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Proof Mooted For Heisenberg's Uncertainty Principle

Soulskill posted about a year ago | from the he's-the-one-who-knocks dept.

Science 158

ananyo writes "Encapsulating the strangeness of quantum mechanics is a single mathematical expression. According to every undergraduate physics textbook, the uncertainty principle states that it is impossible to simultaneously know the exact position and momentum of a subatomic particle — the more precisely one knows the particle's position at a given moment, the less precisely one can know the value of its momentum. But the original version of the principle, put forward by physicist Werner Heisenberg in 1927, couches quantum indeterminism in a different way — as a fundamental limit to how well a detector can measure quantum properties. Heisenberg offered no direct proof for this version of his principle. Now researchers say they have such a proof. (Pre-print available at the arXiv.) If they're right, it would put the measurement aspect of the uncertainty principle on solid ground — something that researchers had started to question — but it would also suggest that quantum-encrypted messages can be transmitted securely."

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That's nice (0)

Anonymous Coward | about a year ago | (#44110081)

But I'm more confused than before. :(

I guess I can't read the article and understand it at the same time. Curse my very small, very limited brain!

Re:That's nice (5, Funny)

Z00L00K (682162) | about a year ago | (#44110173)

Yet another proof of the principle.

Now let's see what the cat has to say about it.

Re:That's nice (1)

RaceProUK (1137575) | about a year ago | (#44110559)

My guess would be 'miaow'

Re:That's nice (2)

dreamchaser (49529) | about a year ago | (#44110779)

My guess would be 'miaow'

Only if it's still alive when you open the box.

Re:That's nice (1)

Dishevel (1105119) | about a year ago | (#44112015)

But before you open the box the answer is "Miaow" as stated by the GP.
The cat being both dead and alive both makes the sound and does not.
Therefore the sound is definitely heard.

Of course if you listen for the miaow then you are in fact making a measurement. :)

Re:That's nice (1)

geekoid (135745) | about a year ago | (#44112135)

Just because something emits a sound doesn't mean you can measure it.

Re:That's nice (1)

The Mighty Buzzard (878441) | about a year ago | (#44112307)

Unless the experiment caused the cat to be patient zero of the zombie apocalypse. Damned physicists, you've doomed us all!

Re: That's nice (1)

JWW (79176) | about a year ago | (#44110671)

Oh wait, the cats dead. Or is it?

Re: That's nice (2)

SeeingMole (1965542) | about a year ago | (#44110811)

Are you sure there's even a cat in the box?

Re: That's nice (2)

Sponge Bath (413667) | about a year ago | (#44111031)

It's just pining for the fjords.

Re: That's nice (4, Funny)

Bengie (1121981) | about a year ago | (#44111443)

The more you know about the position of the cat, the less you know about its velocity. Ever try to measure the position of a cat that you just dropped into the bathtub? You know it has a high velocity, but it's hard to tell where it really is.

Re:That's nice (1)

wbr1 (2538558) | about a year ago | (#44111287)

Please quit conflating Heisenberg and Schrodinger. Besides, due to Brownian motion, Heisenberg ate Schrodinger's cat whilst standing on the shoulders of giant macroscopic particles.

Re:That's nice (0)

Anonymous Coward | about a year ago | (#44111503)

The headline is wrong. The Webster definition for the verb "Moot" is "to reduce or remove the practical significance of; make purely theoretical or academic." This is the exact opposite.

--Garfield

Re:That's nice (0)

Anonymous Coward | about a year ago | (#44110225)

No matter how much you study it, there still remains some uncertainty about the principle.

At last! An excuse for our Congress! (-1, Offtopic)

smitty_one_each (243267) | about a year ago | (#44110241)

The whole "perfect is the enemy of the good argument" (which I can follow, to a point), has devolved into "Hey, it may be a crap sandwich, but rejoice in the bread."
This mooting/affirmation opens the door, lets out the cat, and affords Congress the ability to say: "Our idiocy is a Heisenberg reference!"
My day is made, and it's not 0600.

Re:At last! An excuse for our Congress! (-1)

Anonymous Coward | about a year ago | (#44110367)

Notice how Congress went to shit when we gave women the right to vote? That's because women are subhuman. Take a list of Nobel laureates, remove all "peace" (even the magic negro got one) prizes and divide by zero^Wgender.

Women are manipulative whores, deriving all their power from subjugation of men with their powers of saggy tits. Women don't achieve anything by themselves. How many hard science papers are actually released by women? Nada.

Like all "special interests" groups, women have an unusual sense of entitlement. Except that unlike niggers, they had every chance to "prove" themselves through the history of mankind, not pick cotton all day long (unless they were female nigra).

The moment you don't want to buy that alligator-skin bag, a diamond ring, a status-symbol car, a kitten-fur coat, not only they spit out instead of swallowing, they pull out a gun on you and accuse you of criminal trespass. Then they miss at point-blank range. Such is the result of granting equal rights to the subhuman gender.

I'm all in favor of "separate but equal" amendment -- grant them a right to the kitchen and Valium, and for men to work their ass off trying to make a name for themselves. Praise the ones who make a difference, not the parasite with a victim complex.

"What is the difference between a man and a parasite? A man builds. A parasite asks "Where is my share?" A man creates. A parasite says, "What will the neighbors think?" A man invents. A parasite says, "Watch out, or you might tread on the toes of god..."

Re: At last! An excuse for our Congress! (-1)

Anonymous Coward | about a year ago | (#44110501)

I see you are recently divorced. Me too. We're having a meeting next month. See you there.

Re:At last! An excuse for our Congress! (-1)

Anonymous Coward | about a year ago | (#44110641)

Haha dude, you seriously need to hang around with more laid back chicks!

Re:That's nice (3, Funny)

TWiTfan (2887093) | about a year ago | (#44110923)

I'm more confused than before

Just look in this box. In it, you'll find either a better summary or a dead cat.

You keep using that word... (1)

Anonymous Coward | about a year ago | (#44110109)

Not to be all pedantic, or anything, but "to moot" something is to debate. If they're mooting a proof, then the proof is very much under debate. /sunglasses

Re: You keep using that word... (2, Informative)

Anonymous Coward | about a year ago | (#44110221)

I too found the title odd

[moot]
- adjective
1. open to discussion or debate
2. of little practical value

Re: You keep using that word... (4, Informative)

mrvan (973822) | about a year ago | (#44110291)

http://dictionary.reference.com/browse/moot [reference.com] says:

verb (used with object)
4. to present or introduce (any point, subject, project, etc.) for discussion.
5. to reduce or remove the practical significance of; make purely theoretical or academic.

So meaning 4 seems appropriate. Strange that a word simultaneously means to introduce it and to remove it from consideration, but it is a pretty old word I think so it has probably evolved quite a bit.

Origin:
before 900; Middle English mot ( e ) meeting, assembly, Old English gemt; cognate with Old Norse mt, Dutch gemoet meeting. See meet1

Re: You keep using that word... (1)

guttergod (94044) | about a year ago | (#44110429)

http://dictionary.reference.com/browse/moot [reference.com] says:

verb (used with object) 4. to present or introduce (any point, subject, project, etc.) for discussion. 5. to reduce or remove the practical significance of; make purely theoretical or academic.

So meaning 4 seems appropriate. Strange that a word simultaneously means to introduce it and to remove it from consideration, but it is a pretty old word I think so it has probably evolved quite a bit.

Origin: before 900; Middle English mot ( e ) meeting, assembly, Old English gemt; cognate with Old Norse mt, Dutch gemoet meeting. See meet1

Sounds like "theory" to me. What's with science and ambiguous words? :)

Re: You keep using that word... (2)

RaceProUK (1137575) | about a year ago | (#44110573)

http://dictionary.reference.com/browse/moot [reference.com] says:

verb (used with object) 4. to present or introduce (any point, subject, project, etc.) for discussion. 5. to reduce or remove the practical significance of; make purely theoretical or academic.

So meaning 4 seems appropriate. Strange that a word simultaneously means to introduce it and to remove it from consideration, but it is a pretty old word I think so it has probably evolved quite a bit.

Origin: before 900; Middle English mot ( e ) meeting, assembly, Old English gemt; cognate with Old Norse mt, Dutch gemoet meeting. See meet1

Sounds like "theory" to me. What's with the media's reporting of science and ambiguous words? :)

FTFY

Re: You keep using that word... (0, Flamebait)

Anonymous Coward | about a year ago | (#44110815)

It's a tactic they use to keep the uninformed thinking something is fact when in reality it is just someone's (unproven) idea. It's been working for a number of generations now. You'd be surprised how many people think macro evoloution has been scientifically proven, or global warming. They get one piece of the puzzle and think they've got the whole picture.

Re: You keep using that word... (0)

Anonymous Coward | about a year ago | (#44113027)

Downmodded. But no one can explain the thousands of "missing links" in evolution. Why would non-flowering plants evolve into flowering plants unless it happened spontaneously? Why would wolves evolve into domesticated dogs unless spontaneously? Volumes could be written about this, but everyone accepts macro evolution without infallible proof.

Re: You keep using that word... (1)

Speare (84249) | about a year ago | (#44112121)

I was just about to comment about the "uncertainty" in the use of the word moot; whether it meant "to discuss" or "to dismiss need of discussion." A perfect word for the topic, if you think about it.

contranym (0)

Anonymous Coward | about a year ago | (#44112137)

So meaning 4 seems appropriate. Strange that a word simultaneously means to introduce it and to remove it from consideration, but it is a pretty old word I think so it has probably evolved quite a bit.

These class of words are called auto-antonyms (or contronyms):

http://en.wikipedia.org/wiki/Auto-antonym

There's quite a few of them.

(Heh, CAPTCHA: "instruct".)

Re: You keep using that word... (1)

AlecC (512609) | about a year ago | (#44112577)

I would say the two meanings come from the same source, but with different spins.
Meaning 4: Needs to go to the moot to be debated: truth still uncertain
Meaning 5: Taken out of current consideration by postponing until the moot (which was an annual event)

I.e. meaning 4 regards the moot as a place where complex things are debated, while meaning 5 regards it as an annual event where a lot of hot air is expended about nothing. Both are probably correct.

Re:You keep using that word... (0)

Anonymous Coward | about a year ago | (#44110235)

Not to be all pedantic, or anything, but "to moot" something is to debate. If they're mooting a proof, then the proof is very much under debate. /sunglasses

If you had RTFA (yes I know, this is Slashdot) then you'd know that there's indeed a debate about it.

Re:You keep using that word... (-1)

Anonymous Coward | about a year ago | (#44110391)

yes I know, this is Slashdot

I thought this was /r/slashdot. I wish it were though. Reddit is much better.

Re:You keep using that word... (1)

Barryke (772876) | about a year ago | (#44110583)

I am not a native English speaker butt..

To me, mooted in the past sense meant some (since irrelevant) argument being leveled.
This puts a lot of things i read/heard in the past into a new (almost the opposite) perspective..

Butt pun intended of course.

Re:You keep using that word... (1)

ebno-10db (1459097) | about a year ago | (#44112191)

The joy of English is that it often makes little sense, even to its native speakers (like me). Your understanding of 'moot' is the most common usage, but it can also mean to debate, and a bunch of other vaguely related things.

http://www.merriam-webster.com/dictionary/moot [merriam-webster.com]

Uncertaintiy principle and Foruier Transforms (5, Interesting)

Grantbridge (1377621) | about a year ago | (#44110125)

The uncertainty principle is the same as taking a Fourier transform of a sound pulse. If the time of the wave is short then the uncertainty in the frequency is high, and you get a large width in frequency space. If the wave is on for a long time, you get a nice sine wave and the uncertainty in the frequency is low, but the uncertainty in the time is now high. The maths for momentum/position of electrons comes out the same as time/frequency of sound waves. You get the uncertainty principle with non-quantised waves anyway, its not magic!

Re:Uncertaintiy principle and Foruier Transforms (0)

Anonymous Coward | about a year ago | (#44110161)

The authors understand this of course, as you will see if you look at their paper. They are formulating and proving a different uncertainty principle, more in line with Heisenberg's original physical intuition.

Re:Uncertaintiy principle and Foruier Transforms (1)

wonkey_monkey (2592601) | about a year ago | (#44110245)

If the wave is on for a long time, you get a nice sine wave and the uncertainty in the frequency is low, but the uncertainty in the time is now high.

What do you mean by "the time"? Duration?

Re:Uncertaintiy principle and Foruier Transforms (0)

Anonymous Coward | about a year ago | (#44110289)

he means the position on the time axis (well kinda). In a sense, you can consider the duration as the uncertainty over the time position. The sine is not happening at a precise point in time: since it has a duration it is happening over many point in time.

Re:Uncertaintiy principle and Foruier Transforms (2, Informative)

Anonymous Coward | about a year ago | (#44110299)

He means the location of the sonic event. If you think of sound as particulate (a series of events a la granular synthesis) then the frequency of each event and the location in time of each event satisfy a sort of uncertainty principle. It's because the FFT of sine * normal curve is sine * normal curve, but the width of the normal curve is conjugate in each case (the limiting case is sine * delta -> sine * 1). This width represents the "certainty" that the actual frequency or location in time is at the center point. It's a neat trick but it's not clear how or if it relates to QM, except via the mathematical equivalence. Once you start asking "what, then is h?" or "how does scalar amplitude relate to quantum phase" the illusion of relevance kind of vanishes.

Re:Uncertaintiy principle and Foruier Transforms (0)

Anonymous Coward | about a year ago | (#44110377)

Sorry, my bad, we should have FFT[cosine * 1] -> delta and FFT[cosine * delta] -> 1. There is not a trig function on both sides, and I should be using cosine instead of sine, so I stay in the real domain.

Re:Uncertaintiy principle and Foruier Transforms (1)

Anonymous Coward | about a year ago | (#44110295)

You mean to say that the frequency spectrum of a finite time duration signal is inifinte, while the frequency spectrum of a signal with infinite time duration is finite.

Re:Uncertaintiy principle and Foruier Transforms (0)

Anonymous Coward | about a year ago | (#44110533)

the frequency spectrum of a signal with infinite time duration is finite.

I'm pretty sure that no one means to say that.

Re:Uncertaintiy principle and Foruier Transforms (0)

Anonymous Coward | about a year ago | (#44110653)

The textbook formula is delta X * delta P >= hbar/2.

delta X is the uncertainty in position. delta P is the uncertainty in momentum.

But how do we measure momentum? It's the mass*velocity ==> mass* dX/dT.

So, what we are saying is that we can't know the position (deltaX) very precisely if we know the velocity dX/dT precisely. That makes perfect sense because to know dX/dT, we have to follow the particle for a while, in which case we don't know any more where it is precisely. Or even more basically, as we make dT smaller and smaller, we approach dT=0, at which point the formula is mathematically undefined ( x/0 is always undefined.)

Now, in classical mechanics, one can pretend that he knows these values perfectly and construct a "Worldline" to show a particle's history. But that is an idealization. Quantum Mechanics is what you get when you try to zoom in on things and see what REALLY is going on at the microscopic level. (That's not even touching upon the theory that space itself is quantized.)

Re:Uncertaintiy principle and Foruier Transforms (1)

Mashdar (876825) | about a year ago | (#44110855)

There is no uncertainty in the output of a Fourier transform. What you are refering to are the frequency components of the transients. If you flip a switch, there is a huge amount of non-linearity.

Also, a non-noisy Fourier transform is reversible. This is the exact opposite of uncertainty. :)

Re:Uncertaintiy principle and Foruier Transforms (1)

instagib (879544) | about a year ago | (#44111349)

The uncertainty principle is the same as taking a Fourier transform of a sound pulse.

Which explains why one can't be sure if MP3's are music or not.

Re:Uncertaintiy principle and Foruier Transforms (0)

Anonymous Coward | about a year ago | (#44112367)

justin_beiber.mp3 - definitely NOT music.

Re:Uncertaintiy principle and Foruier Transforms (1)

Connie_Lingus (317691) | about a year ago | (#44111623)

isnt that simply because Dirac's and Schrodinger's QM wave equations are actually Fourier transforms at heart?

Re:Uncertaintiy principle and Foruier Transforms (1)

thrich81 (1357561) | about a year ago | (#44111985)

The AC just stated this, but I'll expound -- the "Fourier transform" uncertainty you describe comes from the simple mathematics of the basics of Quantum theory and I don't really see a way to refute it if you accept those basics (observables of position and momentum are described by linear operators which don't commute). Heisenberg's uncertainty principle (observation of position disturbs momentum and vice versa) is usually described as limitation in the way we can make observations and as such seemed to be (at first glance at least) to be not fundamental and something that could be defeated with clever experimental apparatus.

Re:Uncertaintiy principle and Foruier Transforms (1)

Warbothong (905464) | about a year ago | (#44113285)

observation of position disturbs momentum and vice versa

That's the observer effect, which TFA seems to be talking about. The observer effect implies that there is an exact position and momentum; particles can be little billiard-balls if we like, but any attempt to measure them will disturb them.

The uncertainty principle, as it is currently understood, says that there is no such thing as an exact position or momentum. Particles are wave-packets in force-fields. When we introduce quantum constraints, eg. the integral of (area under) the wave packet is some discrete amount, the uncertainty principle falls out naturally.

It's easiest to imagine the case close to zero. For example, having a near-certain position means not being spread out in space. To maintain the constant area, this requires a large amplitude. Likewise a near-zero amplitude must be spread out in space to make up the same area. This is position/momentum uncertainty.

If we want a packet of near-zero duration (eg. a Dirac delta), then we need to build up lots of Fourier terms, which spreads out the overall wavelength. Likewise, if we want a precise wavelength, we need to get closer to a pure sine wave, but that means we get a longer and longer duration (a completely pure sine wave would last forever). That's basically the energy/time uncertainty.

only "discrete" Fourier/Integral transforms (1)

peter303 (12292) | about a year ago | (#44112421)

The full Fourier Integral has no frequency limits. The discrete transform, i.e the one usually programmed in computers, and its cousin the Fast Fourier Transform, are frequency limited at the small end by the sampling inerval and the large end by the length of the input.

Re:Uncertaintiy principle and Foruier Transforms (0)

Anonymous Coward | about a year ago | (#44112463)

The analogy breaks here: for a sound pulse you can increase the sampling rate and subsequently increase both time and frequency resolution.
In the quantum world you have that annoying speed of light constant that you cannot increase.

Certain uncertainty (1)

Anonymous Coward | about a year ago | (#44110153)

The uncertainty principle applies to everything, not just subatomic particles. Just that most of the time the precision required to test it is impossible to achieve (see the wavelength of the Sun for instance). As examples of macroscopic systems where it does apply, see uncertainty relations for the superconducting state.

Re:Certain uncertainty (1)

VortexCortex (1117377) | about a year ago | (#44110207)

The uncertainty principle applies to everything,

How uncertain are you that this is true?

Re: Certain uncertainty (0)

Anonymous Coward | about a year ago | (#44110403)

The uncertainty principle applies to everything,

How uncertain are you that this is true?

Pretty certain. Don't worry, the conjugate variable has infinite variance so it's all good. :-)

Yo Yo Mr. White,....... (5, Funny)

AbRASiON (589899) | about a year ago | (#44110157)

Don't fuck with Heisenberg folks.

Re:Yo Yo Mr. White,....... (0)

Anonymous Coward | about a year ago | (#44111201)

...bitch

Re:Yo Yo Mr. White,....... (0)

Anonymous Coward | about a year ago | (#44111937)

LOL! I was thinking that, too! :P

Re:Yo Yo Mr. White,....... (0)

Anonymous Coward | about a year ago | (#44111495)

Can someone explain how abrasion got a +5 ? One for each word?

Re:Yo Yo Mr. White,....... (0)

Anonymous Coward | about a year ago | (#44113739)

It was funny to the unintelligent readership slashdot now has. Notice how most comments on this page are uninformed references to a thought experiment designed to show how absurd QM is.

IT = X (-1)

Anonymous Coward | about a year ago | (#44110189)

Solve for X

Infinity

I win

Fixed the summary (1, Informative)

angel'o'sphere (80593) | about a year ago | (#44110201)

... the uncertainty principle states that it is impossible to simultaneously know^H^H^H^H measure the exact position and momentum of a subatomic particle the more precisely one knows the particle's position at a given moment, the less precisely one can know the value of its momentum.

Fix.

Re:Fixed the summary (3, Informative)

Prune (557140) | about a year ago | (#44110259)

It's not just a practical issue for measurement, so your "fix" is invalid. The correct explanation is in this post: http://science.slashdot.org/comments.pl?sid=3904863&cid=44110125 [slashdot.org]

Re:Fixed the summary (1)

angel'o'sphere (80593) | about a year ago | (#44110285)

My fix is valid. The article summary is simply wrong.
The post you link is only a simplified explanation for a lay man (and has nothing to do with heisenberg, it has btw its own name: "Shannons sampling theorem").

Re:Fixed the summary (2, Informative)

Anonymous Coward | about a year ago | (#44110319)

Indeed. I don't know what crap "undergraduate textbooks" people use near the north pole, but here down under, the principle of Heisenberg is taught using _math_.

It has always been about measuring (not "knowing", the universe doesn't give a damn about what you know or don't know or it would forbid god from existing. Instead, it just hampers aquiring new knowledge of the full state vector ;p). And it has always been a nice mathematical, strictly quantified trade off between the precision you'll get out of one of the measurements being inversely correlated to the precision you'll get out of the other measurement because the product of the two must be at least half the reduced plank constant.

Re:Fixed the summary (0)

Anonymous Coward | about a year ago | (#44113761)

No, it is not valid. http://slashdot.org/comments.pl?sid=3904863&cid=44112299

Re:Fixed the summary (0)

etash (1907284) | about a year ago | (#44110509)

you are completely wrong. heisenberg's principle is purely PRACTICAL. it doesn't say that in theory the particle won't have a specific momentum at a specific position. It just states our practical inability to measure with accuracy both simultaneously.

Re:Fixed the summary (0)

Anonymous Coward | about a year ago | (#44110551)

> ... it doesn't say that in theory the particle won't have a specific momentum at a specific position

Actually it says exactly that.

Re:Fixed the summary (0)

etash (1907284) | about a year ago | (#44110753)

nope it doesn't. learn to read and comprehend.

Re:Fixed the summary (1)

geekoid (135745) | about a year ago | (#44112299)

and you can teach you grandmother to suck eggs. You are wrong.

"it doesn't say that in theory the particle won't have a specific momentum at a specific position."
Wow, that's not even wrong.
That's not what anyone is saying. You can not measure it's momentum and position with the same measurement, not to be confused with the observer effect.

The theory says its in the fundamental nature of all quantum systems. IN fact, it's in all systems, just the the quantum system i'ts more obvious.
How to you explain your statement again de Brooglie work? you ARE familiar with de Brooglie's work, right? you would just make such a statement without at least the basic fundamental reading of his work, right? RIGHT?

Ignorance can be fixed, so I don't mind that but bold face incorrect statements from pieces of crap like you piss me off.

Re:Fixed the summary (-1)

Anonymous Coward | about a year ago | (#44114055)

geekoid, you're such a dumb fuck. And it's "bald face" not "bold face". God damn.

Re:Fixed the summary (0)

Anonymous Coward | about a year ago | (#44110767)

Exactly. People's intuition that particles are somehow tiny billiard balls and thus "must" have a specific position and momentum is WRONG. That's what Heisenberg's principle is about. The universe is FAR stranger than our intuitions about it would allow, and one of the ways in which it's stranger is this uncertainty.

People ALWAYS muddle this up with a simple problem from introductory Newtonian mechanics, about how difficult it is to measure things accurately. But that's not Uncertainty. If you learned that it's the same thing you learned WRONG and whoever taught that fucked up, probably because they were trying to teach you without understanding what the hell they were talking about. You will get precisely nowhere in quantum mechanics by believing that the quantum world is just a tinier version of the intuitive human scale world. But that's OK so long as all you really wanted was to get a job on Wall Street or something. It's only a problem if you actually wanted to do Quantum Physics.

Re:Fixed the summary (0)

Anonymous Coward | about a year ago | (#44111107)

to prove something you need to link to something better than the comment section of slashdot

Re:Fixed the summary (1)

The_Wilschon (782534) | about a year ago | (#44114007)

Check chapter 9, (pages 237 and following), of the second edition of Principles of Quantum Mechanics by Ramamurti Shankar. Or, section 1.6 (page 18-20) and section 3.5 (page 110-118), of the second edition of Introduction to Quantum Mechanics by David J. Griffiths.

I'm sorry that I can't hyperlink to a physical book. But maybe you could go to your local public library and find a copy of one of them.

Re:Fixed the summary (2)

The_Wilschon (782534) | about a year ago | (#44113865)

Correct fix: The uncertainty principle states that it is impossible for a particle to be in a state in which both the position and momentum (or any pair of observables represented by non-commuting operators) are exactly defined, or even well-defined beyond a certain limit determinable from the commutator of the pair of operators.

It has nothing to do with measurement, and everything to do with the mathematical existence of quantum states with certain properties. TFA is actually dealing with the observer effect, which does have to do with measurement, and which was Heisenberg's original intuitive idea.

Define "secure" in this day and age. (1)

Anonymous Coward | about a year ago | (#44110255)

"...but it would also suggest that quantum-encrypted messages can be transmitted securely."

Well, I suppose that would depend on the level of ignorance one carries around when defining "secure".

Somehow, I strongly doubt this will be above and beyond NSA's illegal and highly classified activity to ensure we're all safe from terrorists.

Re:Define "secure" in this day and age. (0)

Anonymous Coward | about a year ago | (#44110819)

Even the NSA cannot circumvent the very laws of physics.

Re:Define "secure" in this day and age. (0)

Anonymous Coward | about a year ago | (#44112427)

I don't know about that. Circumventing laws is the stock and trade of the NSA.

Why "Proof Mooted"? (0)

Anonymous Coward | about a year ago | (#44110279)

The headline does not fit the summary at all.

Just accept QM already (0)

Warbothong (905464) | about a year ago | (#44110327)

the uncertainty principle states that it is impossible to simultaneously know the exact position and momentum of a subatomic particle

I find phrases like this misleading. I think it's more intellectually honest to say something along the lines of:

the uncertainty principle states that position and momentum are not independent quantities, but (incompatible) expressions of a more fundamental property.

Popsci keeps claiming that 'everything we thought knew is wrong' based on the slightest whiff of a strange experimental result, yet when quantum mechanics *does* prove wrong everything we thought we knew (like the concepts of position and momentum), with repeated experiments of incredible precision, popsci clings to those old notions and acts like QM is wacky.

Re:Just accept QM already (1)

wonkey_monkey (2592601) | about a year ago | (#44110353)

I find phrases like this misleading.

John Q Public finds that sort of phrase quickly and easily understandable, which, I would say, are not attributes of your proposed replacement.

Re:Just accept QM already (0)

Anonymous Coward | about a year ago | (#44110941)

Look back 1000 years to what we knew then. How much of that remains true today? In the grand scheme of things we know exactly jack schite. What makes you think that when someone went "ahhh, we had that wrong. It actually works like this...." they got it right this time? No, 1000 years from now we'll look as foolish as those who believed the earth was flat and the universe was earthcentric.

I don't say that to defend Popsci, but to point out that they are only doing what science does: continually revise update, and acknowledge that not much is set in stone.

I laughed... (5, Funny)

Valentttine (2420782) | about a year ago | (#44110337)

Heisenberg was speeding down the highway. Cop pulled him over and says "Son, do you have any idea how fast you were going back there?" Heisenberg said, "No, but I knew where I was". The cop says "You were doing 100 miles an hour" to which Heisenberg replies "Great, now I'm lost".

Re:I laughed... (0)

Anonymous Coward | about a year ago | (#44110483)

Heisenbergs wife asks him "Do you know where my car keys are?", "I have no idea" he replies, "but I can tell you exactly how fast they are moving."

Re:I laughed... full version ;) (5, Funny)

HxBro (98275) | about a year ago | (#44110581)

Heisenberg and Schrodinger are driving, and get pulled over.

Heisenberg is in the driver's seat, the officer asks "do you know how fast you were going?"

Heisenberg replies, "No, but I know exactly where I am!"

The officer looks at him confused and says "you were going 108 miles per hour!"

Heisenberg throws his arms up and cries, "Great! Now I'm lost!"

The officer, now more confused and frustrated orders the men outside of the car, and proceeds to inspect the vehicle. He opens the trunk and yells at the two men, "Hey! Did you guys know you have a dead cat back here?"

Schrodinger angrily yells back, "We do now, asshole!"

I just read the article ( arXiv PDF ) (3, Interesting)

vikingpower (768921) | about a year ago | (#44110417)

It seems the paper can be understood with undergraduate mathematics. The 3 authors' argumentation seems quite clear, and their proof rather convincing. One wonders, now and at this point, whether a lab experiment could be set up to falsify the whole thing... If not, Heisenberg stands proven true. Of the impact upon quantum cryptography I am not so sure, however, supposing that it takes "some quite advanced mathematics" ( as Wolfram once said about cyclotomic fields ) to tackle that issue.

Re:I just read the article ( arXiv PDF ) (2)

NoNonAlphaCharsHere (2201864) | about a year ago | (#44110547)

The quantum cryptography issue is a question of whether or not it is possible in principle to eavesdrop on (measure) a quantum system without disturbing it.

Re:I just read the article ( arXiv PDF ) (1)

Anonymous Coward | about a year ago | (#44110693)

Quantum cryptography leans very heavily if it is possible to measure two different attributes of a quanta. For most quantum cryptography the quantum is a single photon and the different attributes:
- horizontal or vertical polarization
- the two diagonal polarization.

It is important that you can only measure either the top two (horizonal/vertical) or the bottom two (two diagonals) but never both.

Re:I just read the article ( arXiv PDF ) (0)

Anonymous Coward | about a year ago | (#44111419)

GCHQ and NSA already tap fiber optics underseas from all countries.

So it is possible. Whether they can detect the evesdropping, that is another mattern but they ARE evesedropping and have been since the days of fiber began.

Proof is already from 1929 (4, Interesting)

johanw (1001493) | about a year ago | (#44110455)

Robertson proved in 1929 already the general form of the uncertainty relation. It has nothing to do with Fourier transforms, wavefunctions and disturbance by measurements, but only with the operator character of (some) quantum mechanical observables. I got the proof from this textbook by Stephen Gasiorowicz, unfortunately they skipped this important result from the latest edition (that circulates on internet in the usual places). More information can be found in https://en.wikipedia.org/wiki/Uncertainty_principle#Robertson.E2.80.93Schr.C3.B6dinger_uncertainty_relations [wikipedia.org]

From Quantum Physics by Stephen Gasiorowicz, ISBN 0 471 29281-8

It is important to note that the uncertainty relation

(Delta A)^2 (Delta B)^2 >= \langle i[A,B] \rangle^2 / 2

was derived without any use of the wave concepts or the reciprocity between
a wave form and its fourier transform. The results depends entirely on the
operator properties of the observables A and B.

Re:Proof is already from 1929 (2)

dpilot (134227) | about a year ago | (#44110759)

I find it interesting that there is generally such discomfort with Heisenberg's Uncertainty. I'll grant that its application to quantum cryptography is practical, but for the most part I think this discomfort is rooted in people not liking that something isn't just unknown, but unknowable.

Doesn't bother me a bit - once you accept that idea that quantum mechanics actually does describe reality.

Or another way of looking at it - if you consider all of reality to be a giant simulation, "Aitch-Bar" (Credit for spelling to college prof, name forgotten. (Phillip Bevington?)) becomes simply the error criteria used by the simulator to define a "step".

Re:Proof is already from 1929 (1)

geekoid (135745) | about a year ago | (#44112349)

unknowable but nor unpredictable. If I know it's movement I can predict* it's location at a latter time of measurement. Of course at the later time I will not know the momentum at that particular time.

*Probably :)

Re:Proof is already from 1929 (1)

wonkey_monkey (2592601) | about a year ago | (#44112471)

unknowable but nor unpredictable.

It is as unpredictable as it is unknowable - that is, to a certain degree as defined by the HUP - because prediction requires knowledge. If your knowledge is imperfect, your prediction will be imperfect.

Re: Proof is already from 1929 (0)

Anonymous Coward | about a year ago | (#44110809)

How would you define operators without touching wave functions?

Re:Proof is already from 1929 (0)

Anonymous Coward | about a year ago | (#44111845)

It has nothing to do with Fourier transforms, wavefunctions and disturbance by measurements

In the very article you link it explains that the Uncertainty Principle gives rise to the Gabor Limit when applied to time-frequency analysis, so it's in fact the same effect, only more generally expressed.

Obligatory Douglas Adams quote:- (0)

Anonymous Coward | about a year ago | (#44110461)

"Rigidly defined areas of doubt & uncertainty"

Re:Obligatory Douglas Adams quote:- (1)

FearTheFez (2592613) | about a year ago | (#44111013)

To be used as the theoretical basis of the Infinite Improbability Drive. Now to go make a really HOT cup of tea. Where did Marvin put the kettle.............

It was a bittersweet occasion (0)

Anonymous Coward | about a year ago | (#44110881)

The acceptance letter:

"We are pleased to announce that your paper has been accepted for publication so-and-so and will appear in issue such-and-such.

Condolences about your cat."

Phrasing (1)

Tyler Durden (136036) | about a year ago | (#44111637)

According to every undergraduate physics textbook, the uncertainty principle states that it is impossible to simultaneously know the exact position and momentum of a subatomic particle...

What always struck me about the above statement is it seems to imply that there is an exact simultaneous position and momentum to subatomic particles that cannot be known. Maybe the truth is stronger than that - subatomic particles simply don't have precise position/momentums.

Duh... (1)

WillyWanker (1502057) | about a year ago | (#44112501)

Everyone knows you need to have good, fully functional Heisenberg compensators, right?

But what if two observers look at the particle? (0)

Anonymous Coward | about a year ago | (#44112603)

One looks at the position and the other looks at the velocity at the same time?
Oh, and they tell each other the position and velocity AT THE SAME TIME.
Apparently Heisenberg didn't have a friend.

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