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.....
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?
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!
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. 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. 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.
Bruce
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