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Uncertainty Sets Limits On Quantum Nonlocality

Soulskill posted more than 3 years ago | from the your-teleporter-concept-will-need-a-redesign dept.

Science 223

An anonymous reader writes "Research in today's issue of the journal Science helps explain why quantum theory is as weird as it is, but not weirder. Ex-hacker Stephanie Wehner and physicist Jonathan Oppenheim showed that the Heisenberg Uncertainty Principle sets limits on Einstein's 'spooky action at a distance.' Wired reports that the discovery was made by 'thinking of things in the way a hacker might' to uncover a fundamental link between the two defining properties of quantum physics (abstract, supplement). Oppenheim describes how uncertainty and nonlocality are like coding problems, enabling us to make a quantitative link between two of the cornerstones of quantum theory."

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GREEN-EYED LADY !! (-1, Offtopic)

Anonymous Coward | more than 3 years ago | (#34282616)

Wind-swept lady !!

Wants your money, Tony Parker !!

for the lulz (4, Funny)

Pojut (1027544) | more than 3 years ago | (#34282624)

I want to believe in quantum physics, but I'm not sure.

Re:for the lulz (1)

windcask (1795642) | more than 3 years ago | (#34282656)

That's like saying you want to believe in helicopters or fried chicken.

Re:for the lulz (1)

errxn (108621) | more than 3 years ago | (#34282712)

I was all ready to break out with the "whoosh"...and then you had to go and mention fried chicken. Because I believe in fried chicken. Delicious, artery-clogging fried chicken.

Re:for the lulz (1, Funny)

Anonymous Coward | more than 3 years ago | (#34282788)

That's like saying you want to believe in helicopters or fried chicken.

I don't know... "airplanes or fried chicken", maybe. But if you ask most pilots, belief is the only thing that keeps helicopters in the air!

Re:for the lulz (1)

errxn (108621) | more than 3 years ago | (#34282948)

Well, what the hell keeps fried chicken in the air, then? QUANTUM PHYSICS, THAT'S WHAT!

Re:for the lulz (4, Funny)

idontgno (624372) | more than 3 years ago | (#34283062)

And delicious golden Brownian motion.

Re:for the lulz (1)

mcgrew (92797) | more than 3 years ago | (#34284146)

Who's giving mod points to non-nerds? Whoever modded that down, a triple WOOOOSH WOOOOSH WOOOOSH to you!

I thought it was hilarious, even though Brownian motion is classical physics rather than quantum mechanics.

One thing it isn't is offtopic. I sure wish they'd bring the old metamoderation system back so dufuses who don't understand nerd culture wouldn't get mod points.

Re:for the lulz (4, Funny)

camperdave (969942) | more than 3 years ago | (#34283442)

But if you ask most pilots, belief is the only thing that keeps helicopters in the air!

Nonsense! Helicopters fly because they are so ugly that the ground repels them.

Re:for the lulz (1)

by (1706743) (1706744) | more than 3 years ago | (#34283772)

That's like saying you want to believe in helicopters or fried chicken.

Not really -- quantum theory is not "right" or tangible (as are your examples). Rather, it accurately describes phenomena under certain circumstances. It's like Newtonian physics -- we know it's not "right," but it does describe things very accurately under certain circumstances.

Re:for the lulz (0)

Anonymous Coward | more than 3 years ago | (#34282674)

well the act of believing in it changes how it acts.

Re:for the lulz (0)

Anonymous Coward | more than 3 years ago | (#34282728)

I changed the way your mom acts by making her believe in the power of my cock.

Re:for the lulz (2, Funny)

Anonymous Coward | more than 3 years ago | (#34282854)

That makes sense. Quantum physics is needed to describe the behaviour of extremely small objects.

Re:for the lulz (1)

boristdog (133725) | more than 3 years ago | (#34282772)

I don't believe in myths, like quantum physics and octopuses.

Re:for the lulz (1)

windcask (1795642) | more than 3 years ago | (#34282792)

I don't believe in Al Gore.

Re:for the lulz (0)

Anonymous Coward | more than 3 years ago | (#34283206)

Al Gore believes in you!
That is, he believed when your mom said you came out of the same hole that he was stretching out by yet another 14" last night.

Re:for the lulz (1)

ArsonSmith (13997) | more than 3 years ago | (#34284006)

He is a quantum octopus.

Re:for the lulz (0)

Anonymous Coward | more than 3 years ago | (#34282862)

Or this slashdot, I've been hearing about. Crazy talk, my magnificent BBS-mate, sheer crazyness.

Re:for the lulz (1)

Monkeedude1212 (1560403) | more than 3 years ago | (#34282888)

Which part?

I mean, like any theory, it has its holes
(Like Gravity, Black Holes, Dark matter, still unexplained).

Quantum Mechanics has enough empirical evidence behind it (We've preformed and verified quantum entanglement at least) - you should be as willing to accept it as any other scientific theory you've come to accept.

Re:for the lulz (1)

MightyMartian (840721) | more than 3 years ago | (#34282928)

Actually QM is probably one of the best attested theories in the history of science. To disbelieve it at this point is no different than being a geocentrist.

Re:for the lulz (1)

adonoman (624929) | more than 3 years ago | (#34283134)

What does it mean to believe in QM, though? I believe that it makes predictions that accurately describe what we can see and measure. Does that mean that the models it uses constitute a true understanding of how the universe behaves? These aren't things you can believe in or not believe in - either they work in a given situation or they don't. I don't "believe" in Newton's laws of motion. They fairly accurately predict what happens in certain real-life situations, but we know that they are only helpful models that simplify what is actually happening. A theory is only useful insofar as it makes predictions about reality. QM does a good job at that, but if something better comes along that is either simpler and makes the same predictions, or makes better predictions, then QM will join geocentrism in the list of useful, but outdated models.

It's not like geocentrism isn't a useful theory - you can come up with complicated fomulae to predict the motions of the planet and whatnot, if you're staying on earth. The geocentric model is much simpler if you just want to observe the orbit of the moon and the sun. It's just when you start looking at the other planets and trying to tie in things like gravity that things get much simpler to model if you switch to a heliocentric view. Is it really that different from switching between polar and cartesian coordinate systems?

Re:for the lulz (1)

lgw (121541) | more than 3 years ago | (#34283422)

Well, what do you mean by QM? Do electrons have quantized energy levels around a nucleus, mirrored in quantized energy levels in photons? Sure, can't get much more grounded in data than that. But that's not the contentious part. The really interesting part that's not just "interpretation" is the Bell inequalities, which seem surprisingly not well tested - is the field really content with a few experiments for something this important to our understanding?

Re:for the lulz (1)

bigstrat2003 (1058574) | more than 3 years ago | (#34282992)

Whoosh!

Re:for the lulz (1)

Monkeedude1212 (1560403) | more than 3 years ago | (#34283066)

And I STILL don't get it. How sad is that?

Re:for the lulz (1)

bigstrat2003 (1058574) | more than 3 years ago | (#34283096)

At the risk of ruining the joke... the joke is based on the uncertainty factor of quantum physics. Hence why he "isn't sure".

Re:for the lulz (0, Offtopic)

delinear (991444) | more than 3 years ago | (#34283130)

Oh well now you've ruined it!

Re:for the lulz (1)

Pojut (1027544) | more than 3 years ago | (#34283284)

Are you sure?

Re:for the lulz (3, Funny)

tom17 (659054) | more than 3 years ago | (#34283460)

He only ruined it if you read the post. Until you observed it, it was both ruined and not ruined.

You just shouldn't have read it.

Re:for the lulz (0)

Anonymous Coward | more than 3 years ago | (#34282954)

Especially with the rate the science is advancing, it's hard to nail down exactly what to believe.

Re:for the lulz (1)

mcgrew (92797) | more than 3 years ago | (#34284082)

You know what Hawking says...

Let me be the first to say... (0)

Anonymous Coward | more than 3 years ago | (#34282636)

Lolwut?

hmmm (1)

Captain Murdock (906610) | more than 3 years ago | (#34282644)

I think you run into issues when you start thinking about non-coding problems from a coding perspective. The universe doesn't behave like a computer as much as you might like it to.

Re:hmmm (2, Funny)

mrjb (547783) | more than 3 years ago | (#34282708)

That's just because a rock accidentally gets misplaced here and there.

Re:hmmm (1)

Monkeedude1212 (1560403) | more than 3 years ago | (#34282844)

It does when you never leave your basement and you view it through a computer.

Re:hmmm (1)

Securityemo (1407943) | more than 3 years ago | (#34282930)

I think you run into issues when you start thinking about unrelated problems from a human-brain perspective. The universe doesn't behave like the model inside your head, as much as you might like it to.

Re:hmmm (1)

dpilot (134227) | more than 3 years ago | (#34282942)

I don't think that's what they were saying, I think they were applying the "hacker mindset", not the coding perspective.

The scientist says, "What is here? How can I describe it? How does it work?"
The hacker says, "How can I bend the rules to get more out of it?"

Two interesting "hacking reality" books were written by Greg Bear - "Anvil of Stars" and "Moving Mars", the latter building on his short story, "Heads". Bear is enough of a physicist to not do the laws-of-physics impossible, just the no-theoretical-way-to-do-it impossible, like changing matter into antimatter. (conserves mass, charge, energy, etc)

Re:hmmm (0)

Anonymous Coward | more than 3 years ago | (#34283258)

They talk about coding as in information theory, not coding as in programming.

More Evidence (0)

Anonymous Coward | more than 3 years ago | (#34282676)

That the universe is actually a computer.

It makes sense! HHGG (1)

mrnick (108356) | more than 3 years ago | (#34282756)

Since the Earth is a 10-million-year program (HHGG) then it makes sense the Universe would be a computer!

Deep thought!

There's no link to the full article here in pDF (3, Informative)

Anonymous Coward | more than 3 years ago | (#34282706)

Definitely not a link to the full article here [sharepdfbooks.com] [Not-PDF warning].

Re:There's no link to the full article here in pDF (0)

Anonymous Coward | more than 3 years ago | (#34283632)

It's real - I checked it and am modding up.

Einstein, Heisenberg... (4, Funny)

srussia (884021) | more than 3 years ago | (#34282736)

Heck, they even hinted at Gödel. Why not throw in Monty Hall too... wait, they did.

Re:Einstein, Heisenberg... (1)

Sockatume (732728) | more than 3 years ago | (#34283160)

There's a quantum version of the Monty Hall problem. Just knowing that scares the shit out of me.

Locality == Free Will? (1)

Eponymous Coward (6097) | more than 3 years ago | (#34282814)

Locality is the only thing stopping me from concluding the universe is entirely deterministic and free will doesn't exist.

Re:Locality == Free Will? (2, Funny)

adonoman (624929) | more than 3 years ago | (#34282902)

No, it's the absolute determinism of the universe that is stopping from concluding that the universe is deterministic. Neither you, nor locality had any choice in the matter.

Re:Locality == Free Will? (2, Insightful)

somersault (912633) | more than 3 years ago | (#34282926)

Even if there were external forces acting to control your will in this universe, how do you know they're non-deterministic themselves?

Individuals certainly are responsible for their own choices anyway, even if you can accurately simulate 100% beforehand what they're going to choose.

Re:Locality == Free Will? (1)

guybrush3pwood (1579937) | more than 3 years ago | (#34283040)

Individuals certainly are responsible for their own choices anyway, even if you can accurately simulate 100% beforehand what they're going to choose.

Demontration, please.

Re:Locality == Free Will? (2, Funny)

delinear (991444) | more than 3 years ago | (#34283102)

I think maybe this [xkcd.com] ?

Re:Locality == Free Will? (0)

Anonymous Coward | more than 3 years ago | (#34283500)

best xkcd ever!

Re:Locality == Free Will? (1)

Tyler Durden (136036) | more than 3 years ago | (#34283274)

Even if there were external forces acting to control your will in this universe, how do you know they're non-deterministic themselves?

If these "external forces" are what define who you are as a person, are they really external?

Re:Locality == Free Will? (1)

benjamindees (441808) | more than 3 years ago | (#34283734)

Is anything really external?

Re:Locality == Free Will? (1)

Eponymous Coward (6097) | more than 3 years ago | (#34283554)

I think as long as you are in the same system as the individual, then that's true. If you can sit outside of the system, I don't think it's true anymore. It would be like saying my computer is responsible for the BSOD that happened this morning.

Re:Locality == Free Will? (0)

Anonymous Coward | more than 3 years ago | (#34283960)

"Individuals certainly are responsible for their own choices anyway, even if you can accurately simulate 100% beforehand what they're going to choose."

Really? Certainly? You must not have been paying attention....

Re:Locality == Free Will? (1)

Eponymous Coward (6097) | more than 3 years ago | (#34283962)

If an individual has a choice, then by definition they have free will and so I would agree with you that they are responsible for their choice.

If the universe turns out to be deterministic, then there is no choice to be made. What does "choice" mean in the context of a giant DFA?

Re:Locality == Free Will? (1)

idontgno (624372) | more than 3 years ago | (#34283076)

I misread the title of that post. I thought someone was giving away a Wii to whoever was in the right place at the right time.

Re:Locality == Free Will? (1)

master_p (608214) | more than 3 years ago | (#34284094)

Even with locality, the universe is still deterministic on the macroscopic level.

a coding problem? (4, Funny)

phantomfive (622387) | more than 3 years ago | (#34282850)

describes how uncertainty and nonlocality are like coding problems,

In that case, I guarantee there is a bug.

Re:a coding problem? (3, Funny)

Monkeedude1212 (1560403) | more than 3 years ago | (#34282916)

It's because when God was whipping things up he had just switched to Dvorak - and he couldn't find the semicolon because it was under his left hand. To remedy this - he ported the universe to VB.

Re:a coding problem? (1)

tool462 (677306) | more than 3 years ago | (#34282972)

If only God had thought to implement the universe in Haskell. We'd be bug-free, though it IS kind of hard to imagine a universe without side-effects...

Re:a coding problem? (1)

rebot777 (765163) | more than 3 years ago | (#34283254)

No, no, that's a feature of physics

Ugh, text shadow (0)

Anonymous Coward | more than 3 years ago | (#34282866)

Okay, I get it, text shadow is the new 'thing' on the internet. But seriously, it makes your article harder to read. There is a time and a place people. And that time and place isn't everywhere all-the-time.

Re:Ugh, text shadow (1)

sexconker (1179573) | more than 3 years ago | (#34283086)

Okay, I get it, text shadow is the new 'thing' on the internet. But seriously, it makes your article harder to read. There is a time and a place people. And that time and place isn't everywhere all-the-time.

None of the links lead to anything that uses text-shadow. You may want to get your eyes checked.

Re:Ugh, text shadow (1)

delinear (991444) | more than 3 years ago | (#34283168)

Okay, I get it, text shadow is the new 'thing' on the internet. But seriously, it makes your article harder to read. There is a time and a place people. And that time and place isn't everywhere all-the-time.

None of the links lead to anything that uses text-shadow. You may want to get your eyes checked.

Actually this one does: http://www.damtp.cam.ac.uk/user/jono/uncertainty-nonlocality.html [cam.ac.uk] - it's faint (depending on your monitor I guess, and obviously whether your browser supports it) and above the text, the style is inherited from the body thus:

body { text-shadow:0 -1px 1px rgba(0, 0, 0, 0.41); }

Define 'observe' (4, Insightful)

Twinbee (767046) | more than 3 years ago | (#34282970)

Okay, rant time.

Whenever I see a beginner's guide to quantum theory, I always invariably see a phrase similar to:
"Stranger still, the electron doesn't even have properties like position and momentum until an observer measures them. "

And every time, I always think "define 'observe'", because that word is incredibly fluffy, vague as well as being immensely irritating. If a bat miles away happens to look in that direction with nothing in the way, is that counted as an observation? Are there a trillion different ways to observe it, and have they all been tried out to see the phenomenon stands? None, I repeat NONE of the articles I have ever read actually even remotely begins to touch upon that subject.

Re:Define 'observe' (2, Informative)

Anonymous Coward | more than 3 years ago | (#34283042)

You are asking a great question, the problem is that no-one knows the answer. This is the "measurement problem", one of the biggest conceptual problems in Quantum Mechanics.

Re:Define 'observe' (2, Insightful)

Sockatume (732728) | more than 3 years ago | (#34283144)

Indeed. It's phenomenologically pretty well-defined, inasmuch as we can set up systems and we know whether we're observing them or not, and what'll happen to them if we do observe them, but we haven't a clue as to the mechanistics of it all.

Re:Define 'observe' (5, Informative)

MozeeToby (1163751) | more than 3 years ago | (#34283052)

I think the closest plain English definition would be: has an interaction with something. More accurate, but more confusing might be: things are undefined until something happens that requires them to be defined in order for that something to happen. An electron doesn't have a position or a momentum until something occurs which require the electrons position and momentum to be known in order to determine the outcome. That might be a human being with an incredibly complex apparatus measuring the properties of an individual electron, or it might be a chemical reaction that is sweeping through the entire sample of whatever the electron is a part of.

Re:Define 'observe' (1)

Monkeedude1212 (1560403) | more than 3 years ago | (#34283124)

An electron doesn't have a position or a momentum until something occurs which require the electrons position and momentum to be known in order to determine the outcome.

Which kind of leads back to the idea that the Electron itself isn't there until it's been observed. And thats where Einstein was all like "Umm. no. Just because I can't see the moon doesn't mean it isn't there".

Thats where a lot of the curfluffle is about.

Re:Define 'observe' (1)

Tyler Durden (136036) | more than 3 years ago | (#34283448)

The electron's there (with "there" being defined by a fuzzy cloud of possible positions/momentums), it's just that it doesn't have a precise position or momentum except at points in time when one of these quantities are "observed", as stated above.

Re:Define 'observe' (1)

ArsonSmith (13997) | more than 3 years ago | (#34284110)

You didn't hear? China blew up the moon while it was passing over them this last time. It's no longer there.

(this is an example of the quantum possibility)

Re:Define 'observe' (2, Interesting)

Just Some Guy (3352) | more than 3 years ago | (#34283194)

That might be a human being with an incredibly complex apparatus measuring the properties of an individual electron, or it might be a chemical reaction that is sweeping through the entire sample of whatever the electron is a part of.

Fair enough. But does that chemical reaction require an observation to define its outcome if it depends on those quantum events? At what point do you decide that the decision must be made?

Re:Define 'observe' (5, Funny)

Anonymous Coward | more than 3 years ago | (#34283240)

So what you're saying the the universe uses "just in time" physics.

Re:Define 'observe' (2, Interesting)

Anonymous Coward | more than 3 years ago | (#34283586)

The universe lazily loads the details when we want to inspect it. In reality the algorithm has optimized these things away. Its like forcing it to load the debugging symbols when you attach to the physics.exe process.

Re:Define 'observe' (1)

KonoWatakushi (910213) | more than 3 years ago | (#34283544)

While your post adequately describes the accepted thinking, it defies rational thought. While we may lack the ability to measure something beyond a certain limit, that is not evidence that the underlying physics is indeterministic, or inherently unknowable.

By accepting that it was, we veered right out of the realm of science, and physics continues to be mired in probabilistic nonsense. You can calculate things, but the model provides no insight into the underlying reality. Seventy years later, and we are still no closer to bridging the fundamental divide in physics.

Oblig: (0)

Anonymous Coward | more than 3 years ago | (#34284148)

Amazing that this hasn't shown up yet:
http://xkcd.com/817/

The alt text is very relevant: "A universe that needed someone to observe it in order to collapse it into existence would be a pretty sorry universe indeed."

Re:Define 'observe' (2, Funny)

guybrush3pwood (1579937) | more than 3 years ago | (#34283058)

None, I repeat NONE of the articles I have ever read actually even remotely begins to touch upon that subject.

Perhaps they don't touch it because you read them. Don't read them, and there's a 50/50 chance they will...

Re:Define 'observe' (1)

Sockatume (732728) | more than 3 years ago | (#34283088)

The technical term is a "measurement", which is an interaction with the particle which requires information on a property (which is defined by an operator). If a billiard ball strikes you, it observes your momentum and position. That's my understanding. I'm more puzzled by how it's possible to interact with a particle in a manner which doesn't cause its superposition to break down...

Re:Define 'observe' (0)

Anonymous Coward | more than 3 years ago | (#34283120)

Why don't you read about how 'observe' is defined in newbie texts? Because the phenomenon of observation has been an integral part of the discussions on the interpretations of quantum mechanics. Most of my undergrad profs did not have a clear idea on the topic and thus they and similarly newbie-book authors are unable address the issue.

What you really need to do is to look for recent quantum information theory books. Also look for "decoherence" in places like Wikipedia.

Re:Define 'observe' (1, Informative)

Anonymous Coward | more than 3 years ago | (#34283132)

Contrary to other commenters in this thread and your own perspective of it - an "observation" in the quantum mechanical sense is far from vague and very easily defined (and yes, people know what it means). Observation = an interaction of a quanta with another quanta, once it has interacted, whether considering a particle wave or composite nature, it ceases to be what it was in terms of position and momentum - passing along only one of the two to a measuring device within our means to construct at present. Though I do agree, quantum mechanics is a horrible branch of physics in all regards - its essentially a hack-job meant to encompass all we knew about 60-80 years ago and its account for *enough* new tech to keep it kicking without building a new branch. In reality, it will probably persist as long as Newtonian physics and relativity - kept in context of the context in which it applies.

Re:Define 'observe' (2, Informative)

Anonymous Coward | more than 3 years ago | (#34283182)

In the quantum mechanical sense "observe" means to measure the property. That is a particle does not have momentum until someone measures it. Thus if a bat miles away happens to measure the the property it would count as an observation.

Essentially, in order for a quantum mechanical system to be observed there must be an interaction between the system and whatever does the observing (such as a photon). Prior to observation the system is thought of to exist in a superposition of states and after observation it is said that the wave function describing the system has "collapsed". The thought experiment of Schrodinger's cat is designed to explain this issue.

Re:Define 'observe' (1)

SlowMovingTarget (550823) | more than 3 years ago | (#34283186)

Definition: [princeton.edu] Observation - The act of making and recording a measurement

In the case of an electron, it is the means used to measure position or energy that necessarily precludes the ability to know both. If I remember my lay-physics right, it has to do with choosing to measure a wave or a particle. Measure one, and measurements of the other become impossible. (Someone please correct my interpretation.)

Re:Define 'observe' (1)

ardle (523599) | more than 3 years ago | (#34283200)

The important word is "measure" not "observer". Your sample sentence could be:

"Stranger still, the electron doesn't even have properties like position and momentum until an armadillo measures them. "

Furthermore, we define the things we measure, not nature. We might not be measuring the most useful things yet.
We know that matter isn't made up of particles but we measure it that way because we know how to do that...

Re:Define 'observe' (5, Informative)

gsliepen (303583) | more than 3 years ago | (#34283262)

The best definition I have heard is this: suppose we have an observer O in state A, and a system S which is in the superposition of the states 1 and 2. When the observer observers the system, the state of S does not collapse, rather the observer and system become one, say OS, and is in a superposition of the states A1 and A2.

You can interpret this in various ways; one could say that this means the observer, or even the whole universe for that matter, branches all the time, and/or all possible states of the observer/universe exist simultaneously, however that again is just a description, not what might really be the case.

Disclaimer: I am a physicist.

Re:Define 'observe' (0)

Anonymous Coward | more than 3 years ago | (#34283412)

If a mime falls in the forrest when no one is around to see it, does anybody care?

Re:Define 'observe' (1)

fred fleenblat (463628) | more than 3 years ago | (#34283426)

I overheard one physicist refer to it not as observation or measurement, but rather *amplification*. If the information about the property (position, momentum, spin, whatever) is amplified to a larger scale than the original property (e.g. neurons firing, pencils moving, printer printing, beam of light moving in a different direction), only then does that collapses the uncertainty.

If the information is merely transferred to another particle without amplification (say, by bumping into it) the uncertainty remains and the information can be un-transferred in the usual weird quantum way.

Re:Define 'observe' (1)

u19925 (613350) | more than 3 years ago | (#34283570)

You have hit the heart of the problem in QM. The observer is YOU. Yes, that is what it is. I can assume everything in the world is made out of fundamental particles and describe a quantum state of it. At this point "nothing" exist (the qm wave is just mathematical probability equation) until I observe. In Schrodinger cat analogy: what if you keep a scientist inside a cage? Well in this case, the scientist mind is in two states too (dead cat and alive cat) until you open the cat and make the observation at which point it falls into one of the states consistent with your rest of the observations. The scientist, cat, and nuclear equipment in the cage form a quantum state and become classical state when you observe. From your perspective, I typed this when you observe this!

Re:Define 'observe' (1)

0123456 (636235) | more than 3 years ago | (#34283578)

None, I repeat NONE of the articles I have ever read actually even remotely begins to touch upon that subject.

How do you know where something is unless you look for it?

It's really that simple: the object is somewhere, but you can't tell where it is unless you look. Until then it could be anywhere.

As for the 'spooky action at a distance', that's merely a consequence of not using the relativistic version of Schrodinger's Equation which gives you two waveforms going in different directions in time. Which is a mathermatical shorthand for 'that object was somewhere but I couldn't tell where until I looked, and now I know where it was since the last time I looked at it'.

Re:Define 'observe' (1)

lanceblack (969852) | more than 3 years ago | (#34283726)

You know, I've never found quantum theory to be anything other than completely logical. I think the trick is to avoid separating humanity from the rest of nature. It's difficult to explain in plain words, but I'll try.

In the case of QT, 'observe' means 'measure.'

Humans, and most (all?) living things, have measuring-machines functions built into them. In a sense, an argument might be made that all life-forms are nothing but measuring-machines and information processors organizing the data that is measured. The sense-organs are biological machines that measure particular variables. The eyes measure the intensity and wavelength of light, the nose and tongue measure variations in the quantity of certain chemicals, the ears measure vibrations, and so on.

The point in QT is quite simple and logical: measurement disturbs that which is measured. Any and all kinds of measurement.

Now, at a macro level, this doesn't really bother us much. We don't (can't?) notice it. The 'disruption' is far too small.

At a very small level, though, when we start looking at stuff reeeeeeeeeealllly closely, we can start to notice that we are disrupting the things that we are trying to measure, by trying to measure them.

It's like we keep trying to move the magnifying glass just that *little bit* closer, and keep bumping the thing we are trying to look at.

At this level, we can never get a 'perfect observation' or attain 'perfect knowledge' about something, because we ourselves are getting in the way.

Now, I know that the 'measurement problem' is deeper than this. That there are certain things which indicate that electrons exist in multiple states at once, and that only being 'observed' do they 'resolve' into a definite state. However, I think these words are misleading. A better way to say it might be:

Due to ourselves getting in the way, we *cannot* know exactly what state an electron is in without measuring it, but we know that by measuring it we are exerting an influence on its state. So it's not that an electron doesn't have a position or momentum until it is observed, it's just that we *cannot*, and by that word I mean *it is impossible due to the fundamental laws of physics* for us to know its position or momentum until we observe it. It exists, until then, outside our possible world of information, and therefore, in the purified world of theory, it doesn't exist.

Schrodinger's cat is alive or dead. It doesn't exist in limbo. The cat is a macro object, following Newtonian laws. The cat is an observer. The box that cat is in is an observer. The air particles in the box are all observers. It's only the very small things that act weird. And by the time the echoes of their actions reach us, up here in the big people's world, the probabilities have already resolved themselves into action. It's just those tiny little things we can't measure as perfectly as we'd like that give us problems. We ourselves, great flesh-bag-bacteria-colonies that we are, are limited. The universe on the other hand, may not be, and may contain things we, by our very nature, by our very size, cannot comprehend.

Either that, or quantum effects are the traces of >4-dimensional reality extruding into our 4-dimensional frame of reference.

See, I told you it was logical :D

It means "interact with something classical" (1)

DrJimbo (594231) | more than 3 years ago | (#34283830)

According to the ideas in Decoherence, the measurement problem, and interpretations of quantum mechanics [arxiv.org] the term "observe" means to strongly interact with a system that is large enough and complicated enough to behave classically. I believe the majority of physicists who think about these things would agree with this definition.

I like to think of it as the particle (or system) being measured becoming classical-like during the measurement before going on its own merry quantum way again.

Re:Define 'observe' (1)

jd.schmidt (919212) | more than 3 years ago | (#34283834)

I have pondered this question for a while this is the best I can understand it.

By definition, observe means at minimum "interact with another object" whatever else it may mean also, be that wave or particle. Now you know how in QM we say that electrons become a wave "orbiting" the nucleus and that the “wave length” of electrons are simply resonance frequencies that “fit” in that particular potential energy well? OK, let me propose that the Proton is “observing” the electron and “forcing” it to exist in a particular way, to wit the famous quantum orbitals.

Now note, in practice every observational experiment a human can perform is effectively the same thing. We can create potential energy wells of different shapes and sizes and have different things happen when something enters, but every observation we make is really an interaction with another particle, and the potential energy field of that particle “forces” the waveform to conform to certain parameters. Change the shape of the potential energy field and you force the electron to take on different parameters (properties!).

Take for instance the famous electron two slit experiment. You get all these dots caused by a chemical reaction triggered by the electron, so we say “aha, this is where the electron hit!”. But no, it is really just a spot on a photographic plate, not an electron at all. You have no idea which electron, now presumably in the plate, actually created the spot, no way to find out and it may not be a sensible question in the first place! You set up a particular potential energy field in your electron/energy trap (or maybe more accurately the chemical on the plate did), thus the electron could only take a particular form when it interacted with the plate.

This also helps understand uncertainty, until you observe (force) a wave to exits in a particular orbital, or let’s face it, to have once existed, because observations destroys the previous state, why couldn’t it be a half strength wave is two orbitals, or maybe in all possible orbitals at once, though with different amounts of energy.

So, if you set up a mousetrap, don’t be surprised if you catch a mouse!

Re:Define 'observe' (1)

BitZtream (692029) | more than 3 years ago | (#34283918)

It is observed when it interacts with something else in some way.

What that something else is and how it interacts is completely irrelevant, however any and all interactions are relevant. In order for something to exist, has to at some point interact with something else, there for ... here it comes ... everything that exists is observed, so ... quantum physics is a bunch of talking in theoretical circles because we don't ACTUALLY have the slightest fucking clue how the universe works and this gives a bunch of douche bags a way to pretend they know what they are talking about so they don't have to come out and admit it, which would be pretty disappointing to hear, don't you think?

Why do they always act surprised? (1)

abbynormal brain (1637419) | more than 3 years ago | (#34283050)

When the article opened up with:

The more one probes the universe at smaller and smaller scales, the weirder matter and energy seem to behave

... I thought "patterns" (like in the Powers of 10 display at the science museum). I don't see why "they" are so surprised that the deeper you probe, the weirder it gets. It's natural - universal even!
I tried it on my bus driver this morning. Had a pleasant conversation, asked lots of questions ... and I'll be taking the bus after that from now on.

Paywall (2, Informative)

zrbyte (1666979) | more than 3 years ago | (#34283116)

If anybody cares to read it, a preprint of the whole article can be found here. [cam.ac.uk]

Re:Paywall (1)

malakai (136531) | more than 3 years ago | (#34283348)

I have to say, it's an interesting read. Even if you don't understand the math, three's some Alice/Bob like narrative that lets you 'kinda' figure out what they are talking about.

For the past 20 or so years, I've felt that software reverse engineers "crackers" could really aid many different disciplines in understanding 'natural' black boxes. The black boxes are the natrual demarcation points where for lack of better technology or limits of physics, we can't look past that point. We can only monitor a set of input/outputs and watch how it interacts with others.

Originally I focused on the brain. I though if people like +ORC/Fravia and those in the community who followed could work with neurobiologist or neuropsychologist (think Ramachandran, Antonio Damasio, Cytowic) we'd have some very interesting breakthroughs. I never through of applying it to physics as a whole, and the area/boundaries where we can only treat some phenomenon as a large black box.

I'm encouraged by this collaboration, and I hope others in the future have the opportunity for cross-discipline analysis of some of these fundamental problems,

Quantum physics certainly is confusing... (1)

hatten (1640681) | more than 3 years ago | (#34283314)

Is it bad that I didn't even understand the summary?

Re:Quantum physics certainly is confusing... (1)

Eudial (590661) | more than 3 years ago | (#34283760)

All the quantum physics classes in the world will not help you understand the summary. I think they're attempting to dumb it down to a layman's level while inserting buzzwords and hip analogies to make it interesting. Whatever they're doing, the end result does not make whole lot of sense.

Wired article completely misleading (4, Informative)

DrJimbo (594231) | more than 3 years ago | (#34283568)

The Wired article "explains" entanglement by talking about Bob predicting what Alice did even though Alice is far away from Bob. This is the fundamental misunderstanding of quantum entanglement and has led to all sorts of wacky (and false) speculations and "theories".

The actual paper [cam.ac.uk] correctly says:

Non-locality can be exhibited when performing measurements on two or more distant quantum systems – the outcomes can be correlated in way that defies any local classical description. This is why we know that quantum theory will never by superceded by a local classical theory. Nevertheless, even quantum correlations are restricted to some extent – measurement results cannot be correlated so strongly that they would allow signalling between two distant systems.

Quantum entanglement (QE) provides a correlation not a communication. What this means is that not only can't you use QE to pass signals (or any information) between Alice and Bob, you actually need some other form of after-the-fact communication between them to detect the correlation in order to determine if QE happened at all. If QE was a method of communication then you could verify it by sending Bob a "cheat cheat" of what Alice was going to do or transmit. Instead, you need to look at the outcome of a series of measurements taken by Alice's and the outcome of a series of measurments taken by Bob just to see if QE actually happened.

Correlation is not communication.

Higgs Boson particle = Null value? (2, Interesting)

Anonymous Coward | more than 3 years ago | (#34283588)

Let me guess... The "God" (Higgs Boson) particle is nothing more than nature's null value to assign properties of something without it actually existing. How would that be for irony?

Car analogy please (0)

Anonymous Coward | more than 3 years ago | (#34283856)

I'm not a hacker, so I still don't get it. Can we get a car analogy, so we can all understand quantum physics?

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