To date, no one has ever traveled in time (at least not officially). But scientists do not stop and the question of whether this is possible at least theoretically is still actively discussed and studied by them.
As you can see in many films, a trip to the future can provoke serious changes in the past and a person then in many cases will not be able to go back. This puzzle is called the grandfather paradox.
The grandfather paradox is a paradox of time travel in which inconsistencies emerge through changing the past. The name comes from the paradox’s description: a person travels to the past and kills their own grandfather before the conception of their father or mother, which prevents the time traveller’s existence.
“Classical dynamics says if you know the state of a system at a particular time, this can tell us the entire history of the system,” said Germain Tobar, a student in the School of Mathematics and Physics at the University of Queensland.
“This has a wide range of applications, from allowing us to send rockets to other planets and modeling how fluids flow.”
“For example, if I know the current position and velocity of an object falling under the force of gravity, I can calculate where it will be at any time.”
“However, Einstein’s theory of general relativity predicts the existence of time loops or time travel — where an event can be both in the past and future of itself — theoretically turning the study of dynamics on its head.”
A unified theory that could reconcile both traditional dynamics and Einstein’s theory of relativity is the holy grail of physics.
“But the current science says both theories cannot both be true,” Tobar said.
“As physicists, we want to understand the Universe’s most basic, underlying laws and for years I’ve puzzled on how the science of dynamics can square with Einstein’s predictions.”
“I wondered: Is time travel mathematically possible?”
Tobar and his colleague, Dr. Fabio Costa from the Centre for Engineered Quantum Systems in the School of Mathematics and Physics at the University of Queensland, found a way to ‘square the numbers’ and their calculations could have fascinating consequences for science.
“The maths checks out — and the results are the stuff of science fiction,” Dr. Costa said.
“Say you traveled in time, in an attempt to stop COVID-19’s patient zero from being exposed to the virus.”
“However, if you stopped that individual from becoming infected — that would eliminate the motivation for you to go back and stop the pandemic in the first place.”
“This is a paradox — an inconsistency that often leads people to think that time travel cannot occur in our Universe.”
“Some physicists say it is possible, but logically it’s hard to accept because that would affect our freedom to make any arbitrary action.”
“It would mean you can time travel, but you cannot do anything that would cause a paradox to occur.”
The team’s work shows that neither of these conditions has to be the case, and it is possible for events to adjust themselves to be logically consistent with any action that the time traveler makes.
The study was published in the journal Classical and Quantum Gravity.