On 11-07-2021 00:59, Bruce Kellett wrote:
On Sun, Jul 11, 2021 at 8:27 AM smitra <smi...@zonnet.nl> wrote:
On 10-07-2021 21:41, 'Brent Meeker' via Everything List wrote:
On 7/10/2021 1:19 AM, Bruno Marchal wrote:
So, in general we can conclude by generalizing this to any large
number of particles that even with what we consider to be
permanent
records, you don't get rid of the theoretical possibility of
interference between the sectors where those records are
different.
We can if the universe is expanding faster than light beyond the
Hubble
radius.
The expansion of the universe is irrelevant. The information needed
to
see the interference pattern continues to exist outside the horizon
when
it isn't accessible to us anymore. And this is irrelevant for the
discussions about observations in quantum mechanics. If an observer
performs a measurement and the claim is that this is a unitary
process
with the observer evolving into a superposition, while the objection
against this claim is that infrared photons are escaping and will
eventually move beyond the Hubble volume, then these photons will
still
not have escaped beyond the Hubble horizon by the time the observer
is
aware of the results of the experiment. So, whether or not the
photons
will eventually no longer be accessible, cannot be relevant.
Once the photons escape from the immediate environs of the experiment,
they are not recoverable. Try shining a torch at night to illuminate a
tree. Now try to stop the illumination already present. You can stop
future illumination by covering the torch, or switching it off. But
once the tree is illuminated it is not reversible. The expansion of
the universe, and the existence of the Hubble horizon, just makes the
irreversibility more obvious.
Nothing stops you from doing the experiment in a closed volume with
mirrors at the boundary. Since what we measure in a experiments is
determined by the laws of physics which are local in nature, the sort of
we impose boundary conditions on photons far away is irrelevant. Whether
or not an observer measuring the z-component of a spin that was
polarized in the positive x-direction ends up in a superposition where
there are objectively both outcomes being realized or only one outcome
does not depend on whether or not all the escaping infrared photons can
actually be captured and be made part of a giant interference experiment
to demonstrate an interference to prove that the superposition indeed
exists.
The existence of the superposition depends on the validity of quantum
mechanics for large systems. One can prove or disprove that in suitable
experiments. Once that's done and, say, collapse theories are ruled out
then it's not necessary to prove this over and over again for each and
every case. As things stand now, we can't rule out that an objective
collapse can happen, but this would require a violation of quantum
mechanics.
Bruce
--
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/CAFxXSLSjqpTNcrnEWiHLsjfV_JgTOooBB-0uaW27DdByMTWrWQ%40mail.gmail.com
[1].
Links:
------
[1]
https://groups.google.com/d/msgid/everything-list/CAFxXSLSjqpTNcrnEWiHLsjfV_JgTOooBB-0uaW27DdByMTWrWQ%40mail.gmail.com?utm_medium=email&utm_source=footer
--
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/081d3f33e13d814a21708ef716725ded%40zonnet.nl.
