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 <[email protected]> > >>>> wrote: > >>>> > >>>>> On 10 Nov 2019, at 20:01, Alan Grayson <[email protected]> > >>>>> 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/ed2ae6ff-5620-45fb-b28e-d68333f75fea%40googlegroups.com.
