On Sunday, May 20, 2018 at 7:29:42 PM UTC, Brent wrote: > > > > On 5/20/2018 3:47 AM, [email protected] <javascript:> wrote: > > > > On Sunday, May 20, 2018 at 6:52:41 AM UTC, Brent wrote: >> >> >> >> On 5/19/2018 8:19 PM, [email protected] wrote: >> >> >> >> On Saturday, May 19, 2018 at 3:59:03 PM UTC, Brent wrote: >>> >>> >>> >>> On 5/18/2018 10:53 PM, [email protected] wrote: >>> >>> >>> >>> On Saturday, May 19, 2018 at 5:29:33 AM UTC, Brent wrote: >>>> >>>> >>>> >>>> On 5/18/2018 10:14 PM, [email protected] wrote: >>>> >>>> >>>> *So why don't you draw the obvious inference? If those other worlds >>>> don't exist -- which if I can read English has been your passionate >>>> position all along -- then quantum measurements in this world, the only >>>> world, are statistical and hence NOT reversible in principle. AG* >>>> >>>> >>>>> but it is different in each branch of the wave function, so reversing >>>>> this branch does nothing for the others, and does not restore the >>>>> original >>>>> superposition. Thus the process is irreversible in principle >>>>> (nomologically >>>>> irreversible -- to reverse violates the laws of physics). >>>>> >>>> >>>> *But if those other worlds don't exist, it makes no sense whatever to >>>> rely on them to establish irreversible in principle in this world (as >>>> distinguished from statistically irreversible or irreversible FAPP). It >>>> seems you want to have it both ways; that many worlds really don't exist. >>>> but quantum measurements in this world are irreversible in principle due >>>> the existence of many worlds. AG* >>>> >>>> >>>> You don't handle uncertainty well, do you. >>>> >>>> Brent >>>> >>> >>> You know, it's not a perfect analogy, but I don't believe that when I >>> pull the one arm bandit with 64 million possible outcomes, that 64 million >>> (minus one) worlds are created, each with an identical copy of me, getting >>> those other outcomes. What do you believe? AG >>> >>> >>> I believe I'll wait for a better theory. One that includes gravity and >>> spacetime and consciousness. >>> >>> Brent >>> >> >> I see. But you seem too ready to defend the MWI when it appears to imply >> irreversible in principle. Or do you accept Bruce's claim that the >> projection operator implies irreversible in principle? AG >> >> >> Either of them implies irreversiblity. Whether it is "in principle" >> depends on what principle you invoke, mathematics, practice, ...? MWI puts >> information in orthogonal subspaces where we exist in copies such that each >> copy can act only in one subspace and hence cannot put together the >> information from other subspaces. A projection operator is just a >> mathematical model of this confinement to one subspace. >> >> Brent >> > > Please; no evasive games. We can forget about the MWI, given its > absurdity. Does, or does not the projection operator imply irreversibility > in principle as Bruce claims? AG > > > Sure, a projection operator throws away information so its action is > irreversible. If I project a star onto the celestial sphere I preserve its > longitude and latitude, but it doesn't show how far away it is. That's why > the MWI advocates say projection conflicts with all the rest of fundamental > physics which is described by evolution that is at least reversible in the > mathematical sense. > > Brent >
But how do you know that the projection operator represents an actual physical process? It could be just a bookkeeping device to describe the fact that when many possible outcomes are possible, we get a particular outcome. ISTM, that to argue for "irreversible in principle", it is insufficient to appeal solely to the properties of the projection operator. AG -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
