Time Travel! Possible?

Hey there! Have you ever thought about traveling through time? I'm sure we all have! Maybe you want to go back to the past to see how things were or even change something. Or would you prefer to go into the future to see how things turn out? Time travel is a popular topic in science fiction, with books and movies imagining the benefits and risks of such an ability. But is time travel actually possible? And if so, what do we need to be able to do it?

To understand how we might go about traveling through time, we must first understand what time is. Classical physics saw the concept of time as something that exists for everyone, everywhere in the universe. It's independent of anyone who perceives it and progresses at the same pace for everyone. This means that a cause is always followed by an effect, never the other way around. This is something that the structure of the universe relies upon.

However, the problem with this understanding of time is that it doesn't hold true in all circumstances. That's why Einstein's theory of relativity is seen as one of the most important scientific breakthroughs ever, because it explains the changing nature of time. The theory of relativity sees time as one element of four-dimensional space-time and can be influenced by other factors. For example, objects moving at high speed experience time slower than those moving with less velocity. There's a similar effect for objects held within gravitational fields.

On a human level, this means that an astronaut orbiting the Earth will age slower than those of us that remain on the planet. But there are far more unexpected consequences of this. Take black holes, for example. They assert the greatest gravitational pulls of any object in the universe. They are so strong that light itself cannot escape and also cause time to slow down to an extreme level. If you were to fall into a black hole while looking out into the rest of the universe, you would, in theory, witness hundreds of millions of years worth of events before ultimately succumbing to your inevitable fate.

So does time travel still seems impossible? Well, it's not as straightforward as that. We might just not know about it yet, or maybe it has already been achieved! These thoughts can really make your mind explode, right? But don't worry, a genius like Albert Einstein took up the challenge over a hundred years ago.

In 1905, Einstein started publishing his famous theory of relativity, which is like the gold standard for all things physics. It's the perfect way to understand time travel. But let me break it down for you. Before Einstein, physicists relied on Isaac Newton and his laws of motion. You've probably heard of the one that says for every action, there's an equal and opposite reaction. Well, Einstein built on this idea and defined his breakthrough by looking at the speed and mass of objects in relation to each other. Here's the cool part: Einstein found that when it comes to the speed of light, things are definitely equal. According to him, nothing can travel faster than the speed of light, which is about 300,000 kilometers or 186,000 miles per second. This led to his famous equation, e equals mc-squared, where energy equals mass multiplied by the speed of light squared. It's some essential math that has had great results for physics, but unfortunately, it also played a role in the creation of the atomic bomb.

Now, let's give Einstein some credit. He couldn't have predicted that his ideas would be used to create weapons of mass destruction. In fact, his theory of relativity has positive applications all around us. Take GPS, for example. It relies on Einstein's concepts. So, we would be quite literally lost without him.

But here's the thing, Einstein didn't come up with his theory all at once. That would be too incredible, even for him! By 1905, he cracked what he called special relativity, which was just the beginning of his groundbreaking work.