Time Travel

Have you ever dreamt of time travel? It's a concept that has captivated our imagination, whether it's the desire to journey to the past, witness historical events firsthand, and maybe even change the course of history, or the curiosity to venture into the future and see how things unfold.

Time travel has been a popular theme in science fiction, explored in countless books and movies, delving into the potential benefits and risks associated with such an extraordinary ability. But the question remains: is time travel actually possible? And if so, what would it take to achieve it?

To comprehend the possibilities of time travel, we must first grasp the nature of time itself. In classical physics, time was considered an absolute entity, existing universally, independent of individual perception, and progressing at a constant rate for everyone. It was believed that cause always precedes effect—a fundamental principle on which the structure of the universe was believed to rely.

However, this understanding of time doesn't hold true in all circumstances. This is where Albert Einstein's theory of relativity comes into play, recognized as one of the most significant scientific breakthroughs. The theory of relativity views time as an element of four-dimensional space-time, influenced by various factors.

For example, objects moving at high speeds experience time dilation, where time appears to pass slower for them compared to objects moving at lower velocities. Similarly, the presence of strong gravitational fields also affects the flow of time.

On a human scale, this means that an astronaut orbiting the Earth would age slower than individuals remaining on the planet's surface due to the relative motion and gravitational influences experienced. However, the consequences of this understanding extend far beyond our everyday experiences.

Consider black holes, which possess the most powerful gravitational pull in the universe. Their gravitational force is so immense that even light cannot escape, causing time to slow down dramatically.

In theory, if one were to approach a black hole—like the ill-fated Matthew McCaughey character in the movie Interstellar—they would witness time slowing down to an extreme extent.

Looking out into the universe, they would observe events spanning hundreds of millions of years before eventually succumbing to the black hole's inevitable fate or, in a comical twist, getting trapped behind some bookshelves. Time would pass so differently outside the black hole that life would be unrecognizable.

Another peculiar aspect of time occurs in relation to the speed of light. As an object accelerates and approaches the speed of light, time slows down for it. This continues until reaching the theoretical maximum speed attainable—the speed of light itself. At this speed, time has slowed to such an extent that events seemingly happen instantaneously.

For instance, imagine a photon of light emitted by a star on the other side of the universe. Despite its incredible speed, it would still take many millions of years to reach us on Earth and be visible to our eyes as a twinkle in the sky. However, for the photon, the journey would be instantaneous—it is created and reaches us in the same instant.

When traveling at the speed of light, time remains neutral, not progressing forward or backward. So, if the faster you go, the slower time appears for you compared to everything else, it presents a potential route for traveling forward in time.

By speeding away from Earth and returning, many years would pass outside while you age relatively little. However, going backward in time is the truly challenging part. If time stagnates at the speed of light, then could traveling faster than light allow us to move backward in time?

Some researchers believe so, and there is a theory suggesting the existence of subatomic particles called tachyons that do precisely that. However, tachyons are purely theoretical and have never been observed.