On Thu, Nov 20, 2014 at 10:43 AM, Bruno Marchal <marc...@ulb.ac.be> wrote:
> > On 19 Nov 2014, at 19:43, Richard Ruquist wrote: > > In MWI it is rather difficult to reverse time and unsplit the universe. > > > The "mutiverse" is only the quantum configuration space taken seriously. > The SWE describe all quantum evolution as a rotation (a unitary > transformation) of a state vector in the Hilbert space. I can hardly > imagine something more reversible. > > > It's not Hermitian > > > It is unitary. > Well it lacks enough energy to go forward in time, going backwards cannot be that hard. > > Bruno > > > > > Richard > > On Wed, Nov 19, 2014 at 1:40 PM, John Clark <johnkcl...@gmail.com> wrote: > >> On Tue, Nov 18, 2014 at 12:06 AM, Russell Standish <li...@hpcoders.com.au >> > wrote: >> >> >> I'd say that by about 1850 when people started to have a understanding >>>> of what Entropy was physicists had all they needed to have known that the >>>> universe must have started out in a very very low entropy state, that is to >>>> say they could have predicted the Big Bang in the early to mid 19th >>>> century; and they wouldn't have needed to go near a telescope to do so. But >>>> unfortunately they didn't, it's one of the great failures of nerve or >>>> imagination in the history of science. >>>> >>> >>> > Boltzmann indeed predicted a low entropy state sometime in the past. >> >> >> Yes but Boltzmann thought that you could ignore boundary conditions and >> the second law of thermodynamics alone was enough to logically deduce that >> in the distant past the universe must have been in a very low entropy >> state, but in 1876 Loschmidt pointed out that Boltzman was wrong about >> that, he said you can't deduce a irreversible process, like the increase of >> entropy, from classical dynamics alone because if you just reverse the >> velocity of the particles in high entropy state B it will evolve back into >> the low entropy state A that produced it. And knowing that there are >> VASTLY more high entropy states than low entropy states and asked what >> state produced the stat we're in now you'd have to answer that it was >> almost certainly one of those enormously numerous high entropy states >> UNLESS you made a further assumption, the past hypothesis, the idea that >> the universe must have started out in a very very low entropy state. >> >> John K Clark >> >> >> >> >> >> -- >> 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 post to this group, send email to everything-list@googlegroups.com. >> Visit this group at http://groups.google.com/group/everything-list. >> For more options, visit https://groups.google.com/d/optout. >> > > > -- > 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 post to this group, send email to everything-list@googlegroups.com. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > > > http://iridia.ulb.ac.be/~marchal/ > > > > -- > 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 post to this group, send email to everything-list@googlegroups.com. > Visit this group at http://groups.google.com/group/everything-list. > For more options, visit https://groups.google.com/d/optout. > -- 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 post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
