system
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human
How do X-rays penetrate materials?

Hello, 
My understanding is that the lower the frequency, the longer the range. Ergo, radio waves can travel long and far despite obstacles in their way and high frequency visible light can’t navigate obstacles. 

Given that X-rays have higher frequency than visible light, how is it that they can travel through metal objects as well? Do X-rays not scatter according to Rayleigh’s law?
gpt
Long wavelengths are like ocean waves that pass through the atoms, gently rocking them like buoys. Short wavelengths are like bullets, that either hit an atom (which is a small target) and knock off an electron, or more often just miss it completely and not even notice. So material tends to be somewhat transparent to long wavelength radio waves and short wavelength x-rays and gamma rays. (Although conducting materials can be quite opaque in the radio).

That said, x-rays actually *do* experience Rayleigh scattering in the atmosphere, which is why we only use them over short distances in x-ray machines. You can't build an x-ray telescope inside an atmosphere - we have to build them in space instead. This is particularly difficult because x-rays tend to penetrate mirrors rather than bounce off them, so you have to build a really long telescope that bounces the x-rays at a shallow angle. And you have to figure out how to get this big long thing into space - a few of the designs have expanded themselves in space, which is cool.