen don't realize is that Everett was talking about a mind-boggling number of "worlds", that would be far more uncountable than the number of particles in the entire universe. But it works in quantum field theory. It's just a question of whether philosophically we should look at this in terms of virtual interactions, or alternate worlds. Unfortunately, Everett's ideas have quickly become the grist for many science fiction stories suggesting "alternate world lines", where doppelganger characters deal with different outcomes. That's just a gross oversimplification. Everett's theory should be called, "Everett's mind-bogglingly-many worlds theory", so that everybody should understand what it really entails.
3. The wave function of the original atom exponentially decays in amplitude while that of the daughters' grows towards unity, just like the Schrodinger Equation says it does. The only difference between Everett and Copenhagen is that, in the former, the amplitude of the observer *not* detecting the decay decays exponentially too.