Later On

A blog written for those whose interests more or less match mine.

Is Light Fundamentally A Wave? Or A Particle?

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Ethan Siegel writes in Forbes about a limitation in our knowledge of the world:

One of the most bizarre aspects of quantum physics is that the fundamental entities that make up the Universe, what we know as the indivisible quanta of reality, behave as both a wave and a particle. We can do certain experiments, like firing photons at a sheet of metal, where they act like particles, interacting with the electrons and kicking them off only if they individually have enough energy. Other experiments, like firing photons at small thin objects — whether slits, hairs, holes, spheres, or even DVDs — give patterned results that show exclusively wave-like behavior. What we observe appears to depend on which observations we make, which is frustrating, to say the least. Is there some way to tell, fundamentally, what the nature of a quanta is, and whether it’s wave-like or particle-like at its core? That’s what Sandra Marin wants to know, asking:

“I wonder if you could help me to understand John Wheeler – the delayed choice experiment and write an article about this.”

John Wheeler was one of the most brilliant minds in physics in the 20th century, responsible for enormous advances in quantum field theory, General Relativity, black holes, and even quantum computing. Yet the idea about the delayed choice experiment hearkens all the way back to perhaps our first experience with the wave-particle duality of quantum physics: the double-slit experiment.

The idea of a double slit experiment goes way back to Christiaan Huygens, a prominent scientist in the 17th century who, in many ways, was a formidable rival to Isaac Newton. Newton insisted that light was a particle-like ray — a corpuscle, in his words — pointing to phenomena like the refraction of light through a crystal. Huygens, however, realized there were properties of light that were much better explained with waves, like interference and diffraction.

If you were to drop an object in a steady, still pool of water, for instance, you’d watch as it generated ripples that traveled outward: waves. If you set up a barrier to block the waves, but . . .

Continue reading.

More on the double-slit experiment in this article.

Written by Leisureguy

8 January 2021 at 1:14 pm

Posted in Science

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