Can we travel faster than light? According to our current understanding of physics and the limits of the natural world, the answer is sadly no. Albert Einstein's theory of special relativity, summarized in the famous equation E%3Dmc2, states that the speed of light (c) is a cosmic speed limit that cannot be exceeded. This universal constant is known as c or speed of light and is measured at 299,792,458 meters (983,571,056 feet) per second, which is approximately 186,282 miles per second. Light can propagate freely in a vacuum but its speed of propagation and wavelength depend largely on the properties of the medium through which it travels.
A light-year is the distance light can travel in a year, about 6 trillion miles (10 trillion kilometers). Even if you put a lot of energy into a massive particle, it will still travel slower than light. For example, light that travels through the Earth's atmosphere moves almost as fast as light in a vacuum but slows down just three-ten-thousandths of the speed of light. When a very fast particle travels through a medium, it is generally charged and the medium itself is made up of positive (atomic nuclei) and negative charges (electrons).
This has the effect of immediately changing the speed at which light travels. This is also the speed at which any form of pure radiation, such as gravitational radiation, must travel and also the speed at which any massless particle must travel according to the laws of relativity. In an act of intuition, Rømer determined that it took a measurable amount of time for light to travel from Io to Earth. The charged particle, when traveling through this medium, has the possibility of colliding with one of the particles it contains but since atoms are mostly empty spaces, the odds of collision are relatively low over short distances.
Empedocles proposed that light must have a travel speed and thus must travel. Traveling faster than light enables countless sci-fi franchises since it condenses vast stretches of space and allows characters to come and go between star systems with ease. However, according to our current understanding of physics and the limits of the natural world, this is not possible.
