Everyone has thought about time travel at least once in their life. Maybe you’ve wanted to go back in time and try to change something from your past. There’s even a lot of science fiction movies out there that involve time travel, or were inspired by time travel in some way or another. But is it really possible to travel back or forward in time? And if it really is possible, what would we have to do in order to make time travel a reality? The very thought about time travel and what it would take to make it a reality is mind-boggling. It is something that scientists, especially astrophysicists, have long thought about. The most fantastic thing? It’s probably possible. We should probably start off with the bad news about time travel. We probably can’t travel back in time and watch the Egyptians build the pyramids. However, there are a number of theories that have suggested that it is possible to take a leap forward in time. But going back in time is far more complicated. That’s not saying it’s impossible though. The great 20th century scientist Albert Einstein developed a theory called Special Relativity. While most people think of time as a constant, Einstein showed that time is an illusion; it is relative in that it can vary for different observers depending on your speed through space. The ideas of Special Relativity are very hard to imagine because they aren’t about what we experience in everyday life, but other scientists have confirmed this theory. The theory says that space and time are really aspects of the same thing which is called ‘space-time’. There is a speed limit of 300,000 kilometers per second (or 186,000 miles per second) for anything that travels through space-time, and light always travels this speed limit through empty space. So more about this illusion of time, ‘Special Relativity’ says that a surprising thing happens when you move through space-time, especially when your speed relative to other objects is close to the speed of light. Time goes slower for you than for the people you left behind. You won’t notice this effect until you return to those stationary people. So as an experiment, let’s say you were 15 years old and you left Earth in a spacecraft traveling at about close to the speed of light, and you celebrated only five birthdays during your space voyage. When you got home at the age of 20, you would find that all your classmates who were the same age as you when you left were 65 years old, retired, and hanging out with their grandchildren! The reason for this is because as time passed more slowly for you, you would have experienced only five years of life, while your classmates will have experienced a full 50 years.