Slashdot Mirror

← Back to Stories (view on slashdot.org)

Proof Mooted For Heisenberg's Uncertainty Principle

Posted by Soulskill on from the he's-the-one-who-knocks dept.

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."

158 comments

  1. That's nice by Anonymous Coward · · Score: 0

    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!

    1. Re:That's nice by Z00L00K · · Score: 5, Funny

      Yet another proof of the principle.

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

      --
      If builders built buildings the way programmers wrote programs, then the first woodpecker would destroy civilization.
    2. Re:That's nice by Anonymous Coward · · Score: 0

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

    3. Re:That's nice by RaceProUK · · Score: 1

      My guess would be 'miaow'

      --
      No colour or religion ever stopped the bullet from a gun
    4. Re: That's nice by JWW · · Score: 1

      Oh wait, the cats dead. Or is it?

    5. Re:That's nice by dreamchaser · · Score: 2

      My guess would be 'miaow'

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

    6. Re: That's nice by SeeingMole · · Score: 2

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

    7. Re:That's nice by TWiTfan · · Score: 3, Funny

      I'm more confused than before

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

      --
      The cow says "Moo." The dog says "Woof." The Timothy says "Thanks, valued customer. We appreciate your input."
    8. Re: That's nice by Sponge+Bath · · Score: 2

      It's just pining for the fjords.

    9. Re:That's nice by wbr1 · · Score: 1

      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.

      --
      Silence is a state of mime.
    10. Re: That's nice by Bengie · · Score: 4, Funny

      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.

    11. Re:That's nice by Anonymous Coward · · Score: 0

      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

    12. Re:That's nice by Dishevel · · Score: 1

      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. :)

      --
      Why is it so hard to only have politicians for a few years, then have them go away?
    13. Re:That's nice by geekoid · · Score: 1

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

      --
      The Kruger Dunning explains most post on /. http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
    14. Re:That's nice by The+Mighty+Buzzard · · Score: 1

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

      --
      Violence is like duct tape. If it doesn't solve the problem, you didn't use enough.
    15. Re: That's nice by davester666 · · Score: 1

      Is the box in the shape of a hat?

      --
      Sleep your way to a whiter smile...date a dentist!
    16. Re: That's nice by Migraineman · · Score: 1

      The "uncertainty" in this principle is whether or not you will be mauled by a ball of fur-and-claws should you open said box. Your curiosity compels you to determine if the box contains a cat ... because it's kinda stupid like that. However, your self-preservation instinct is aware of the potential to condense an angry-cat reality via observation. What to do? What to do? ...

      Oh, open the goddamned box already, ferchrssakes.!

    17. Re:That's nice by Anonymous Coward · · Score: 0

      I'm more confused than before

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

      A dead Slashdot editor would be best.

      Although one could certainly argue being dead or alive has no effect on their ability to edit. Or rather their lack of ability.

    18. Re: That's nice by Anonymous Coward · · Score: 0

      It's at the bottom (dead cat).

      Duh....

    19. Re:That's nice by Anonymous Coward · · Score: 0

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

      Instead of summary, package contained bobcat.

      Would not buy again.

    20. Re:That's nice by dreamchaser · · Score: 1

      If you hear it then you've measured it.

    21. Re:That's nice by Meski · · Score: 1

      Would a quantum cat zombie eat brain cat food?

    22. Re: That's nice by Meski · · Score: 1

      It's safer to drop a hair-drier into a bathtub than a cat. (whether or not you are in the bath)

    23. Re:That's nice by Meski · · Score: 1

      I'd say mod that to funny, but a bit wasted on an AC.

  2. You keep using that word... by Anonymous Coward · · Score: 1

    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

    1. Re: You keep using that word... by Anonymous Coward · · Score: 2, Informative

      I too found the title odd

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

    2. Re:You keep using that word... by Anonymous Coward · · Score: 0

      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.

    3. Re: You keep using that word... by mrvan · · Score: 4, Informative

      http://dictionary.reference.com/browse/moot 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

    4. Re: You keep using that word... by guttergod · · Score: 1

      http://dictionary.reference.com/browse/moot 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? :)

      --

      Apple built a platform for their ideas, Google built one for everyone's.

    5. Re: You keep using that word... by RaceProUK · · Score: 2

      http://dictionary.reference.com/browse/moot 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

      --
      No colour or religion ever stopped the bullet from a gun
    6. Re:You keep using that word... by Barryke · · Score: 1

      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.

      --
      Hivemind harvest in progress..
    7. Re: You keep using that word... by Anonymous Coward · · Score: 0, Flamebait

      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.

    8. Re: You keep using that word... by Speare · · Score: 1

      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.

      --
      [ .sig file not found ]
    9. Re:You keep using that word... by ebno-10db · · Score: 1

      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

    10. Re: You keep using that word... by AlecC · · Score: 1

      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.

      --
      Consciousness is an illusion caused by an excess of self consciousness.
    11. Re: You keep using that word... by Anonymous Coward · · Score: 0

      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.

    12. Re: You keep using that word... by Jamu · · Score: 1

      There are missing links because the fossil records can't be found. They disappear in a process akin to particulate adhesion to linear pastaforms (and the resulting consumption). Evolution is then obviously due to divine interference by noodly appendage, and the missing links are evidence of this.

      --
      Who ordered that?
    13. Re: You keep using that word... by c++0xFF · · Score: 1

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

      Wow! I finally understand the term Entmoot. Thanks!

    14. Re: You keep using that word... by radarskiy · · Score: 1

      Or gravity

    15. Re: You keep using that word... by Belial6 · · Score: 1

      It's not just strange, it bad.

    16. Re: You keep using that word... by alva_edison · · Score: 1

      http://www.talkorigins.org/indexcc/CC/CC200.html
      http://www.talkorigins.org/indexcc/CC/CC250.html
      http://en.wikipedia.org/wiki/Origin_of_the_domestic_dog
      http://www.talkorigins.org/indexcc/CB/CB901.html

      --
      He effected a bored affect.
    17. Re:You keep using that word... by Jane+Q.+Public · · Score: 1

      "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"

      My thought exactly. To moot is to label something debatable, or (perhaps more accurately in context) to make something inconsequential or to render it of no importance.

      But I saw nothing in TFA that suggests to me the word "moot". Not a thing.

    18. Re: You keep using that word... by Jane+Q.+Public · · Score: 2

      "So meaning 4 seems appropriate"

      4 may be appropriate, but I think it's a thin argument. But even so... so what? Even if 4 is the way it was intended to be used, how is that even remotely headline-worthy?

    19. Re: You keep using that word... by Anonymous Coward · · Score: 0

      The definition of moot that involves discussion is archaic. I suggest you get a better dictionary. The submitter was likely meaning that Heisenberg's specific proof was made moot by a more general proof. That is jumping the gun as this new proof has not yet met rigorous scrutiny.

    20. Re: You keep using that word... by RockDoctor · · Score: 1

      Wow! I finally understand the term Entmoot. Thanks!

      Given that Tolkein's day job was as a philologist and etymologist for the OED, I'm moderately surprised that you didn't know by the time you'd finished reading the chapter where the Entmoot starts. Or am I the only person here who first read the book curled up in a chair beside the bookshelves with dictionaries, encyclopedia, etc?

      --
      Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
  3. Uncertaintiy principle and Foruier Transforms by Grantbridge · · Score: 5, Interesting

    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!

    1. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 0

      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.

    2. Re:Uncertaintiy principle and Foruier Transforms by wonkey_monkey · · Score: 1

      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?

      --
      systemd is Roko's Basilisk.
    3. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 0

      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.

    4. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 1

      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.

    5. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 2, Informative

      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.

    6. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 0

      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.

    7. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 0

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

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

    8. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 0

      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.)

    9. Re:Uncertaintiy principle and Foruier Transforms by Mashdar · · Score: 1

      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. :)

    10. Re:Uncertaintiy principle and Foruier Transforms by instagib · · Score: 1

      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.

    11. Re:Uncertaintiy principle and Foruier Transforms by Connie_Lingus · · Score: 1

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

      --
      never bring a twinkie to a food fight.
    12. Re:Uncertaintiy principle and Foruier Transforms by thrich81 · · Score: 1

      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.

    13. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 0

      justin_beiber.mp3 - definitely NOT music.

    14. Re:Uncertaintiy principle and Foruier Transforms by Anonymous Coward · · Score: 0

      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.

    15. Re:Uncertaintiy principle and Foruier Transforms by Warbothong · · Score: 1

      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.

    16. Re:Uncertaintiy principle and Foruier Transforms by ggraham412 · · Score: 1

      Another interesting way to think about it is in terms of seeing if you can figure out where you are in the graph by looking only at the curve. For example, if the frequency curve is a simple blip, you can tell exactly where you are on the frequency axis by looking only at the blip, it's like driving past the Lonely Mountain on the highway. But then you couldn't tell where you are on the time axis by looking only at the curve because the FT of the blip is a sine wave. It would be like driving down a long featureless highway where the mile markers all say "2 pi" - no telling where you are!

    17. Re:Uncertaintiy principle and Foruier Transforms by AdamHaun · · Score: 2

      What do you mean by "the time"?

      Frequency (or period, or wavelength) is an inherently non-local idea. It's easy to forget when you're looking at a graph, but mathematically, sine waves are eternal -- they go from t= -inf to +inf. The period is defined such that for all time:

      sin(t) = sin(t + period)

      If you cut off the sine wave (making a pulse), that's no longer true, and you can't say it has one period (or frequency, or wavelength) anymore. The shorter your sine pulse gets, the less meaningful that single number becomes. Now let's say you cut your pulse down to just part of one cycle -- say, the rising part at the beginning, so your signal is now an eternity of silence with a little bump in the middle. Does it still have a period (or frequency, or wavelength)?

      Asking when a pure, eternal sine wave "happens" makes no sense -- it's always "happening". But it does have a well-defined frequency. An infinitesimally short pulse happens at a definite, well-defined time. But it makes no sense to talk about its frequency. In between those two extremes, things get weird.

      Fourier Analysis lets us approach this in a more concrete way. It says that a signal can have many frequencies (expressed as sums of pure, eternal sine waves). That infinitesimally short pulse is actually every frequency put together. More complex signals can cover a range of frequencies (approximately finite). As a result of all this, there's an inverse relationship between localization in the time domain and localization in the frequency domain. It's easiest to see with a Gaussian (normal) distribution, which is its own Fourier transform. When the width (standard deviation) expands in the time domain, it narrows in the frequency domain, and vice-versa.

      Replace "time" and "frequency" with "position" and "momentum", replace the Gaussian with the statistical distribution of your observations, and you have the Heisenberg Uncertainty Principle.

      --
      Visit the
    18. Re:Uncertaintiy principle and Foruier Transforms by Pausanias · · Score: 1

      You don't even need a Fourier transform to get an intuition for the principle. Both the Fourier transform and the uncertainty principle are consequences of the Cauchy-Schwarz integral inequality:

      http://en.wikipedia.org/wiki/Cauchy%E2%80%93Schwarz_inequality#Physics

      So like everything else in physics, it's a consequence of math, not incomprehensible magic.

  4. Certain uncertainty by Anonymous Coward · · Score: 1

    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.

    1. Re:Certain uncertainty by VortexCortex · · Score: 1

      The uncertainty principle applies to everything,

      How uncertain are you that this is true?

    2. Re: Certain uncertainty by Anonymous Coward · · Score: 0

      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. :-)

  5. Yo Yo Mr. White,....... by AbRASiON · · Score: 5, Funny

    Don't fuck with Heisenberg folks.

    1. Re:Yo Yo Mr. White,....... by Anonymous Coward · · Score: 0

      ...bitch

    2. Re:Yo Yo Mr. White,....... by Anonymous Coward · · Score: 0

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

    3. Re:Yo Yo Mr. White,....... by Anonymous Coward · · Score: 0

      LOL! I was thinking that, too! :P

    4. Re:Yo Yo Mr. White,....... by Anonymous Coward · · Score: 0

      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.

    5. Re:Yo Yo Mr. White,....... by Anonymous Coward · · Score: 0

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

      Mr White is a character on Breaking Bad. His alias is Heisenberg.

      Why people rate stupid stuff as funny? No explanation.

  6. Fixed the summary by angel'o'sphere · · Score: 1, Informative

    ... 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.

    --
    Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
    1. Re:Fixed the summary by Prune · · Score: 3, Informative

      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

      --
      "Politicians and diapers must be changed often, and for the same reason."
    2. Re:Fixed the summary by angel'o'sphere · · Score: 1

      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").

      --
      Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
    3. Re:Fixed the summary by Anonymous Coward · · Score: 2, Informative

      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.

    4. Re:Fixed the summary by etash · · Score: 0

      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.

    5. Re:Fixed the summary by Anonymous Coward · · Score: 0

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

      Actually it says exactly that.

    6. Re:Fixed the summary by etash · · Score: 0

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

    7. Re:Fixed the summary by Anonymous Coward · · Score: 0

      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.

    8. Re:Fixed the summary by Anonymous Coward · · Score: 0

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

    9. Re:Fixed the summary by geekoid · · Score: 1

      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.

      --
      The Kruger Dunning explains most post on /. http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
    10. Re:Fixed the summary by Anonymous Coward · · Score: 0

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

    11. Re:Fixed the summary by The_Wilschon · · Score: 2

      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.

      --
      SIGSEGV caught, terminating

      wait... not that kind of sig.
    12. Re:Fixed the summary by The_Wilschon · · Score: 1

      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.

      --
      SIGSEGV caught, terminating

      wait... not that kind of sig.
    13. Re:Fixed the summary by etash · · Score: 1

      do not change the subject for the sake of covering your ignorance. Heisenberg's principle says it's impossible to _know_ ( as in MEASURE ) with HIGH accuracy both the momentum and the position. It doesn't say ANYTHING at all about it having or not a particular ( definite ) position or momentum. REREAD the heisenberg's principle.

    14. Re:Fixed the summary by angel'o'sphere · · Score: 1

      Your definitionis wrong, sorry. Perhaps read it up on wikipedia, or perhaps tze american wikipedia page is wrong, too?
      Bottom line it is notmeven about quantum states ... a moving free electron already falls under the uncertainty principle.

      --
      Cost free eBook I read (by iBook/Kobo/Amazon/ObookO/Gutenberg etc.): "The Green Odyssey" by Philip Jose Farmer.
    15. Re:Fixed the summary by maxwell+demon · · Score: 1

      Learn some quantum mechanics. And no, I don't mean popular science versions of quantum mechanics. I mean the real theory.

      And yes, I am a physicist. I have learned that stuff. And no, the uncertainty relation is not just a limit on measurement. The quantum state itself does not and cannot contain information about exact position and exact momentum at the same time. Indeed, even though you can formally write down states where at least one of them is exactly defined, those states are not physical. Physical states have neither a well-defined position nor a well-defined momentum. Independent of any measurement.

      --
      The Tao of math: The numbers you can count are not the real numbers.
    16. Re:Fixed the summary by etash · · Score: 1

      right, so from http://en.wikipedia.org/wiki/Heisenberg's_principle

      Historically, the uncertainty principle has been confused[4][5] with a somewhat similar effect in physics, called the observer effect, which notes that measurements of certain systems cannot be made without affecting the systems. Heisenberg offered such an observer effect at the quantum level (see below) as a physical "explanation" of quantum uncertainty.[6] It has since become clear, however, that the uncertainty principle is inherent in the properties of all wave-like systems, and that it arises in quantum mechanics simply due to the matter wave nature of all quantum objects. Thus, the uncertainty principle actually states a fundamental property of quantum systems, and is not a statement about the observational success of current technology.[7] It must be emphasized that measurement does not mean only a process in which a physicist-observer takes part, but rather any interaction between classical and quantum objects regardless of any observer.[8]

      and from http://en.wikipedia.org/wiki/Observer_effect_(physics)

      The uncertainty principle has been frequently confused with the observer effect, evidently even by its originator, Werner Heisenberg.[8] The uncertainty principle in its standard form actually describes how precisely we may measure the position and momentum of a particle at the same time — if we increase the precision in measuring one quantity, we are forced to lose precision in measuring the other.[9] An alternative version of the uncertainty principle,[10] more in the spirit of an observer effect,[11] fully accounts for the disturbance the observer has on a system and the error incurred, although this is not how the term "uncertainty principle" is most commonly used in practice.

      So you are obviously right. Though I have to be forgiven since even Heisenberg meant what I said and later it became clear that it was an inherent property of the wave like systems.

      HOWEVER I will still say (taking einstein's position) that quantum theory is not how the world actually IS. it's just a semi-accurate representation, like gases laws which give us an approximation and not the accurate position of each molecule of the gas. It's just that the variables are so many and the total particles in all of the universe so many (all of them interacting with all others) that we have to invent an approximate theory (like quantum mechanics) but in reality all atomic and subatomic particles do have a very particular position and momentum. I'ts just our inability to detect it due to the universe being very complex and us being part of it, thus affecting it. (so even schrodinger's cat is in reality wrong).

    17. Re:Fixed the summary by maxwell+demon · · Score: 1

      But Bell's inequality shows that quantum mechanics isn't compatible with local realism. So you'll at least have to give up locality if you want to maintain that assumption. Moreover, you'll probably get problems with noncontextuality (even in the de-Broglie-Bohm interpretation the measured momentum is not one of the particle's intrinsic properties, but the measurement value only arises through interaction with the measurement apparatus).

      --
      The Tao of math: The numbers you can count are not the real numbers.
    18. Re:Fixed the summary by Chuckstar · · Score: 1

      Schrodinger and his cat disagree with you.

      Just like the cat is in a superposition of states before you measure, so is the particle in a superposition of states before you measure. The particle is not in a single classical-like state until disturbed by the measurement.

    19. Re:Fixed the summary by etash · · Score: 1

      of course. the principle of locality is just an approximation too for practical reasons. Every particle in the universe affects all others, nomatter how far it is no matter how small the effect is. It's just that for approximation reasons we don't take (and we can't) them into consideration. But in reality even the mass of an electron on mars' soil will affect by let's say 0.000000000000000000000000000000000000000000000000000000000000000000000000000001% electrons here on earth and that's the cause of the "randonmness".

    20. Re:Fixed the summary by maxwell+demon · · Score: 1

      Nonlocality doesn't just mean that particles affect each other over large distances (for that, long-range forces are more than enough), it means that they do so instantaneously. And anyway, even if you accept nonlocality, there's still the noncontextuality problem.

      --
      The Tao of math: The numbers you can count are not the real numbers.
    21. Re:Fixed the summary by etash · · Score: 1

      i am not a physicist, what is the noncontextuality problem?

    22. Re:Fixed the summary by maxwell+demon · · Score: 1

      Not all measurement results can be well-defined deterministic properties of the system. If all of them are determined, they cannot be just system properties, but must depend on the way they are measured (i.e. they are contextual), and if all of them are pure system properties (i.e. non-contextual), they cannot be determined.

      I'm not sure whether the problem also occurs with position and momentum, but I'd not be surprised if it does.

      See Wikipedia for details.

      --
      The Tao of math: The numbers you can count are not the real numbers.
    23. Re:Fixed the summary by etash · · Score: 1

      I read that a couple of times, though I'm not sure i understand it perfectly. Here is my point of view:

      everything is deterministic, all the properties are exactly determined, it's just that since we are part of the system ( = universe ) it's computably impossible to measure their exact and determined values. It's like godel's incompleteness theorem applied to the universe. We would have to be "out of the universe", know all the data, all the laws and simulate it, in order to have an exact measurement, otherways the measurement itself will affect the end result. These errors are higher, the smaller is the scale of the events ( subatomic particles ) we want to measure.

      there can't possibly be (in my humble opinion) an inherent probabilistic behaviour of subatomic particles. particles don't have a mind (conciousness) of their own, it would also violate the most important of the laws of motion ( that a body will change its momentum only if a force is applied to it ). Now I know that this law is not a god given law, but it sounds sane enough, much more sane than saying that there is an inherent probabilistic nature in elements. Why would a subatomic particle be either here or there? I think it's obvious that it can't, it's just that the factors affecting its position and momentum are so many that to us it looks like probabilistic.

      I'm not sure but i think that what i said provides an answer about the contextuality problem: of course the properties are predetermined. but no, their properties are not independent of the way they are measured because WE ( the physicist, the apparatus is part of the system).

      from Kochen–Specker theorem in wikipedia: The theorem proves that there is a contradiction between two basic assumptions of the hidden variable theories intended to reproduce the results of quantum mechanics: that all hidden variables corresponding to quantum mechanical observables have definite values at any given time, and that the values of those variables are intrinsic and independent of the device used to measure them. The second assumption in my opinion is wrong, the hidden variables properties are still determined, but NOT un-affected by the measurement.

  7. Define "secure" in this day and age. by Anonymous Coward · · Score: 1

    "...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.

    1. Re:Define "secure" in this day and age. by Anonymous Coward · · Score: 0

      Even the NSA cannot circumvent the very laws of physics.

    2. Re:Define "secure" in this day and age. by Anonymous Coward · · Score: 0

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

  8. Why "Proof Mooted"? by Anonymous Coward · · Score: 0

    The headline does not fit the summary at all.

  9. Just accept QM already by Warbothong · · Score: 0

    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.

    1. Re:Just accept QM already by wonkey_monkey · · Score: 1

      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.

      --
      systemd is Roko's Basilisk.
    2. Re:Just accept QM already by Anonymous Coward · · Score: 0

      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.

    3. Re:Just accept QM already by Anonymous Coward · · Score: 0

      John Q Public is continuously mislead about physics concepts due to sloppily constructed catch phrases just the one OP is complaining about. It makes no sense to say you can't "know" things if they aren't actually properties of that system. Some people are just more interested about getting a rise out of people by wow-ing them with awesome-sounding statements rather than actual explanation.

  10. I laughed... by Valentttine · · Score: 5, Funny

    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".

    --
    Here today, gone tomorrow
    1. Re:I laughed... by Anonymous Coward · · Score: 0

      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."

  11. I just read the article ( arXiv PDF ) by vikingpower · · Score: 3, Interesting

    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.

    --
    Religous speak to God. Insane are spoken to by God. When all shut up, one can finally hear Shostakovich in peace
    1. Re:I just read the article ( arXiv PDF ) by NoNonAlphaCharsHere · · Score: 2

      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.

    2. Re:I just read the article ( arXiv PDF ) by Anonymous Coward · · Score: 1

      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.

    3. Re:I just read the article ( arXiv PDF ) by Anonymous Coward · · Score: 0

      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.

  12. Proof is already from 1929 by johanw · · Score: 4, Interesting

    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

    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.

    1. Re:Proof is already from 1929 by dpilot · · Score: 2

      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".

      --
      The living have better things to do than to continue hating the dead.
    2. Re: Proof is already from 1929 by Anonymous Coward · · Score: 0

      How would you define operators without touching wave functions?

    3. Re:Proof is already from 1929 by Anonymous Coward · · Score: 0

      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.

    4. Re:Proof is already from 1929 by geekoid · · Score: 1

      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 :)

      --
      The Kruger Dunning explains most post on /. http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
    5. Re:Proof is already from 1929 by wonkey_monkey · · Score: 1

      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.

      --
      systemd is Roko's Basilisk.
    6. Re: Proof is already from 1929 by The_Wilschon · · Score: 1
      You say to yourself something like:

      Ok, here is some mathematical object called a state. What can I do with a state? Well, I can apply linear operators to a state. Given the properties of linear operators, there are some states that are unaffected (up to an overall scalar multiplication) by each operator. Call those "eigenstates". Call one of the operators the "position" operator. Find the eigenstates of the position operator. Now, I can compute, for any given state, how much overlap with each position eigenstate there is as a function of the corresponding eigenvalue. That overlap is a complex scalar function of position, which we can call a wave function, if we like.

      It's actually much cleaner to start from this sort of abstraction and define the more concrete "wave function" from it than the other way around, partly because it allows you to more easily consider state spaces that, for example, don't have any operators with continuous eigenvalue spaces, like the spins of the ions in a ferromagnetic lattice, or the excitations of atoms/molecules in laser cavity.

      --
      SIGSEGV caught, terminating

      wait... not that kind of sig.
    7. Re: Proof is already from 1929 by Jamu · · Score: 1

      Kind of difficult if A and B are Hermitian.

      --
      Who ordered that?
    8. Re: Proof is already from 1929 by Anonymous Coward · · Score: 0

      You take a class in advanced algebra, specifically vector spaces. Then you go back to QM and realize that you just understood the algebraic formalism and that the wave function is just a projection of the state vector unto the Cartesian coordinate system.

    9. Re:Proof is already from 1929 by hawkfish · · Score: 1

      Yeah. this all sounds like what we went through one week in my Functional Analysis class back in Grad School circa 1988. Anyone know what is new?

      --
      You will not drink with us, but you would taste our steel? - Walter Matthau, The Pirates
    10. Re:Proof is already from 1929 by Belial6 · · Score: 1

      That probably has to do with the fact that since the first days of 'science', and even before the learned men of knowledge have declared things 'unknowable' which later proved out to be knowable. Heisenberg's Uncertainty reeks of the same logic that would declare knowing the will of Helios as he rides his fiery chariot across the sky.

      It smells of learned men believing that while they might not know everything, anything that they don't even know where to start with must be magic. How many times does humanity have to learn how to know the 'unknowable' before we start to question declarations of 'unknowable'?

    11. Re:Proof is already from 1929 by johanw · · Score: 1

      OK, I should have been more clear. Of course it is applied to wavefunctions and measurements, but the derivation of the uncertainty principle can be done completely without those concepts.

    12. Re:Proof is already from 1929 by Sulik · · Score: 1

      Doesn't have to be a simulation. Any abstract function that leads to consciousness would become reality for said consciousness. In other words, there is really no difference between abstract and reality. If an abstract function that desbcribes consciousness can exist it would in fact "exist" (therefore the universe must exist).

      --
      Help! I am a self-aware entity trapped in an abstract function!
    13. Re: Proof is already from 1929 by hendrikboom · · Score: 2

      I believe it was Heisenberg that formulated QM as infinite matrices, rather than waves. And Schroedinger came up with Schroedinger's equation, which is a partial differential wave function.

      Then Dirac came on the scene and formulated it all with abstract infinite-dimensional linear spaces, and pointed out that, depending on the coordinate systems you used on those spaces, you could get either Heisenberg's formulation or Schroedinger's.

  13. Obligatory Douglas Adams quote:- by Anonymous Coward · · Score: 0

    "Rigidly defined areas of doubt & uncertainty"

    1. Re:Obligatory Douglas Adams quote:- by FearTheFez · · Score: 1

      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.............

  14. Re:I laughed... full version ;) by HxBro · · Score: 5, Funny

    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!"

  15. It was a bittersweet occasion by Anonymous Coward · · Score: 0

    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."

  16. Phrasing by Tyler+Durden · · Score: 1

    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.

    --
    Happy people make bad consumers.
    1. Re:Phrasing by The_Wilschon · · Score: 2

      subatomic particles simply don't have precise position/momentums.

      This is exactly correct. Exact position and exact momentum are not properties that a particle may possess simultaneously, no matter how well or poorly you might try to measure them.

      --
      SIGSEGV caught, terminating

      wait... not that kind of sig.
    2. Re:Phrasing by Anonymous Coward · · Score: 1

      Yes, the truth is as you explain. Particles don't have precise positions and momentums.

      The only way to coherently persuade yourself that they DO have a precise position when you know their momentum is to believe in a global hidden state model of the universe. Basically you say "Oh, the universe knows where exactly that particle is, but sadly that information is stashed outside of our light cone so we can't access it". Which is pretty ridiculous and most physicists agree it's a more ridiculous thing to believe than that the particles just don't have such a property at all. At first some people though there was local hidden state, the universe knows where the particle is and we just need to figure out how to reveal the secret. But no, in a local system the universe is as ignorant as we are, and allows particles to do things that would be impossible if they actually had a precisely defined location when we know their momentum. So the _local_ universe doesn't know where the particle is either and at that point is becomes reasonable to conclude that there isn't something hidden from us, it isn't known because there's nothing to know.

    3. Re:Phrasing by Anonymous Coward · · Score: 0

      A particle can have a precise position or a precise momentum. Mathematically an (infinitely precise) position is identical to a superposition of all the possible momenta (and vice versa). One of the momenta in that superposition would have to be special for you to know the momentum too. The theory makes no distinction. Measuring the momentum, "collapses" the superposition to a single value, at random. If the momentum was knowable it wouldn't be at random, it would be that special momentum. Experimentally no such special value has ever been discovered. And, I could argue, never will, otherwise we'd have received a message about it from the future.

  17. contranym by Anonymous Coward · · Score: 0

    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".)

  18. only "discrete" Fourier/Integral transforms by peter303 · · Score: 1

    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.

    1. Re:only "discrete" Fourier/Integral transforms by tenco · · Score: 1

      This has nothing to do with discrete transforms. "Simple" example: \int_{-\inf}^{+\inf} \delta(x) f(x) dx = f(0)

      where \delta(x) is the Dirac delta distribution and f(x) a smooth function (e.g.: exp(-itx)/sqrt(2\pi) ).

      This uncertainty is also the cause why every laser has a finite spectral width: even a perfect sinoidal electromagnetic wave must have a length in the time regime which is finite - else the wave would hold an infinite amount of energy.

  19. Duh... by WillyWanker · · Score: 1

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

  20. But what if two observers look at the particle? by Anonymous Coward · · Score: 0

    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.

    1. Re:But what if two observers look at the particle? by maxwell+demon · · Score: 1

      If they try to do the measurements at the same time, they will disturb each other's measurement.

      --
      The Tao of math: The numbers you can count are not the real numbers.
    2. Re:But what if two observers look at the particle? by Anonymous Coward · · Score: 0

      For certain values of "same".
      But seriously, why isn't anyone considering relativity in this context?

    3. Re:But what if two observers look at the particle? by maxwell+demon · · Score: 1

      Because the only thing that relativity changes in respect to the uncertainty relation is is that the velocity is no longer proportional to the momentum, so you cannot say "velocity" instead of "momentum" here (in particular, the uncertainty relation also holds for the photon, but that doesn't change the fact that the photon goes exactly with c, because for photons a momentum uncertainty does not translate to a velocity uncertainty). But other than that, relativity doesn't add anything relevant to the uncertainty relation.

      --
      The Tao of math: The numbers you can count are not the real numbers.
    4. Re:But what if two observers look at the particle? by maxwell+demon · · Score: 1

      Ah,. now I get how you got relativity in. Well, if we measure the same particle, we necessarily do it at the same location, and the relativity of "same time" only happens for measurement on different places; more exactly, for spacelike intervals. Operators belonging to spacelike separated points commute, and therefore there's no uncertainty relation between them (well, formally there's the uncertainty relation with >=0, but since on the left there are only nonnegative quantities anyway, that inequality doesn't restrict anything).

      --
      The Tao of math: The numbers you can count are not the real numbers.
  21. A Clarification by rabtech · · Score: 2

    In the early days, people debated whether uncertainty was just a practical issue of imperfect measuring devices/methods or a fundamental feature of the system.

    We now know that it is a fundamental feature. Even if you had a perfect measuring device that did not disturb the system being measured, the act of measuring in any capacity is subject to uncertainty and collapsing of the wave function.

    Despite the fact that it seems to violate our common sense (developed at room temperatures with macroscopic physical forces, thus unsuited for quantum reasoning), the world at that tiny level really is probabilistic. It is not a side-effect of our measurement methods or anything else... It simply works that way. Reality as we know it is just a side-effect of all those quantum states interacting and causing wave function collapse... Same reason a quantum computer is harder and harder to make the more bits it has.

    --
    Natural != (nontoxic || beneficial)
    1. Re:A Clarification by Corwn+of+Amber · · Score: 1

      Nope. There is no limit to the resolution of reality, only of the instruments we use to measure it. So stop trying to make others accept your obscurantist idea that there's a limit to what there is to know.

      --
      Making laws based on opinions that stem up from false informations leads to witch hunts.
  22. Re:At last! An excuse for our Congress! by alva_edison · · Score: 1

    https://en.wikipedia.org/wiki/Marie_Curie

    --
    He effected a bored affect.
  23. FINALLY! by Corwn+of+Amber · · Score: 1

    They ended up recognizing the fucking difference between the limitation of the INSTRUMENT and the precision of REALITY.

    Took long enough. We're living in interesting times.

    --
    Making laws based on opinions that stem up from false informations leads to witch hunts.
  24. Role Playing and FINALLY! by tmjva · · Score: 1

    My search for the perfect AD&D random number generator has finally ended!

    --
    Tracy Johnson
    Old fashioned text games hosted below:
    http://empire.openmpe.com/
    BT
  25. Instrument loading by cwsumner · · Score: 1

    All of this is probably just a description of instrument loading effects, The answer is easy, just find instruments that are smaller than the sub-atomic particles ! 8-)

  26. Impications? by Anonymous Coward · · Score: 0

    Does the new proof has any implication for Heisenbug??

  27. Re:At last! An excuse for our Congress! by Meski · · Score: 1

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

    fixed.