On Tuesday, November 12, 2019 at 1:43:56 PM UTC-7, smitra wrote: > > On 12-11-2019 01:02, Alan Grayson wrote: > > On Monday, November 11, 2019 at 3:40:04 PM UTC-7, smitra wrote: > > > >> On 11-11-2019 22:44, Alan Grayson wrote: > >>> On Monday, November 11, 2019 at 4:35:13 AM UTC-7, Bruce wrote: > >>> > >>>> On Mon, Nov 11, 2019 at 8:37 PM Bruno Marchal <mar...@ulb.ac.be> > >>>> wrote: > >>>> > >>>>> On 10 Nov 2019, at 20:01, Alan Grayson <agrays...@gmail.com> > >>>>> wrote: > >>>> > >>>> On Sunday, November 10, 2019 at 5:42:50 AM UTC-7, Bruno Marchal > >>>> wrote: > >>>> > >>>> Once the cat is alive + dead, he remains in that state for ever. > >>>> > >>>> THEN HOW COME WE NEVER OBSERVE THAT STATE? AG > >>> > >>> Because the observable are defined by their possible definite > >> outcome, > >>> and for reason already explained, macroscopic superposition > >> decoder, > >>> that is get entangled with the environment at a very high speed. > >> So, > >>> if you look at the cat in the a+d state, you are duplicate almost > >>> immediately into a guy seeing the cat alive + the guy seeing the > >> cat > >>> dead, and QM explained why they cannot interact, although they > >> might > >>> interfere themselves. > >>> > >>> That is exactly a preferred basis -- which you seem to want to > >> deny. > >>> > >>> Bruce > >>> > >>> In the case of a radioactive atom in state |decayed> + > >> |undecayed>, > >>> what's the justification and advantage of the interpretation that > >> it's > >>> in both states simultaneously? AG > >> > >> This is what happens, as confirmed by experiment. In case the decay > >> happens fast and there is more than one decay channel, the decay > >> will > >> happen to a superposition of the different possibilities. It's then > >> not > >> a decay to one of the possibilities and we just don't know which > >> one. > >> The difference between the two scenarios has in principle > >> experimentally > >> verifiable consequences. For example, the Delta++ particle decays > >> to a > >> proton and a positive pion due to the strong interaction. The strong > >> > >> interaction obeys isospin symmetry. From this one can deduce by > >> applying > >> a rotation in isospin space that the delta+ particle should decay to > >> the > >> superposition sqrt(1/3)|n>|pi+> + sqrt(2/3)|p>|pi0> where |n> > >> denotes a > >> neutron|p> a proton and |pi0> and |pi+> are neutral and positive > >> pions. > >> Experiments have confirmed the relative decay probabilities of 1/3 > >> and > >> 2/3. > >> > >> Saibal > > > > I don't see how this relates to my question. If the relative decay > > probabilites > > are what you state, does this mean that the system PRIOR to decay is > > several different states simultaneously? AG > > The system will in general be in a superposition, this follows from the > Schrodinger equation. The fact that a decay can happen at all means that > the particle states are not eigenstates of the full Hamiltonian. If you > consider a decay in a fixed volume and you impose reflecting boundary > conditions, then you won't get a permanent decay at all. The > superposition will end up oscillating back and forth from the original > particle to the decay products and back. When we compute the decay rate > in QM we need to take the limit to an infinite volume to eliminate this > oscillation effect and make the long term decay visible. But in > principle the superposition between the original undecayed particle and > the decay products will always continue to exist. > > Saibal >
Thanks, but the issue I am raising is not whether a superposition continues to exist, but the proper interpretation of it. For example, can a radioactive source be decayed and undecayed simultaneously, or is Philip correct in claiming both states are simultaneous possibilties? Huge difference. 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/ed2ae6ff-5620-45fb-b28e-d68333f75fea%40googlegroups.com.
