Photo First: Light Captured As Both Particle and Wave

mpicpp sends word that scientists have succeeded in capturing the first-ever snapshot of the dual behavior of light. "It's one of those enduring Zen koans of science that we've all grown up with: Light behaves as both a particle and a wave—at the same time. Einstein taught us that, so we're all generally on board, but to actually understand what it means would require several Ph.D.s and a thorough understanding of quantum physics. What's more, scientists have never been able to devise an experiment that documents light behaving as both a wave and a particle simultaneously. Until now. That's the contention of a team of Swiss and American researchers, who say they've succeeded in capturing the first-ever snapshot of light's dual behavior. Using an advanced electron microscope – one of only two on the planet – at the EPFL labs in Switzerland, the team has generated a kind of quantum photograph of light behaving as both a particle and a wave. The experiment involves firing laser light at a microscopic metallic nanowire, causing light to travel — as a wave — back and forth along the wire. When waves traveling in opposite directions meet, they form a "standing wave" that emits light itself — as particles. By shooting a stream of electrons close to the nanowire, the researchers were able to capture an image that simultaneously demonstrates both the wave-nature and particle-nature of light. 'This experiment demonstrates that, for the first time ever, we can film quantum mechanics — and its paradoxical nature — directly,' says lead researcher Fabrizio Carbone of EPFL, on the lab's project page. The study is to be officially published this week in the journal Nature Communications."

Comments

It's the measurement

[thebes]

If you attempt to measure it in the way you would measure a wave, it will present itself as a wave.

If you attempt to measure it in the way you would measure a particle, it will present itself as a particle.

Light doesn't choose to be a particle or a wave at any given time, the measurement we use defines the characteristics it has. Nothing more, nothing less.

Re:My brain is full

[youngone]

There's no way of doing that. Feynman said "I think I can safely say that nobody understands quantum mechanics". You've probably got no chance. :-)

Re:not the first time

[stoborrobots]

The wave-particle duality is not a quantum superposition like you're describing (which would break down under measurement), although the caricatured manner in which we teach it might lead you believe that. It's a little more simple than that.

In our world, we are used to two kinds of things: particles, and waves. We are used to this distinction, and describe most things in one of these manners. Sound is a wave, a billiard ball is a particle, vibrations are waves, bricks are particles. If something is a particle, it has certain properties, like position, size, and shape. If it is a wave, it has certain other properties like wavelength, frequency, and amplitude. In addition, there are some common properties like velocity and direction.

When it came to studying light (and many other quantum stuffs), we can't directly see what it's made of. But we can take measurements of each "puff" of light, and infer its properties that way. When we do this, we notice that puffs of light have some properties which are particle-like, and some which are wave-like. So the term "particle-wave duality" became popular to describe this new material that was behaving simultaneously like a particle and a wave. It doesn't make sense to ask which one it is - a "puff" of light is neither a particle, nor a wave, but a different kind of stuff which has some properties of each.