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Physicists Do What Einstein Thought Impossible 193

Posted by Soulskill
from the i'm-not-sure-he-cares-anymore dept.
An anonymous reader writes "Einstein worked on Brownian motion (the movement of small particles in a fluid as they collide with the fluid's molecules) in 1905, but said it would be 'impossible' to determine the speed and direction of a single particle during this dance. Now researchers have gone and done it, by suspending a dust-sized glass sphere in air (which slowed down its dance moves, since it had fewer collisions with spaced-out air molecules than it would have had with water molecules). The researchers held the sphere in place with 'laser chopsticks,' and then watched how the glass bead bounced around to determine its direction and speed (abstract)."
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Physicists Do What Einstein Thought Impossible

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  • by fahrbot-bot (874524) on Monday May 24, 2010 @02:08PM (#32327162)
    You had me at "laser chopsticks".
  • To avoid confusion (Score:5, Insightful)

    by CorporateSuit (1319461) on Monday May 24, 2010 @02:09PM (#32327170)
    Laser chopsticks were invented to keep chow mein hot until the end of the meal.
    • by MBGMorden (803437)

      Nonsense. No one, except me apparently, actually eats chow mein.

      I've never actually ordered chow mein without the clerk checking to make sure I didn't really mean lo mein.

      Once they checked twice. Ordered chow mein.

      Them: "You want chow mein not lo mein?"
      Me: "Yep, chow mein."

      Them: "You SURE you want chow mein right? Chow mein have no noodle.".

      I get the feeling that they have to redo most chow-mein orders . . .

      • That's strage because Chow Mein IS a noodle dish, the name means literally "stir fried noodles" whereas lo mein means "mixed/stirred noodles".

        • Re: (Score:3, Informative)

          by MBGMorden (803437)

          Must be regional variation. Around here chow mein is mostly cabbage with onions, celery and your choice of meat cooked in. No noodles at all. Looking at the wiki article on chow mein, that particular dish looks like what is usually called chow mei-fun in the local restaurants.

          • Re: (Score:3, Interesting)

            by macshit (157376)

            Must be regional variation. Around here chow mein is mostly cabbage with onions, celery and your choice of meat cooked in. No noodles at all. Looking at the wiki article on chow mein, that particular dish looks like what is usually called chow mei-fun in the local restaurants.

            Yeah, but the thing is that the word which "chow mein" is a transliteration of literally means "fried noodles." Offering a dish called "fried noodles" which doesn't contain noodles, does seem a wee bit odd.

            Silly regional dialects [articlesof...cation.com]...

  • by natehoy (1608657) on Monday May 24, 2010 @02:10PM (#32327178) Journal

    How will the Infinite Improbability Drive work now? It depended on Brownian motion. Now probability can never come off 1:1 and it'll never work!

    We must discover time travel immediately so we can go back and stop these researchers immediately! I mean, sooner!

    Tomorrow is Towel Day! We cannot allow a travesty like this to stand.

    • by sorak (246725) on Monday May 24, 2010 @03:21PM (#32328146)

      So are you suggesting that the infinite probability drive is improbable? Maybe it can run off of it's own improbability.

    • Re: (Score:3, Insightful)

      by rickb928 (945187)

      By design, all claims that the Improbability Drive doesn't actually work are false.

      Claims that it doesn't work well are also false.

      Nice try, though. Tea is the secret. They only MEASURED Brownian motion, no word on how they might either predict it, control it, or even duplicate it. But if they could in fact duplicate a Brownian circumstance, the Improbablity Drive stil works, because, well, despite the elegant engineering, it is improbably successful. Or something like that. Keep your towel handy.

  • by wiredog (43288) on Monday May 24, 2010 @02:10PM (#32327182) Journal

    In the way that a nice cup of tea is?

  • Keep in mind (Score:5, Insightful)

    by Anonymous Coward on Monday May 24, 2010 @02:10PM (#32327184)

    When people say "impossible" they generally mean "not possible given what I currently understand about XYZ"

    Unless Einstein explicitly said "this will not be possible, ever"

    I mean, heck the article demonstrates this itself:

    "In 1907, Einstein likely did not foresee a time when dust-sized particles of glass could be trapped and suspended in air by dual laser beam “optical tweezers.”"

    I'm sorry but: No freaking shit. In 1907 I doubt many people would have foreseen that

    • by noidentity (188756) on Monday May 24, 2010 @02:30PM (#32327464)

      "In 1907, Einstein likely did not foresee a time when dust-sized particles of glass could be trapped and suspended in air by dual laser beam "optical tweezers.""

      I'm sorry but: No freaking shit. In 1907 I doubt many people would have foreseen that

      Warning: Do not attempt to foresee any more laser-related developments with remaining eye.

    • Re: (Score:3, Insightful)

      by Nevo (690791)
      My understanding is that Heisenberg pretty much said "this will not be possible, ever." But I'm not a Heisenberg nor an Einstein so I'll have to read TFA to find out what's going on.
    • by Ossifer (703813) on Monday May 24, 2010 @03:49PM (#32328584)
      Looking at pictures of Einstein, I don't think he knew what "tweezers" meant...
    • Re:Keep in mind (Score:5, Informative)

      by Jherico (39763) <bdavis@s[ ]tandreas.org ['ain' in gap]> on Monday May 24, 2010 @04:08PM (#32328864) Homepage
      Heisenberg was talking [wikipedia.org] about subatomic particles, not specks of dust. Its basically a consequence of not being able to measure both the speed or position of a subatomic particle without affecting the other property. The more accurately you measure one, the less you know about the other. While this principle does apply to macroscopic objects like dust particles, the level of uncertainty about the size and position of something macroscopic (even something as small as a dust particle) is vanishingly small (like on the order of the width of an atom).
    • Re: (Score:3, Insightful)

      by syousef (465911)

      When people say "impossible" they generally mean "not possible given what I currently understand about XYZ"

      People don't understand the scientific method, and many don't want to. I had a discussion on slashdot yesterday about Galileo (brought on by the story about Copernicus) and someone had the simple mindedness to suggest that since Galileo didn't know that the orbits of bodies were elliptical rather than circular, that the Roman Catholic church was justified in their treatment of him and suppression of his ideas. A clearer demonstration of misunderstanding of the scientific method I could not have thought up.

      • Re: (Score:3, Interesting)

        by SoVeryTired (967875)

        They were justified to some extent. The geocentric theory based on epicycles had predictive power too: it could be used to predict eclipses to a reasonable accuracy. The heliocentric model explained the retrograde motion of planets, but also made predictions about parallax of heavenly bodies, which was not observed (since the measurements available at the time were not sensitive enough).

        Bot theories had merit, and given the information available at the time, neither was perfect. That doesn't excuse the chur

    • Unless Einstein explicitly said "this will not be possible, ever"

      He did not - as you suspect what he meant was that it was "not possible with current technology" and certainly not that it was impossible in the same vein as "it is not possible to travel faster than light". It would be like someone today saying that it is impossible to build a 500PB hard disk - what they clearly mean is that it is impossible AT THIS MOMENT IN TIME to build a 500PB disk not that it will never, ever be possible to do so.

      Of course being a famous physicist the media have no qualms about hy

    • by DinZy (513280)

      Also keep in mind that they did not measure the speed and direction of a free Brownian particle. They confined it so it's not really the same problem. However I it is possible to watch a small fluorescent labeled protein molecule move around too. In that case if the protein is small enough and the concentration is dilute enough one can basically film their trajectories.

  • by olddotter (638430) on Monday May 24, 2010 @02:13PM (#32327240) Homepage
    If you "hold it" doesn't that effect the out come of the experiment? Is this a bad test or just bad reporting?
    • If you "hold it" doesn't that effect the out come of the experiment? Is this a bad test or just bad reporting?

      After years of observing experimentations and reporting, I would venture to guess that the later is more probable than the former... but I may be wrong.

    • Re: (Score:3, Insightful)

      by Chris Burke (6130)

      Because you can come up with a question that is not explicitly answered by the article does not necessarily imply either a bad experiment or bad reporting.

      It means you probably want to read the paper.

      • by Machtyn (759119)
        Not having read the paper, I would assume they took this into account by first learning how the lasers affected the particles (perhaps by suspending the dust thin glass in a vacuum). Once the knowns are known, they can subtract that out of the final results and observe the actual result.
  • So does this tell us how to travel faster than light?

  • by ayahner (696000) on Monday May 24, 2010 @02:22PM (#32327380)
    Ha. Einstein. What an idiot.
  • by PatTheGreat (956344) on Monday May 24, 2010 @02:31PM (#32327480) Homepage
    This Einstein fella - I keep on hearing about how he's been proven wrong or might be proven wrong or how people are picking his ideas apart. It's like he hasn't even SEEN a modern physics paper in like, the last 50 years.
  • by Anonymous Coward on Monday May 24, 2010 @02:32PM (#32327498)
    Einstein only said it was impossible from a tecnical point of view. Given he used brownian motion as direct evidence for the atomic/molecular nature of matter I am pretty sure he appreciated that with future technology it may be possible to do this kind of experiment...
  • by jeffmeden (135043) on Monday May 24, 2010 @02:34PM (#32327526) Homepage Journal

    If the glass bead were moving in such a way that was too subtle for them to measure, would they even know they couldn't measure it? What if Einstein was right and was simply implying that the movements eventually broke down so far that they were unobservable (similar to Planck's work)?

  • Since when is 'dust' a unit of size?

  • by repepo (1098227) on Monday May 24, 2010 @02:36PM (#32327558)
    TFA doesn't refute any of Einsteins conclusions about Brownian motion. It only shows that it was something impossible to do at Einsteins time. What a cheap way to grab attention!
  • by raving griff (1157645) on Monday May 24, 2010 @02:38PM (#32327580)

    I've seen a couple of comments (more than one thread or else I would have posted a reply there) that seem to suggest that this breaks quantum physics by accurately predicting the speed and direction of particles, but it should be noted that the Heisenberg Uncertainty Principle states that it is impossible to accurately calculate both the velocity and its position. Speed and angle are components of velocity, therefor the only conclusion of this experiment is that velocity can be calculated under these conditions.

    • by jfengel (409917) on Monday May 24, 2010 @02:50PM (#32327716) Homepage Journal

      That's correct. What's at issue here is a matter of engineering, not physics.

      Physicists reserve "impossible" for the truly mathematically unavoidable, while engineers expand it to the wildly impractical. When you say something "is" true, you're speaking in the former sense. When you say you "believe" something to be true, as Einstein did, you're speaking in the latter sense.

      So it's not overthrowing any physical principles. It's merely confirming something else Einstein said: the universe is not only stranger than we imagine, it's stranger than we can imagine.

    • Uncertainty is not relevant here because the "particles" involved are macroscopic bits of dust, not elementary particles.

  • Maybe pollen grains aren't "small" but I remember observing them doing Brownian motion in high school. Assuming the microscope is calibrated (i.e. you know the gain) and you can mount a camera on it to capture the movements (or even use a gridded background and call out to an assistant with pen and paper), how can it not be possible to measure the velocity?

    • Re: (Score:3, Insightful)

      by maird (699535)
      Yes, a letter i in your subject.
    • Re: (Score:3, Interesting)

      by maird (699535)
      If I understood the article, what you saw at high school isn't all the motion that took place. So you couldn't use what you saw to measure the velocity of a particle. What you saw was limited by the speed of light and there are changes in direction and speed that happen between the instants you observe. That's as far as I can follow it though. I don't see, for example, why it isn't frequency that's relevant to measuring it. After all, you can sample other events occurring every 100ns at only a 20MHz frequen
  • but... (Score:2, Insightful)

    by alienzed (732782)
    there's no such thing as 'instantaneous'.
  • Dumb summary (Score:5, Insightful)

    by Fnkmaster (89084) on Monday May 24, 2010 @02:54PM (#32327762)

    If you read the PhysicsWorld [physicsworld.com] article, you'll see it actually says:

    But he believed that it would be impossible in practice to track this motion, given the incredibly short timescales over which the Brownian fluctuations take place

    Ahhh... still don't have the original source quotation from Einstein here, but it sounds like Einstein believed it was "impossible in practice" - in other words, that the technology didn't exist at that time to measure rapid fluctuations over microsecond or even nanosecond time scales, and maybe he couldn't even imagine such technology existing.

    So he never actually said he thought it was beyond the physical limits of the universe. There was no proof or physical law involved.

    Now call me up when somebody figures out how to move matter or information faster than the speed of light (i.e. group velocity greater than c). Einstein really did believe that was *impossible*.

  • by borroff (267566) on Monday May 24, 2010 @03:44PM (#32328488) Journal

    One thing interesting that isn't mentioned specifically: This work, using "optical tweezers", is based on research done by Nobel Laureate Steven Chu's group at Berkeley. Dr. Chu also happens to currently be the US Secretary of Energy.

    No job too big, no job too small, Steve Chu does 'em all.

  • holy mother of god (Score:3, Insightful)

    by nimbius (983462) on Monday May 24, 2010 @03:47PM (#32328540) Homepage
    this has got to be the coolest science ive seen on slashdot in a while. find a suitable nano-shark and we can start talking laser sushi.
  • by vdorie (1106873) on Monday May 24, 2010 @03:48PM (#32328568)
    Brownian Motion is a mathematical construct, which, among other things, is nowhere differentiable (almost surely). You can pin a BM down into sets with high probability, but no, you can't really predict it. It is merely used to *model* the movement of a particle in a fluid, it is not actually the process by which the molecules move. Indeed, "such a path represents the motion of a particle that in its wanderings back and forth travels an infinite distance in finite time. [BM] does not in its fine structure represent physical reality." (Billingsley, "Probability and Measure"). At least the science is interesting.
    • Precisely. Mathematical Brownian motion has a *wonderful* property known as infinite variation. This means that if you took an accurate plot of Brownian motion over a finite time interval, say the interval [0,1], and tried to measure the length of the curve, you would find that it is infinite. You can take one "piece" of Brownian motion and stretch it out the whole way across the universe.

      If a particle was moving according to mathematical Brownian motion, its velocity would be infinite, which is clearly imp

    • The subject is not the mathematical idealization of Brownian motion. It's the real thing.

  • Einstein did what many physicists thought was impossible, so now they are even.

  • (I Am An Armchair Physicist)
    I propose to test these results on Brownian Motion by direct and lengthy observation of the phenomenon of the forty ounce bounce. [40ozbounce.us]

Nothing will dispel enthusiasm like a small admission fee. -- Kim Hubbard

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