LogFAQs > #926361069

Many worlds breaks the Gordian knot of "deterministic" wave function in theory vs "probabilistic" measurements in reality by asserting essentially that the probabilistic nature of quantum mechanics is identical to the probabilistic nature of experiments where a bunch of clones of experimenters are created.

To give an illustrative, but not quantum mechanical example, imagine you see a house with two rooms, one with an arrow pointed left and one with an arrow pointed right. Then you're knocked out, your brain + body split exactly in half + the missing half cloned (such that there's no question on which one is the "original"; if you can come up with an objection just pretend the splitting is even more fine grained or pretend that you literally can't tell) and each version of you is placed into the room.

So even though there was a deterministic thing going on (a single house that exists, and two versions of you), the chance that you wake up and see a left arrow is 50% (and same with right arrow).

In this case, the analogy corresponds to solving the wave function with two results being discovering the house has two rooms and the case of measuring the result being waking up and seeing what room you're in. Many world's asserts that this set of observations is commiserate with having split versions of you.

(There's more complicated ways that you can explain this by talking about entangled states / actually weird quantum experiments like the delayed choice quantum eraser, but the intuition behind many worlds I think is much easier to explain.)

Note that I haven't talked about some other objections against like the "basis problem" (where some people protest that there's no "objective" way to split the universe) or the "people who don't understand many worlds or occam's razor talk about occam's razor" problem (where, if you believed that many worlds is more complicated than one world, you goddamn well better explain how "many atoms" is simpler than "four elements")