On Mon, Aug 5, 2019 at 6:07 PM Bruno Marchal <[email protected]> wrote:
> On 5 Aug 2019, at 03:27, Bruce Kellett <[email protected]> wrote: > > On Sat, Aug 3, 2019 at 10:52 AM Jason Resch <[email protected]> wrote: > >> On Fri, Aug 2, 2019 at 7:33 PM 'Brent Meeker' via Everything List < >> [email protected]> wrote: >> >>> On 8/2/2019 5:12 PM, Jason Resch wrote: >>> >>> On Fri, Aug 2, 2019 at 6:51 PM 'Brent Meeker' via Everything List < >>> [email protected]> wrote: >>> >>> >>> Wherever it happens, it's one world. Worlds are things things that are >>> orthogonal on to one another so that's why they're separate. I don't know >>> what Deutsch believes. >>> >>> In any case, you have still managed to avoid the question of the reality >>>> of the 10^1000 intermediate computational states. I won't press for an >>>> answer if you don't have one. >>>> >>>> >>>> I already gave the answer. There is only one intermediate state. It >>>> just happens to have lots of components in the basis you used to express >>>> it. >>>> >>> >>> And each of those components represents a trace of a computation >>> performed on one of the many possible values of the input qubits, do they >>> not? >>> >>> >>> That's one way of representing them. Just as citing the Fourier >>> components of a firecracker going off shows the many components of the >>> sound. >>> >> >> That would be a convincing counterpoint, except here this "way of looking >> at the many components" performs a computation that would not otherwise be >> possible if all the atoms of the universe were mustered to perform the >> computation. >> > > The fact is that it is possible. The 2^n dimensions of the Hilbert space > for n qbits is ample space for the computations. The trouble with looking > to parallel worlds to do the computations is that there are an uncountable > infinity of possible bases for the Hilbert space. What picks out just one > base to represent all these parallel worlds? That is the real problem. You > are ignoring the basis problem, just as Deutsch does. You naively assume > that the computational base that you used to set up you quantum computer in > the first instance is the only possible basis in which to view it. If you > take the view that the single ray in Hilbert space represents all that is > possible to know about the QC, and that computations are nothing more than > rotations of this state ray in the space, then all these silly notions of > parallel worlds evaporate. > > > But then the interference between different branch of the universal ray, > whatever base is used to describe it, will disappear. > No they won't. You obviously do not understand Hilbert space. The rotations in this space cause exactly the necessary interferences. The notion of world is fuzzy. I prefer to use the notion of relative state, > That is OK. The trouble with the relative state notion is that the state is relative to an observe i.e., in a decohered setting. Since there is no decoherence in the rotations of the QC state vector, there are clearly no relative states (or worlds, for that matte). The only time you get relative states is in the final measurement, when you determine a measurement basis in which to get the final answer. > and the local base describing your brain is pick out by your > consciousness, but is no more real or less real than any other relative > state in which consciousness can be supported by a quasi-classical > computation. > > Now, this use mechanism, and this makes necessary to justify the wave or > the “physical” apparent winning (locally) universal number from all > computations in arithmetic. > > (Well, you, Bruce, does not need to do that, as you do not assume > Mechanism). > Of course not. Mechanism is a dog! Bruce -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLRUne-2pcy9YT1GGXPLtzUpA4OymJZkx1GWBY-QMLsJKw%40mail.gmail.com.
