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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Authors
Robert is a science writer and visiting professor of science at Aston University. He likes maths, West End musicals and hamsters.
