Quantum physics goes to the movies

30 Mar

This movie shows one of the most beautiful – and mind-boggling – experiments in physics: particles behaving as waves as they pass through a diffraction grating.

Each speck of light represents a single molecule that has passed through the grating. If the molecules obeyed the laws of classical physics – the laws that describe the motion of everyday, macroscopic objects – we’d see a pattern corresponding to the slits in the grating, as if we’d thrown a load of blackcurrants through some railings (as you do).

Instead, we see an interference pattern, even though the molecules go through the grating one by one. This can be explained by each molecule having its own wavefront which goes through all the slits at once – it’s a bit like a blackcurrant turning into a wave (of Ribena?), rippling through all the railings, and combining again into a blackcurrant as it hits the wall. Crazy, I know.

This phenomenon is called wave-particle duality, and this movie is the first time it’s been captured on camera for large molecules. As physicists carry out these kinds of experiments with larger and larger molecules, they’ll be able to understand more about the differences between the world we see around us and the strange, surreal world of atoms and molecules.

If you’re interested in finding out more, I wrote an article about this movie for physicsworld.com – click here to have a read.

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