If we know the exact speed of light then it’s clearly not infinite. If that’s the cause, what is preventing us from sending something faster then the speed of light( ignoring our current technology limitations).
In: Physics
Relativity isn’t exactly a ELI5 sort of subject, but I’ll take a stab at it. The speed of light, c, is the speed of light through space, but is the speed of all things through spacetime. Everything travels at c. This is the only possible speed. The catch is that the speed of any object has two velocity components: its speed through space, and its speed through time. Photons travel at the speed of light through space, so from the perspective of a photon, it doesn’t experience time. The entire journey of a photon is instantaneous from its perspective. Conversely, an object which travels at c exclusively through time would not move through space at all. We’re pretty close to that, though we do move slowly through space, so our speed through time slows down ever so slightly the faster we travel.
Photons can travel at c through space because they have no mass, and hence there is no energy required to accelerate them. Conversely, any massive object requires energy to accelerate it to move faster through space, and the amount of energy required increases the closer that velocity through space gets to c, the only possible speed of objects through spacetime. As such, no matter how much kinetic energy you add to any moving object, the best you can do is to approach c asymptotically. To actually get there would require an infinite amount of energy input, which is of course impossible.
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