Speed of Light

Einstein’s special theory of relativity governs our understanding of both the flow of time and the speed at which objects can move. In special relativity, the speed of light is the ultimate speed limit to the universe. Nothing can travel faster than it. Every single moving object in the universe is constrained by that fundamental limit.

Speed of Light and Sound
This isn’t something like the speed of sound. Early scientists wondered if we could ever go faster than that speed, not because of some fundamental rule of the universe, but because we didn’t know if our engineering and materials science capabilities could withstand the extreme turbulence generated by moving at such speeds. But everyday objects already surpass the speed of sound. For example, the crack of a whip is caused by the tip creating a sonic boom as it travels faster than the sound speed.

The problem with trying to surpass the speed of light is that as you go faster, the more kinetic energy you have. But relativity tells us that energy is the same as mass, so the faster you go the more massive you become (and yes, this means that a moving baseball has more mass than one standing still, but that’s a tiny effect).

As you approach the speed of light, your mass balloons up to infinity. The closer you get to the speed of light, the more out of control your mass becomes. With higher masses, you must push yourself harder to accelerate, and you quickly find yourself in a position where it would take an infinite amount of energy to overcome light speed.

Exploring Light Speed
This isn’t just a matter of clever engineering or figuring out some trick – this is built into the fabric of the universe.

That said, there are proposals out there for designing specialized devices that could supposedly overcome this limit without outright breaking relativity. These concepts work because special relativity is a law of local physics: It tells you that you can never measure nearby motion going faster than light speed.  READ MORE...