One of the first things you learn in physics or astronomy 101 is that the speed of light is a constant. We call it by the letter "c", and it's equal to 299,792,458 meters/second or 670,616,629 mph. According to the theory of relativity, nothing can travel faster than the speed of light. Why? It's not something Einstein made up, it comes from the theory of physics. Light has properties of both particles and waves. It tends to travel like a wave (similar to a sound wave), but interacts like a particle (like two objects bumping into each other). The crucial piece to all of this is that light has no weight. It can interact with objects, and it has energy, but no weight. So what does this have to do with speed? Physics says that as you move faster, your mass (how "heavy" you are in a sense) increases. Now I don't mean speeding up from 0 to 60mph in a car, I mean traveling very close to the speed of light. The closer you get to c, the "heavier" you get. If a person were to travel at the speed of light, their mass would be infinity. This is why people, or other massive objects, can't travel at light speed. But since light waves/particles have no mass, they can travel at the speed of light no problem! Experiments show us that light has no mass, and travels a given speed "c". Therefore, any object with zero mass can travel at a maximum speed of c. And since objects can not have negative mass, there is no physical way for anything to travel faster than c. Or is there?.... Tune in later this week to learn about objects called neutrinos that may somehow have the ability to travel faster than the speed of light!
