Re: Quantum mystics

On 09/06/2024 21:08, john larkin wrote:

On Sun, 9 Jun 2024 20:46:53 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:
 

I just watched a talk by Anton Zeilinger, professor of physics
at the university of Vienna, and 2022 Nobel laureate, about
quantum effects and entanglement.

Link please? It is impossible to comment without seeing his talk.

>
I feel a rant bubbling up!

 Good so far!

It was true when I was an undergraduate and it is still just as true today that if you claim to fully understand quantum mechanics then you don't fully understand quantum mechanics.

The guy is a mystic, a fraud! He pretended to demonstrate that
light consists of particles by showing a little box that starts
clicking, like a Geiger counter, when exposed to light. Even if
the little box really did detect light, that means nothing! Light
*detection* is quantized, yes, but that does not imply that light
itself is so too.

 Light isn't packaged in discrete photons of measurable energy?

It is a bit more nuanced than that. You can certainly show from metal work functions that the energy they carry is quantised and also that for very low photon densities such that only one photon can be in the instrument at a time the diffraction pattern still occurs. That is pretty conclusive evidence that QM is a real phenomena.
Likewise you can get diffraction patterns from silver ions or buckyballs. I'm not sure what the current record mass is today.
We can haggle about mechanism and it is likely that a better theory will eventually come along that is much less "action at a distance" than the QM one we have now. In the same way that GR displaced Newtonian gravity.

Of course you can't say much about a thing that has never been
detected. It's just a rumor.

Everything that we observe has to be detected somehow.
It is possible for systematic errors to creep in. The speed of light with error bars as a function of time is a salutary lesson on that.

He attempted to convince the public that entanglement means that
the results of measurements made at two remote places come out
identically, and without any time delay. That's just not true,
but he didn't even give a hint of how this really works. He did
not mention that you have to make *correlated* measurements to
detect entanglement.

 Do people still say "duh" ?

The intensity interferometer Hanbury-Brown & Twiss was a canonical example of a QM prediction that almost no physicists believed at the time until they actually made it work at Jodrell Bank. Today they can do long(ish) baseline coherent optical interferometry up to the near IR.

For that, you need to communicate *what*
measurement is to be made at each location, and that implies
that you either prescribe the exact measurement in advance or
select a subset of the results after the fact. Either way, this
skews the data.

 Most measurements, and the measuring instruments, are defined in
advance of the event.  Calibrated even.

Life gets tricky in relativistic QM but you can still get around it by making the signals travel around loops and/or moving atomic clocks very slowly to each measurement point. 5km long optical fibres are relatively cheap...
"Simultaneous" is only well defined at a particular point in space-time.

He's in it for the money and the fame. Grrr. And he's one of
many, too.

 That's hardly usual, or a reason to call him wrong. He won the Nobel
Prize just to get free plane tickets.

I'm not quite sure what he has said that annoyed JB - usually any popular science programme for a general audience dumbs down quantum mechanics to a point where it is completely unrecognisable to professional physicists.
--
Martin Brown