Einstein’s theory of relativity is probably one of the most intriguing theories ever conceived of; and probably the most interesting aspect of this is the phenomenon known as time dilation. As explained by the article Slowing Time to a Standstill with Relativity, “Time dilation is the idea that as you move through space, time itself is measured differently for the moving object than the unmoving object”. However, this difference becomes all the more discernible as one approaches a black hole; a black hole is formed when a gargantuan star collapses upon itself. A black hole is essentially a region in space that exudes such a powerful gravitational force that all bodies, particles and radiations cannot escape from its pull—not even light. So, as an object approaches a black hole, it experiences severe time dilation—that is, the elapsed time intervals lengthen.
This phenomenon has become a popular topic in science fiction books and films. For instance, if a spaceship comes closer and closer to the event horizon of a black hole, every passing second would indicate the passage of hundreds and thousands of years back on earth. This theme was explored in the science-fiction movie Interstellar—wherein the space team reaches a planet (which has the potential to be a new home for mankind) on which every passing hour is the equivalent of the elapsing of seven years back on earth.
There is another way time dilation can be experienced—and that is when a body approaches speeds equaling that of light (3 × 108 ms-1). One way this was verified was through the observation of muons; a muon is an unstable subatomic particle which has a mass that is around 200 times that of an electron. Muons are produced by cosmic rays in the atmosphere—mainly in the ionosphere and magnetosphere (approximately 16,000 meters above the ground). Scientists have claimed that the life of a muon is 2 microseconds, and that its velocity is 0.9c (“c” denotes the speed of light in vacuum). So, using these two numbers, it can be calculated that a muon would only be able to travel 600 meters in its lifetime. However, these particles are able to travel a gaping 16,000 meters from the upper reaches of the atmosphere, to the earth’s surface. So, the only explanation is time dilation. Indeed, while time dilation may seem like the speculations fit for science fiction movies and novels, they are still seen in real life—from the towering reaches of the earth’s atmosphere, to the ground far below.
It’s amazing to know that people can actually be prevented from aging; for instance, if a crew traveled around the galaxy at the speed of light and returned back on earth, they would come back to their home planet and realize that they’re still years younger than people who were originally younger than them! And what’s even more fascinating is the speculation that if we were to travel faster than the speed of light, time would actually go in reverse! And regardless of how unrealistic this may seem, these theories have actually been verified by extremely accurate, scientific clocks. And who knows? —if we’re able to accelerate to the speed of light one day, humanity may become an immortal species… Such is the power of time dilation and relativity.