The concept of Traveling in time has always occupied a special place in the imagination of physicists, but is it possible after all? Of course, it is.
We are doing it every day, even right now. We travel in the future, second by second. However, this is not what we are going to discuss today. We will talk about real traveling, the one that you have seen in “Harry Potter” or “Back to the Future”.
Hawking party for time-travelers
On June 28, 2009, Stephen Hawking hosted a party with balloons, snacks and chilled champagne at Cambridge University. Everyone was invited, but no one showed up. Hawking had been expecting this, as he sent out invitations only after the party had ended. As he said, it was a party for time-travelers that would come from the future. It was just an ironic experiment to confirm his 1992 guess that time travel was impossible.
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Although he is an authority on physics, Hawking might be on the wrong side. Recent experiments support the possibility of time travel, at least in mathematics. These studies are more than just science-fiction-worthy explorations, as they reveal the foundations of the world and enable quantum cryptography and computing.
Theory of relativity
Einstein’s theory of relativity allows the possibility that time can be bent at such an angle that it forms a loop. Imagine you are traveling in this loop. This means that at some point you will return to the past and experience the same moments again. Like Deja-vu, only you will not realize it.
In recent decades, famous physicists such as Kips Torn and Stephen Hawking studied the possibility of time machines. The main conclusions from previous studies are that nature prevents the formation of time loops. This seems best explained in Hawking’s “Chronology Protection Conjecture”, which says that nature prevents a change in its past, shielding us from the paradoxes that would occur if time travel would be possible.
Perhaps the best-known of the three paradoxes that can arise during travel is the so-called “grandfather paradox”, where a person travels past and kills his own grandfather. It changes the course of history in such a way that the traveler himself was never born and thus does not exist.
Other phenomena, such as the need for “exotic” matter, can also prevent time loops from forming. Simply put, “exotic” matter is a substance with a negative mass. The problem is that there is no negative mass in nature.
Traveling to the Future
According to Einstein’s theories, if we could move faster than light, then we could travel in time. The problem is that no one can figure out how to make people move faster than light. The speed of light is 186,282 miles per second (299,792 kilometers per second)
If scientists would succeed in building a spacecraft that can fly faster than light, one day onboard would be one full year on Earth. Every day onboard would be equivalent to one year on Earth. At this rate, traveling to the other side of the galaxy would be 80 years for those on board the spacecraft.
Brian Green, a theoretical physicist at Columbia University, explains: “You are one year older when you get off the ship, but many, many years have passed on Earth. It can be 10,000 or 100,000 years old, depending on the speed of the spacecraft. ”
Another idea about traveling in time is based on moving between “wormholes” in space-time, connected to other places. Mitchi Kaku, a physicist at the University of New York, explains: “Wormholes are the future and wormholes are the past. We must be very careful with them. The fuel needed to activate the time machine is superior to anything we can create with today’s technology. ”
It would take half of the matter and energy of the universe to create enough wormholes to travel to the past. At this point, it is definitely worth putting aside the dream of traveling in the past.