
Loopholes and the 'Anti-Realism' of the Quantum World - jonbaer
https://www.wired.com/story/quantum-world-anti-realism/
======
lisper
> The photon, in other words, has definite reality at the beginning and end.

That's not true. In a low-flux time-delay interferometer you cannot assign a
definite emission time to a detected photon.

[http://blog.rongarret.info/2018/05/a-quantum-mechanics-
puzzl...](http://blog.rongarret.info/2018/05/a-quantum-mechanics-puzzle.html)

[http://blog.rongarret.info/2018/05/a-quantum-mechanics-
puzzl...](http://blog.rongarret.info/2018/05/a-quantum-mechanics-puzzle-part-
deux.html)

[http://blog.rongarret.info/2018/05/a-quantum-mechanics-
puzzl...](http://blog.rongarret.info/2018/05/a-quantum-mechanics-puzzle-part-
drei.html)

~~~
asterismic
Serious question: Doesn't it seem to be a deep and cutting flaw, that an
entire branch of physics attempts to draw conclusions about subatomic behavior
based on the macroscopic interference noted when photons pass through
polarized sunglasses, or perhaps electrons travel through the diffraction
grating of a cathode ray tube?

It seems fundamentally incorrect to show hobbyists and laymen these partial
examples, and then cross ones arms and say " _that 's the way it is_" and
venture no further.

Polarization experiments and the double slit experiment are continually hauled
out onto the stage, again and again, and never enlighten anyone. Taking a
relativistic particle, and shooting it through or bouncing it off of a
standing wall of atoms (e.g. polarization filters and diffraction gratings),
doesn't really introduce an air of mystery into anything, because the wall of
atoms operates its own subatomic state, which is selectively ignored. It's
basically like setting a murder mystery inside a super max prison.

~~~
kakarot
I think a lot of these scientists would rather focus on solving these
theoretical problems than trying to explain to random laypeople the nuances of
quantum physics.

I've spent hundreds of hours studying particle and quantum physics and I still
have a multitude of unanswered questions because there is a certain
mathematical wall you hit where real-world experiments that could be explained
to regular folk are simply not useful as models, and until I master those
mathematics, it doesn't matter how long a particle physicist tries to explain
things to me.. I won't get it.

EDIT: If you're interested in other kinds of experiments I would check out the
work being done with Quark–gluon plasma, specifically with lattice structures
that cause quantum perturbations to scale to a macro level where we can
perform experiments and get some pretty cool results.

The general idea is creating a state of extreme entanglement by homogenizing
as many properties between the particles in the lattice as possible. This,
combined with an near absolute-zero temperature and a lattice so flat it could
be considered two-dimensional, means that the entropy in the system is low
enough that you can watch small-scale perturbations bubble up unimpeded by
surrounding entropy.

Further reading:
[https://arxiv.org/pdf/1611.01533.pdf](https://arxiv.org/pdf/1611.01533.pdf)

------
brianfitz
TL;DR: There was a loophole found in an older thought experiment that
indicated that at the quantum level, nothing is real until it is observed.

A discovery was recently made that found a way to add an unknown variable into
the mix such that an expiriment where the future seems to affect the past was
possibly explained away by a classical model.

However, a new experiment was proposed to show whether the new classical model
actually was the explanation — and it turns out this classical “loophole” can
not explain it.

So we’re now back to the beginning where it once again appears that nothing is
real until observed at a quantum level which is also referred to as “anti-
realism”.

~~~
Diggsey
Pretty sure local hidden variable theories were ruled out as an explanation of
quantum mechanics a long time ago. What's new here?

~~~
21
Wikipedia says that this is the conclusion of Wheeler's experiment:

> _Any explanation of what goes on in a specific individual observation of one
> photon has to take into account the whole experimental apparatus of the
> complete quantum state consisting of both photons, and it can only make
> sense after all information concerning complementary variables has been
> recorded. Our results demonstrate that the viewpoint that the system photon
> behaves either definitely as a wave or definitely as a particle would
> require faster-than-light communication. Because this would be in strong
> tension with the special theory of relativity, we believe that such a
> viewpoint should be given up entirely._

~~~
Diggsey
Local hidden variable theories were disproved by violations of Bell's
inequality, not by a thought experiment.

[https://en.wikipedia.org/wiki/Bell_test_experiments](https://en.wikipedia.org/wiki/Bell_test_experiments)

Are you saying that all of these experiments were flawed in some way?

~~~
21
No, I'm saying that the Wheeler experiment seems to be more concerned with the
wave/particle duality, not with the hidden variables.

And as this article shows, the Wheeler experiments are not thought
experiments, they are very real ones.

~~~
brianfitz
Wheeler’s delayed choice excitement is referred to as a thought expirement
both by the physicists in the article as well as the first line in its
Wikipedia entry. Like Einstein, he worked through many thought excitements
that suggested an outcome, but couldn’t be tested at the time. However, many
of Einstein’s proposed experiments that have since been observed are still
referred to as his thought expiriments.

We may be saying the same thing, but worth making the distinction.

For the other poster (diggsey), it will be difficult to answer your question
about the novelty of these newly run expiriments without a full read of the
article.

