While Einstein's theory of relativity shows the relationship between time and speed. Theoretical ideas such as wormholes offer possible methods, but practical challenges and paradoxes, such as the "grandfather paradox", complicate the feasibility of time travel in practice
By Adi Ford, University of Maryland at Baltimore
Time travel, a perennial issue in the field of science fiction, remains a complex and unresolved concept in science. The second law of thermodynamics requires that time can only move forward, while Einstein's theory of relativity shows the relationship between time and speed. Theoretical ideas such as wormholes offer possible methods, but practical challenges and paradoxes, such as the "grandfather paradox", complicate the feasibility of time travel in practice.
Will time travel ever be possible?
Have you ever dreamed of traveling through time, like characters do in science fiction movies? For centuries, the idea of time travel has captured the imagination of many people. Time travel is the idea of moving between different points in time, just like you move between different places. In the movies, you may have seen characters use special machines, magical devices, or even a futuristic car - to travel back or forward in time.
But is this just a fun movie idea, or could it really happen?
The science behind time travel
The question of whether time is reversible remains one of the greatest unsolved questions in science. If the universe works according to Laws of thermodynamics, this may not be possible. The second law of thermodynamics states that things in the universe can stay the same or become more disordered over time.
It's a bit like saying you can't turn an omelette back into an egg. According to this law, the universe can never return to exactly what it was before. Time can only move forward, like a one-way street.
Time is relative
Yet, Einstein's special theory of relativity suggests that time passes at a different pace for different people. Someone speeding on a spaceship approaching the speed of light - a billion km/h - will experience time more slowly than a person on Earth.
Humans have not yet built spacecraft that can travel near the speed of light, but astronauts visiting the International Space Station circle the Earth at speeds approaching 17,500 km/h. Astronaut Scott Kelly spent 520 days on the International Space Station, and as a result aged a little slower than his twin brother – and fellow astronaut – Mark Kelly. Scott was 6 minutes younger than his twin brother. Now, because Scott was traveling much faster than Mark and for so many days, he 6 minutes and 5 milliseconds younger.
Time is not the same everywhere – Theoretical possibilities and challenges
Some scientists are exploring other ideas that could theoretically enable time travel. One concept involves wormholes, or hypothetical tunnels in space that could create shortcuts to travel across the universe. If someone could build a wormhole and then find a way to move one end close to the speed of light – like the hypothetical spacecraft mentioned above – the moving end would age more slowly than the stationary end. Whoever entered the moving end and exited the wormhole through the stationary end would have exited in the past.
However, wormholes remain theoretical: scientists have yet to identify such a hole. It would also be very challenging to send humans through a wormhole tunnel in space.
Paradoxes and failed dinners
There are also paradoxes associated with time travel. "The grandfather paradox” The famous one is a hypothetical problem that could arise if someone traveled back in time and accidentally prevented their grandparents from meeting. This would create a paradox where you were never born, which begs the question: how could you travel back in time in the first place? This is an amazing puzzle that adds to the mystery of time travel.
Stephen Hawking explored the possibility of time travel by Organizing a celebratory dinner where orders specifying the date, time and coordinates were sent only after this happened. His hope was that his invitation would be read by someone living in the future, who had the ability to travel back in time. But no one came.
as he is Please specify: "The best evidence we have that time travel is not possible, and never will be, is that we have not been invaded by hordes of tourists from the future."
Telescopes are time machines
It is interesting to note that astrophysicists armed with powerful telescopes have a unique form of time travel. When they peer into the vastness of the cosmos, they are looking into the primordial universe. Light from all galaxies and stars takes time to travel, and these light beams carry information from the distant past. When astrophysicists view a star or galaxy through a telescope, they do not see it as it is now, but as it existed when light began its journey to Earth millions to billions of years ago.
Telescopes are a kind of time machine - they allow you to peek into the past.
While it's unlikely we'll have time machines like the ones in the movies anytime soon, scientists are actively exploring new ideas. But for now, we'll have to enjoy the idea of time travel in our favorite books, movies and dreams.
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