Faster-than-light (FTL) travel and communication are the conjectural propagation of matter or information faster than the speed of light. According to the special theory of relativity, only particles with zero rest mass may travel at the speed of light. However, there are certain scenarios where it might appear that something is moving faster than light, but in reality, no information is actually traveling faster than light. For example, if a laser beam is swept across a distant object, the spot of laser light can easily be made to move across the object at a speed greater than the speed of light, but no information is actually traveling faster than light. Similarly, the expansion of the universe during the Big Bang is often cited as an example of something expanding faster than light, but this does not violate the speed of light barrier as it involves the expansion of space itself rather than the movement of matter through space.
The hypothetical elementary particles that are thought to always move faster than light are called tachyons or tachyonic particles. However, attempts to quantize them have failed to produce faster-than-light particles, and instead illustrated that their presence leads to an instability.
In a non-vacuum setting, light itself can technically travel faster than the speed of light, but only when not in the vacuum of space. However, regardless of the medium, light will never exceed its maximum speed of 186,282 miles per second.
In summary, while there are conjectures and hypothetical scenarios, there is currently no known phenomenon or particle that travels faster than light. The concept of faster-than-light travel remains a subject of scientific inquiry and speculation, with no confirmed practical application at present.
