Time is one of the most confusing concepts in the world. To an average person, time feels absolute, but we are all aware that it is a relative quantity. The idea of time travel has been a part of science-fiction for decades. The notion of time and space and their reality twists our minds when we think about it.
The 20th-century genius, Albert Einstein suggested that time and space are one and the same: spacetime. We can travel through space then we should be able to travel through time. We can move through three dimensions visibly and time is just the fourth. According to Einstein’s theories, one can travel through time if they are able to move faster than the speed of light. The speed is nearly 3E8 (299 792 458) meters per second. Managing to move at a speed higher than that will allow us to move through time. How to make that possible is another question, but if we are able to build a spaceship that can move at that speed, a day aboard that ship will amount to a year on Earth.
Would it feel like a year or would it feel like a day? So much mumble jumble.
The 21st-century genius Stephe Hawking explained the phenomenon:
“It would take six years at full power just to reach these speeds. After the first two years, it would reach half light speed and be far outside the solar system. After another two years, it would be traveling at 90 percent of the speed of light. After another two years of full thrust, the ship would reach full speed, 98 percent of the speed of light, and each day on the ship would be a year on Earth. At such speeds, a trip to the edge of the galaxy would take just 80 years for those on board.”
If you have heard of the planet Proxima Centauri which is potentially habitable, you can consider going there in just 4.22 years with this speed. If that happens, do go there with your family because if you don’t, they would probably be dead by the time you come back. Theoretical physicist and string theorist Brian Greene explains how you will age through that time, ” When you step out of your ship, you’re one year older but Earth has gone through many, many years. It can have gone through 10,000, 100,000 or a million years depending on how close to the speed of light you traveled.”
Moving with the speed of light is one idea, the other is through wormholes. A physicist at the City University of New York, Michio Kaku explained this saying, “Wormholes are the future, wormholes are the past. But we have to be very careful. The gasoline necessary to energize a time machine is far beyond anything that we can assemble with today’s technology.”
The concept of time travel in our minds is instilled by science-fiction which generally only implies going to the future and seeing the same things or maybe the past but it, in fact, is just experiencing time dilation, no matter how much. Time travel has happened for real; Russian Cosmonaut Sergei Krikalev holds the record of staying the longest in space for 803 days, nine hours, and 39 minutes. He also holds the record for being the human who has traveled the farthest in time. For all his time in space, he has lived a total of 0.02 seconds less than the people on earth. That means a travel of 0.02 seconds into the future.
Going to future in time makes sense but moving back to the past? Hmm, it is possible, theoretically. But doing that would require half the matter and energy of the entire universe. Yeah, we are sure you don’t want that.