On Fri, Jan 3, 2014 at 1:46 AM, meekerdb <meeke...@verizon.net> wrote:

>  On 1/2/2014 10:38 PM, Jason Resch wrote:
>
>
>
>
> On Fri, Jan 3, 2014 at 12:20 AM, meekerdb <meeke...@verizon.net> wrote:
>
>>  On 1/2/2014 7:37 PM, Jason Resch wrote:
>>
>>
>>
>>
>> On Thu, Jan 2, 2014 at 8:35 PM, LizR <lizj...@gmail.com> wrote:
>>
>>>   On 3 January 2014 14:31, meekerdb <meeke...@verizon.net> wrote:
>>>
>>>>
>>>>   Then I'll start by saying I don't reject MWI, I just have
>>>> reservations about it, not so much that it's wrong, but that it doesn't
>>>> really solve the problems it claims to - which implies criticism of the
>>>> position that MWI has solved all the problems of interpreting QM.  A lot of
>>>> the above claimed advantages knocking down straw men built on naive
>>>> interpretations of Bohr.  Some are just assumptions, e.g that physics must
>>>> be time reversible and linear.
>>>>
>>>>   I thought linearit was probabilities adding up to one, which isn't a
>>> radical assumption???
>>>
>>>
>>  I think you might be thinking of unitary vs. non-unitary:
>> http://en.wikipedia.org/wiki/Unitarity_(physics)
>>
>>
>>
>>>   Time reversibility is an observed phenomenon in (almost) all particle
>>> interactions, so surely not an assumption at all?
>>>
>>>
>>  I agree, things like CPT symmetry, determinism, etc. aren't just
>> assumptions, but underlie every other known physical law that is known.
>>
>>  http://en.wikipedia.org/wiki/CPT_symmetry
>>  The *CPT theorem* says that CPT symmetry holds for all physical
>> phenomena, or more precisely, that any Lorentz 
>> invariant<http://en.wikipedia.org/wiki/Lorentz_invariant>
>>  local quantum field 
>> theory<http://en.wikipedia.org/wiki/Quantum_field_theory> with
>> a Hermitian <http://en.wikipedia.org/wiki/Self-adjoint_operator>
>> Hamiltonian<http://en.wikipedia.org/wiki/Hamiltonian_%28quantum_mechanics%29>
>>  must
>> have CPT symmetry.
>>
>>  Collapse of the wave function would be the only phenomenon in quantum
>> mechanics that is non-unitary, non-linear, non-differentiable, and
>> discontinuous. It would also be the only principle in physics that
>> non-local, non-causal, non-deterministic, and violates special relativity.
>>
>>  I can understand that Brent's ambivalence toward MWI, it may not be the
>> final answer, but I think it is a good step in that direction. However, I
>> am surprised that anyone well-versed in the known physics of today, could
>> consider collapse as anything but a wild, unsupported, and
>> almost-certainly-false conjecture.
>>
>>
>>  That's what I mean by attacking a straw man.  Fuchs and Peres et al,
>> including Bohr only considered 'collapse of the wave function' as a change
>> in one's information.
>>
>
>  I agree Bohr was closer to Fuchs and Peres, but Heisenberg, von Neumann,
> Wigner, etc. all believed in collapse, and CI is still taught as the
> orthodox interpretation in most places. It's not exactly a straw man.
>
>  To say the theory is only about our information seems like a kind of
> cop-out to me.  We don't see other theories in science described as only
> speaking about the information that we can gain not about anything that
> real external to us. Why can't QM be a realist theory like everything else
> in science?
>
>
> I sort of see the opposite trend.  More and more physicists are looking
> for an information based fundamental theory.
>
>
But where is the information coming from?  If no where or nothing, this is
just a form of idealism.


>
>
>
>>  Bohr said QM is not about reality, it's about what we can say about
>> reality.  Only later did people try to invent real collapse theories, e.g.
>> Penrose, and while I don't consider any of them likely I wouldn't say they
>> are almost certainly false.
>>
>>
>  Let's say someone proposed a new theory to explain why when something
> falls into a black hole we can no longer see it, but it ignored that other
> theories already explain why we can't see things that fall into a black
> hole.
>
>
> Or how about a theory that it's both destroyed at the event horizon and
> also falls through to the singularity?
>
>
That's fine.


>
>   Moreover, imagine that this theory, if true, would require faster than
> light influences, as well as violations in the second law of thermodynamics
> and conservation of mass energy.  Would you say this theory was only
> "unlikely"?
>
>
> Are you claiming that Penrose's idea does all those things?
>
>
No, it is only an example of the kind of thing collapse represents. An
extraneous theory, having no motivation and which contradicts core ideas
and principals across physics.


>
>
>
>>
>>   There is so much well-established physics that must be given up; for
>> apparently no other reason than the ontological prejudice some harbor for
>> the idea that the universe is no bigger than we previously thought.
>>
>>
>>  That's as good a prejudice as every thing must be determined from the
>> beginning.
>>
>>
>  Now who is fighting straw men? (You always pretend this this is the
> primary, or only motivation for Everett)
>
>
> I don't know about you, but Bruno has said he considers fundamental
> randomness to be completely unacceptable.
>

So that makes collapse 1 of about 10 other serious problems with it.


>   What do you think about the idea that the whole course of the universe
> was set at that (near) singularity at the beginning of the universe?
>

What do you mean by universe? Clearly we don't remain (or aren't in) just a
single possible ((future) history).

Jason

I realize it was probably not Everett's motivation - he was more interested
> in the Heisenberg cut problem.
>
> Brent
>
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