# According to many worlds interpretation, to which world will I go?

From my understanding, many worlds interpretation views the actual world (universe) has many branch points. For example, coin flipping may cause two outcomes, but I will experience only on outcome or the other. Which outcome of universe will I go to?

• this one ! MWI is equivalent to a chain of events where all the other possibilities vanish
– user46925
Commented Feb 3, 2016 at 2:03
• There is only one world and MWI is bunk. Commented Feb 3, 2016 at 2:28

In the Many Worlds Interpretation, you go to both worlds after a branching point. That's why its called a "branch," because the present universe splits into two or more viable outcomes. In one world the coin lands heads up and in the other it lands tails up, but in each you are there to see it if you were there to flip it.

Note that this assumes simple binary, "either/or" branches. In reality there would be uncountably many branching points, most with a handful of possible outcomes each.

• In MWI there would be infinities of infinities of infinities potentiated to infinities many worlds. And that was just one second ago, now there would be infinitely more than that. I think I am getting dizzy... from laughter. Commented Feb 3, 2016 at 2:30
• @CuriousOne that's the sense of absurdity that I hoped to hint at in the second paragraph. Commented Feb 3, 2016 at 5:20
• @JohnForkosh I get "uncountable" from the fact that we can't record every possible state of every particle in the universe using only the actual states of every particle in the universe. Commented Feb 3, 2016 at 5:22
• @JohnForkosh I don't think 'representation' and 'recording' are equivalent, though. I can represent the population of the world with just a few characters (”over 7 billion") but I can't record 7 billion people with only a few characters. Actual:possible is not a 1:1 either; a photon has one actual energy out of a continuous spectrum of possible energies. Besides, I didn't intend "uncountable" in a mathematically lexical manner to begin with. Commented Feb 3, 2016 at 7:16
• Uncountable has a precise mathematical meaning; I didn't take the answer to be referring to this, but simply some unimaginably large number. Commented Feb 3, 2016 at 7:59

MWI is a minority position amongst interpretations in QM; famously Deutsch is an exponent.

It gives the wave function of a QM ontological weight; with branching occurring at measurement, where typically, in the Copengagen-type interpretations, collapse occurs; I think Everrets original motivation was to remove this 'discontinuity'.

But this can't be quite right; for if no collapse occurs, then the wave simply evolves in time; and branching ought to be synonymous with the wave itself; this renders the notion of branching problematic - after all when one does a measurement, a specific eigenvalue and state is selected from the spectrum of all such that evolve; this suggests that branching is part of the story told to popularise MWI, a kind of myth like Newtons apple.

If then there is no branching, then there are no new worlds for your coin to fall into or choose between.

There is just one world, but quite what what this means is the problematic here, where potentialities are given actual weight, and are rendered visible in the small.

• It's quite simple, in my opinion... quantum mechanics gives us exactly the open future that we long for when we are asking for free will, and the very second we get that from a physical theory, many of us shriek in horror and are trying to get back into the fully deterministic womb of classical mechanics as fast as they can. It's kind of comical, really. Commented Feb 3, 2016 at 6:19
• @curiousone: sure that's how I first understood it when coming across QM - why would nature miss a trick like indeterminism? Those that want to run back into the womb of classical physics, should try running back earlier and look at the physics of antiquity ie Lucretious swerve ... Commented Feb 3, 2016 at 7:23
• Yes! It took me a while, but the older I get the more I appreciate nature's escapades with the human mind. It sure has taken us a while before the lights went on... dimly. Commented Feb 3, 2016 at 7:30