According to Einstein’s relativity, nothing can surpass the speed of light in a vacuum. In his Theory of Relativity, Einstein stated that the speed of light—299,792 kilometers per second (186,282 miles per second)—is the ultimate speed limit in the universe. As objects move faster, they require more energy to keep accelerating. If an object were to reach the speed of light, it would need infinite energy, which is impossible according to our current understanding of physics.
This rule applies to all matter, meaning that even the fastest spacecraft or particles in particle accelerators cannot break this limit. However, light itself, which is made of massless photons, can travel at this maximum speed in a vacuum, where there is no air or other materials to slow it down.
Strange things happen as objects approach the speed of light. Time slows down, distances appear to shrink, and an object’s mass effectively increases. This is why astronauts traveling near light speed would age more slowly compared to people on Earth—a concept known as time dilation.
