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
* Normally, how fast something is going depends on who is asking.
If you are sitting in a bus, you aren’t moving. But if the bus is moving, someone standing on the side of the road will see you moving at a particular speed. Someone driving by in a car will see you moving at a different speed. Someone walking down the aisle in the bus will see you moving at another speed. Provided things are not accelerating (so changing speed or direction) there is no “preferred” viewpoint. Each is just as valid as any other, so speeds are all *relative.*
* But it turns out there is a special speed that is the same for everyone (locally);
So if something is travelling at this speed according to one person, it is travelling at this speed *according to everyone*. So something moving past you at this speed is also moving at that speed according to the person on the side of the road, or in the car, or walking in the bus, no matter how fast any of them are going compared to you. Conventionally, this speed is called “*c*”, and is about ten million miles per minute (fun fact; *c* is an example of convergent labelling – it came from several different areas of physics, where it stood for something different, but where it turned out they were all related).
For example, if you were sitting on the bus, and your bus was travelling at 1/2*c* (which would be very fast for a bus), something travelling at *c* faster than you, would still be travelling *c* faster than someone stood on the side of the road (not 1.5 *c*, as we would expect).
* This means something cannot get to that speed, or if at that speed, cannot change speed.
If this speed is the same for everyone, you can *never* accelerate up to it. Imagine trying to catch up to something travelling at this speed; you start speeding up and get to 1/2 *c*. But because *c* is the same for everyone, that thing is still travelling *c* faster than you. So you speed up some more. Except it is still going *c* faster than you. And so on. No matter how much you speed up, it is always going faster than you (effectively, space and time warp a bit around you so this works).
If someone is travelling at this speed already, everything kind of gets messed up. Due to how space and time are warped, *no time can pass for that person*, so there is literally no time for them to speed up or slow down.
* “Light” travels at this speed (sometimes – as with everything, physics is more complicated) because it has no mass.
Mass is the stuff that slows us down (the more mass, the more work it takes to speed us up). Light doesn’t have any mass to slow it down, so it will go as fast as it can – and the fastest it can go is this speed, *c*.
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