On 09-04-2022 07:03, Bruce Kellett wrote:
On Sat, Apr 9, 2022 at 11:28 AM smitra <smi...@zonnet.nl> wrote:
On 08-04-2022 07:19, Bruce Kellett wrote:
Permanent records do follow from entanglement and decoherence.
There
is no reason to suppose that algorithms processing information are
going to produce permanent records. Unless they do, they are
useless
as a model of observation. In the words of David Albert
(paraphrased):
"The task of fundamental physics is to explain the manifest image
."
Decoherence is never complete it can in principle be reversed.
No. Measurements are in principle irreversible. Whenever you have a
result entangled with the environment (by decoherence) you inevitably
have low energy IR photons that escape into space. Since these vanish
at the speed of light, they cannot be reversed. The records of results
are permanent, not just FAPP, but in principle, according to the laws
of physics.
These IR photons have nothing whatsoever to do with observation. And
it's FAPP, not in principle, anyway. If I observe something then that's
due to my brain processing information, so, it's the processing of
information by a particular algorithm that's the key thing here, not
that decoherence happens and that IR photons would make this
irreversible.
That this is FAPP and not in principle, follows from the fact that IR
photons can be reflected back. So, one can consider a closed system
within which an observer exists. If we impose reflecting boundary
conditions at some distance, then the number of modes of the
electromagnetic field below a certain energy E is finite. And the amount
of information carried by photons with wavelength much larger than the
size of the experimental system is small, as for those photons that are
emitted, there are only a small number of distinct photon states.
It cannot
reasonably be the case that I can only observe something right now
because a record of the observation is going to exist for eternity.
If
the universe were to reverse its time evolution in 10^15000 years in
a
unitary way, causing all records to be exactly erased, then we could
not
make any observations. What's the physical basis for making this
assumption?
What's the physical basis for assuming the universe can or could
reverse at some point in the future?
That's not a relevant issue here. It's simply that you are linking
observations to physical processes that have nothing to do with what's
relevant for observations, which would link it to things like the far
future of the universe.
You may argue that a FAPP permanent record is good enough for
observation, but you cannot define a physical plausible rigorous
boundary of your FAPP criterion.
I can and have. The irreversibility occasioned by the escape of IR
photons is a rigorous boundary.
The escape of IR photons has nothing whatsoever to do with the ability
of the brain to process information.
One can always subtract 1 second from
your time limit the universe must keep on expanding before starting
to
evolve backward. One then eventually ends up with the criterion that
there must be enough time for the brain processes that cause the
conscious experience of the observation to be completed.
Irrelevant speculation.
The irrelevant thing here (IR photons) was introduced by you.
Saibal
Bruce
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