On 2/21/2020 4:00 PM, smitra wrote:
On 16-02-2020 05:48, 'Brent Meeker' via Everything List wrote:
On 2/15/2020 9:30 AM, smitra wrote:
The main issue is unitary time evolution. This is a rather
unambiguous thing that one can check in experiments. A breakdown of
unitary time evolution has never been observed.
As Brent has pointed out, unitary evolution breaks down every time
we
observe a particular result for a measurement (to say nothing of
black
holes). Your focus on unitary evolution is misplaced -- it is not
universally observed.
This has no bearing on the unitary time evolution of an isolated
system. We can infer from measurements that an isolated system does
evolve in a unitary way. Non-unitary time evolution would violate the
known laws of physics.
Only the "known" law that all time evolution is unitary. In the
Transactional interpretation there are random violations of unitary
evolution, as there are GRW and other real collapse versions of QM. You,
like most MWI proponents, assume your purist version is a "law of
physics" when the whole question is "What are the laws physics."
Brent
The information paradox involving black holes
is a problem precisely because of this. No one believes that the
solution involves a non-unitary evolution. Even Hawking who originally
did propose such ideas later reversed himself.
arXiv:hep-th/9503024v3
23 May 1995
Brent
And Hawking also published another argument about non-unitary
evolution around the same time, arguing that the effect may be
observable in processes involving scalar particles, making the Higgs
particle potentially observable. While you can find a few such papers,
the physicist community at large does not take these ideas seriously.
With the exception of a few people (e.g. 't Hooft, Hossenfelder etc.)
there are no serious efforts that invoke this issue in fundamental
physics. The idea is more popular among the people who think about the
foundations of QM and also within the condensed matter community, but
their ideas don't get traction in the field of fundamental physics.
Also, non-unitary evolution does not necessarily imply a single
universe anyway....
Saibal
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