A quantum experiment suggests there’s no such thing as objective reality | Hacker News Reader

A quantum experiment suggests there’s no such thing as objective reality

technologyreview.com

55 pointshansoolo17 comments

This seems like another case where the alternate of "...or simply use the DeBroglie Bohm interpretation and most of the mysticism of this goes away."

I'm not remotely an expert in this, but non-locality always seems like the "simpliest" explanation. Like two boat floating on a lake, things you do in your boat that create waves can affect me in my boat even though our boats never touch.

The world around us has a similar lake surface which explains all of this without giving up objective reality.

Every QM article I read, I try to repicture using DeBroglie Bohm and it always gives an easier to grasp, although less sensational explanation.

It surprises me it's never presented.

The article explicitly states that non-locality could explain it:

>But Proietti and co’s result suggests that objective reality does not exist. In other words, the experiment suggests that one or more of the assumptions — the idea that there is a reality we can agree on, the idea that we have freedom of choice, or the idea of locality — must be wrong.

I personally think that the idea that we have freedom of choice is the incorrect one.

I believe our idea of free will is an illusion created by how our mind works. Instead, our decisions come from totally predictable processes and we hallucinate the choice afterwards.

I'm going to go out on a limb and guess that, of the possibilities, "reality we can agree on" is the least likely to be wrong.

I agree. I'm in the non-locality camp myself.

How are you interpreting this experiment with DeBroglie-Bohm? This is bumping up into the area where the theory gets into trouble, as photons aren't described by the Schrodinger equation or Dirac equation, and don't have wave functions at all. However in interferometry you might talk about the wave function of a photon if it is not emitted or absorbed.

Re: Locality. The issue is not nearly as simple as you are making it out to be. You are not allowed to naively dispense with locality because locality, described quantitatively by Lorentz invariance, is one of the most well tested physical principles in the history of science. You don't get to ignore observations to conform to your philosophical biases regarding interpretations of your theories.

The principles of special relativity and quantum mechanics are combined in quantum field theory, which is the most accurate and well tested description of the world we currently have. Non-relativistic Quantum Mechanics (where debroglie bohm is nice and simple) is a (0+1) dimensional quantum field theory, whereas our universe is described by (3+1) dimensional quantum field theories like quantum electrodynamics or the standard model. To dispense with locality in a non-naive way requires extending the theory to this more complicated setting, which is an unsolved problem, and an active are of research. According to the wikipedia page, even developing a complete theory of the photon is an active area of research! Whereas developing QED the first time around only took a handful of people 15 years...and they didn't know what the answer was going to turn out to be! I think we can conclude from this that the theory is no longer so simple and easy to grasp.

https://www.scottaaronson.com/blog/?p=3975

Here's Scott Aaronson arguing that the theoretical work underpinning this experiment is flawed.

"There's no such thing as objective reality".

We did an experiment to prove it, so it must be objectively true!

In other news:

"This sentence is false".

You are confusing two different ontological domains. The key word is "objective" not "reality". The experiment, regardless of the interpretation, does not deny the existence of reality.

Not sure what I'm missing here. "superposition" is more of an explanation of not knowing the result of a measurement until it is measured. So saying that one person performing the measurement and not telling someone else what is was, so that person sees it as in the "superposition" state vs. the measured state is not two conflicting realities. One person just has access to different facts.

If I witnessed a murder and withheld that information, and someone else thinks the person committed suicide based on the evidence they have, we aren't living in two different realities.

I assume this is true for observation of a single quantum particle, but on macro scale statistically speaking everyone observes essentially the same

I really wonder how it is possible to have different realities at the quantum level that -- seemingly -- converge at a single shared reality at the macro level.

We were able to deal with time and space being relative, we can deal with superposition being relative. It was kind of obvious anyway, since superposition can affect non-elementary particles as well.

So all this experiment is saying is that wavefunction collapse is observer-dependent and not a global property. It's hard to comprehend that the superposition state exists after the other group makes their measurement and says they've done so. When the wavefunction collapses for the second group, it still has to agree with the first right? So how could the superposition state continued to have existed when only one outcome was possible?

Because the second group is still in superposition relative to the first. It's kind of exactly like the schrödinger's cat, where the cat is in the same position as the second group.

>Wigner then performs an interference measurement to determine if the measurement and the photon are in a superposition.

Could anyone explain this interference measurement? Thanks.

“Accepting the photons’ status as observers”, says the paper.

In other words, this is just another experiment confirming QM predictions.

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