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MWI doesn't explain much. Why should this electron be able to cross universes and talk to another one and interfere, while nothing else can cross universes? Ca

by ars 7y ago

MWI doesn't explain much. Why should this electron be able to cross universes and talk to another one and interfere, while nothing else can cross universes? Can I setup my experiment so that quantum decay decides if I emit an electron or not - and then wait for no electron, but I somehow detect the electron that was released in a another universe? MWI also doesn't explain why the individual electrons would take different paths and interfere with each other - the universes are identical, so why are the electrons taking different paths?

ridewinter 7y ago
Why should this electron be able to cross universes and talk to another one and interfere, while nothing else can cross universes? See "decoherence": https://en.m.wikipedia.org/wiki/Quantum_decoherence https://en.m.wikipedia.org/wiki/Quantum_decoherence
jiggawatts 7y ago
> cross universes? MWI is a local theory. Changes spread out at the speed of light, they just spread out (and back from) adjacent universes as well. https://www.hedweb.com/manworld.htm#local https://www.hedweb.com/manworld.htm#local > the universes are identical... Think of a 3D volume of space with a plane wave travelling through it, such as a beam of coherent laser light. An alternative way of thinking about this is that each point emits a spherical wave and the plane wave is just constructive interference of a continuum of spherical waves. In many worlds theories, you can think of each point as also spreading out into non-spatial dimensions that are directions towards other universes. Similarly, aggregate behaviour is the constructive interference of not just the points in "one" universe, but also the points in a neighbouring "volume" of universes. If the neighbouring universes are identical, or nearly so, it's like the coherent laser scenario. If they're all different, it's more like white light -- it's unpredictable and "random", but otherwise it's still just ordinary light. Very slight deviations would result in various interference effects, such as the double-slit scenario.
kanzenryu2 7y ago
These are exactly the sort of thing MWI precisely explains. It take time to go through, but this is the best explanation I've ever seen https://www.lesswrong.com/posts/apbcLXz5zB7PXfgg2/an-intuitive-explanation-of-quantum-mechanics https://www.lesswrong.com/posts/apbcLXz5zB7PXfgg2/an-intuiti...
- AgentME 7y ago
  +1, this series of posts is my favorite explanation of it. I love the focus on it from the philosophy of science angle.
juped 7y ago
Because "world" doesn't actually mean anything - it's an analogy that is intuitive and snaps into place with the math for some people but not others. The intuition that works for others is "collapse", for me it's massive informational entanglement (information is physical).
baddox 7y ago
I don’t think MWI would explain why particles from different universes should be able to interfere with one another. I’m not sure what that even means. But quantum mechanics and MWI certainly does explain precisely in what ways they do interfere. The universes aren’t identical, of course. There’s a universe for every path of the electron that is physically possible.

by ars 7y ago

ridewinter 7y ago

Why should this electron be able to cross universes and talk to another one and interfere, while nothing else can cross universes? See "decoherence": https://en.m.wikipedia.org/wiki/Quantum_decoherence https://en.m.wikipedia.org/wiki/Quantum_decoherence

jiggawatts 7y ago

> cross universes? MWI is a local theory. Changes spread out at the speed of light, they just spread out (and back from) adjacent universes as well. https://www.hedweb.com/manworld.htm#local https://www.hedweb.com/manworld.htm#local > the universes are identical... Think of a 3D volume of space with a plane wave travelling through it, such as a beam of coherent laser light. An alternative way of thinking about this is that each point emits a spherical wave and the plane wave is just constructive interference of a continuum of spherical waves. In many worlds theories, you can think of each point as also spreading out into non-spatial dimensions that are directions towards other universes. Similarly, aggregate behaviour is the constructive interference of not just the points in "one" universe, but also the points in a neighbouring "volume" of universes. If the neighbouring universes are identical, or nearly so, it's like the coherent laser scenario. If they're all different, it's more like white light -- it's unpredictable and "random", but otherwise it's still just ordinary light. Very slight deviations would result in various interference effects, such as the double-slit scenario.

kanzenryu2 7y ago

These are exactly the sort of thing MWI precisely explains. It take time to go through, but this is the best explanation I've ever seen https://www.lesswrong.com/posts/apbcLXz5zB7PXfgg2/an-intuitive-explanation-of-quantum-mechanics https://www.lesswrong.com/posts/apbcLXz5zB7PXfgg2/an-intuiti...

AgentME 7y ago
+1, this series of posts is my favorite explanation of it. I love the focus on it from the philosophy of science angle.

juped 7y ago

Because "world" doesn't actually mean anything - it's an analogy that is intuitive and snaps into place with the math for some people but not others. The intuition that works for others is "collapse", for me it's massive informational entanglement (information is physical).

baddox 7y ago

I don’t think MWI would explain why particles from different universes should be able to interfere with one another. I’m not sure what that even means. But quantum mechanics and MWI certainly does explain precisely in what ways they do interfere. The universes aren’t identical, of course. There’s a universe for every path of the electron that is physically possible.