In science fiction films, characters use special machines, even jumping into futuristic cars to travel backward or forward in time.
Is time travel merely an intriguing concept for movies, or could it actually happen?
According to The Conversation, the question of whether time can be reversed remains one of the greatest unanswered questions in science.
If the universe adheres to the laws of thermodynamics, then it may be impossible. The second law of thermodynamics states that everything in the universe can either remain the same or become more chaotic over time.
According to this law, the universe can never return to exactly how it was before. Time can only move forward, like a one-way street.
Is time reversible? It remains one of the biggest unanswered questions in science – (Image: THE CONVERSATION).
Relative Time
However, Albert Einstein’s theory of special relativity shows that time passes at different rates for different people.
Someone on a spaceship traveling nearly at the speed of light, over 1 billion km/h, will experience time slower than a person on Earth.
Humanity has yet to create a spacecraft capable of moving close to the speed of light, but astronauts visiting the International Space Station orbiting Earth at speeds exceeding 28,000 km/h.
Astronaut Scott Kelly spent 520 days on the International Space Station, resulting in him aging slightly slower than his identical twin brother, Mark Kelly, who is also an astronaut.
Paradoxes and Failed Parties
There are also paradoxes related to time travel. The “Grandfather Paradox” (The Grandfather paradox originates from a 1943 work by French author René Barjavel) famously posits that if someone travels back in time and inadvertently prevents their grandparents from meeting, it creates a paradox: “If the grandparents do not meet, then there are no parents, and of course, that person is never born.”
The question arises: How could that person travel back in time in the first place? This is a perplexing puzzle that adds to the mystery of time travel.
Renowned physicist Stephen Hawking experimented with the possibility of time travel by hosting a champagne party for time travelers with premium Krug champagne and hors d’oeuvres in 2009.
The invitation card specified the exact time and place of the party, accompanied by the message: “You are cordially invited to a party for time travelers“. He only sent the invitations after the party had already concluded.
His hope was that someone living in the future, who could time travel, would read the invitation. But no one showed up.
Hawking pointed out: “Time travel is impossible and will never happen. This is because we have not yet been invaded by tourists from the future.”
The Telescope as a Time Machine
Interestingly, astronomers equipped with powerful telescopes possess a unique form of time travel.
When they look into the vastness of space, they are observing the universe in the past.
Light from all galaxies and stars takes time to travel, and these beams of light carry information from distant times.
When astronomers observe a star or galaxy through a telescope, they do not see it as it is in the present; instead, they see it as it existed when the light began its journey to Earth millions to billions of years ago.
Nasa’s James Webb Space Telescope is currently observing galaxies formed at the time of the Big Bang, approximately 13.7 billion years ago.
While it may be a while before we have time machines like those in the movies, scientists are actively researching and exploring new ideas.
