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Science

'Zeno Effect' Verified: Atoms Won't Move While You Watch (cornell.edu) 168

An anonymous reader writes: One of the oddest predictions of quantum theory – that a system can't change while you're watching it – has been confirmed in an experiment by Cornell physicists. Graduate students Yogesh Patil and Srivatsan Chakram created and cooled a gas of about a billion Rubidium atoms inside a vacuum chamber and suspended the mass between laser beams (abstract).

In that state the atoms arrange in an orderly lattice just as they would in a crystalline solid. But at such low temperatures the atoms can "tunnel" from place to place in the lattice. The famous Heisenberg uncertainty principle says that position and velocity of a particle are related and cannot be simultaneously measured precisely.

The researchers observed the atoms under a microscope by illuminating them with a separate imaging laser. A light microscope can't see individual atoms, but the imaging laser causes them to fluoresce, and the microscope captured the flashes of light. When the imaging laser was off, or turned on only dimly, the atoms tunneled freely. But as the imaging beam was made brighter and measurements made more frequently, the tunneling reduced dramatically.

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'Zeno Effect' Verified: Atoms Won't Move While You Watch

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  • by JJJJust ( 908929 ) <JJJJust&gmail,com> on Saturday October 24, 2015 @12:44PM (#50793401)
    I watched a pot once... it boiled anyways.
  • by SofiKadaj ( 4025561 ) on Saturday October 24, 2015 @12:45PM (#50793403)
    Weeping Atoms dept
  • by Anonymous Coward on Saturday October 24, 2015 @12:46PM (#50793411)

    Is it the laser or is it the looking? Sounds to me like you found an effect triggered by the laser over a certain intensity, as, the way I read it, under that intensity everything works just great, even if you enter a staring contest.

    • by Anonymous Coward

      They could easily find out which one it is by checking whether the effect persists when illuminating but not observing the atoms. Why didn't they do it? Are they afraid the answer will ruin their catchy headline?

      • by fisted ( 2295862 )

        How would they know what the atoms do without observing them?

        • by Anonymous Coward

          The summary says that they have a way to measure the amount of "tunneling" irrespective of whether the imaging laser is on, off, or turned on only dimly. So just do that.

        • by ShanghaiBill ( 739463 ) on Saturday October 24, 2015 @03:40PM (#50794237)

          How would they know what the atoms do without observing them?

          Check back later, and see how many tunneled while they weren't looking. If they tunneled, they will be in a different location.

          If they find there was tunneling while they weren't looking, that is pretty strong evidence that we are living inside a simulation. The universe behaves differently if we are not looking, so that God can save computing resources. There is no point in calculating details that no one will see. Just like the way OpenGL can skip the shading of hidden polygons.

          • by fisted ( 2295862 )

            If they find there was tunneling while they weren't looking, that is pretty strong evidence that we are living inside a simulation.

            I doubt it. It's still kind of looking if you arrange for it to do something that you can look at later to indirectly observe what went on when you weren't looking.

            • It's still kind of looking if you arrange for it to do something that you can look at later to indirectly observe what went on when you weren't looking.

              But if the behavior is different if you watch continuously vs. looking away and then looking back, then how does the universe "know" that it is being observed? The obvious answer is that the universe isn't real. It is a simulation run for our benefit, so it only continuously generates what we can see. If we look away, the simulation is paused, and then when we look back it is quickly updated in batch mode.

              This is just like rotating a multi-faceted polyhedron in OpenGL. The shaders skip the hidden polygo

              • Re: (Score:3, Interesting)

                by Anonymous Coward

                Not really. It just means reality doesn't conform to your classical notion of particles and 3D space-time. Why that is, no one really knows. But, the math works -- quantum mechanics, I mean. Essentially, nothing at the subatomic particle scale has a defined size or specific position in three dimensions. Things only appear to interact at specific locations. The more interactions at one location, the less likely a quanta or "particle" is to interact somewhere else. This is the basis of the particl

              • by lhowaf ( 3348065 )
                Wow, I've long thought religion was arrogant with the whole I'm-so-special-my-soul-must-last-forever thing. This the-universe-is-a-simulation-for-my-benefit thing takes that to whole other level.
            • by Anonymous Coward

              Observing at small scales is not a passive activity. You have to inject energy into the system to make an observation. That injection of energy alters the system. So the universe does know when you are actively looking at it. Think of looking as not just looking with eyes passively but also shining a high energy flashlight in the direction of looking.

              • Think of looking as not just looking with eyes passively but also shining a high energy flashlight in the direction of looking.

                You are missing the point. What happens when you shine the high energy flashlight, but DON'T LOOK at the result? An observed system behaves differently, whether there is energy input or not.

            • Observing at small scales is not a passive activity. You have to inject energy into the system (and have it reflect back) to make an observation. That injection of energy alters the system. So the universe does know when you are actively looking at it. Think of looking as not just looking with eyes passively but also shining a high energy flashlight in the direction of looking.
          • by Cito ( 1725214 )

            The entire universe is like a video game.

            There's a render distance ;-)

            As we move through space things within range pop into existence. Or move away they derez to save resources.

            Like the Render distance setting in Witcher 3

            hehe :-P

          • A Matter of Minutes... Twilight zone wins every time.

            https://en.wikipedia.org/wiki/... [wikipedia.org]

          • It's interesting you say that. Saving computer resources in a simulation environment... The only counter I have is that there are (at least to us) countermeasures for "discovering the secret" in many different systems. Theoretically and most probably (IMSHO) you would be destroyed or cease to exist once you realize the truth behind the system. No point in punishing; just remove the potential problem (you, in this case). Since I'm reading what you typed, the system is not designed to do that -or- it's m

      • Re: (Score:2, Insightful)

        by Anonymous Coward

        Since when do the science news articles let what the scientists actually did prevent them from using catchy headlines?

        And they didn't check that because is pretty well established that the human is not the important part of the observation, but it is entirely the interaction of the system under consideration with something outside of the system being modeled (e.g. the laser light source). The whole popsci woo about quantum mechanics depending on an observer implying there is something special about humans

      • by HiThere ( 15173 )

        Perhaps you need to understand what "observing" means in quantum theory. Hint: You don't need an intelligence to have observation. You don't even need a human.

        What isn't clear to me is how illuminating them with photons doesn't count as observation...perhaps they aren't recording any interactions? (If that seems silly, see the double slit experiment variations.)

        • by ceoyoyo ( 59147 )

          In quantum mechanics the likelihood of quantum effects diminishes as the particle interacts with larger systems of particles. One photon might leave a decent chance of tunneling while a million photons makes it extremely unlikely.

    • by Anonymous Coward

      The imaging laser=the observing/looking.
      Watching (or not) the fluorescent pulses generated by the atoms does not influence that.

      • by Anonymous Coward

        Watching is not the same as illuminating. In quantum mechanics, watching a property means that you made a macroscopic record of it. When you illuminate the atoms without watching them, they become entangled with the photons you threw at them and still behave in a quantum way.

    • Exactly. Now that a good protocol has been established, it should be relatively simple to shut down the mystical kooks once and for all. Or validate them.

      Run the experiment under intense laser and observe the atoms with your eyeballs. Then run it again with same intensity laser, but do not observe it, don't even record it for future use. Compare the amount of tunneling for both.

      The problem so far as I can see has been that quantum physicists didn't say "shooting photons on an experiment changes the results"

      • Re: (Score:3, Insightful)

        by Gavagai80 ( 1275204 )

        It really is the same thing. When you look at the world around you, you're using the sun to shoot photons at everything which then bounce off the object into your eyes.

      • "Run the experiment under intense laser and observe the atoms with your eyeballs. Then run it again with same intensity laser, but do not observe it, don't even record it for future use. Compare the amount of tunneling for both."

        Isn't that still 'observing' for the purposes of the meaning of observing? Really not sure - the whole thing is nuts...
      • by HiThere ( 15173 )

        The equivalent has already been done multiple times with the double slit experiment. Those who want to believe differently just don't look at the results. This wouldn't be any different. People still see the word "observation" and imagine it means a person is involved. (That's even happened earlier in this very list.)

    • Sounds to me like you found an effect triggered by the laser over a certain intensity, as, the way I read it, under that intensity everything works just great, even if you enter a staring contest.

      True, but less light intensity also means you can't see as well.

      You can't observe a system without interacting with it, which will disturb it. The more accurate measurements you make the stronger the effect becomes. If the system is small enough, the disturbances caused by measuring one property means other, linke

      • by cfalcon ( 779563 )

        Media will never explain this fact, because all their clicks come from pretending its some mental thing where if a PERSON observes it, that locks it down. The fact that its due to interacting with other particles is rarely gone into.

        • pretending its some mental thing where if a PERSON observes it, that locks it down.

          This is not an invention of "the media". Many famous physicists have hypothesized that consciousness causes collapse [wikipedia.org], and this has never been conclusively falsified.

    • You missing the point. There is nothing to "see" without illumination, which has an effect.
    • by ceoyoyo ( 59147 )

      Whenever a pop science article talking about quantum mechanics says "observed" think "is in contact with a large number of other particles." You can't see anything without peppering it with particles, true, but quantum effects also become highly unlikely when a particle is in contact with a large particle system as well. That's why you don't come home to find that your desk chair has tunneled into the basement. Socks are an exception. They exist in a unique state of quantum grace.

  • by willworkforbeer ( 924558 ) on Saturday October 24, 2015 @12:52PM (#50793435)
    So, it's the "DOT Road Crew Effect."
    • Won't move while you watch?

      My wife can tell you I don't move when I watch football. Does that count as the Zeno Effect?

      • by Anonymous Coward
        That would be the Dorito Effect.
        • That would be the Dorito Effect.

          The Dorito Interial Reference Frame: all other reference frames are unobserved until half time.

  • by Anonymous Coward

    I know I'm a complete idiot, but shouldn't the conclusion be : Atoms won't move while illuminated by an imaging laser?

  • If you can hold them still, would they be easier to smash?

  • by RyanFenton ( 230700 ) on Saturday October 24, 2015 @01:05PM (#50793491)

    The important thing about being 'observed' is if it has an effect on something else - such as the photons from the laser used to record it.

    What is most certainly does NOT mean is that it does anything because a human consciousness is watching the process. A robot or mote of dust could have been 'observing' it (and in effect WAS), and the same effect would happen.

    That's what I strongly dislike about the terminology around 'observer' effects. It makes people evoke touchy-feely human awareness stuff, when it's really just referencing microscale interaction events. What matters is that if events occur which COULD matter outside the system, like photons bouncing against the atom, then that's an 'ovservable' event in the context.

    In the microscopic landscape of these experiments, we're a distant afterthought - a bacterium would be almost too big to sensibly consider - and trillions of bacteria would barely be observable to us. In other words, it's really not about US, to any sensible interpretation. Psuedoscience is all about us - keep that in mind when you see the sales pitches, as they'll be using the bad interpretation all the time they can.

    Ryan Fenton

    • Re: (Score:2, Informative)

      by narcc ( 412956 )

      What is most certainly does NOT mean is that it does anything because a human consciousness is watching the process.

      That's still an open question.

      • by cfalcon ( 779563 )

        You can control for a person watching it versus something else in many ways. It has nothing to do with a human consciousness, and everything to do with interactions.

        • by narcc ( 412956 )

          You've missed the point. There are competing theories, the one you dismiss without justification is among them. What you believe or what you want to believe isn't relevant. To merely assert knowledge, like you do here, on no other basis that the idea makes you uncomfortable is irrational. It's exactly what you see from creationists and other similar groups.

          • by ceoyoyo ( 59147 )

            The general idea that consciousness causes wavefunction collapse is non-falsifiable and therefore not scientific. That's an excellent justification for dismissing it. If you propose a *specific*, falsifiable dependence on consciousness, such as "a human has to be watching in realtime" then those have already been disproven.

            • by narcc ( 412956 )

              That's true of many other competing theories, the popular (among laypersons) many worlds approach among them. If you want to be rational, you need to be consistent. That's the whole point.

              Nonsense is nonsense, regardless of your intentions, feelings, or personal beliefs. We're seeing a rejection here based on personal incredulity and the fear it may lend support to new age beliefs. Boil it down and you have "I reject this idea because it might lead people to believe something with which I personally dis

              • by ceoyoyo ( 59147 )

                Many worlds is considered unscientific fiction by many physicists. I agree: it's a nice story, but until it makes some testable predictions, at least in principle, it's not science. This is a pragmatic viewpoint: a theory that does not make testable predictions has no predictive, and thus no practical value.

                Rejecting many worlds and consciousness-causes-collapse isn't due to personal incredulity, it's due to both of those ideas being non-scientific. The scientists who proposed the consciousness-causes-co

                • by narcc ( 412956 )

                  Well, it is being rejected based on personal belief, in this specific case. Science is loaded with things that any reasonable person would consider non-science. (String theory being the standard pop-sci example, though you'll find things like it in other branches.) I don't really have a problem with that, it very often leads to real progress. Science is messy, after all. It's never been the perfectly clean and hyper-rational exercise the public imagines it to be. (An argument could be made that that ste

                  • by ceoyoyo ( 59147 )

                    String theory, at least the core idea, makes predictions that are testable in principle. Even so, it's often criticized as being unscientific for not making predictions that are testable in the foreseeable future. Even so, there's the hope that, with further development, it might do so.

                    The general idea that consciousness causes wave function collapse cannot be tested. You simply cannot test whether a wave function collapsed or not without, at some point, being cognizant of the result. More restricted form

      • Everything is an open question to gullible fools, including "Do leprechauns exist?"
    • by dak664 ( 1992350 )

      Exactly, and the same point removes the paradox from Schroedinger's cat. "We" don't have to open the box to force the cat into one state or another, it's the radioactive decay that observes the cat death. We simply find out whether it has happened or not when we open the box.

      But this could be a useful phenomenon, using a light beam to switch tunneling on and off.

      • by wonkey_monkey ( 2592601 ) on Saturday October 24, 2015 @03:45PM (#50794261) Homepage

        The whole point of Schroedinger's cat is that the entire setup - radioactive element, poison phial, cat - can all be in a superposition until we open the box.

        In real life, of course, the surrounding environment interacts with the box in more ways than just light, all of which would collapse the wavefunction before we opened the box. But that's not the point of the thought experiment.

        • I think the point is that if something is made detectable, it will have an effect on that thing. There is a bias to our Universe, such as being made of matter instead of anti-matter, things spin to the right, and not to the left, and those which spin to the left get annihilated. Except in the world of the very small where time has little effect on the energy, and the moment those quantum energies are made detectable, they enter our system of things and change properties to adjust. The observer in this in
        • by ceoyoyo ( 59147 )

          It was an interesting thought experiment in the early days of quantum mechanics, to illustrate the idea of superposition. You can't take it literally though. Even if you could somehow get a vial of poison into superposition, the cat is far too big.

        • by dak664 ( 1992350 )

          Even abstracting away the surrounding environment, doesn't the cat qualify as a observer of its own death?

          How about if you take the place of the cat and securely lock the box so on one can open it - do you become immortal?

          But as you say, idealized imaginary constructs rarely model reality.

    • A system is based in whole on the constituent components comprising that system. We've only just recently discovered quantum effects play a role in the processing of information within the dendrites of the brain, it seems outlandish from both a logical and metaphysical standpoint to believe our cells could have around 4 billion years to evolve with the only bounds of "grow things that better exploit the rules which govern you" and not harness any possible effects within their reach. If there is a quantum
      • We've only just recently discovered quantum effects play a role in the processing of information within the dendrites of the brain

        Have we really? Or is it another speculative idea that's been seized upon by quantum kooks?

      • by ceoyoyo ( 59147 )

        We have? Penrose advanced that theory in the 80s but there's now a lot of evidence against it. It's quite difficult to imagine that something as big and messy as the brain could maintain superposition states.

  • by wonkey_monkey ( 2592601 ) on Saturday October 24, 2015 @01:09PM (#50793509) Homepage

    One of the oddest predictions of quantum theory – that a system can't change while you're watching it

    Ah, stop right there.

    Before the quantum kooks crawl out of the woodwork, the atoms don't stop moving because "you" (click-bait headline alert) are watching. They "stop moving" because they are being continuously "measured" (interacted with in ways that stop them going all quantum-y) by lasers.

    A conscious observer is not required. And if you turn off the laser that's doing the measuring, peering through the window at the atoms with your actual peepers isn't going to stop them tunneling anywhere.

    • They "stop moving" because they are being continuously "measured" (interacted with in ways that stop them going all quantum-y) by lasers.

      The obvious solution is the stroboscopic laser... with clicking noises and loud screechy dissonant music...

    • by Nemyst ( 1383049 )
      I'm pretty sure the summary and submitter were going for that exact interpretation, but didn't want to spend a paragraph being pedantic.
    • by Solandri ( 704621 ) on Saturday October 24, 2015 @02:52PM (#50793975)
      Put another way, imagine the universe is a simulation. The programmer didn't want to waste CPU cycles simulating every single atomic particle, so when no meaningful atomic-scale interactions are occurring, the simulation uses a simpler statistical model instead.

      When the laser light is striking the atoms in the lattice, the interactions between the light and lattice force the simulation to model every individual atom and photon. So each them are modeled precisely, and no tunneling occurs.

      When the laser light is not striking the atoms in the lattice, there's no need to model every (non-)interaction and the simulation reverts to a statistical model. When the laser is turned on again you can locate the position of every atom again. Since the original lattice arrangement was not "saved", the simulation has to generate a new arrangement of atoms in the lattice. This new arrangement is statistically identical to the original, but little details like the positions of individual atoms are not identical. The misplaced atoms appear to have "moved", and we call those movements "tunneling".

      Have fun sleeping tonight. -- The Matrix
      • While I do feel there is growing evidence to support the simulation theory, I do take issue with this idea that the sim needs to save CPU cycles.

        The universe, simulated or not, is a huge and very complex place. The CPU power and programming code needed to create and run this is probably beyond our comprehension and may always remain that way. But clearly whatever would be capable of doing this would be extremely powerful. A CPU with effectively infinite processing power.

        Therefore, I find it silly to su

      • So you're saying, if we all turn on our lasers at the same time the universe will crash?
      • There's no need to imagine anything unusual at all actually. There are no shortcuts taken when the atoms aren't observed, and by "observed" we mean interacted with by our external stimuli, i.e. our laser. When not interacted with, or more appropriately, "interfered" with, the atoms' tunneling behavior proceeds as normal. It's a real and ongoing physical process (not an optimization such as a simulation CPU saving measure). But since any attempt to observe the atoms directly cause the tunneling behavior
    • A conscious observer is not required.

      In medical circles where it matters, patient's level of consciousness is defined in terms of how responsive to external stimuli they are. By extrapolation it would seem fair to say that a subatomic particle does, in fact, possess a very simple consciousness since it's capable of both observing its environment (by absorbing particles), sending messages (by emitting particles) and storing information (by changing its state as a result of these events).

      I like this view bec

      • I'm sorry, but I think this definition is too far-fetched. A dead person bombarded by light will be observed, eg absorb particles and emit particles, but has no consciousness. The person is dead. The ability to interact with the external world is not consciousness. It's a part of being in the world (Thermodynamics anyone?).
    • by Toad-san ( 64810 )

      Damn it! I _really_ wanted that Nobel Prize! Now you've gone and spoiled it :-(

    • by ceoyoyo ( 59147 )

      Also, they don't stop moving. They stop tunneling.

  • Frozen (Score:5, Funny)

    by dhaen ( 892570 ) on Saturday October 24, 2015 @01:34PM (#50793571)
    My wife can freeze thing just by looking..
  • by 140Mandak262Jamuna ( 970587 ) on Saturday October 24, 2015 @01:55PM (#50793651) Journal
    The word "watching" invokes just observing passively without doing anything to disturb the system. Here they are continually measuring it by firing lasers. So when they were passively watching things were changing. When they fired all those lasers the activity stopped. So all they proved was, "if you fire lots of lasers at the mass, you can change its behavior".

    Only outcome of this experiment was that they will publish a paper with huge list of authors and a minor finding. Now a days many particle physics papers have more authors than there are words in the paper.

    • > The word "watching" invokes just observing passively without doing anything to disturb the system.

      UmNo... do you understand Schrodinger? The whole delta-p delta-x vs. h-bar of the Heisenberg Uncertainty principle? Because at subatomic particles isn't passive, by definition. The idea is that a photon is so energetic that it gives small particles a hefty kick. There is no such thing of 'just observing passively', there's just 'big things move imperceptibly when observed, small ones move more'.

      Besides

      • They get a salary for doing regular work. You don't get authorship of a paper just because you did regular maintenance on a routine equipment. Thousands of lab workers feed lab animals on the correct schedule. Why their names are not in the bio papers? Why the janitors are not named in all the papers? The entire staff demand to be named in every paper, for pushing buttons only in particle physics.

        They did observe without changing anything and got one level of activity. They turned on the lasers and it cha

        • by ceoyoyo ( 59147 )

          The requirement for authorship on a paper is that you make a novel intellectual contribution. Collecting data in some standard way doesn't qualify, but coming up with a new way to do it does. In particle physics, many people get their names on papers because they've worked on building and designing equipment for that experiment. But that equipment is novel. In biology, the lab tech who runs a western blot doesn't (shouldn't) get her name on the paper. But the tech who invents an optimized western blot

  • ...pumping energy into a system makes it behave differently!
  • Stun Gun (Score:5, Funny)

    by Art3x ( 973401 ) on Saturday October 24, 2015 @02:23PM (#50793817)

    It's because you set your lasers to stun.

  • by koan ( 80826 )

    The famous Heisenberg uncertainty principle says that position and velocity of a particle are related and cannot be simultaneously measured precisely.

    What if 2 people watch? One for position and one for velocity.

    Also, I'm not clear on how making the laser brighter causes the effect in the way the researchers state, if you can see them at lower levels of laser brightness then should behave the same then as they do when watched at brighter levels.
    You can either watch them or not seems logical (to me anyway), this article seems to imply a gradient of the effect rather than an absolute.

    • The famous Heisenberg uncertainty principle says that position and velocity of a particle are related and cannot be simultaneously measured precisely.

      What if 2 people watch? One for position and one for velocity.

      That violates the principle; you cannot measure one to any useful degree of precision without making the other quantity ever more uncertain in its measured value.
      You could get rough and useless ballpark estimates by not measuring either well at all, but:
      the more usefully precise you get with one measurement, the more the imprecision of your measurement of the other value head off towards infinity; AKA "Useless Value Achievement" Unlocked!.

      IANAP, Obviously. The foregoing is based on what is in the tr

    • by ceoyoyo ( 59147 )

      It doesn't matter how many people are watching. You cannot make a measurement without interacting with the thing you're measuring. You need to bounce at least one test particle off your target to measure anything about it, and that interaction will change the thing you're trying to measure, as well as it's complementary property. You can optimize your measurement so that it has a minimal effect on position, but it will then have a big effect on momentum. If multiple people make different measurements at

  • Or somebody is. Possibly some PR person at their university with zero clue. What they have is that shining the second laser seems to decrease tunneling. This could be a measurement error, it could be an unexpected, yet perfectly fine different effect, and it could, if all else is reliably being ruled out, indeed be the effect claimed. But making physical measurements is very tricky and misinterpreting the results is very easy.

    Remember the guys that measured FTL particles and asked for help because they (san

  • So I the answer to "If a tree falls in a forest and no one is around to hear it, does it make a sound?" has been answered. Resounding NO! It doesn't, absolutely. Cuz 'speriments.

  • (no pun intended).

    If the system cannot change while I'm watching, how am I able to watch moving pictures on my TV?

  • How does that comply with Eisenberg principle? The particle is stopped, hence we both know where it is and its velocity: zero

When we write programs that "learn", it turns out we do and they don't.

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