Researchers bend complementary rule and observe light as wave and particle - Polidicks

[quote=BBC News][b]Researchers have bent one of the most basic rules of quantum mechanics, a counterintuitive branch of physics that deals with atomic-scale interactions.[/b] Its "complementarity" rule asserts that it is impossible to observe light behaving as both a wave and a particle, though it is strictly both. In an experiment reported in Science, researchers have now done exactly that. They say the feat "pulls back the veil" on quantum reality in a way that was thought to be prohibited by theory. Quantum mechanics has spawned and continues to fuel spirited debates about the nature of what we can see and measure, and what nature keeps hidden - debates that often straddle the divide between the physical and the philosophical. For instance, a well-known rule called the Heisenberg uncertainty principle maintains that for some pairs of measurements, high precision in one necessarily reduces the precision that can be achieved in the other. One embodiment of this idea lies in a "two-slit interferometer", in which light can pass through one of two slits and is viewed on a screen. Let a number of the units of light called photons through the slits, and an interference pattern develops, like waves overlapping in a pond. However, keeping a close eye on which photons went through which slits - what may be termed a "strong measurement" - destroys the pattern. Now, Aephraim Steinberg of the University of Toronto and his colleagues have sidestepped this limitation by undertaking "weak measurements" of the photons' momentum. The team allowed the photons to pass through a thin sliver of the mineral calcite which gave each photon a tiny nudge in its path, with the amount of deviation dependent on which slit it passed through. By averaging over a great many photons passing through the apparatus, and only measuring the light patterns on a camera, the team was able to infer what paths the photons had taken. While they were able to easily observe the interference pattern indicative of the wave nature of light, they were able also to see from which slits the photons had come, a sure sign of their particle nature. The trajectories of the photons within the experiment - forbidden in a sense by the laws of physics - have been laid bare. On one level, the experiment appears to violate a central rule of quantum mechanics, but Professor Steinberg said this was not the case. He explained to BBC News that "while the uncertainty principle does indeed forbid one from knowing the position and momentum of a particle exactly at the same time, it turns out that it is possible to ask 'what was the average momentum of the particles which reached this position?'" . "You can't know the exact value for any single particle, but you can talk about the average." [b]Philosophical beginnings[/b] Marlan Scully of Texas A&M University, a quantum physicist who has published on the idea of sneaking around this quantum limit before, said: "It's a beautiful series of measurements by an excellent group, the likes of which I've not seen before. "This paper is probably the first that has really put this weak measurement idea into a real experimental realisation, and it also gave us the trajectories." He said that the work would - inevitably - raise philosophical issues as well. "The exact way to think about what they're doing will be researched for some time, and the weak measurement concept itself will be a matter of controversy - but now we have a very pretty experiment with these weak measurements," he added. For his part, Professor Steinberg believes that the result reduces a limitation not on quantum physics but on physicists themselves. "I feel like we're starting to pull back a veil on what nature really is," he said. "The trouble with quantum mechanics is that while we've learned to calculate the outcomes of all sorts of experiments, we've lost much of our ability to describe what is really happening in any natural language. "I think that this has really hampered our ability to make progress, to come up with new ideas and see intuitively how new systems ought to behave."[/quote] TL;DR this video (which you have seen 5 times before) is what science used to be like: [media]http://www.youtube.com/watch?v=DfPeprQ7oGc[/media] Based on this, it became a basic principle of quantum mechanics that while light can behave as both a wave and a particle, it is impossible to observe this behaviour. But now researchers have managed to observe it using a different method. As the BBC puts it, "The trajectories of the photons within the experiment - forbidden in a sense by the laws of physics - have been laid bare."

so... they're breaking the laws of physics? someone explain please, I'm lost :saddowns:

[QUOTE=larrylumpy;30242594]so... they're breaking the laws of physics? someone explain please, I'm lost :saddowns:[/QUOTE] No, they're not. Anything in particular?

[QUOTE=larrylumpy;30242594]so... they're breaking the laws of physics? someone explain please, I'm lost :saddowns:[/QUOTE] Anyone should be able to understand my explanation in the OP

[quote]He explained to BBC News that "while the uncertainty principle does indeed forbid one from knowing the position and momentum of a particle exactly at the same time, it turns out that it is possible to ask 'what was the average momentum of the particles which reached this position?'" . [B] "You can't know the exact value for any single particle, but you can talk about the average[/B]."[/quote]I think this is the important bit. They aren't breaking any fundamental laws.

[QUOTE=Turnips5;30243651]I think this is the important bit. They aren't breaking any fundamental laws.[/QUOTE] I think this was theorized already. I don't know for sure from the article if this experiment was to prove the theory or if it was revolutionary on its own.

[QUOTE=Glorbo;30243780]I think this was theorized already. I don't know for sure from the article if this experiment was to prove the theory or if it was revolutionary on its own.[/QUOTE] I think it is significant in that it supprts the usage f weak measurements, and that they have a valid use. the rest is just the usual 0MG cured cancer stuff that ges int science news.

[QUOTE=larrylumpy;30242594]so... they're breaking the laws of physics? someone explain please, I'm lost :saddowns:[/QUOTE] The laws of physics are set by us. We think that it's how it truly works, so we assign a law to it. We can be easily wrong, and break our own laws, but it doesn't have much to do with bending physics, but breaking our own expectations about it.

that video was funny

Speaking generally, this doesn't even seem to be the case.