On Tuesday, December 5, 2017 at 12:50:54 AM UTC, Bruce wrote: > > On 5/12/2017 11:38 am, [email protected] <javascript:> wrote: > > On Tuesday, December 5, 2017 at 12:26:58 AM UTC, Bruce wrote: >> >> On 5/12/2017 3:15 am, Bruno Marchal wrote: >> > On 01 Dec 2017, at 01:49, Bruce Kellett wrote: >> >> On 1/12/2017 8:57 am, Bruce Kellett wrote: >> >>> On 1/12/2017 4:21 am, Bruno Marchal wrote: >> >>>> On 29 Nov 2017, at 23:16, Bruce Kellett wrote: >> >>>> On 30/11/2017 2:24 am, Bruno Marchal wrote: >> >>>>>> On 29 Nov 2017, at 04:59, Bruce Kellett wrote: >> >>>>>> >> >>>>>>> I would suggest that there is no such world. Whether a coin >> >>>>>>> comes up head or tails on a simple toss is not a quantum event; >> >>>>>>> it is determined by quite classical laws of physics governing >> >>>>>>> initial conditions, air currents and the like. >> >>>>>> >> >>>>>> It depends. If you shake the coin long enough, the quantum >> >>>>>> uncertainties can add up to the point that the toss is a quantum >> >>>>>> event. With some student we have evaluate this quantitavely (a >> >>>>>> long time ago) and get that if was enough to shake the coin less >> >>>>>> than a minute, but more than few seconds ... (Nothing rigorous). >> >>>>> >> >>>>> That is a misunderstanding of quantum randomness. For the outcome >> >>>>> of a coin toss to be determined by quantum randomness, we would >> >>>>> have to have a single quantum event where the outcome was >> >>>>> amplified by decoherence so that it was directly entangled with >> >>>>> the way the coin landed. Schematically: >> >>>>> >> >>>>> |quantum event>|coin> = (|outcome A> + |outcome B>)|coin> >> >>>>> = (|outcome A>|coin heads> + |outcome B>|coin tails>) >> >>>> >> >>>> The coin is quantum. >> >>> >> >>> The coin is classical, consisting of something of the order of 10^22 >> >>> atoms. Indeterminacy in position as given by the Heisenberg >> >>> Uncertainty Principle, is undetectably small. >> >> >> >> I think it is worth while to put some (approximate) numbers around >> >> this. The reduced Planck constant, h-bar, is approximately 10^{-27} >> >> g.cm^2/s. The Uncertainty Principle is >> >> >> >> delta(x)*delta(p) >= h-bar/2. >> >> >> >> For a coin weighing approximately 10 g and moving at 1 cm/s, the >> >> momentum is mv = 10 g.cm/s. Taking the momentum uncertainty to be of >> >> this order, the uncertainty in position, delta(x) is of the order of >> >> 10^{-28} cm. A typical atom has a diameter of about 10^{-8} cm, so >> >> the uncertainty in position is approximately 20 orders of magnitude >> >> less than the atomic diameter. >> > >> > I think that is enough to get the macroscopic superposition, as, like >> > I explained, you have to take into account not just the quantum >> > indeterminacy, + the classical chaos. You might need to shake for some >> > minutes. >> >> You could shake for longer than the age of the universe and you will >> still not convert quantum uncertainties and classical thermal motions >> into a macroscopic superposition. Do you know nothing about coherence? >> And the fact that coherent phases between the components are what >> separates a superposition from a mixture? > > > Are the phase angles of components of a superposition identical? If so, is > this the definition of coherence? TIA, AG > > > No, why should they be equal. You really do have to learn some basic > quantum mechanics, Alan, and stop bothering the list with such questions. > > Bruce >
Was I bothering the list when I started this thread, and others? I recall from class the answer is NO, because the probabilities are unaffected when taking complex conjugates (ignoring interference), but other comments on Avoid2 for example, when I was a member, indicated otherwise. Also, the poster here you're replying to seemed not to understand as well. Next time take THAT into account. AG > > Random quantum uncertainties >> and thermal motions are not coherent, so cannot form superpositions. >> > -- 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 post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
