On 12/9/2013 5:31 PM, Jason Resch wrote:
On Mon, Dec 9, 2013 at 4:28 PM, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
On 12/9/2013 12:06 PM, Jason Resch wrote:
On Mon, Dec 9, 2013 at 12:57 PM, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
On 12/9/2013 12:44 AM, LizR wrote:
On 9 December 2013 20:56, meekerdb <meeke...@verizon.net
<mailto:meeke...@verizon.net>> wrote:
On 12/8/2013 4:36 PM, LizR wrote:
On 9 December 2013 07:41, John Clark <johnkcl...@gmail.com
<mailto:johnkcl...@gmail.com>> wrote:
On Sun, Dec 8, 2013 at 11:48 AM, Jason Resch
<jasonre...@gmail.com
<mailto:jasonre...@gmail.com>> wrote:
>> Determinism is far from "well established".
> It's a basic assumption in almost every scientific theory.
In the most important theory in physics, Quantum Mechanics, no
such
assumption is made, and despite a century of trying no
experiment has
ever been performed that even hinted such a deterministic
assumption
should be added in.
I believe the two-slit experiment hints that QM is deterministic by
implying the existence of a multiverse.
Wasn't it you, Liz, that pointed out this was circular. Everett
assumes a
multiverse in order to make QM determinsitic.
I did say something like that, didn't I? [insert embarrassed emoticon
here].
I think I was saying that it was too strong to say that QM "follows the
principle of determinism" (or something like that) because it appears
to be
indeterminate and only becomes deterministic thanks to Everett.
However, the
two-slit experiment does /suggest/ the multiverse as a valid
explanation, in
that any other explanation requires other principles to be violated
(causality, locality...)
I think I was attempting to position myself between John and Jason - to
say
that determinism is reasonably well established, but only as a result
of a
long and winding process of experiment, conjecture and so on.
But it isn't. As Roland Omnes says, quantum mechanics is a
probabilistic
theory so it predicts probabilities - what did you expect? Among
apostles of
Everett there's a lot of trashing of Copenhagen. But Bohr's idea was
that the
classical world, where things happened and results were recorded, was
*logically* prior to the quantum mechanics. QM was a way of making
predictions
about what could done and observed. Today what might be termed
neo-Copenhagen
is advocated by Chris Fuchs and maybe Scott Aronson. I highly recommend
Scott's book "Quantum Computing Since Democritus". It's kind of heavy
going in
the middle, but if you're just interested in the philosophical
implications you
can skip to the last chapters. Violation of Bell's inequality can be
used to
guarantee the randomness of numbers,
http://arxiv.org/pdf/0911.3427v3.pdf,
assuming only locality.
Bell's theorm proves that local hidden variables are impossible which
leaves only
two remaining explanations that explain the EPR paradox:
1. Non-local, faster-than-light, relativity violating effects
That's non-local hidden variable - which is exactly what a parallel
universe is.
There is nothing non-local about Everett's theory. You start with the electron and
positron left over from the decay of a pi meson. They are each in a superposition of
having a negative spin in the y axis and a positive spin on the y axis, but they are
correlated in the following way:
(e↑ × p↓) + (e↓ × p↑)
Then one electron is sent to Earth and the other to the closest star, Proxima Centauri,
where they are measured at about exact same time. After the scientists on Earth measure
the electron, the state is as follows:
(Earth↑ × e↑ × p↓) + (Earth↓ ×e↓ × p↑)
Where Earth↑ represents earth scientists who measured the electron to have an up spin
and Earth↓ represents earth scientists who measured the down spin for their electron. So
far so good, nothing non-local has happened, only people on Earth are affected by the
measurement of the electron (they have become part of the superposition). A fraction of
a second later, the scientists at Proxima Centauri (4 light years away) measure their
position, and the resulting superposition becomes:
(Earth↑ × e↑ × p↓ × Proxima↓) + (Earth↓ ×e↓ × p↑ × Proxima↑)
So now the scientists at Proxima Centauri have become part of the superposition, having
measured both possible values. There is no need to enforce at speeds faster than light,
any kind of agreement with the measurement by the remote groups of scientists, since
both scientists measure both outcomes.
Now when the scientists at Proxima Centauri measure their positron's spin, and send the
result to Earth (to arrive 4 years later), the Earth scientists necessarily find that
the radio signal indicates a result that corresponds to their own measurement. This is
because the radio broadcast correlates with the measurement at Proxima Centauri, which
is correlated with the positron, which is correlated with the electron, which is
correlated with the measurement of the Earth scientists. Since they exist in distinct
states of the superposition, it is impossible for the Earth↑ scientists to hear from or
otherwise interact with the Proxima↑ scientists, the Earth↑ scientists can only hear the
radio broadcast that comes from the Proxima↓ scientists.
Thus, the EPR paradox is solved without hidden variables (which were defined as
extraneous properties not described by in quantum mechanical theory), and moreover, does
so without violating special relativity. This solution comes directly from the literal
reading of the Schrodinger equation. All the apparent paradoxes come from the assumption
that collapse is fundamental.
If you want collapse to be taken seriously, you must show evidence for it commensurate
with the evidence that exists for other concepts in physics, because if the Copenhagen
interpretation is true, then special relativity is false, locality is false,
time-reversibility is false, determinism is false, causality is false, quantum computers
are impossible, and observers are magical. This is a lot to give up for an
interpretation that is not well-defined (how and when observation triggers collapse and
even observation itself are not even defined), inconsistent in its treatment of multiple
observers, and shown by Everett to be entirely redundant given the Schrodinger equation.
Do you really think the Copenhagen interpretation is defensible given what we now know
today?
Jason
You keep assuming that every criticism of MWI is a defense of real collapse - it isn't. I
think a proper reading of Copenhagen is epistemic collapse; in any case that seems to be
the viable alternative.
Brent
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