each observer takes some note of the trailing digits of collected data…

doesn’t matter what those digits are, but we know they are different to each observer…

we then use these trailing digits to formulate a date and time and show up to our favorite restaurant at that date and time…

now we have split the universe for more than just a few moments, for all our other observers are eating at different times, at different tables, and having different meals… further creating a butterfly effect on the macro scale on all the other people the observer encounters…

quantum physics can become contagious it seems…

And it’s not so much that they’re multiple universes, but that there are multiple, approximately classical, approximately non-interacting “worlds” of the infinite-dimensional Hilbert space.

I personally think that “multiple universes” is just bad use of language, as “universe” means all that exists. So you can’t, by definition, have multiple universes. It’s just that different components of the wavefunction of the universe can’t interact with one another to any significant degree. These different components are viewed by observers within them as worlds unto themselves, because they can’t see what else is out there.

ok, still, so i can envision the dividing observers… but what comes after?
do they un-divide at some point or splinter off infinitum?

If there are multiple observers there must be multiple universes to go along with them, right?

i think the information loss aspect allows for the infinite splitting to go on without having to consider it… if it happens, it happens in a way that we can’t see and therefore doesn’t matter… ok…

but if it’s supposed to only be a limited experience then there are issues… like, what to do with all these “you’s” that just saw different things but are supposed to react the same…

The many worlds theory only comes into play when an observation is made of a quantum state? Ok, that is a relief of sorts…

That would mean only quantum physicists could be affected by this.

Haha, well, it’s not quite that simple. Basically it’s just difficult to understand quite what the quantum mechanical effects on macroscopic, highly complex systems like our own bodies are. I mean, we understand quite well what the classical limit is, but we don’t really understand how this all translates back to quantum mechanics, so it’s not really worth worrying about (unless, of course, you’re interested in discovering those details).

What’s basically happening with the many observers is that they’re continually dividing, each one only seeing one of the possible outcomes. Recovering some sort of symmetry would be effectively the same as a reducing entropy. We see the effect as, in essence, a loss of information to the environment. These other worlds are inaccessible to us. Basically, portions of the wavefunction of the universe which we can now interact with will become inaccessible to us later through decoherence: the information content of those portions of the wavefunction are effectively lost to us.

The many worlds theory only comes into play when an observation is made of a quantum state? Ok, that is a relief of sorts…

That would mean only quantum physicists could be affected by this.

Does the multi-verse re-enter a symmetry with the rest of us after the observation, or are we all experiencing a butterfly effect from the various different observations made by these quantum observers?

But i would also like to have the issue of sperm addressed… as in, if every sperm reaches the destination, then the many worlds are of every potential variation of every potential life that ever could have transpired?

It doesn’t necessarily mean this. There is no reason to suspect that macroscopic probabilities due to ignorance of all of the relevant variables are the same thing as superpositions of quantum states. That is to say, sperm are quite large enough that they’re largely classical objects. So there is no reason to suspect that every one makes it in a different one of the many worlds.

The proliferation of worlds within quantum mechanics means that every possible outcome occurs, but this doesn’t mean that every imaginable outcome occurs. And it further doesn’t mean that every outcome which, given our limited information, we think might occur will do so. Many outcomes that we think might occur may, given fuller information, prove to be impossible.

As for the amount of information, well, the Hilbert space that describes quantum mechanics is an infinite-dimensional space. There is no limit to the amount of information.

But i would also like to have the issue of sperm addressed… as in, if every sperm reaches the destination, then the many worlds are of every potential variation of every potential life that ever could have transpired?

It isn

@ Jason Dick: that’s definitely a good point. Thanks for this discussion

Those worlds are probabilistically-suppressed just as they are in any interpretation of quantum theory. We still don’t expect to see such violations because they’re going to be so rare.

As for quantum suicide/immortality, I think it ignores something crucial: death isn’t instantaneous. If, for example, the “me” in the current world is going to die in ten seconds, but the “me” in a different world from which I have already decohered will not, it is of no help whatsoever as far as my future is concerned. It also ignores the fact that the elimination of consciousness is going to be a gradual process, such that death itself is an inherently classical phenomenon.

Is there an up to date review of BQP and its relation to various classical computational complexity classes (and any other quantum ones as well)?

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I would suggest Lecture 10 in Scott Aaronson’s class (and maybe some previous lectures as well, depending on what your background is:

http://www.scottaaronson.com/democritus/

Wouldn’t the scale be tipped in favor of the direction/world that received the most energy and that determines whether the cat is dead or alive? Once the scale has tipped, with that original quantum break, it has a cascading effect to the macro level, so that while at the quantum level there is inherent fuzziness, this doesn’t carry to the macro level, since valid worlds built around both events would require sufficient energy to manifest them. ?

I don’t think we’ll get non-conservation of energy in any interpretation of quantum mechanics, let alone with MWI. The basic problem is all of the interactions in quantum mechanics conserve energy, and since any change in the energy levels will involve an entanglement between some other particle that carries off or supplies the energy of the state, it seems to me that the most you’ll be able to do is have energy reshuffled differently in the different worlds of the MWI.

Here is, basically, what you would need for energy conservation to be violated:

1. Start with a single, discrete energy state.
2. Make a change to the system so that it is split into a two-level state with different energies, without transferring energy to/from the environment
3. Make a measurement of the energy level of the system: some of the worlds will measure an energy increase, some an energy decrease.

It’s the bolded point in step two that I don’t think is going to ever be possible.

As for the heat bath theory paper you mentioned, I think it’d be interesting to compare the entropy transfer of that setup with the entropy required to perform the measurements. Somehow I suspect that we’ll find that the measurement itself requires an entropy increase that makes up for the decrease in entropy of the system. If not, then this will be a method to obtain free energy (that’s why I strongly doubt that it’s going to be the case).

Hi,

I definitely think your last answer is correct according to MWI. I don’t understand, however, how one can consider it’s enough to solve the problem.

Yes the energy is conserved overall, but that’s not the same as “each world in MWI must have the same energy content”.

Energy conservation [I]as MWI predicts it[/I] corresponds to the former. Energy conservation [I]as we see it[/I] correspond to the latter. If it is a natural feature of MWI that both correspond… well then I just missed something, please let me know what.

In fact, MWI would offer a natural explanation if energy would prove to be [I]not[/I] conserved in our (partial) world, as one might imagine from this http://fr.arxiv.org/abs/0804.2178

So you want to constrain and condense the argument for an unconstrained and un-condensed view of reality?

Maybe a bipolar argument is necessary to support a bipolar reality.