On Fri, Aug 9, 2019 at 1:15 AM Bruce Kellett <bhkellet...@gmail.com> wrote:
> On Fri, Aug 9, 2019 at 3:52 PM Jason Resch <jasonre...@gmail.com> wrote: > >> On Thursday, August 8, 2019, Bruce Kellett <bhkellet...@gmail.com> wrote: >> >>> On Fri, Aug 9, 2019 at 2:15 PM Jason Resch <jasonre...@gmail.com> wrote: >>> >>>> On Thu, Aug 8, 2019 at 10:19 PM Bruce Kellett <bhkellet...@gmail.com> >>>> wrote: >>>> >>>>> On Fri, Aug 9, 2019 at 11:57 AM Jason Resch <jasonre...@gmail.com> >>>>> wrote: >>>>> >>>>>> On Thursday, August 8, 2019, Bruce Kellett <bhkellet...@gmail.com> >>>>>> wrote: >>>>>> >>>>>>> On Fri, Aug 9, 2019 at 4:50 AM Jason Resch <jasonre...@gmail.com> >>>>>>> wrote: >>>>>>> >>>>>>>> >>>>>>>> A multitude of classical computational traces can be found in a >>>>>>>> quantum computation. You point out this multitude of computation >>>>>>>> traces >>>>>>>> can be viewed as one state of a larger space. Viewing it this way, >>>>>>>> however, doesn't eliminate the multitude of the classical computational >>>>>>>> traces. >>>>>>>> >>>>>>> >>>>>>> But viewing it in terms of "multiple classical computational traces" >>>>>>> does not prove that there are multiple parallel worlds. You can change >>>>>>> the >>>>>>> basis vectors, or the clustering properties of the components, to any >>>>>>> extent that you like. That does not change the fact that there is only >>>>>>> one >>>>>>> overall state, in one world, and no parallel worlds anywhere. >>>>>>> >>>>>> >>>>>> Not immediately, the logic to get to many worlds is as follows: >>>>>> >>>>>> >>>>>> 1. There are multiple classical computational traces in the quantum >>>>>> computer. >>>>>> >>>>> >>>>> The operation might be representable in this way. But that does not >>>>> mean that this is what actually happens. Description in a different base >>>>> leads to a different perspective. >>>>> >>>> >>>> You say this is merely a way of representing what is happening (and >>>> implying what I suppose to be happening is not really real), but then this >>>> line of reasoning fails to give any account of how Shor's algorithm factors >>>> the 1000 bit semi-prime. >>>> >>> >>> We have explained how Shor's algorithm factors the 1000 bit semi-prime: >>> by rotations in the 2^1000dimension Hilbert space -- all one world. >>> >>> >> >> Can we agree then that this 2^1000 dimensional Hilbert space is more than >> just a matter of some perspective? >> > > The Hilbert space is the quantum description of the 1000 qbits. > > > 2. If the classical computational traces are computations of conscious >>>>>> minds, there are multiple conscious minds and points of views. >>>>>> >>>>> >>>>> Consciousness requires decoherent interaction with an environment, and >>>>> there is no decoherence within the QC. >>>>> >>>> >>>> Then you get either (a) violations of Church-Turing or (b) >>>> philosophical zombies. Which do you suppose it is? >>>> >>> >>> Philosophical zombies, assuming that these computations report "I am >>> conscious". They are actually lying. I can write a program that prints out >>> "I am conscious." That does not prove that it is conscious. >>> >> >> Okay. That is at least consistent with your rejection of digital >> mechanism. (The computational theory of mind). >> >> Do you believe that the same computation run on a classical computer >> *would* be conscious? >> > > What computation? A conscious computation on a QC will be conscious if it > is performed on a classical computer. But for this computation to be > conscious, the QC is no different from a CC. > What role do you see decoherence playing in consciousness? In other words, could you explain why shedding IR photons into an external environment necessary for the mind to be conscious? > > > 3. The quantum computer maintains the superposition of the multiple >>>>>> computational traces by virtue of being isolated from the environment. >>>>>> >>>>> >>>>> So there cannot be conscious points of view within it. >>>>> >>>> >>>> According to what theory of mind? >>>> >>> >>> The theory of mind that says that conscious minds interact with the >>> physical environment. >>> >> >> Dreams are impossible under such a theory. >> > > Dreams are the product of unconscious interactions with the environment -- > of the brain if not of the external environment. > > > 4. Our own minds are isolated from the rest of the environment for some >>>>>> definition of the environment (e.g. a sphere with a 200 light year radius >>>>>> centered on Earth). >>>>>> >>>>> >>>>> The immediate environment even within our own skulls is sufficient to >>>>> decohere anything quantum. >>>>> >>>> >>>> Dechorence is relative. Nothing in your brain is interacting with >>>> anything 200 light years away (at least not for 200 years). >>>> >>> >>> Nothing in my brain need to interact with anything 200 ly away-- it need >>> only interact with my skull (or itself) to decohere. >>> >> >> But coherence and decoherence are relative. What is it about the qubits >> that allows them to interact with other qubits and remain coherent? Why >> don't those other qubits count as part of their environment? >> > > Coherence is the maintenance of phase relations. Phase relations between > qbits and their interference is what make the QC work. Decoherence involves > entanglement with uncountable environmental degrees of freedom. One cannot > maintain the phase relations under this conditions. Why do you think > quantum computers are so hard to construct and operate? > > > 5. From the perspective of a scientist outside this sphere, we can be >>>>>> viewed as a superposition of many possible states. >>>>>> >>>>> >>>>> There is no such perspective, because if he is outside the future >>>>> light cone he can get no information about the state at the centre. If he >>>>> interacts with it, he decoheres it and it is just another "relative state" >>>>> (single world). >>>>> >>>> >>>> I am speaking of the time between your birth and the time he interacts >>>> with your state. During this time your brain is in a superposition of many >>>> possible states (from his vantage point). When he interacts with it, 200 >>>> years from now, he becomes part of the superposition (maintained for the >>>> entity 400 light years away). >>>> >>> >>> No, he is more intelligent than that. He knows that Wigner's friend has >>> already decohered the wave function, and that quantum superpositions of >>> decohered objects do not exist. >>> >> >> You speak as if decoherence is an objective property if the wave function. >> > > In effect, it is. > But in principle is it? Is the time of decoherence down to the nanosecond different for the cat, Wigner's Friend, and Wigner? > > >> If we run a simulation of every atom of Wigner's lab in a quantum >> computer, when does decoherence happen? >> > > When you lose track of the phase relations. Don't forget the IR photons > that escape at the speed of light. The number of environmental degrees of > freedom is not constant. So no computer simulation is ever going to be able > to track everything indefinitely. > Let's say the simulation had strict boundaries such that constant memory was sufficient for the simulation (anything particle on a course to leave the dimensions of the lab was reflected back perfectly). When would decoherence happen in that case? > > > 6. Hence we experience "many worlds" in the sense that the wave function >>>>>> for the state of the earth becomes a superposition of huge number of >>>>>> possibilities. (From the POV) of the scientist outside the sphere. >>>>>> >>>>> >>>>> There is no such perspective. Even if there were, the "outside" >>>>> observer would not see a superposition, because there are no internal >>>>> multiple worlds -- there is only the one world with one result from the >>>>> quantum computation. >>>>> >>>>> This is just the "Wigner's friend" argument. And that has been shown >>>>> many times not to imply many worlds, or coherent superpositions of >>>>> decohered objects. >>>>> >>>> >>>> You said before decoherence results when a system interacts with it's >>>> environment. Well here the system of earth won't react with its external >>>> environment for 200 years. >>>> >>> >>> What is the environment? You cannot restrict it this way. >>> >> >> >> There's no objective distinct between a system and it's environment. The >> universe as a whole can be viewed as a system without any external >> environment. >> > > So decoherence acts within that larger system. As soon as you look at any > part of the system, it remains entangled with the rest, and you lose > coherence. A part of a pure state is a mixed state. > You said as soon as I look at it. What about from the perspective of someone 200 light years away? Does decogerence happen for them as soon as I look at it, or as soon as they look at it? > > > It is isolated in the same way the qubits are in the quantum computer. >>>> >>> >>> Qbits in the QC interact coherently, so there is no decoherence. My >>> interaction with my environment is not coherent. There is the difference. >>> >> >> The difference is only that you're prevented from interacting with the >> qubits for some time. >> > > Which maintains the coherence, as I said. > So it is a relative phenomenon then, is it not? The qubits are interacting with each other but not with anything outside, they remain in coherence. Likewise, in my example, you interact with earth, but not anything outside the 200 ly sphere, you and the earth remain in coherence (from this outside viewpoint). > > > >> So what is the difference? Why does the superposition persist in the >>>> quantum computer but not in the Earth isolated from points in space 200 >>>> light year away? Can you reference a rule or equation in quantum mechanics >>>> that suggests an error in this reasoning? >>>> >>> >>> Rule: Decohered objects do not form quantum superpositions. >>> >>> >> There's no objective decoherence so you can't speak of decohered objects. >> Only objectives that have decohered relative to you or some other system. >> > > That is objective enough for all practical purposes. You want to speak of > parts of the system. Then the part that you are not speaking of is an > environment with which you are entangled -- and to which you have lost > coherence. I suppose, if you only ever talk about the whole universe, then > you might be right. But that is not how we do science. > How do you do science? Is it not okay to ask questions in science, such as the nature of the wave function for the whole universe? Jason -- You received this message because you are subscribed to the Google Groups "Everything List" group. 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