Re: Branching on real-world decisions
On Fri, Nov 29, 2019 at 7:15 PM Philip Thrift wrote: > On Thursday, November 28, 2019 at 5:50:18 PM UTC-6, Bruce wrote: >> >> On Fri, Nov 29, 2019 at 1:27 AM Bruno Marchal wrote: >> >>> On 26 Nov 2019, at 22:39, Bruce Kellett wrote: >>> >> >> I think it is becoming generally accepted in the physics community that >>> the entangled state is intrinsically non-local: acting on one part of it >>> affects the rest, even across the entire universe. >>> >>> >>> That would mean some FTL actions, but I very much doubt this. >>> >> >> No, there is no need of FTL. For example, in the third (2011) edition of >> his book 'Quantum Non-Locality and Relativity', Maudlin shows that Flash >> GRW theory, as developed by Tumulka, gives a perfectly relativistic >> account of the EPR correlations without any FTL action. >> >> Bruce >> > > > *The GRW flash theory: a relativistic quantum ontology of matter in > space-time?* > https://arxiv.org/pdf/1310.5308.pdf > > whenever there is a spontaneous localization of the wave-function in > configuration space, that development of the wave-function in configuration > space represents an event occurring in physical space, namely there being a > flash centred around a space-time point. The flashes are all there is in > space-time. That is to say, apart from when it spontaneously localizes, > the temporal development of the wave-function in configuration space does > not represent the distribution of matter in physical space. It represents > the objective probabilities for the occurrence of further flashes, given an > initial configuration of flashes. As in BM, there hence are no > superpositions of anything existing in physical space. However, by contrast > to BM, GRWf does not admit a continuous distribution of matter: there are > only flashes being > sparsely distributed in space-time, but no trajectories or worldlines of > anything > > > Over and above the flashes being the primitive stuff in physical space, > the initial configuration of flashes instantiates a dispositional property > – more precisely a propensity – that fixes probabilities for the occurrence > of further flashes. The occurrence of such further flashes is the > manifestation of that propensity. The propensity of any given configuration > of flashes to manifest itself in the occurrence of further flashes is > represented by the wave-function. The GRW law supervenes on that propensity > in the sense that whenever such a propensity is instantiated in a possible > world, the GRW law holds in that world. By contrast to what is admitted by > Humeanism, that disposition or propensity hence is a modal property. > > ... > > In conclusion, one may go for an event ontology instead of a particle > ontology. But the > flash ontology is too sparse an ontology: since it does not provide for > anything like > continuous sequences of events, it does not have the means at its disposal > to account for > interactions that are supposed to trigger the occurrence of further > flashes (such as e.g. > measurements). In the end, therefore, it seems that the flash ontology > hardly is a convincing > answer to the question of what quantum mechanics tells us about what there > is in space-time. > Which is not to say that there is anything clearly wrong with the GRW -flash idea: it is just that Esfeld and Gisin do not like it much. 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/CAFxXSLTROdOpWzjSyCjqO6-3%3DCc0ycLmijx3U3ApRouxCaDABQ%40mail.gmail.com.
Re: Energy conservation in many-worlds
On Sat, Nov 30, 2019 at 12:35 PM 'Brent Meeker' via Everything List <
everything-list@googlegroups.com> wrote:
> On 11/28/2019 4:17 PM, Bruce Kellett wrote:
>
>
> Right. The subsystem we are considering (an electron fired at a screen or
> through an S-G magnet) is just a subspace of the full Hilbert space. We can
> take the tensor product of this subspace with the rest of the universe to
> recover the full Hilbert space:
>
> |universe> = |system>{\otimes}|environment>
>
> We can then analyse the system in some basis:
>
>|system> = Sum_i c_i |basis_i>,
>
> where c_i are complex coefficients, and |basis_i> are the basis vectors
> for (i = 1, ..,, N), N being the dimension of the subspace.
>
> It is assumed that the normal distributive law of vector algebra acts over
> the tensor product, so each basis vector then gets convoluted with the same
> 'environment' in each case, we have
>
> |universe> = Sum_i c_i (|basis_i>|environment>).
>
> Each basis vector is a solution of the original Schrodinger equation, so
> it carries the full energy, moment, change etc, of the original state.
>
>
> ?? The basis just defines a coordinate system for the Hilbert space. It
> doesn't mean that the wf ray has any component along a basis vector.
>
The formalism supposes that the state represented by each basis vector
becomes entangled with the environment to leave a record of the result of
the measurement. Coordinate systems do not become entangled with anything.
So the schematic above must represent the particle or whatever that is
being measured (considered of interest, if you wish to avoid the "M" word.)
> The c_i can be zero; in which case that basis vector doesn't carry
> anything. No every Schrodinger equation solution is realized because
> initial conditions may make it zero.
>
Irrelevant to the main point.
> The environment is just the rest of the universe minus the quantum
> quantities associated with the system of interest. So each term in this sum
> has the full energy, charge, and so on of the original state.
>
> If we take each component of the above sum to represent a self-contained
> separate world, then all quantum numbers are conserved in each world.
> Whether there is global conservation depends on how we treat the
> coefficients c_i. But, on the face of it, there are N copies of the
> basis+environment in the above sum, so everything is copied in each
> individual world. Exactly how you treat the weights in this situation is
> not clear to me -- if they are treated as probabilities, it seems that you
> just have a stochastic single-world model.
>
>
> Yes, I think that's right. Which is the attraction of the epistemic
> interpretation: you treat them as probabilities so you renormalize after
> the measurement. And one problem with the ontic interpretation is saying
> what probability means. But it seems that the epistemic interpretation
> leaves the wf to be a personal belief.
>
Yes, I find this easier to understand in a single-world situation. In
either case, you have to renormalise the state -- energy, charge and
everything -- for each branch in many-worlds as much as in a single-world.
In fact, as Zurek points out, even in many-worlds you end up on only one
branch (stochastically). So the other branches do no work, and might as
well be discarded. If you are really worried about the possibility of fully
decohered branches recombining, take out life insurance..
Bruce
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Re: C60 Interference
On 01-12-2019 09:12, Alan Grayson wrote: On Tuesday, November 26, 2019 at 6:11:41 AM UTC-7, Alan Grayson wrote: On Monday, November 18, 2019 at 12:10:26 PM UTC-7, Alan Grayson wrote: On Monday, November 18, 2019 at 11:01:17 AM UTC-7, Brent wrote: On 11/17/2019 11:07 PM, Alan Grayson wrote: I forget if I raised this issue here or on another thread. I am beginning to doubt that isolation is possible. When a particle is created, how can it be isolated from the environment? If it cannot be isolated, if it's never really isolated, the decoherence model fails to establish anything. AG Interactions are quantized like everything else. There's smallest unit of action, h. So if the interaction is less than this it's zero. So it is possible to isolate variables. Brent But if, say, a particle is created by some process, won't it be entangled with the causal entities defining the process and therefore be initially, and forever, non-isolated? AG If that's too hot to handle, try this: if we write the standard superposition of a decayed or undecayed radioactive atom, is there any inherent problem with interpreting this superposition to mean it has a probability to be in one state or the other by applying Born's rule to each amplitude? Why did this interpretation apparently fall to the wayside, and was substituted for the baffling interpretation of the system being in both states simultaneously? AG It seems like a simple question aching for an answer. Why do physicists, many of them at least, prefer a baffling unintelligible interpretation of superposition, say in the case of a radioactive source, when the obvious non-contradictory one stares them in their collective faces? AG The interpretation of a superposition as representing a system that can be in one or the other state, is incompatible with interference experiments. And physicist don't care much about interpretation and the language used to communicate what certain concepts mean. So, many physicists may say that a particle in a superposition between being in position x and y is at x and y simultaneously, even though they know that's not really what a superposition means (obviously there is only one particle not 2). What matters is the mathematical formulation of the theory, not the words used to describe this. Saibal -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/e291c638812ba3d1ef9737d85d746d2b%40zonnet.nl.
Re: C60 Interference
On Sunday, December 1, 2019 at 1:51:34 AM UTC-7, Philip Thrift wrote: > > > > On Sunday, December 1, 2019 at 2:12:38 AM UTC-6, Alan Grayson wrote: >> >> >> It seems like a simple question aching for an answer. Why do physicists, >> many of them at least, prefer a baffling unintelligible interpretation of >> superposition, say in the case of a radioactive source, when the obvious >> non-contradictory one stares them in their collective faces? AG >> > > > > > The fundamental and psychological problem many physicists have is that > they take some mathematics (in some particular theory) and assign physical > realities to its mathematical entities. Most of them do not understand the > nature of mathematics: It's a language (or collection of languages) about > mathematical entities - which are thought of differently depending on one's > philosophy of mathematics. (It is best to say they are *fictions*.) This > is especially true when probability theory (as defined in mathematics) is > involved. This hopping between physical realities and mathematical entities > leads them to them being unable to distinguish between them, or to > communicate to the public the true nature of physics. > > @philipthrift > Thanks for that! I'd like to hear Brent's and Bruce's opinion in this matter. 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/b982c7d8-6d59-4582-b46a-2d4e4a5cbfbe%40googlegroups.com.
Re: C60 Interference
On Sunday, December 1, 2019 at 2:12:38 AM UTC-6, Alan Grayson wrote: > > > It seems like a simple question aching for an answer. Why do physicists, > many of them at least, prefer a baffling unintelligible interpretation of > superposition, say in the case of a radioactive source, when the obvious > non-contradictory one stares them in their collective faces? AG > The fundamental and psychological problem many physicists have is that they take some mathematics (in some particular theory) and assign physical realities to its mathematical entities. Most of them do not understand the nature of mathematics: It's a language (or collection of languages) about mathematical entities - which are thought of differently depending on one's philosophy of mathematics. (It is best to say they are *fictions*.) This is especially true when probability theory (as defined in mathematics) is involved. This hopping between physical realities and mathematical entities leads them to them being unable to distinguish between them, or to communicate to the public the true nature of physics. @philipthrift -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/80acd639-93ba-4689-97ae-475af5ac63b4%40googlegroups.com.
Re: Are Real Numbers Really Real?
On Saturday, November 30, 2019 at 6:11:37 PM UTC-6, Lawrence Crowell wrote: > > On Saturday, November 30, 2019 at 4:30:28 PM UTC-6, John Clark wrote: >> >> >> >> On Sat, Nov 30, 2019 at 4:36 PM Lawrence Crowell < >> goldenfield...@gmail.com> wrote: >> >> *> The Planck unit of length and time does not mean space or spacetime is >>> discrete. All it means is this is the smallest scale one can localize a >>> quantum bit of information. It does not mean that spacetime is somehow >>> discrete.* >>> >> >> If discrete spacetime does not mean there is a smallest scale that a >> Qubit of information can be localized then what does "discrete spacetime" >> mean? >> > >> John K Clark >> > > It is a form of quotient geometry. For > > 1 → G → H → K → 1 > > for G = U(1), H = U(N) and K = PSU(N) = SU(N)/Z_N this short exact > sequence defines a discrete gauge group. The projective Lie group is a > Kleinian and for a manifold associated with SU(N), say AdS_5 = U(2, > 2)/O(4,1) the quotient defines an underlying discretization. Of course to > do this in greater generality we need to have a discrete system with > polytopes that define cells. So G could be the Coxeter group for a > polytope. Say for G the Coxeter group for the 4-dim icosian H the group > O(3,2) ≈ AdS_4×O(3,1) then K would be this spacetime, with the Lorentz > group, in a quotient with a lattice space. > > LC > https://arxiv.org/pdf/1803.06824.pdf : One may object that this view is arbitrary as there is no natural bit number where the transition from determined to random bits takes place. This is correct, though not important in practice as long as this transition is far away down the bit series. The lack of a natural transition is due to the fact that, in classical physics, there is no equivalent to the Plank constant of quantum theory. But this is quite natural, as the fact is that when one looks for this transition in the physical description of classical systems, one hits quantum physics. In summary, physics with all its predictive and explanatory powers can well be presented as intrinsically non-deterministic. The dominant view according to which classical physics is deterministic is due, first, to a false impression generated by it’s huge success in astronomy and in the design of clocks and other simple mechanical (integrable) systems, and, second, to a lack of appreciation of its implication for (infinite) information density. Finally, an indeterministic world is hospitable to Res Potentia and to the passage of time. https://arxiv.org/pdf/1709.03595.pdf It is argued that quantum theory is best understood as requiring an ontological duality of res extensa and res potentia, where the latter is understood per Heisenberg's original proposal, and the former is roughly equivalent to Descartes' 'extended substance.' However, this is not a dualism of mutually exclusive substances in the classical Cartesian sense, and therefore does not inherit the infamous 'mind-body' problem. Rather, res potentia and res extensa are proposed as mutually implicative ontological extants that serve to explain the key conceptual challenges of quantum theory; in particular, nonlocality, entanglement, null measurements, and wave function collapse. It is shown that a natural account of these quantum perplexities emerges, along with a need to reassess our usual ontological commitments involving the nature of space and time. @philipthrift -- 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 view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/ef100b7a-610c-45ef-9c3b-909ea4f8456d%40googlegroups.com.
Re: C60 Interference
On Tuesday, November 26, 2019 at 6:11:41 AM UTC-7, Alan Grayson wrote: > > > > On Monday, November 18, 2019 at 12:10:26 PM UTC-7, Alan Grayson wrote: >> >> >> >> On Monday, November 18, 2019 at 11:01:17 AM UTC-7, Brent wrote: >>> >>> >>> >>> On 11/17/2019 11:07 PM, Alan Grayson wrote: >>> > >>> > I forget if I raised this issue here or on another thread. I am >>> > beginning to doubt that isolation is possible. When a particle is >>> > created, how can it be isolated from the environment? If it cannot be >>> > isolated, if it's never really isolated, the decoherence model fails >>> > to establish anything. AG >>> >>> Interactions are quantized like everything else. There's smallest unit >>> of action, h. So if the interaction is less than this it's zero. So it >>> is possible to isolate variables. >>> >>> Brent >>> >> >> But if, say, a particle is created by some process, won't it be entangled >> with the causal entities defining the process and therefore be initially, >> and forever, non-isolated? AG >> > > If that's too hot to handle, try this: if we write the standard > superposition of a decayed or undecayed radioactive atom, is there any > inherent problem with interpreting this superposition to mean it has a > probability to be in one state or the other by applying Born's rule to each > amplitude? Why did this interpretation apparently fall to the wayside, and > was substituted for the baffling interpretation of the system being in both > states simultaneously? AG > It seems like a simple question aching for an answer. Why do physicists, many of them at least, prefer a baffling unintelligible interpretation of superposition, say in the case of a radioactive source, when the obvious non-contradictory one stares them in their collective faces? 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 everything-list+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/6dcadbf4-063d-46b4-a462-b184a57c4bfb%40googlegroups.com.
