On Apr 17, 1:21 pm, Brent Meeker <meeke....domain.name.hidden> wrote:
> Telmo Menezes wrote:
> > On Thu, Apr 17, 2008 at 2:37 PM, Bruno Marchal <marc....domain.name.hidden> wrote:
>
> >> Are you saying that the second law is verified in each of all
> >> "branches" of the (quantum) multiverse?
>
> > I'm not saying that.
>
> >> I would say the second law is
> >> statistical, and is verified in most branches. In the MWI applied to
> >> quantum field it seems to me that there can be branches with an
> >> arbitrarily high number of photon creation without annihilation, and
> >> this for each period of time.
>
> I'm not sure what source of photon creation you have in mind, but QFT
> doesn't allow violation of energy conservation.
Maybe it was vacuum energy Bruno was referring to, or else perhaps the
creation of virtual particle pairs? Stephen Hawking (who by the way
apparently regards Everett's theory as trivally true, in other words,
instrumentalistic and without physical significance) used virtual
particles to explain how black holes may evaporate. But I don't want
to put words in anyone's mouth, and plus, I am not knowledgeable
enough on these matters to discuss them.
But if I may raise one possibility, it seems to me that despite the
existence of fluke branches in which the second law is not inviolate,
there are no possible branches that experience the outcome of a double
slit experiment that does not result in an interference pattern.
This is according to my understanding that the interference actually
takes place across branches, as each path of the photon interferers
constructively and destructively with itself.
The upshot of this is simply a recognition that not every outcome is
possible, and there remain situations that are not realized in any
extant universe.
>
> > Yes, I would tend to agree with that, although I can't say I'm 100%
> > convinced. Anyway I'm a relative newcomer to this list so I don't feel
> > I have an informed opinion yet. Need to catch up with all the
> > arguments. Also have a thesis to finish, which tends to get in the way
> > :)
>
> > I'm just arguing that the experiment with the rifle and the geiger
> > counter does not imply any second law anomaly. Yes, you are "forcing"
> > your consciousness to "move" to states where the atom never decays,
> > but if you consider the larger system, entropy is increasing as normal
> > because of the preparation and maintenance of the apparatus needed for
> > the experiment.
>
> > Do you think this makes sense?
>
> > Telmo Menezes.
>
> The idea of the multiverse derives from quantum mechanics, e.g. the
> Everett no-collapse interpretation. But in that model the (microscopic)
> entropy never increases (or decreases), because QM evolution is unitary.
> It is only the coarse-grained entropy, i.e. restricted to this branch,
> that increases. Certainly within this branch you are correct that the
> entropy increase due to firing a gun is very much greater than the
> decrease due to an atom not decaying.
But the gun would only fire if the atom did in fact decay. It would
not fire in the branches where no decay was detected.
>
> Brent Meeker- Hide quoted text -
>
> - Show quoted text -- Hide quoted text -
>
> - Show quoted text -
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Received on Sat Apr 19 2008 - 01:12:15 PDT