On Sunday, November 12, 2017 at 11:24:15 PM UTC-7, agrays...@gmail.com wrote: > > > > On Sunday, November 12, 2017 at 11:15:33 AM UTC-7, John Clark wrote: >> >> On Sun, Nov 12, 2017 at 1:01 AM, <agrays...@gmail.com> wrote: >> >> > >>> What is your definition of non-realistic? >>> >> >> Nonrealistic means when something is not being observed it doesn't exist >> in any one definite state. >> >> >> > > You have to be careful here. For example, when the Earth-Moon system > formed, it existed in a definite state, but was NOT observed. So not > everything in a definite state must be observed, by detectors or conscious > entities. OTOH, when an electron is prepared for a double slit experiment, > it is in a superposition of states; that is, NOT in a definite state. If it > were in a definite state, we'd observe the classical probability > distribution. So quantum experiments, and QM in general to the extent it > relies on superposition of states, is NONREALISTIC, whereas the macro world > is generally REALISTIC. I can't speak to why the macro world is realistic. >
FWIW, I left out an important reason why some systems are in definite states, like macro systems, and others not, such as quantum systems prepared for measurements. It's likely related to whether the systems in question are ISOLATED. A photon hits a horizontally polarizing filter and the universe splits in >> two if Many Worlds is right, in one the photon makes it through the filter >> and the inhabitants of that world conclude it is 100% horizontally >> polarized , in the other world it doesn't get through the filter and they >> conclude it must have been 100% vertically polarized, but in the world >> before the split, before it hit the filter, the inhabitants of that world >> would conclude (if they believed in Many Worlds) that the photon did not >> have any one definite polarized state at all. >> >> >>>> >> >>>> That is not unique to the MWI. In a accelerating Einsteinian universe >>>> such as ours energy is not conserved at the cosmological level. >>>> >>> >>> > >>> There was some unique condition that gave rise to our universe. >>> >> >> The multiverse may have always existed, if so then nothing, unique or >> otherwise, gave rise to it, >> >> > > You're conflating Multiverse with the MWI. In the former, OUR universe > emerged due to unique, unknown initial conditions from an entity which, if > it exists, is likely infinite in age and extent. In the MWI, universes > allegedly emerge when Joe the Plumber shoots an electron at a slitted > screen. The two situations are in no way comparable, and the latter seems > hugely overblown IMO. So where the energy comes from in the MWI cannot be > easily dismissed by the lack of global energy conservation in GR, or by > referring to unknowns related to the emergence of our universe from a > hypothetical Multiverse. > > >> >> >>> > >>> MWI has it happening wily-nily when someone performs a slit experiment >>> in a lab (and uncountably many times). Hardly a conservative interpretation >>> IMO. >>> >> >> Many Worlds is very conservative if the mathematics doesn't say >> anything about a wave collapse. And it doesn't. >> >> >> >>>> they can't even say what is observation is. >>>> >>> >>> > >>> I can. They can. In a SG experiment, e.g., an observation occurs when >>> the electron's spin state is aligned, or anti-aligned to the magnetic >>> field. >>> >> >> Observation is the wrong word if no observer is involved, then its just >> a change and a change is the criteria Many Worlds uses. >> > > Agreed that "observation" is misleading when there is no consciousness > involved in a quantum experiment. We should speak of detectable changes > recorded by instruments; aka "measurements". > > >> In MWI everything that can happen does happen, so when a photon >> approaches 2 slits the universe splits and one photon goes through the >> right slit and one goes through the left slit. If after that the photons >> hit a photographic plate (or a brick wall) then the photons no longer exist >> in either universe and so they merge back together into one universe and >> this merger causes the interference lines. If instead after passing the >> slits there is no photographic plate (or brick wall) and the photons are >> allowed to continue on into infinite space then the 2 universes remain >> different and remain separated forever. >> > > So if David Deutsch takes a right turn at an intersection, there's another > identical David Deutsch in another identical universe who takes a left > turn? I can't disprove it, but why would anyone of sound mind want to > assert it? > >> >> The universe splits because there is a difference, in one the photon went >> through the left slit and in another it went through the right slit, and >> the wave function never collapses it just keeps on going. And there is >> nothing special about me, I split just like everything else in the >> universe, the fact that I am conscious is irrelevant. That's another great >> advantage of Many Worlds, unlike Copenhagen it doesn't need to explain what >> consciousness is or how it works because consciousness has nothing to do >> with it. >> > > As I previously pointed out, the alleged collapse of the wf has nothing to > do with consciousness regardless of what Bohr or others might have > speculated in the early days of QM. As Feynman clearly explained, you can > have a detector recording outcomes, and if the detector is designed to > determine which-way, the interference will be destroyed. In other words, > we can have quantum observations without any conscious "observer". > >> > >> > Can only a person make a observation or can a cockroach collapse the wave > function too? > > > >>> Feynman is conclusive on this point. No person or cockroach needed; just >>> an instrument to record the result. >>> >> >> If an instrument is anything that can exist in at least 2 states then I >> would be fine with that, but that sounds much more like Many Worlds than >> Copenhagen. All that's needed is a change, any change, it need not be >> anything as dramatic as a change in something as complex as a brain. >> >> > >>> Does every event require an observer or instrument to witness it? I >>> think not. >>> >> >> I think every observation requires a observer to witness a change, and >> Copenhagen requires an observation to trigger the collapse of the wave >> function. >> > > Not for macro events as pointed out above, or even quantum events. > Detectors to record changes are sufficient as "observers". > > Many Worlds just requires a simple change to trigger a split, a change in >> anything, and nothing triggers >> the collapse o >> f >> the wave function >> because the mathematics doesn't even hint at such a thing happening, >> the Copenhagen people just tacked that on. >> > > Not exactly true IMO. When the measurement occurs, the probability becomes > unity for the value of the measurement, implying collapse of the > probability density to a delta function. > > >> Somebody said that Many Worlds is cheap on assumptions but expensive in >> universes and I think that's true, I'm a fan because universes are cheaper >> than assumptions. >> > > Thanks for an interesting discussion. > >> >> John K Clark >> >> >> -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
