Why can't we exceed the speed of light?

I posted this in another thread, but here is the copy and paste:

To really understand this, you need to consider in essence what time and space is (and this requires some imagination, because it requires you to think in terms of the basic interaction of particles). The very basic unit of information is a subatomic particle, like and electron or a photon, interacting with something. Its not binary, either, a detector does not "know" when a photon hasn't arrived, it can only react when the photon arrives. So when measuring time, you essentially are measuring sequences, not an entity that is time. The very basic clock is a photon bouncing back and forth in a tube, and every time it comes back to the origin, it interacts with something, which keeps an internal counter. And this is how you as a human percieve time - all the microscopic atomic interactions in your body happen due to the interactions of the atomic particles, which happen at the speed of light. And in your brain, when you see a sequence of flashes and you know the "time" between them, what you are really perceiving is how many "internal interactions" happened inside your brain between the flashes. Likewise, with space, the most basic way to know how far something is away is to bounce a particle like a photon off of it, and measure the time, and multiply by the speed of light. Now the things is that you really have to compute the speed of light first, which requires a notion of defining distance in the first place. And the only way to define distance is in comparison to some arbitrary basic clock. Say you send out a photon, and it comes back, and when it does, you resend it again. You have no reference point of time or space before, but you just created one. Now, you send out a photon in another direction along with the original one, and it comes back after 5 photons have came back from the original direction, and this is consistent. You now have a basic clock, call every 5th photon 5 light seconds. Likewise, you can assign a distance to this measurement, calling it 5 light distance units. And as you can see, no matter how you measure the speed of light, you will come out with the same measurement no matter what: 1 light unit/1 light second. This is a non-mathematical explanation of why the speed of light is constant in every reference frame, and how the notions of time and space are very related.

/r/askscience Thread