Is time travel theoretically possible?
Hop into the TARDIS or hop into the DeLorean and step out into any era in the universe. In this genre of science fiction, technology is nothing. Supersonic travel in a futuristic vehicle is not limited to space. You can also travel anywhere in time in the science fiction world.
For example, to yesterday, so as not to lose the lost set of keys. To the Middle Ages, to take a look. Or to the year 2375 to find out if the world really ended. It's all fictional Sciences. But what does non-fiction science say about time travel?
Time is relative
In theory, time travel is possible. But how can that work? Let us first delve deeper into this theory.
The universe consists of four dimensions. Three of them are spatial dimensions: top to bottom, left to right, and front to back. The fourth dimension is time: early – later. Space and time are inseparable. The first person to realize this was the most famous physicist of all time: Albert Einstein.
In 1905 Einstein formulated the theory Special relativity. It states that energy and mass are interchangeable, according to the world-famous formula E=mc2. According to the same indisputably proven theory, space and time (in short: space-time) are distorted as a result of the speed at which an object moves. Time passes more slowly for faster things. That is, time appears to pass more slowly than at a fixed point. So: time is relative.
Time travel suddenly makes you younger than your twin brother
Time passes more slowly on board a spacecraft than outside it. At least, from a fixed (or slower moving) point there. This means that in theory you can travel into the future. We explain how this complex phenomenon works with the so-called twin paradox.
Suppose you took a long flight in a spacecraft at lightning speed and traveled all the way to the neighboring star Betelgeuse and back again. Meanwhile, your twin brother will remain on Earth. If you return, sixty years have passed, and he is old. But your spaceship flew at the speed of light (almost), making time pass relatively slower for you. That's why she's only a few years older.
Once you returned to Earth, you ended up in your twin brother's future. To you, it still feels like your present, which it is, but from your brother's point of view, your time has slowed down. Strange, isn't it? But measurements using atomic clocks have proven that this is indeed possible.
You can never stop yourself from being born
Time travel to the past is much more complicated. Most scientists agree that time travel is impossible. It would also cause very strange paradoxes.
For example, what if you killed your parents in the past, which means you would never have been born and therefore could never travel back in time? Besides, surely someone who returned to the present from the future would have already told us that?
Will your pet also notice if your time is too late? And how fast must your spaceship fly to exceed the speed of sound?
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