On Tuesday, December 5, 2017 at 3:03:51 AM UTC, Russell Standish wrote: > > On Tue, Dec 05, 2017 at 12:18:02PM +1100, Bruce Kellett wrote: > > On 5/12/2017 11:53 am, Russell Standish wrote: > > > On Tue, Dec 05, 2017 at 11:26:53AM +1100, Bruce Kellett wrote: > > > > On 5/12/2017 3:15 am, Bruno Marchal wrote: > > > > > 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? Random quantum uncertainties and > thermal > > > > motions are not coherent, so cannot form superpositions. > > > > > > > To repeat - coherence and superposition are orthogonal concepts. A > > > fully decohered multiverse is still in a superposition. > > > > But that superposition is only of the whole multiverse, and we do not > have > > access to that. The concepts are not orthogonal, because any finite > physical > > system will not, in general, be in a superposition of any kind. The > > distinction between pure states -- coherent superpositions -- and mixed > > states is fairly fundamental if you want to make any progress in > fundamental > > physics. > > Of course. My point is simply that a mixed state is still a > superposition, just not a coherent one.
*A system in a superposition is said to be in multiple states simultaneously, which is much different from a mixed state where the system is conceived as being in one of several states, but with different probabilities. This is standard terminology AFAIK. AG* > It may just be a pernicketty > language thing, but I do see a lot of disagreements on this list just > because people are using language in different ways. > > > > > > Re the length of time for quantum uncertainty to affect macroscopic > > > state, much less than the age of the universe is required. > > > > The Poincaré recurrence time for the general decohered state is > certainly of > > the order of the age of the universe. Quantum uncertainties can affect > the > > macroscopic state in some circumstances -- particular when there is a > clear > > route for amplification of the quantum effects, as in most quantum > > experiments. It has been suggested that the chaotic rotation of Saturn's > > moon Hyperion is related to quantum effects, but that is a particularly > > unstable system. > > > > The Poincare recurrence time is usually much longer than the mixing > time of a chaotic system. I'm not sure what the relevance is to what > we're talking about. > > > > Whilst the StosszahlAnsatz will be strictly speaking incorrect, as I > > > understand it it is very approximately true. This will entail that > quantum > > > randomness will affect classical randomness on about the same > > > timescale as the mean free time of molecules in a gas at room > > > temperature, or about 0.1 ns. > > > > I think this remains to be proved for the general case. > > > > > Unless you are ... -- 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.
