Quantum Physics Parts Ways With Reality 568
aeoneal sends us to PhysicsWeb for news guaranteed to induce headache in those wedded to the reality of, well, reality. Researchers from the University of Vienna have shown the violation of a stronger form of Bell's inequality known as Leggett's inequality. The result means that we must not only give up Einstein's hope of "no spooky action at a distance," we must also give up (some of) the idea that the world exists when we are not looking. From the article: "[Studies] have ruled out all hidden-variables theories based on joint assumptions of realism, meaning that reality exists when we are not observing it; and locality, meaning that separated events cannot influence one another instantaneously. But a violation of Bell's inequality does not tell specifically which assumption — realism, locality, or both — is discordant with quantum mechanics." From the Nature abstract: "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." Only subscribers to Nature, alas, can know what features those are, as PhysicsWeb doesn't tell us.
bye-bye! (Score:5, Funny)
Re:bye-bye! (Score:4, Insightful)
Re:bye-bye! (Score:5, Informative)
Nope, and a lot of physicists think that quantum mechanics is fundamentally broken beyond the level of fixing - though it is a massively useful theory from a calculational point of view, it has deeper problems than just the ones involved in this experiment, including the measurement problem [wikipedia.org].
Nobody is really sure what quantum physics says about reality or locality. Each of the interpretations is flawed or incomplete in some way. You might be interested to read about David Bohm's interesting theory [amazon.com] - though a lot of people think it's garbage, it does illuminate the lengths you must go to to fashion a theory that is consistent with quantum mechanics yet doesn't completely shred your common sense notions of reality. I have no idea if the experiment in this article has anything to say about so-called "Bohmian mechanics," as the blurb was completely uninformative and I don't subscribe to Nature...
Re:bye-bye! (Score:5, Insightful)
When we see an insect being tricked into thinking an orchid is a female insect we think "That orchid doesn't look anything like an insect, what a strange mistake to make", and a bat might use echo location and see us being aroused by something that simply has the texture and shape of a piece of paper which doesn't resemble the texture or shape of a female human and wonder how we could make such a mistake.
Our common sense and intuition don't necessarily tell us what's true, especially when it doesn't relate the world we evolved in, so we have to rely on experiments, and quantum theory constantly makes accurate predictions. If it's beyond our common sense and intuition then that's too bad for us.
Re: (Score:3, Interesting)
Re: (Score:3, Insightful)
Re: (Score:3, Interesting)
One reason for not accepting this is the existence of the universe. If conservation of energy were not constrained to only work within a universe, then this would have required an unbelievable amount of energy.
FWIW, suppose that we take these results as proof that the universe is being run on a simulator. In that case multiple copies would result in greater consumption of ram, and slower execution, as observed from OU
Re:bye-bye! (Score:5, Insightful)
Or worse; are you saying science isn't worthwhile as a search for truth, and that scientific pursuits are only worthwhile when it helps create new products for consumption?
Re: (Score:3, Insightful)
That was sarcasm.
Re:bye-bye! (Score:4, Insightful)
An even better example: There would be no way to build a current CPU (or even an old 8-bit 8080) without QM. The only existing computers would still be room-sized energy-hungry monsters which could be beaten by our pocket calculators. There would be no PC, no mobile phone, no mp3 player, no CD or DVD player. There would be no GPS (atomic clocks need QM, too!), no LCD screens and no LEDs.
Yeah, science always follows technology (Score:3, Interesting)
I mean, Euclidean geometry, Riemannian geometry, Ricci tensors, topology, Lorentz contraction, Maxwell's demon, algebraic set theory, noncommutative geometry, and Quantum Mechanics were all instances of science following technology.
It's an impossible thing to quantify without some sort of rigorous definition of technology, but I'd say technology follows science as much as science follows technology.
Re: (Score:3, Insightful)
Well, it makes sense (Score:5, Interesting)
Think of going farming for copper and tin ore in, say, the Gold Coast Quary in WoW. A particular ore spawn point might have been spawned as tin (most often), or as silver (rarely) or not at all. Would it already be spawned and in memory, if noone was there to see it? Or would it exist only as a probability until someone actually gets in range?
Or say you're hacking away at a copper ore vein with your trusty cold iron pickaxe, like a good dwarf. Sometimes you get just a piece of copper ore, sometimes you also get 1-2 pieces of stone, sometimes you get a Shadowgem, or a Tigerseye or Malachite. Were they already there before you started to hack at the ore vein? Or did they exist only as a probability until someone actually gets that loot window?
Of course, once you got a certain set of ore, stone and/or gems, closing the window and hacking at it again, won't change it. It stays the same set of, say, 1 ore, 2 stone, 1 gem until you actually loot them.
I can tell you, the best gnomish engineers and mages have worked hard for an answer to those questions, but everyone came up empty. We just can't figure out a way to see what's there without seeing what's there. Even warlocks sending their Eye Of Killrog into the mine didn't manage to fool the system. That and the eye got killed by the bandits in the mine. The best priests whined... err... prayed piously to the great gods of Blizzard, and got no answer. Etc.
Re:Well, it makes sense (Score:5, Interesting)
Big things seem to move in simple and obvious Newtonian physics. But as we look smaller and smaller, things seem to jump from place to place, go through each other, and behave randomly. This is precisely what happens in a simulation as you approach 0 in floating-point. You can get seemingly random effects by adding very very small numbers together. It is also similar to what happens if an object in a video games moves very quickly relative to the the frame rate. The bullet may pass through things, especially other things moving quickly.
Maybe, in a few generations, we will be able to break out of this universe, and see what is really out there.
Re: (Score:3, Interesting)
Re: (Score:3, Funny)
Yes and no. Mostly no. (Score:3, Interesting)
Floating point errors tend to be more chaotic and unpredictable. QM is actually quite predictable and you can calculate useful stuff with it. E.g., it's not just that an electron in a potential well sometimes "tunnels through" (or rather, due to uncertainty principle constraints, it might have enough energy to jump or it might already be on the other side.) You can actually calculate how many will tunnel, and under which
Re: (Score:3, Informative)
Max Planck and Claude Shannon beat you to it.
Re: (Score:3, Insightful)
Religious texts (Score:4, Funny)
Yes, well... (Score:3, Funny)
Think explaining Linux or the Internet to my old grandma (otherwise a smart woman, but doesn't even have a computer) and see if you don't end up dumbing it down to "it's like some tubes" oversimplification to get it over with. Now think she goes forth and writes a book about it. Ouch. It's not going to be very accura
Re:bye-bye! (Score:4, Insightful)
Well, people think quantum mechanics are flawed behond repair since before it come to be. Just remember that Plank after proposing that light is quantized spent most of he's career fighting that same idea.
Quantum mechanics is not intuitive, but it pass every test we make with it. It's explaining things for the best part of a cetury now*, always proposing weard things, and aways getting it right. It's hard to replace a theory that works that well.
* More than a century if you count since Plank, not Schrödinger.
Re: (Score:3, Interesting)
This is only true if you discard things we haven't figured out yet. Then again, the same can be said for literally any theory, correct or not. There was a point at which we had the phlogiston pretty well figured out too. We had Newtonian Dynamics nailed down well enough to predict the motions of everything from pinball to the celestial spheres. There was a point at which we could predict how much energy a fire would pull out of
Re: (Score:3, Interesting)
Re:bye-bye! (Score:4, Interesting)
Re:bye-bye! (Score:5, Insightful)
In particular, theories are judged based on what you might call 'philosophical' notions. And in fact, the great physicists - Newton, etc. - all had very deep philosophical ideas about their theories (although those are perhaps less well-known).
As an example, we now consider Newton's law of gravity to be correct (up to relativistic considerations). Yet, at the time, many thought this to be philosophical nonsense. For what is gravity - it is 'action at a distance', with no mechanism! When a billiard ball hits another, the operation of force is clear, but why should some force exist between two billiard balls far apart? This is pretty much the same issue as the 'nonlocality' issue with QM. It took quite a lot of convincing to get the scientific world to agree with Newton's 'action at a distance', and the discussion was both practical (numbers, experiments) and 'philosophical' (how it fits into the rest of the current picture of 'reality' at the time).
Anyhow, just trying to point out that science and philosophy are not disconnected. As science gets more specialized, it may seem so, since scientists don't get any philosophical training these days (they used to, though!).
Re:bye-bye! (Score:5, Interesting)
I was using "theory" in the sense that F = G (m1m2) / r^2 is the theory of gravity, and this [wikimedia.org] is a major part of the theory of QM. And, apparently, Newton didn't offer a philosophical "interpretation" for gravity*, while for QM we have "infinite number of worlds with consistently inconsistent histories entangling while moving backwards in time, located everywhere at once and communicating instantly", or whatever your favorite is
I am not saying that that part isn't important - Newton's theory was superseded by one rooted in such a theoretical/philosophical concept ("curved spacetime"), after all. Just saying that these theoretical models only become useful when they start making testable predictions.
* Came across this great quote from him in Wikipedia: And general relativity takes a similar position, it describes how matter/energy curves spacetime, but makes no attempts to explain why that would happen.
To put it another way - I agree with what you said.
Re: (Score:3, Insightful)
I've never understood why people get so hung up on having philosophical interpretations of it-- they aren't necessary or particularly useful.
Re: (Score:3, Insightful)
You could create an accurate predictive model of the universe using the metaphors of religion and the language of words if you were so inclined.
Not that anyone has.
Re: (Score:3, Informative)
Physical Laws are analogous to mathematical axioms. We use them to derive theories and learn about the universe. They are declared assumptions.
Disproving this theory... (Score:5, Funny)
Re: (Score:3, Funny)
Tachyeons (Score:3, Funny)
It always worked on Voyager.
yeah (Score:5, Funny)
i knew it - i was right... (Score:4, Funny)
A layman's view (Score:4, Funny)
Re: (Score:3, Insightful)
Re:A layman's view (Score:5, Funny)
Re: (Score:3, Insightful)
Why yes, I do (Score:4, Insightful)
Hey kids. Get a degree in something you love, like Latin, or poetry, or whatever.
Then go get a job doing your hobby, like computers (I'm not good enough to be a pro surfer). And keep practicing your love (yes, every kind of love).
This will prevent quantum weirdness like waking up at 35 and realizing you hate your life.
As far as the nature of reality
Re: (Score:3, Insightful)
Re:A layman's view (Score:4, Insightful)
Re:A layman's view (Score:5, Funny)
and the quantum version lets both be right.
Re: (Score:3, Insightful)
Epicycles was the only game in town from the 3rd century all the way through the 16th... until Copernicus came along with the correct explanation for the data and made 1300 years of scholars look like raving lunatics.
How then could Epicycle's proponents have known they were headed down a blind alley? Simple really: instead of proving it outright, each major new dataset required more refinements and additions to the theory -- Epicycles within Epicycles.
Quantum Mecha
Re:A layman's view (Score:5, Insightful)
First Post! (Score:5, Funny)
What does it mean for us to observe something? (Score:3, Interesting)
Re: (Score:2)
Re: (Score:3, Insightful)
So, logically, the universe is powered by photons? Or reality as we perceive it is the interaction of particles, rather than the particles themselves? I'm not seeing much of a reason to panic and start worrying that the great turtle might awaken from his dream, but maybe it's just me.
Re: (Score:2)
Crazy theories ahoy ! (Score:5, Insightful)
Funny you should say that.
Ever since I started studying physics/chemistry in high-school (at about the same time, 5th grade or so), I stopped thinking of "matter" as the defining issue, and started focusing on interactions between them almost exclusively.
It makes no difference wether a particle/molecule/object actually "exists" or what "internal make-up" it has, the only thing you should ever care about is what types of interactions it can have with other particles/molecules/objects... nothing more, nothing less.
Well, the "knowing about possible types of interaction" issue kind of makes it almost mandatory to understand exactly what any entity is actually "made of", but that's a secondary issue... if you know how something behaves in any possible situation, regardless of what's inside... do you really need to know what's inside ?
Or, rather, if you know how something reacts to any imaginable interaction, would you have any actual means to determine without the shadow of a doubt "what's inside" ?
My personal answers are both negative: you don't need to know, and there's no way to know for sure.
Heh, here's the craziest thory: what if "space", "time" and "energy" don't actually exist (or worse, what if they're ALL discrete, not continuous) ?
Would we even be able to notice ? Or have we noticed that already (Planck's h) but can't grasp the concept ?
For all intents and purposes, the entire universe actually existing (on one hand) or being a completely fictional construct/simulation (on the other hand) makes no difference whatsoever.
So, basically, all what's left of reality is simply interactions between entities, not any of the entities themselves.
Re: (Score:3, Interesting)
Re:What does it mean for us to observe something? (Score:5, Informative)
Re: (Score:3, Interesting)
There seems to be a flaw in that.
It implies every thing is, in one way or another, being observed by something.
That would mean that all things are observed at all time
Re:Observation (Score:5, Informative)
Waveform collapse is not relative to the observer!
It might seem like it should be, because it is slightly more intuitive that way, but it is not. This is very important.
Your explanation is entirely incorrect, and you're kind of doing a disservice to those who read it an think they now understand QM a bit more, when in fact you have just led them further astray.
Re: (Score:3, Insightful)
A known is provided by each observation. Each observation will yield information about the past as well, but until it takes place, that past is uncalculable, so from the viewpoint of the latest observer, they don't know anything about the past until the last observation.
The "waveform" is what actually? I mean, other than a statement about our state of knowledge and other than the worst concept QM has? Not a friggin' thing.
The cat is alive or dead. The waveform is your knowledg
Re: (Score:2, Insightful)
In regards to the article, I think more than a few already known quantum phenomenon make the idea of the universe not making a sound when no one is there to hear it, one of the less mind boggling ideas. Although its only mind boggling because we use our min
Re: (Score:3, Insightful)
I view that as the primary form of a reverse-anthropic principle:
The universe is comprehensible because the mechanisms of comprehension evolved within it by conferring an advantage to those organisms that have them. This only occurs for those aspects of comprehension which operate correctly within the universe
Re:What does it mean for us to observe something? (Score:5, Interesting)
Just how sure are we that the universe is comprehensible?
It's one of the axioms of science. It's not a question of being sure, it's a question of necessarily assuming it's true in order to proceed. There are basically three axioms you assume any time you're doing science, because there'd be absolutely no point to doing it if they aren't, and it appears science is useful, so we roll with the assumptions despite them being unproven (and in fact unprovable, even in principle).
First, we assume that nature is lawful. Things happen in accord with these laws and nothing happens except in accord with these laws. That doesn't necessarily mean the universe is deterministic or anything like that -- laws can be probabilistic, after all. In any case, since the point of science is to determine what the laws of the nature are, they better be there or the whole game is a fool's quest.
Second, we assume that the laws of nature are universal -- they're good any time, any place. If something behaves differently in one circumstance than another, this doesn't mean the laws change, it just means the laws are complex and take factors into account that make those two circumstances different with regards to them. We just need to understand the law completely to know why. This assumption needs to be true, or else there's absolutely no point in making observations or conducting experiments, since they would only tell you something about the laws in that place at that time. For observation and experiment to be useful, it must be the case that the laws apply in other places and times than the time and place of the observation.
And third, we assume that the laws of nature are comprehensible and discoverable. Again, the whole scientific endeavor is devoted to discovering these laws, and that's simply not possible if they aren't discoverable (and our being unable to comprehend them would preclude us from discovering them).
One could argue one doesn't have to believe these things are true to do science, but any time one does science, one is necessarily accepting them as axioms, assuming them to be true for the purposes of doing science, at least for the moment. I suppose you could ultimately view the scientific endeavor as a whole as a test of these three things. If it succeeds, it will have proven them true. If it ultimately fails in the end, perhaps they weren't. But of course you can never know that, it may be they were true, we just didn't manage to find all the answers, but in principle we could have. One can never be sure of success, either, so in the end, we'll never truly know.
But they've sure proven useful so far. If nothing else, one can make a mighty powerful pragmatic argument for thinking them true.
Re:What does it mean for us to observe something? (Score:4, Funny)
Logic? (Score:3, Interesting)
"We have experimentally excluded a class of important non-local hidden-variable theories. In an attempt to model quantum correlations of entangled states, the theories under consideration assume realism, a source emitting classical mixtures of polarized particles (for which Malus' law is valid) and arbitrary non-local dependencies via the measurement devices. Besides their natural assumptions, the main appealing feature of these theories is that they allow us both to model perfect correlations of entangled states and to explain all existing Bell-type experiments. We believe that the experimental exclusion of this particular class indicates that any non-local extension of quantum theory has to be highly counterintuitive. For example, the concept of ensembles of particles carrying definite polarization could fail. Furthermore, one could consider the breakdown of other assumptions that are implicit in our reasoning leading to the inequality. These include Aristotelian logic, counterfactual definiteness, absence of actions into the past or a world that is not completely deterministic. We believe that our results lend strong support to the view that any future extension of quantum theory that is in agreement with experiments must abandon certain features of realistic descriptions."
_______________________
I may be a simple man but a breakdown in Aristotelian logic? What are they going to use to argue against logic? I would assume logic.
Re:Logic? (Score:4, Informative)
Not just reality (Score:2)
The Universe (Score:3, Interesting)
Re: (Score:2, Funny)
Re:The Universe (Score:5, Funny)
Original paper... (Score:5, Informative)
Re: (Score:2)
Re: (Score:2)
From the ostriche's beak... (Score:5, Funny)
we must also give up (some of) the idea that the world exists when we are not looking
Does this mean that sticking your head in the sand actually works?
Re: (Score:2)
this is a test (Score:5, Funny)
if you are reading this, congratulations, you have participated in bringing this comment into reality
Theistic fun (Score:2)
Re: (Score:2)
Deists don't claim that God doesn't watch over the Universe. They merely postulate that God doesn't interfere or meddle in its day-to-day operation.
Schwab
Re: (Score:2)
Techno-theology (Score:3, Funny)
Re: (Score:2)
Re: (Score:2)
Re:Theistic fun (Score:5, Funny)
The virtual reality of it all... (Score:3, Funny)
It's a no brainer that marrying a real woman would be more trouble than marrying a virtual woman.
Well that explains everything! (Score:4, Funny)
reality (Score:2)
Bleh, no real new science here (Score:5, Interesting)
Not that Bohmian mechanics should be viewed as a correct theory. It's clearly an artificial construct. But it's a better theory than QM for the simple fact that it talks about particle positions instead of observers. One assumes, after all, that physics goes on even when physicists aren't there to observe it.
Re: (Score:3, Interesting)
There is new science here. What they have shown is that any "reasonable" nonlocal theory cannot reproduce the results of experiment (which are correctly predicted by quantum mechanics.) This is building on the foundations that Bell laid, but is a significant new result.
What they do is assume that the down-conversion source produces pairs of photons that have real polarizations. They then put some limits on th
Question (Score:2)
If the theory of evolution is correct, and we did not always exist in our current form, which means we have not been around to observe the universe through most of its life, how does it exist? Perhpas it was created spontaneously? Spooky!!!!!!
Quantum mechanics works at the level of the atom; I think it's safe to say that when I go to bed tonight, my house and all its furnishings are not suddenly going to cease to exist or even waver in their existence while I'm dreaming.
I'm way ahead of them (Score:2)
reminds me of... (Score:2)
Master: (hits student with a cane)
Philosophical ramblings (Score:2)
They're not saying the universe needs us to look. (Score:5, Interesting)
Quantum mechanics has a set of descriptions of matter/energy that "feel" incomplete.
To "classical physics" thinking the collapse of wave functions of entangled particles seems to require either some faster-than-light communication between the entangled particles (to tell the far one about how the near one was observed - violation of "locality") or some hidden variable (to carry information slower-than-light from the point in space-time where they became entangled to the point where each is observed - "realism" would include this hidden variable as part of the particles' state). Quantum mechanics doesn't describe either. It just describes a situation where this sort of thing just happens - in a way that you can't use it to carry information faster than light from one spacetime location to another.
Lots of work is being done to see if quantum mechanics can be "patched" into a more classical theory, in a way that preserves realism and locality by figuring out some way that a hidden variable can carry, from the entanglement to the observation at no more than lightspeed, the information necessary for a classical mechanism to produce the same result.
This work shows that some simple experiments have already eliminated a very broad class of such hidden variable theories - to the point that "realism" patches involving hidden variables carrying additional information with the particles looks pretty hopeless. This is another step toward the "quantum mechanics really is all there is to it" viewpoint.
(Of course I Am Not A Physicist so I could be reading it wrong.)
So I was right! (Score:4, Funny)
MEASURE, not OBSERVE (Score:3, Informative)
Re: (Score:2)
Re: (Score:2, Funny)
That is because "spooky weird LSD-like shit goin' down" takes too long to say.
Re: (Score:2)
Re: (Score:3, Funny)
Re: (Score:2)
I saw a man who wasn't there
he wasn't there again today
I wish that man would go away
Entanglment Applications Exist (Score:4, Interesting)
"quantum entanglement would be pretty cool if an applicable use was found for it.
Applications already exist [physicsweb.org], at least if you count the demonstration of instantaneous transfer of information regardless of distance. And this experiment is years old.
So yes, quantum entanglement is indeed pretty cool.
Re:Entanglment Applications Exist (Score:4, Informative)
Science (Score:2)
One may be able to predict future outcome based on current/past state with some degree of accuracy, but claiming that anything can ever be KNOWN smells of religious fanaticism to me. Science is built to adapt, not to "prove" antiquated theories and latch on to them forever.
Of course reality exists when you aren't looking.
I would argue that perfect destruction and recreation of real
Re: (Score:3, Funny)