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
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