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The linked article is titled "Experiment confirms quantum theory weirdness". Please don't exaggerate the title. These experiments do not show that "reality doesn't exist until it's measured".

First, "realism" [1] is not the same thing as "reality". "Realism" basically means "physical quantities have a definite value". "Reality" is that thing that determines your experimental outcomes. Don't mix them up.

Second, interpretations of quantum mechanics disagree wildly about what kind of weird you use to explain things. Some interpretations have "realism", some don't. Some interpretations have retrocausality, some don't. Some interpretations have FTL effects, some don't. Since all the interpretations give (mostly) the same experimental predictions, it's misleading to single one out and say just that particular brand of weirdness was confirmed.

We confirmed that there's weird there. We didn't distinguish what brand of weird it is. Physicists widely disagree about which brand of weird to use, with no position achieving even a majority [2]. The original title was better.

1: https://en.wikipedia.org/wiki/Na%C3%AFve_realism#Realism_and...

2: http://www.preposterousuniverse.com/blog/2013/01/17/the-most...

A standard case of mixing (or actually confusing) epistemology with ontology. That is to say that something doesn't exist until we get to know something about it. Or, by all means, knowing something about something is posterior to us being here AND that something being there. Here lies the danger of dismissing philosophy as a bag of words when compared with the Holy Science that works, bitches.
I don't think the title is a misrepresentation of the article, just the physics:

From the article: "It proves that measurement is everything. At the quantum level, reality does not exist if you are not looking at it..."

The article does appear to be (incorrectly) arguing that this experiment proves one interpretation of QM correct. It's definitely incorrect - some years back myself and others used non-experimentalist interpretations of QM to get the same result - but it's not a misrepresentation of the article.

To be fair, the submitted title is directly culled from the first sentence of the article:

> The bizarre nature of reality as laid out by quantum theory has survived another test, with scientists performing a famous experiment and proving that reality does not exist until it is measured.

And perhaps someday we'll get to meet the great programmer in the sky the developed the simulation we are living in and we will ask him why he designed it that way and he will say something like "oh I just wanted to optimize the code so I simply excluded reality subroutines when there were no beings looking. I just never thought you guys would notice. As soon as I saw that you guys noticed the flaw, I was going to load a patch but then the confusion it was causing with the simulated beings became interesting and so I just left it in as an accidental feature of the game." Meh, but probably not.
I always find it fascinating at just how much of our fundamental physics ends up being constraints on information movement. The laws of thermodynamics are about entropy, general relativity puts constraints on the movement of information (for example, Spooky Action as a Distance(tm) is faster than light, but you can't transmit information with it), the Uncertainty Principle puts limits on how much information you can have on a given system.

Information information everywhere you look in fundamental physics. It does make me wonder why.

In other words, reality is lazily evaluated and is written in Haskell ?
That would quite possibly be the worst optimization ever.

"Yeah, I could have tracked and updated n values pretty cheaply, but instead I decided to exponentiate an exponentially huge matrix and use that to update a vector containing 2^n complex numbers associated with the possible assignments of the original n bits. Also, you should use bogosort. It's the best."

Off to be the Wizard by Scott Meyer is a very funny fiction book that is based on the concept of reality being a computer program that hackers can manually manipulate to do cool stuff. It mostly occurs in King Arthur's Court, which happens to be the chosen time and place all these hackers wind up.
Reality frustrum culling?
Surely, "As soon as I saw that you guys noticed the flaw, it became part of the ABI and had to be maintained."
I'm not familiar with this particular experiment, but all my pondering on the subject - as a layman - leads me to a simple conclusion.

The properties these experiments are measuring are simply bogus. They are not well defined. The answer that comes out is not some intrinsic property of the "particle", but the result of the environment in which the particle interacted with the "measurement" system, so to speak.

The particle has some other properties, but what's being "measured" is not one of those properties.

How can I explain?

Imagine someone who has never tried any Korean food, and you try to ask him/her: what's your favorite Korean food? There's no answer. So you try to "measure" it by feeding him some Korean items and recording his facial expressions. He will like some items more than others, but it has nothing to do with "his favorite Korean food", and has more to do with how the items were prepared and his mood at the time.

A "point" location for a photon is never defined; it's not a property of a photon that it exists in a point in space. When you fire a photon at a "wall" and see a "blip", you're not seeing the position of the photon at some point in time. You're seeing the rough position of the atom that had an electron that absorbed the photon's energy, and I'm not even sure the atom has a well defined point position either. The whole thing is an artifact (a side effect) of some interaction between several systems and doesn't really tell you anything fundamental about the photon (or the quantum object).

At least that's how I understand it.

This is of course extremely interesting and probably important for understanding our universe—but how is it helping anyone to say something like, "...with scientists performing a famous experiment and proving that reality does not exist until it is measured." The statement is like a distraction at a magic show, drawing the reader to the glittery 'reality' and 'exist,' which are totally undefined so the reader's imagination can rove without limit.

Maybe this is really just a fundamental challenge to our assumptions about motion of particles or information transfer in the universe. Isn't that interesting enough without these vague, human aggrandizing assertions about creating reality?

The press around this experiment uses misleading language that leads people like Deepak Chopra to think that we create reality through consciousness. It has nothing to do with consciousness. This article explains it:

http://theness.com/neurologicablog/index.php/more-quantum-we...

John Wheeler's delayed choice thought experiment was already confirmed in the lab over ten years ago. It's neat that they were able to get results with baryonic matter, and it was definitely worthwhile to try to do that, but this article seems to be implying that the results could have been anything else than what they were, or that there is new physics here, and is wrong on both counts.

Also the deference to the Copenhagen interpretation is annoying - it's wrong. What they've observed is a consequence of how decoherence works, and 'observation' has nothing to do with it. Not faulting the researchers on this but seriously, it's time to stop talking about mythical 'observation' as though it's some integral part of quantum theory.

http://www.simulation-argument.com/simulation.html says: at least one of the following propositions is true: (1) the human species is very likely to go extinct before reaching a “posthuman” stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation. It follows that the belief that there is a significant chance that we will one day become posthumans who run ancestor-simulations is false, unless we are currently living in a simulation. A number of other consequences of this result are also discussed.

COMPUTER SIMULATION vs HOLOGRAPHIC UNIVERSE

http://www.crystalinks.com/holographic.html http://thelaymansanswerstoeverything.com/2013/01/scientific-...

What does it mean to exist? A thing exists specifically when it affects something else. What is measurement? It's a reciprocal affecting.

So does a thing which is not affecting anything else and not being measured exist? No! QED

Clever optimization by our simulators, Big up
I find it fascinating how the speed of light, quantum indeterminacy and Planck's length could all be seen as allegories for computational optimisations in a simulated universe.

This is something that I've thought about for some time, I posted a question about this a number of years ago on Reddit: http://www.reddit.com/r/Physics/comments/g287k/quantum_indet...

If I'm standing here, all the stuff that the atoms in my body could conceivably interact with have to be backfilled for me to interact with them according to this experiment, but since I'm not special to the universe, atoms three billion light years over, they are still interacting with each other, just not with me. So am I decohered to them? Is this like a divergent timelines theory such that coherence is defined as when different possibilities converge while following possibilities, reducing them and then so must necessarily collapse as other possibilities drop off? So what's the difference between cohered and decohered reality then? It sounds then like it would just be one of those paths, the one that we happen to be on that we only notice because we're conscious so that's our arbitrary (to the universe) observation point. That's the only way I can make sense out of this without attaching significance to human observation.
Let us not forget about Pilot-Wave theory, where it has both particle and wave-like properties simultaneously. In fact, I don't quite get why people are so enamored by these fanciful interpretations when Pilot-Wave is so much more down-to-earth.
Just remember that in quantum physics, any interaction between two particles is a measurement.
Observation does not exist until observed, experiment finds.
We know that light bends near a gravitational field with a big gradient before it is "measured".

Sounds like that light existed and generated and responded to a gravitational field after it was emitted and before it was detected or measured.

armchair musings of a layperson physicist/philosopher follow:

the non-interference pattern is the optimized result of a deterministic universe that requires the observation to occur. The measurement didn't reach back in time, the results were specifically determined by the same causal chain that determined an experiment would be performed.

I always found the notion that "If you measure it, it behaves differently" to be really confusing. When considering the double slit experiment - In both cases (whether we are observing the particle going through a single slit or otherwise observing the interference pattern left afterwards), we are in fact simply measuring 'observable effects' in both cases - It's just that we are measuring them in different ways.

If you didn't measure both cases, you wouldn't be able to compare their outcomes. It seems that it is not about whether or not the event was measured/observed but about HOW and WHEN it was measured.

In neither case do we actually 'witness it happen' - In both cases, we are just observing effects of those events.

The light which allowed us to 'directly observe it' is as much a byproduct of the actual event as the interference pattern left behind on the surface.

> "At the quantum level, reality does not exist if you are not looking at it"

So much physics reporting mistakes science for philosophy. It leads to so much confusion among laypeople.

In the time of Empiricism, the philosophers George Berkeley and John Locke proposed something similar. I believe it was called it immaterialism, or the idea that nothing exists without being perceived. Berkeley went further saying that objects only exist in the mind, or something like that.
"If one chooses to believe that the atom really did take a particular path or paths then one has to accept that a future measurement is affecting the atom's past, said Truscott."

Is that equivalent to "reality doesn't exist until it is measured"? Because I don't see the latter claim (which is the headline on HN) anywhere in the text?

Also, didn't Feynman explain in q.e.d. that it's not either a wave or a particle, it's always a particle and the probabilities for the path the particle takes behave like waves? (Something like that, I am foggy on the details).

The jokes above that say that this was done by our simulators to save on computation are amusing but wrong. Quantum computation is famously harder than classical computation.
So, the Sun doesn't exist when experimenter is unconscious? I see.

It seems like at least Philosophy 101 should be mandatory to quantum physicists.)

Reality doesn't depend on an observer (who distorts it by his observation). Reality just is.

There are light and other temporary states of what we call "energy". That's it. Time, space, relativity are human concepts - the hard-wired modes of perception which conditions our experience. From a Photon's perspective none of these exist.

Reality is just a giant whirling layer of infinite View Master-like multidimensional slides, overlaid one upon the other. Every slide locks into place to be seen as we are looking in whichever direction, at whatever time. I'd wager time travel is never discovered by humanity, but that some sort of time or dimensional goggles are created, eventually.

Essentially, we're all watching our own multi-dimensional, multilayer, composite TV channels and seeing shadows of each other across our screens. Allegory of the Cave meets 3D Ray Tracing and such.

That's nothing, though. Not compared to the realization that every face is a mirror, and we're all stuck here until we can treat each other as ourselves.

Maybe it's not true, maybe it's insane ramblings. But it does explain the crazy doods muttering to themselves on the corner and those people in your life who "just aren't watching the same channel as the rest of us."

Like me!

Guys I'm a total quantum physics noob but when I read this post I couldn't help but think of Alan Watts and the Taoist definition of the theory of time (quoted below). HN in your opinion how does this theory hold up to the to new finding (if at all)?

Big thanks to anyone taking the time to humour me, I really appreciate your time.

'So when you have this happening the other illusion that a Westerner is liable to have is that it's determined in the sense that what is happening now follows necessarily from what happened in the past. But you don't know anything about that in your primal ignorance. Cause and effect? Why, obviously not! Ha ha ha! Because if you're really na•ve you see that the past is the result of what's happening now. It goes backwards into the past like a wake goes backwards from a ship.'

The Many Worlds Interpretation explains all of this quite intuitively http://lesswrong.com/lw/r8/and_the_winner_is_manyworlds/
For me the only way I can make wave-particle duality and associated observations believable is to think that light and similar entities always travel as a wave, but sometimes interact like particles.

This understanding is in line with this experiment without believing that future affects the past. It's just that atom is never a particle until it reaches detector at the end. Only there it displays ability to exchange momentum with one other single atom as if two billiard balls hit. Throughout the whole experiment it travels as a wave, both paths, grating or no grating. It just either interferes if there was second grating or not if there was no second grating.

Quantum Bayesianism [0] treats such effects explicitely as Bayesian belief updates of the experimenter. This leads to an interpretation of quantum mechanics free of such paradoxical/counterintuitive statements about reality. I'd like to hear other physicists' opinions on minority interpretations like this.

[0] layman-friendly article / interview: https://www.quantamagazine.org/20150604-quantum-bayesianism-...

If you could change how you measure it, could you change your reality?
But , who was measuring before the big bang , and the millions of year before we appear ? what is so special about measurement? I thought that our brain was merely a quantum computer ?
So that's why kids cover their eyes when they want to hide.
QM explained by a software engineer:

https://m.youtube.com/watch?v=dEaecUuEqfc

Or, maybe, Everett was right.
How can you measure what doesn't exist?
For us, Reality by definition, is what we perceive. Our mind/brain/consciousness interprets the perceptions, draws conclusions makes up reality by interfacing an Electromagnetic medium. When trying to explain Popular Quantum Physics, one should avoid using the word Reality loosely.
What does this mean? If there was a supernova eons ago in another galaxy and I'm the only human who had been hit by a cosmic ray, does that mean it didn't exist or happen until ... ?

Does measurement have to include an agent? Could measurement mean interaction with other atoms?

Is it not possible that it could have been observed no other way? Is observation driving the behaviour or behaviour driving the observation(or an external factor driving both)?
Deepak Chopra is going to have a field day with this one.
Most of these articles / experiments focus on the perspective of being the observer...

What is the conclusion if you are the thing being observed?