Life's Great Mysteries - Is time travel possible?

Time travel is one of the most frequent themes in science fiction. In fact, I’ve written a number of novels involving time travel. People love to imagine what it would be like to travel back or forward in time. So, is time travel really possible?

Let’s consider the past first. I hate to say this, but currently there are few physics concepts that indicate traveling into the past will ever be possible. Well, there are some, but they are theoretical, with little hope of becoming practical things we can create and control. One example is to create a time curve—if a person follows the path, they would eventually find themselves back where they started. This was first shown to be mathematically possible in 1949, and many times since then. But there’s no evidence such a phenomenon actually exists anywhere in the universe.

A few other scenarios have been proposed. There’s a wild idea involving two cosmic strings moving past each other in opposite directions, thus creating a time curve looping around the strings. Another idea is wormholes, in which space-time can fold like a piece of paper. These sound great, but they are mathematical in nature and have not been observed to exist. The barriers to creating and controlling them are overwhelming, to say the least. So… time travel into the past is probably not within our reach.

Time travel to the future, on the other hand, is definitely possible. Yay!

Technically, we are already traveling into the future at one hour per hour. But you knew that already. How can we travel into the future faster than one hour per hour? It’s simple—all we have to do is move through space very fast.

According to Einstein’s Special Relativity theory, if you move through space at a really high speed (relative to other objects), time goes slower for you than for the people you left behind. This is called time dilation, and it’s an observable fact. It’s the reason the clocks on GPS satellites disagree with the clocks on Earth by seven millionths of a second for every day they are in orbit. Sergei Krikalev (a Russian cosmonaut) spent 803 days, 9 hours, 39 minutes orbiting our planet at 17,500 miles per hour. So, he traveled into his own future by 0.02 seconds.

The closer you get to the speed of light, the faster your time travel. Let’s say a 10-year-old boy leaves Earth in a spaceship traveling at 99.5% the speed of light, then returns to Earth after five years have passed on the spaceship. The boy would be 15 years old, but his classmates would now be 60 years old. From the boy’s perspective, only five years passed, but fifty years passed on Earth.

This is real time travel into the future. The problem is, the faster an object travels, not only does time pass faster, but the object also increases in mass (Special Relativity again), which means more fuel is needed to accelerate the object. At the speed of light, the object’s mass becomes infinite, which is why no physical object can travel the speed of light. With our current technology, we cannot accelerate any object to 99.5% the speed of light (or any velocity even close to that). So, while time travel into the future is certainly possible, it isn’t easy or practical.

But that doesn't stop me from thinking about time travel frequently.

Photo Credits:
- Time Travel image - Midjourney 6.1