Why the "Many-Worlds" Theory doesn't make sense...

Discussion in 'Physics & Math' started by stateofmind, Feb 12, 2015.

  1. PhysBang Valued Senior Member

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    Aaaaand... I'm done. Ciao, peeps. Good luck.
     
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  3. paddoboy Valued Senior Member

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    Just to put that in context..........this is what was said in its entirety....
     
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  5. paddoboy Valued Senior Member

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    So you also dispute the SR edict of all frames of refeences being as valid as each other?
    Albert would be pleased!
    Saying that when we see M31 2.5 million years ago is cobblers, is exactly saying that SR is cobblers.
    There is no Universal now....no way no how!
    If I went to M31 and sent you a message to synchronise your clock, it takes 2.5 million years before you receive my request to synchronise.
    I will always be 2.5 million years in your past.

    If I travelled at 99.999% "c" for six months, turned around and came back at the same 99.999% "c" I will have aged 12 months...The earth will have aged approximately 230 years.
    That is time travel in any ones language, and most logically accept that as time travel.
    Time travel is not only not forbidden by GR and the laws of physics, the solutions to achieve it are given in GR.
    We just as yet do not have the technology to achieve such speeds and energy requirements.

    You so often quote tracts of what Einstein claimed a 100 years ago, yet at the same time, you deny what his theory of relativity tells us.
     
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  7. Farsight

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    The latter. We have no issue with the "now" of here and now. And we know that when we look at Alpha Centauri 4 light years from Earth, what we see here and now isn't what's happening there now, because we have to allow for the light travel time. Then we know that you then move, your motion doesn't instantly change what's happening on Alpha Centauri, it doesn't make Alpha Centauri instantaneously jump a light year closer to Earth, and it doesn't change the speed of light through the universe.

    Edit: I've said previously that the invariant Lorentz interval is because the light-path lengths are the same for the out-and-back parallel-mirror clock and the stay-at-home parallel-mirror clock. One light path is zigzag, the other is up and down, but the light path lengths are the same. What separates now from now is the motion of light through space, whether it's out or back from here to there or up and down here or whatever. That's all it is. Remember the science fiction movies: the guy has a gizmo that "stops time", but when he presses the button everything stops moving. Because what it really stops is motion, not time.
     
    Last edited: Mar 12, 2015
  8. RJBeery Natural Philosopher Valued Senior Member

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    This paragraph directly contradicts itself. If you allow for light travel time to calculate the distant "now" but you ignore your own changes in motion because it "doesn't instantly change what's happening on Alpha Centauri" then you are not being consistent with your own definition! If two of us are walking in different directions on Earth which one's calculation of Alpha Centauri's "now" is the right one?
     
  9. brucep Valued Senior Member

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    Just about the redshift. There is an observable universe so there is an event horizon. This event horizon is associated with the position where the observation is being made. Thery're only redshifted out of existence for the remote observer when they cross the horizon associated with that observers observable universe. The only reason I mention this is some of the folks Quarkhead was referring to think photons give up energy to the local gravitational field.
     
    Last edited: Mar 12, 2015
  10. Farsight

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    There is no contradiction. You allow for your own changes in motion. You know that things merely look different to you because you changed your motion, but that those things didn't change.

    Both calculations are right provided we calculate them correctly. A calculation that says you can rewind time on Alpha Centauri by stopping walking is not correct.
     
  11. RJBeery Natural Philosopher Valued Senior Member

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    This doesn't work. You can't "allow for your own changes in motion" and get consistent results. If A and B are colocated but in relative motion they will not be able to do any mathematical flimflammery to mutually arrive at an objective plane of "now" without granting ONE of them a preferential perspective. This would break the concept of relativity. There isn't and cannot be a universal "now" associated with a point in spacetime in SR, and this is a mathematical fact. To the extent that SR is correct, there is no objective, universal now.

    I really hate to say this, Farsight, because I find some of your ideas interesting and you use analogies very well, but this is an area where your lack of mathematical rigor is causing you issues. I hope you think through this enough to appreciate my objection.
     
  12. Farsight

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    Yes you can. It's simple.

    Says who? Einstein never said that, he employed coordinate independence, but that's not the same thing. The people who say this sort of thing can never back it up, and they ignore the CMBR rest frame. That's the reference frame of the universe. It isn't an absolute frame in the strict sense, but the universe is as absolute as it gets. And all observers can gauge their motion through the universe from it.

    I say SR is correct, and that there is a universal now.

    It's not my lack of mathematical rigor that's causing me issues. The mathematics of SR is little more than Pythagoras's theorem, it's straightforward. It's a lack of understanding of the reality underlying the mathematics that's causing other people issues. Come on now, you stop your car, and the invasion fleet is suddenly no longer on its way, but instead hasn't taken off yet? Mathematical rigor does not tell you that. Mathematical misinterpretation tells you that.

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  13. paddoboy Valued Senior Member

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    The only paradox is in your sense of what we interpret as now.
    You are mangling what SR does say, you contort impossible situations to
    fit your own Interpretations, and as usual, you misinterpret the great one.
    You are literally claiming that one of the postulates of SR is not valid. You know the one...all Frames of references being valid.
    But perhaps you still have me on ignore with the dozen or so others you also have on ignore to avoid hearing the true reality of things.

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  14. paddoboy Valued Senior Member

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    I also offer in evidence of support for the SR derived fact that we cannot have a Universal NOW, the thread at.......
    http://www.sciforums.com/threads/sn-refsdale.145252/
    where it says in part.......
    "Because of the expansion of the universe, the star and its galaxy are receding from us so fast that, according to relativity, clocks there appear to run markedly more slowly than clocks here. As a result, two months from the point of view of the supernova corresponds to nearly six months on Earth.

    From our point of view, Dr. Kelly said, “it’s going on in slow motion.”

    A star might die only once, but with Einstein’s telescope, if you know where to look, you can watch it scream forever".
     
  15. Fednis48 Registered Senior Member

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    Fair enough.

    I think you're skimming over the most challenging part, which is how the wavefunction actually collapses. In an optical Fourier transform, the presence of a lens alters the propagation of a light wave, such that a sine wave will evolve into a point and vice-versa. There's a one-to-one mapping between inputs and outputs, and everything is deterministic. Moreover, the entire output distribution must be in the future light cone of the lens that produced it. Compare this to measurement collapse, in which one wavefunction can produce a random distribution of outcomes and measurements on entangled systems can have instant ramifications light years away. For "real wavefunction" interpretations, the whole challenge is to come up with a sensible way that these things could be true without invoking some kind of hidden variable. If you just say that something happens and the wave becomes a point, that's shut-up-and-calculate-ism.

    I disagree that you could describe everything in terms of photon-photon entanglement, since the photon basis is not a complete basis for the space of all states a detector could be in. But everything has a wavefunction, so it's certainly true that you can talk about wavefunction-wavefunction entanglement. The important part is that when you get a detector involved, the resulting entanglement is extremely complex. It is not the case that everything can be reduced to entanglement between pairs of particles; entanglement within a detector will generally be highly multipartite, i.e. involving the collective properties of many particles. This complexity - and the fact that it is usually uncorrelated with any system you might be studying - is why entanglement with a detector is enough to break quantum coherence without explicitly invoking measurement collapse.

    Please elaborate.

    Then please explain what you think weak measurement is. I'm honestly curious, although I'll preempt one possible answer: Based on your seismic wave analogy, it sounds like you might think that weak measurement involves measuring the wavefunction's amplitude on some part of Hilbert space while leaving the rest of the wavefunction alone. This is definitely not the case, as such a measurement would violate the linearity of quantum mechanics.

    I'll admit that the density matrix formalism is just that: a formalism. It isn't an interpretation, and it doesn't tell us what's "really" going on. What it does do is provide a complete framework for predicting experimental outcomes without explicitly invoking observers, so questions of interpretation are reduced to philosophical ones.

    Sure. But again, this is stopping just short of addressing the real problem. How can an interaction between two (or more) wavefunctions produce a definite but non-deterministic outcome?
     
  16. Neddy Bate Valued Senior Member

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    So Farsight wants everyone to transform their own coordinates right now to the CMBR frame, so that we can finally determine what the current "universal now" is for distant locations.

    So there are many "non-universal nows" but only one "universal now".

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  17. Fednis48 Registered Senior Member

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    To everyone going after Farsight's statements about the universal now:

    According to special relativity, all reference frames are equally valid, and complete information in any one reference frame is sufficient to predict all experimental results in all reference frames. If this is true, we should be able to arbitrarily choose one reference frame that's "right" and reinterpret Lorentz transforms as telling us how observers in other reference frames will be wrong about the speed of light, the passage of time, the lengths of rulers, etc. It would be misleading to call such a theory SR, but shouldn't it lead to all the same predictions?
     
  18. brucep Valued Senior Member

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    Put the nitwit cranks on ignore and talk about science when you feel like it.
     
  19. brucep Valued Senior Member

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    I don't think you meant "....predict all experimental results in all reference frames...." For each spacetime event you can transform your measurements to other reference frames observing the spacetime event from different coordinates. When you do that you predict the results of measurements made for the spacetime event from the frame you transformed to. Every frame agrees on the measurements made at the spacetime event.
     
    Last edited: Mar 13, 2015
  20. Fednis48 Registered Senior Member

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    Good point. I was referring to more general "experiments" in which multiple measurements are made at various spacetime coordinates, and the results are compiled to get at a higher-level conclusion. For instance, say two observers in two different reference frames (one CMBR, the other moving fast with respect to CMBR) want to test Newton's laws of motion. They weigh some masses, measure some distances and look at some clocks, and each comes to the conclusion that Newton's laws do indeed hold (at least in the appropriate limits). According to SR, each observer is taking valid measurements, and neither test is more correct than the other. According to Farsight's picture, one of the observers is very wrong about many of the quantities he's writing down in his lab notebook, but he's wrong in such a way that the errors cancel each other out and he comes to the right conclusions about the laws of physics. Moreover, Lorentz transforms allow the correct observer to predict exactly how his fast-moving counterpart will be wrong.
     
  21. Neddy Bate Valued Senior Member

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    Farsight says that SR does not predict the effects described in the Andromeda paradox, because SR has a "universal now." That is just wrong.
     
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  22. brucep Valued Senior Member

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    Using the physics to do an analysis over the events entire path. I don't read Farsight beyond reading your answers to his bullshit nonsense. The problem with cranks is the physics is a bore but being right is the essence of being. He can't be as stupid as he pretends to be. He insists on being right. Must be a tough road always being right.
     
  23. brucep Valued Senior Member

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    BTW by events I'm generally talking about experiments.
     

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