On 11/12/2017 10:30 pm, smitra wrote:
On 11-12-2017 03:08, Bruce Kellett wrote:
On 11/12/2017 12:21 pm, smitra wrote:
On 11-12-2017 00:55, Bruce Kellett wrote:
What you have to do if you want to claim that all chance outcomes are
of quantum origin is compare the relative magnitudes of quantum and
thermal fluctuations at room temperature -- room temperature because
that is where we do the experiments. And you haven't done that;
neither has Albrecht in the paper you reference. That is why his paper
is a load of nonsense.
Thermal fluctuations do not need to be eliminated, as they are of
pure quantum mechanical origin. However, if one has to argue about
that then one loses the point of the proposed experiment. At
absolute zero the thermal fluctuations are due to zero point motion,
take e.g. the harmonic oscillator which then has an energy of 1/2
hbar omega.
In generic non-integrable systems you'll have chaotic behavior where
small perturbations grow exponentially.
Not necessarily. It depends on the relevant Lyapunov exponents. The
mean speed of molecules in a gas does not grow exponentially.
Typically the exponents are positive, there is a vast literature on
this subject with some exactly solved cases, e.g. oddly shaped
billiard balls.
Thermal fluctuations will then originate from quantum fluctuations.
Why then are thermal fluctuations temperature dependent? But be that
as it may, thermal fluctuations, and the random motions of molecules
in a gas, say, are not coherent, and there are no interference effects
between the molecules of a gas. Consequently, whatever their origin,
the motion is manifestly classical at room temperature.
Interference is a straw man. It's totally irrelevant whether or not
some particular quantum aspects shows up in an experiment. Thing is
that classical mechanics has already been falsified experimentally, so
it's wrong to invoke a classical picture of what's going as a
fundamental truth and put the burden of proof each time on a QM
picture when it's not readily visible.
That is completely wrong-headed. Classical physics is perfectly good for
everyday situations, and for putting a probe in orbit around Saturn. All
the calculations of trajectories are done classically -- general
relativity is completely irrelevant for the orbit of Saturn -- GR
effects are barely detectable for the orbit of Mercury!
There is a philosophical point that any theory that has been shown not
to apply universally, has technically been falsified. But most
philosophers acknowledge that classical theories have not been falsified
in their appropriate realms of applicability. So you merely obfuscate by
claiming that we cannot use classical physics in those situations,
merely because the theory does not apply in other situations.
QM + decoherence only allows you to use classical reasoning to compute
macroscopic observables with negligible errors, but this does not
means that the macroscopic physical world is classical. It's just like
the fact that GR reduces to classical mechanics, as far as the results
of computations are concerned, but GR is still correct and the
classical picture is still wrong no matter how weak the gravitational
fields are.
As I have said before, the biggest challenge for quantum physics is to
explain the emergence of the classical world from the quantum substrate,
so that classical calculations actually get the correct answers in those
classical situations. If you do not believe that these classical
calculations are correct, then I advise you not ever to drive your car
on a busy road.....
Bruce
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