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

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.

Comments

So which one is it?

[Anonymous Coward]

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.

Re:So which one is it?

[Gavagai80]

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.

Re:So which one is it?

[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 is bunk, and comes from people not understanding what observation means in the context of quantum mechanics.

Re:On pot watching and atomic motion...

[fustakrakich]

My pot just went up in smoke

It's nothing to do with "you"

[wonkey_monkey]

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.

Re:Important distinction: Obervable vs watching...

[wonkey_monkey]

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.