In June 2009, physicist Stephen Hawking organized the “Time Travelers Party”, inviting travelers in the past to go there, since in theory they should have been informed of the event from the future. But no one came.
Time travel, a great fantasy exploited to a large extent by science fiction, is restricted by a whole series of paradoxes which have made it unthinkable until now. One of them – perhaps the best known – called the “grandfather paradox” assumes that if someone traveled to the past, they could prevent their grandfather from having children, thus erasing his own existence.
However, a recent study, published on December 12, 2024 in the journal Classical and Quantum Gravity, offers an intriguing solution to this phenomenon. By combining general relativity, quantum mechanics and thermodynamics, the study shows that time travel could be feasible without causing logical contradictions, according to Live Science.
Japan: a journey through time
From immutable to temporary: the solution to the “grandfather paradox”
One of the most fascinating predictions of the theory of relativity, completed by Einstein in 1915, is the possibility of closed time curves, which would allow a person to visit the past.
The study led by Lorenzo Gavassino, a physicist at Vanderbilt University, demonstrated that the behavior of thermodynamics – which governs the transformations of matter – fundamentally changes over a closed time curve. Quantum fluctuations occur, allowing entropy to be erased.
-In physics, entropy is a measure of the decay of matter and energy, which applies for example to the aging process in humans. In everyday life, entropy continues to increase, leading things towards degradation and then death.
“Increasing entropy is why we die. What happens when you reverse death?“, asked Gavassino. In a closed time loop, the erasure of entropy would lead to canceling the immutability of things. If the action of killing one’s grandfather is irreversible in our space-time, it would become temporary during a trip to the past.
Time travel…still a distant project
“My work provides the first rigorous derivation of this principle of internal consistency directly from established physics. More precisely, I applied the standard framework of quantum mechanics (…) and demonstrated that the internal coherence of history follows naturally from quantum laws“, explains the researcher.
However, although the valuable work of Lorenzo Gavissimo offers a convincing theoretical framework, time travel would be possible only in the case where the existence of time loops can be proven. A notion still widely debated by the scientific community.
