What the hell does this mean?

[Rye]

link

An experimental test of non-local realism

"Most working scientists hold fast to the concept of 'realism'—a viewpoint according to which an external reality exists independent of observation. But quantum physics has shattered some of our cornerstone beliefs. According to Bell's theorem, any theory that is based on the joint assumption of realism and locality (meaning that local events cannot be affected by actions in space-like separated regions) is at variance with certain quantum predictions. Experiments with entangled pairs of particles have amply confirmed these quantum predictions, thus rendering local realistic theories untenable. Maintaining realism as a fundamental concept would therefore necessitate the introduction of 'spooky' actions that defy locality. Here we show by both theory and experiment that a broad and rather reasonable class of such non-local realistic theories is incompatible with experimentally observable quantum correlations. In the experiment, we measure previously untested correlations between two entangled photons, and show that these correlations violate an inequality proposed by Leggett for non-local realistic theories. Our result suggests that giving up the concept of locality is not sufficient to be consistent with quantum experiments, unless certain intuitive features of realism are abandoned."

[dragon]

Hum I think I get what their trying to say but theres no way in hell I can express it my language skill sucks.

[Twoyboy]

Quantum entanglement allows "communication" between subatomic particles which appears to be faster than light - in fact instantaneous. If you believe in realism - that what we observe actually exists and is not just one mass hallucination and locality - that things are separated by space, then this shouldn't be possible.

I don't think we have to ditch these concpets, but there's something going on that we need someone whose better a physics than me to explain.

Did that help?

[Mobiboros]

Quantum entanglement allows "communication" between subatomic particles which appears to be faster than light - in fact instantaneous. If you believe in realism - that what we observe actually exists and is not just one mass hallucination and locality - that things are separated by space, then this shouldn't be possible.

I don't think we have to ditch these concpets, but there's something going on that we need someone whose better a physics than me to explain.

Did that help?

I'm far from a physics/math guy but from the reading (and to add to the above) it seems like the group of scientists is trying to scale up quantum events to justify their belief that reality is just a factor of our observation and doens't exist objectively.

[OmegaGuy]

I thought quantum entanglement doesn't allow FTL communication

[Surlethe]

Realism is the idea that an objective reality exists outside of observation. Locality seems to be the idea that an event can't be influenced by events outside of its light cone -- i.e., if light can't travel between two events, then nothing can. I don't know that the negation of realism is essentially mass hallucination or solipsism, but the abstract seems to be claiming that locality certainly contradicts observation and so do some tenets of realism.

As for objective reality outside of observation, we've known for over a century that characteristics of the observer do determine some observations. Take relativity as a prime example: given an object, the relative velocity of the observer affects the observed mass, length, time, etc., of the object.

[metavac]

Quantum entanglement allows "communication" between subatomic particles which appears to be faster than light - in fact instantaneous. If you believe in realism - that what we observe actually exists and is not just one mass hallucination and locality - that things are separated by space, then this shouldn't be possible.

I don't think we have to ditch these concpets, but there's something going on that we need someone whose better a physics than me to explain.

Did that help?

This paper is also available on Arxiv. Basically, Groblacher et. al. are reiterating Bell's theorem that rules out joint local (influences propagate along timelike paths) and realistic (measurements depend on previous states of observables) and pointing out that realism itself, at least in a class of reasonable theories, is incompatible with quantum mechanical theory and experiment. Bell's theorem is agnostic about what choices you make provided that you don't try and adhere to both locality and realism, Groblacher is one of several scientists trying to find further inequalities that may favor one or the other or neither as a means of weighing different interpretations of quantum mechanics.

[metavac]

Realism is the idea that an objective reality exists outside of observation.

That's a epistemological definition, one which while driving the physical interpretation may in fact capture a bit too much intuition in its expression. On one level this paper is challenging the intuitive baggage that comes with the term realism by providing experimental evidence ruling out reasonable non-local theories that feature it.

I don't know that the negation of realism is essentially mass hallucination or solipsism, but the abstract seems to be claiming that locality certainly contradicts observation and so do some tenets of realism.

That's exactly what it's saying. To be as mundane as possible about it, Groblacher et. al. argues that at the very least the notion of definitive state independent of measurement is in question. IIUIC, this notion is compatible with interpretations of QM that treat the wavefunction rather than the observable as real.

[Zixinus]

Excuse me for my ignorance, but these experiments are dealing with things on the quantum scale, not larger, thus these findings only apply to things that are at quantum scale. Right?

[Darth Wong]

Excuse me for my ignorance, but these experiments are dealing with things on the quantum scale, not larger, thus these findings only apply to things that are at quantum scale. Right?

Yes. Religious people often interpret QM to mean that we basically create reality in our minds, which is (to say the least) an overenthusiastic interpretation of the concept. A tree exists independently of your observation of it.

[Astarial]

Excuse me for my ignorance, but these experiments are dealing with things on the quantum scale, not larger, thus these findings only apply to things that are at quantum scale. Right?

Yes. Religious people often interpret QM to mean that we basically create reality in our minds, which is (to say the least) an overenthusiastic interpretation of the concept. A tree exists independently of your observation of it.

Why are religious people specifically prone to interpreting QM that way? Wouldn't a reality that exists only in your mind deny the existence of an omnipotent god?

[Zixinus]

Why are religious people specifically prone to interpreting QM that way?

I'd guess for them to have a bit more honest validity to the claim "look, science says God exists!".

[Dooey Jo]

Excuse me for my ignorance, but these experiments are dealing with things on the quantum scale, not larger, thus these findings only apply to things that are at quantum scale. Right?

Yes. Religious people often interpret QM to mean that we basically create reality in our minds, which is (to say the least) an overenthusiastic interpretation of the concept. A tree exists independently of your observation of it.

Why are religious people specifically prone to interpreting QM that way? Wouldn't a reality that exists only in your mind deny the existence of an omnipotent god?

I take it you have never met the New Agers. Or the theosophers. Some would say things like "woo Copenhagen interpretation reality is in our minds woo, therefore we are all one with God woo woo, touch my harmonical quantum wave crystal which surely is not quartz and feel cosmic joy wee" (shortened version of the 12-page rambling an actual New Ager would give, but I tried to stay true to the level of nonsense).

More traditional fundies can also take a liking to quantum mechanics, though in their minds it's everyone else's reality that doesn't exist, or God is the only thing that exists, and things like that. They only bother reading about the things they can twist into confirming their own ideas, of course.

[Darth Servo]

Wouldn't a reality that exists only in your mind deny the existence of an omnipotent god?

No because its the omnipotent god thats showing them the film.

[The Duchess of Zeon]

It would be correct to say that our minds interpret what they see in ways which are not necessarily representative of the actual, perfect representation of what we're seeing, but that is a fundamental result of the fact that any measuring instrument has error in it.

[Elaro]

Wait... Quantum mechanics has to do with the quanta, a.k.a. the photon, which is energy, right? So the article is essentially saying that realism and locality don't apply to quantas. So realism and locality don't apply to energy. But the article doesn't say anything about mass.

So, this guy isn't trying to disprove the notion that matter/mass doesn't objectively exist, but rather the notion that energy objectively exist.

I think.


Did I understand correctly? Keeping in mind I'm a pre-university student?

[Alerik the Fortunate]

The funny thing about religious/new age enthusiasts of perception molding reality, is that they ignore the fact that transformations between reference frames are governed by rules that apply the same to everyone. Plus, it seems that they take it from the universe appears different to people in different situations, to the universe is whatever you believe it to be, as though your will determined reality. Why did that photon hit that particular point on the photo plate? Why, because I wanted it to! If only we could just focus our will enough the world would become a paradise of paradox, where every desire was satisfied and contradictions mean nothing!

[metavac]

Wait... Quantum mechanics has to do with the quanta, a.k.a. the photon, which is energy, right? So the article is essentially saying that realism and locality don't apply to quantas. So realism and locality don't apply to energy. But the article doesn't say anything about mass.

One, QM deals with a great deal more than photons or other gauge bosons (the mediators of interactions like EM, strong, and weak). Two, QM is a stochastic theory, like statistical mechanics only concerned fundamentally with discrete quanta rather than ensembles. The article expands on an already theoretically and experimentally well-established observation that quantum mechanical theories that presume that actions are defined locally cannot assume that the wavefunction describing the probable states of an observable (position, momentum, energy, etc.) is a physical object and visa versa--a notion quantified in the Bell's inequalities. Specifically, Groblacher et. al. derive and test additional inequalities that show certain classes of non-local theories that treat the wave function as a physical object are inconsistent with QM predictions and observations. The significance is that we now have a way to weigh interpretations of QM that assume non-local realism.

There's also another assumption at play here, the idea that the wavefunction always yields a single result--regardless of whether a measurement has actually taken place. The many-worlds interpretation saves local realism from Bell's inequalities by getting rid of this notion of counterfactual definiteness and assuming that all states of the wave function occur and that we only perceive one in our reality/universe/whatever.

[Twoyboy]

Yes. Religious people often interpret QM to mean that we basically create reality in our minds, which is (to say the least) an overenthusiastic interpretation of the concept. A tree exists independently of your observation of it.

When we all know that in reality the results of QM experiments have been altered by the FSM's noodly appendage.