Question: What if the x-ray beams made you look at stuff on the subatomic particles scale? Would it be any use?

Richard Fielder answered on 30 Sep 2020:

It could be very useful, but unfortunately that’s not how x-rays work. Light generally interacts with things that are a similar size to the light’s wavelength. So we see things with visible light because that has the right wavelength to interact with larger molecules and objects, while radio waves are useful for long distance communication because they don’t even notice small things like air and people so they keep travelling without being interrupted. X-rays have shorter wavelengths and can be the right size to interact with individual atoms, which makes them very useful for seeing the structure inside molecules.

In order to see at the subatomic scale, we’d need light with much shorter wavelengths again, but that comes with a few problems. First of all, shorter wavelength means higher energy. We can produce bright visible light with a small battery-powered torch, but to produce really bright x-rays we need a particle accelerator (old CRT TVs were so much bigger than modern ones because they contain a very small, low energy particle accelerator). To get to the small wavelengths needed for subatomic scale, we’d need huge accelerators using a massive amount of power, and obviously that would be a lot more expensive as well.

Secondly, it would be much more difficult to actually use them to look at anything. The reason x-rays are useful is because they pass through most matter instead of just bouncing off it, but that also makes them harder to detect. If we wanted to use even higher energy light, it would be even more difficult to detect, because it wouldn’t just pass through the samples we want to look at, it would pass straight through our detectors as well.

Thirdly, it would be difficult to use that sort of radiation safely. X-rays are useful to look inside things because they pass through matter fairly easily, but that means it’s difficult to shield against them as well. That’s why we need lead shielding, or thick conrete walls, when using x-rays. Shorter wavelengths would penetrate even more, and need much more shielding to be used safely. At the energies needed to look at the subatomic scale, you’d likely need shielding tens or even hundreds of metres thick, which would take up so much space you’d hardly have room left for the actual experiments.

This is why high energy physics tends to use particle colliders. Trying to look inside the structure of atoms directly using light isn’t realisticly possible, so instead we try to smash things apart and collect whatever is produced. It’s more complicated to figure out what’s going on that way, but the tools required are much easier to build and use.