X-Ray Absorption When I went to the doctor for my broken leg, I thought it was strange how the x-rays passed right through me. Yep, you're not the only one who feels that way. Röntgen, the person who discovered x-rays, was intrigued that x-rays could partially pass through people. But how does it happen? I never felt the x-rays inside of me. That's why Röntgen called them x-rays, because he didn't know what was going on or why. "X" is a way of labeling something as mysterious. Like Planet X or the X-files. Right, only now we know better. X-rays are high-energy photons, just like ordinary visible light, except with more energy and a shorter wavelength. But ordinary light doesn't pass through people. ...something you won't see very often That's because they are "too thick". Try this experiment. I'll give you a souped-up flashlight that can emit any frequency (or color) of light including x-rays. Shine it on a chunk of matter and see what comes out the other side. Only the x-rays pass through, but you didn't say why. Photons can pass through a substantial thickness of matter only if they have high enough energies.

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