Hacker News Reader

Comment by LinAGKar | Hacker News Reader

This only works if the many-worlds-interpretation is true, which has not been confirmed

It's not possible to distinguish between many worlds or any other interpretation, so it will never will be confirmed (nor will the Copenhagen interpretation). The only ones that can be confirmed are the "objective collapse" theories, as they produce very slightly different predictions than normal QM.

I think it's fair to say that if we ever put a full human being into superposition with a large enough environment for decoherence to happen within the experiment, many worlds is all but confirmed.

This relates to an interpretation of QM that I have not personally found much reading material on, the idea that wavefunction collapse is actually just entanglement; that is to say that as soon as a system in a superposition interacts with the outside universe, the outside universe becomes entangled with the system, thus putting the entire universe into a superposition where both outcomes are observed.

That's precisely Many Worlds! The process you describe is a pretty close match for what's called decoherence. Perhaps you'll have more luck with those search terms, there are quite a few really good resources out there. Just be careful to steer clear of the partisans. However much I disagree with them, the shut-up-and-calculate people give the best overall picture, even when describing a particular interpretation.

Is it? For one reason or another I thought there was a distinction, although reading back what I wrote a second time I can't figure out what it would be.

It's interesting to consider the implications of this line of thinking though; it seems like it would imply that causally-disconnected regions of spacetime (i.e. things outside of our light cone) are forever in a superposition of all possible quantum states, from our perspective, among other things.

> It's not [currently] possible to distinguish between many worlds or any other interpretation so [unless or until that changes] it will never will be confirmed (nor will the Copenhagen interpretation).

Seems like the minimum editorializing to make your statement science and not religion, no?

I would argue that with further knowledge (e.g if we figure out Quantum Gravity), these interpretations will no longer apply at all, as they are equivalent descriptions of an incorrect (or, "effective"/approximate) theory. It's not that we lack the tools to distinguish between Copenhagen and MW, but that they are designed to be not possible to distinguish. Further science will produce theories who have different interpretations (hopefully, just one :)

I listened to a talk by David Deutsch and he talks about creating an quantum computer based AI and then asking the AI if there are other worlds - (hope I'm not remembering this wrong)

And if we’re in one of the universes where it is true.

This is a common misconception, so if you're just joking I'll prepare myself to be wooshed in the hopes it helps someone else reading this. There is a concept of many universes which permits slightly differing laws of physics (actually different fundamental constants), but many worlds isn't that one. Many Worlds just says that quantum wavefunctions don't collapse. It doesn't posit any "universe" that the Copenhagen interpretation doesn't allow, it just lets them exist side by side.

It was a joke but your comment was interesting nonetheless.

You sound like you'd be interested in Max Tegmark's "Our Mathematical Universe". There are probably multiple levels of multiverses, and in our local "stack" we have 4, where the Many Worlds mechanism is sitting on level 3. Some don't have this level 3, but may have fewer or more levels, using mechanisms foreign to this multiverse, depending on their laws of physics.

Reply on news.ycombinator.com