Parallel universes make quantum sense?

[JesseM]

In as far as those others are purely hypothetical, and there's no chance for you to ever observe any effect of your goodness or your evil on them ? My personal stance on that is: couldn't care less!

Does that mean, for example, that you would have no problem with leaving a hidden nuclear bomb under a major city, with a timer set to make it explode in 200 years? Since you probably won't live that long (ignoring quantum immortality ), the negative effects are purely hypothetical to you, but I think most people would consider this highly immoral.

So let us not push things too far. The MWI view on quantum mechanics is a way of giving "ontological" (and hence hypothetical) substance to some formulas written on paper which work very well in the lab (quantum mechanics) in order for us humans to grasp a bit better how this formal machinery works. This is a far cry from having moral considerations for these "mental pictures" ! After all, we don't know what will be the next physical theory, and what "ontological" pictures its formalism will eventually suggest.

I don't expect that the precise details of the MWI will survive to the "next physical theory", but in broad strokes, the violation of Bell's inequality in QM suggest only a few different options for any theory/interpretation which preserves them and still describes some sort of objective reality--"hidden" nonlocal communication between separated particles, backwards-in-time influences of the measurement on the original traits of the particles when they were created, weird conspiracies in the initial conditions of the universe, of local splits in each experimenter (with the copies of each experimenter only needing to be matched up once a signal has had time to pass between them, so that locality is actually preserved). It looks to me like the universe goes to a lot of trouble to avoid the possibility of FTL signalling at the overt level so "hidden" FTL signalling seems sort of klunky and inelegant, and conspiracies in initial conditions seem doubly inelegant, so I'd bet on either the backwards-in-time explanation or the splitting-copies explanation, and of the two the latter seems more likely to me, since there are also a lot of strong hints that chronology protection is also built into the laws of physics in a basic way (plus the difference between allowing 'hidden' backwards-in-time signals and allowing 'hidden' FTL signals seems cosmetic, since a nonhidden ability to send information backwards in time would naturally lead to a nonhidden ability to send information faster than light).

 

[reilly]

I have a deep suspicion of the good Dr. Deutsch, and, civility precludes any expression of my feelings about his work. A few years ago a friend mentioned Deutsch's book, The Fabric of Reality. He knows me and my views well, and said I would find it interesting. I did -- it was full of errors and opinions stated as fact. I gave away my copy, and threw away my notes on the text. What's to do next?But my biggest problem came from his loony idea of shadow photons -- something about going from alternate unifverse to alternate universe, or a reasonable facsimile thereof. There's probably 20 pages on these shadow photons, which I found to be unintellegeable, and unintegrated, So, I spent several hours charting his arguments and assumptions only to find contradictions -- his idea was nonsense. And boy did he push his shadow photons as the next really good thing. Looks like the physics community does not pay much attention to Dr. Deutsch; no shadow photons as yet.

I can show that typical predator-prey models do pretty well in modeling nuclear fission -- in bulk matter. So, I guess uranium fission is really a biological process. Also epidemiologists and petri dish magers work with systems that can be described by probability trees. In fact any probability system with dynamics, based on conditional probabilities uses probability trees.

For the believers, what is the rate of alternate universe creation/sec?
Regards,
Reilly Atkinsonj

 

[JesseM]

There's probably 20 pages on these shadow photons, which I found to be unintellegeable, and unintegrated, So, I spent several hours charting his arguments and assumptions only to find contradictions -- his idea was nonsense. And boy did he push his shadow photons as the next really good thing. Looks like the physics community does not pay much attention to Dr. Deutsch; no shadow photons as yet.

Wasn't Deutsch just talking about different position-states in the superposition that is a photon's wavefunction between measurements? Or different paths in the Feynman path integral for a photon, perhaps? Either way, these are standard ideas, it'd just be a philosophical question whether you choose to view them as "real" or just elements of a calculation used in predicting the photon's position when you do measure it.

For the believers, what is the rate of alternate universe creation/sec?
Regards,
Reilly Atkinsonj

As I understand it, "many worlds" is somewhat deceptive in that there's really only one big wavefunction for the entire universe, and the appearance of different "worlds" is subjective, having to do with the notion that decoherence causes macroscopically different states in this huge superposition to no longer "interact" (i.e. interfere) in a way that's practical for anyone to detect. But they never really stop interfering even if this interference is too hard for us to measure, so they aren't really wholly separate.

 

[vanesch]

Does that mean, for example, that you would have no problem with leaving a hidden nuclear bomb under a major city, with a timer set to make it explode in 200 years? Since you probably won't live that long (ignoring quantum immortality ), the negative effects are purely hypothetical to you, but I think most people would consider this highly immoral.

I wouldn't DO such a thing, as I don't want to hurt people on purpose and I wouldn't be able to find one good reason for myself to do so. As you point out, there' s also the principle of precaution: suppose that for one or other reason, I happen to live so long (medical advances, miracle, whatever...) or my direct relatives live so long. But in general, it is true that I don't care in general about what will happen to hypothetical people (if humanity still exists) in 200 years, in the following sense. Imagine that I would discover that some major catastrophe would hit the Earth in 200 years from now, probably whiping out humanity. This wouldn't mean anything to me. If we want to avoid that suffering in 200 years, it is sufficient to stop having kids 100 years from now. Sooner or later, humanity will come to an end. What matters for me, is if I'm going to live it or not ; not exactly how far this happens in time beyond my "event horizon" (my death).

Now, there is of course a reason for me to PRETEND that I care, and that is social pressure! As you point out, certain people (for reasons that I ignore) seem to care about what would happen to planet earth, or humanity or whatever beyond their life span. So in order not to trigger (observable) negative reactions and their consequences from this lot, it might be necessary to pretend to care about that. In the same way as you better pretend to worship the deity on duty in an untolerant theocracy. (so maybe I shouldn't post this )

It is in exactly the same way that I don't care about my eventual copies that might live in parallel universes, and that are being eaten right now by two tyrannosaurs. If you care about all that, you don't move a finger, and you stop breathing immediately.

 

[vanesch]

I think I will move this to GD, as this has really not much to do anymore with quantum physics per se...