If atoms are mostly empty space, why is matter not transparent?
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Sure there's lots of empty space within atoms, but that doesn't mean there's nothing there to see.
Asked by: Duncan Henderson, Ruislip
While atoms are indeed mostly empty space, the void is filled with the electromagnetic fields generated by the electrons within the atom. These affect light waves as they move through materials, preventing them from passing straight through unimpeded. Switching to radiation of shorter wavelength, like X-rays or gamma rays, allows even relatively dense materials to become transparent.
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Robert is a science writer and visiting professor of science at Aston University.
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