Checking Up On The Speed Of Light

in #science3 months ago

Sometimes scientists just want to check whether things work as they think they should work. So, now they did this with the speed of light.


Image by FelixMittermeier from Pixabay

Einstein's relativity still rules. But physicists aren't just sitting around happy with that so they are always looking for holes in it that could open a way to some kind of new physics. One of the key parts of relativity is the fact that the speed of light is constant everywhere in space. This was the thing the unique high-mountain gamma observatory HAWC (High Altitude Water Cherenkov Observatory) decided to look into. And, to no longer keep you waiting – the speed of light remains the same even at truly extreme energies.

High-Tier Observatory

The observatory can be found on the side of the Sierra Negra volcano in Mexico – roughly 4,100 meters above the sea level. It observes gamma radiation and also cosmic radiation. Using 300 water detectors it can see Cherenkov radiation that is created when high-energy radiation hits the atmosphere.

According to Pat Harding from the Los Alamos National Laboratory (LANL) who is part of the international HAWC Collaboration team – how the speed of light behaves at extremely high energies is essential for physics and even reality itself. The thing is, quantum models predict that the rules entangled with relativity change at high energies. And such things can be verified using only “natural” space experiments in deep space as we cannot reach such energies in our experiments on Earth.

High Energy? No Problem!

The constant speed of light is a key part of the Standard Model of physics. But there exist a number of other theories that would like to conquer the Standard Model. If the speed of light changed at extremely high energies many doors for exotic new physics would open. For example, we could find out that gamma-ray photons fly a little faster (or slower) than the visible part of light. If it was faster then such photons could quickly decay into less energetic particles and never reach Earth.

The HAWC observatory recently detected a good number of astrophysical sources of radiation that give out photons with energies over 100 TeV – about a billion times more than is the energy of visible light. So, the energetic photons can obviously reach Earth. So, now we know that the speed of light stays the same even at energies about a hundred times higher then we had verified before.

But this isn't the end for checking up on the speed of light. Scientists will now try to upgrade their equipment and they hope to verify even higher energies. And then we will see whether Einstein holds up even there.


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