On 09 Dec 2017, at 00:03, Bruce Kellett wrote:
On 9/12/2017 4:21 am, Bruno Marchal wrote:
On 08 Dec 2017, at 00:22, Bruce Kellett wrote:
On 8/12/2017 3:31 am, Bruno Marchal wrote:
On 06 Dec 2017, at 12:19, Bruce Kellett wrote:
But as I pointed out, thermal motion gives momenta of magnitudes
such that the quantum uncertainties are negligible compared to
the thermal randomness. And thermal motions are not coherent.
You seem to work in Bohr QM, with some dualism between the
quantum reality and the classical reality.
Not at all. The (semi-)classical world emerges from the quantum
substrate; if you cannot give an account of this, then you have
failed to explain our everyday experience. And explaining that
experience is the purpose of physics.
No problem with this, except for your usual skepticism of Everett's
program (say).
Skepticism is the scientific stance.....
Sure. But then you need to be skeptical on "n universes" to, whatever
n is (0, 1, ..., omega, ... aleph_one, ...).
You are right that this does not change anything FAPP, but our
discussion is not about practical applications, but metaphysics.
No, we were talking about tossing a coin, we were not talking
about metaphysics. Your metaphysics has served merely to confuse
you to the extent that you do not understand even the simplest
physics.
That is ad hominem remark which I take as absence of argument.
You don't take kindly to criticism, do you Bruno?
I appreciate criticism of idea and argument, not of person, which move
I take indeed as a sign of losing an argument.
All I said is that without collapse, shaking a box with some coin
long enough would lead to the superposition of the two coin state.
You seem to be the one confusing the local decoherence with some
collapse. The Heisenberg uncertainties are great enough to amplify
slight change of the move of the coin when bouncing on the wall.
That is simply assertion on your part, without a shred of argument
or justification. When one looks at the arguments, such as that put
forward by Albrecht and David (referred to by smitra), one finds
that the emperor has no clothes!
I don't see this. You might elaborate.
Similarly, a shroedinger car, once alive + dead, will never become
a pure alive, or dead cat. It will only seems so for anyone looking
at the cat, in the {alive, dead} base/apparatus. Superposition
never disappear, and a coin moree or less with a precise position,
is always a superposition of a coin with more or less precise
momenta. The relation is given by the Fourier transforms, which
gives the relative accessible states/worlds.
I pointed out that for a macroscopic object such as a coin, the
uncertainty relations give uncertainties in positions and/or
momentum far below any level of possible detection.
Of possible practical detection. That is good FAPP, but irrelevant for
theoretical consideration.
And I gave an argument with an actual calculation -- not just an
assertion. Uncertainties in the constituents of the object are
uncorrelated, random, and cancel out.
Once the coin meet just one molecule, that molecule is entangled with
the coin, and that spread quickly to all molecules. At no point get we
a reduction, as we asssume SWE without reduction, and tiny change get
locally amplified. If that was impossible, measurement would not exist.
So although the superposition originating from the big bang is
intact from the bird's point of view, it is so completely irrelevant
for everyday purposes that it is an insult to even refer to the
classicality of the world as FAPP -- it is complete. Relying on the
charge of "FAPP" as a justification for your assertions is nonsense.
That seems to me being non-sense. You can't deduce something in the
theory from the fact that in practice we nullify some terms, when the
theory explains they cannot be null.
Bruno
Bruce
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