I know what the speed of light is basically the speed limit of everything in the universe, and no information can travel faster than light itself. Light also exhibits many interesting properties and also serves as a constant for many formulae and equations in physics. The space-time continuum changes depending on what fraction of the speed of light at which you are travelling.
However, why light? Why is light and only light the one “phenomenon” that dictates most of physics? What makes light so special? My apologies if the question is phrased kind of strange.
In: Physics
As far as know there are 4 fundamental forces in the universe. Every other “force” is based on these 4. Two of those fundamental forces act on VERY small ranges (ie less than the size of atoms). The other ones are gravity and electromagnetism.
Gravity requires a LOT of mass to work but it extends to very long distances. It keeps planets orbiting stars, gives us the weight we feel on earth. Because of this, at human levels, gravity is generally felt as a “constant”. For us, it pulls us and all the stuff on earth towards the ground. We don’t “feel” the gravity of the sun etc because earth’s gravity is large enough to make all other sources of gravity generally irrelevant day to day (except for tides – caused by the moon in ELI5 terms)
The last remaining force electromagnetism is what causes all the other interactions that we study. Electromagnetic forces can operate at “medium distances” and “medium strength”. This is very useful because nearly everything humans do are at this scale. Things like chemical reactions, why we don’t fall through our chairs, what makes electricity and magnets work, radio waves, light, human biology and physics – all of these are basically various forms of electromagnetism in operation. The object that “carries” electromagnetic forces is the photon. Some photons interact with our eyes and we call it light. Many other varieties of photons are not visible to humans. Since pretty much everything that we experience except gravity operates through photons, knowing how it works is pretty much the bulk of physics.
Now this doesn’t explain WHY it is this way. It is this way because the universe appears to work this way.
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