Time travel has long remained a mystery to theoretical physics because of the so-called “killed grandfather paradox”: what happens if a traveler to the past prevents his grandfather from having children, thereby denying his existence? A new study offers a solution to this dilemma. A new study by Lorenzo Gavassino, a physicist at Vanderbilt University, combined general relativity theory, quantum mechanics and thermodynamics to show that time travel might be possible without logical contradictions.
The traditional view of time is based on Newtonian physics, where events unfold linearly. However, Einstein’s general theory of relativity, completed in 1915, shows that space-time can have forms that even defy common sense, such as black holes. One of its most intriguing predictions are closed time curves – loops in space-time that allow a traveler to go back in time.
Lorenzo explains that all forms of energy and momentum affect gravity. For example, if matter rotates, it can “pull” space-time along with it. This effect is almost imperceptible on planets and stars, but if the entire Universe were rotating, space-time could warp so much that time would form a loop. In such a system, the spacecraft could return to its starting point not only in space but also in time.
Paradoxes of time travel
The main problem with such journeys are the paradoxes they create. The “killed grandfather paradox” is just one example. They arise from the assumption that the laws of thermodynamics, which control heat and energy, operate in the same way on time loops.
The law of entropy growth, which measures the degree of disorder in a system, is the only physical law that distinguishes between past and future. Entropy determines many aspects of our lives, from aging to memory. But how would these processes work in a time loop?
Quantum solution of paradoxes
Gavassino’s study, published in the journal Classical and Quantum Gravity, offers an interesting solution. Based on the work of physicist Carlo Rovelli, he proved that thermodynamics changes on a closed time curve due to quantum fluctuations that can reduce entropy. This discovery means that memories can fade, and aging can come back again.
For example, entropy reduction can make death temporary in a time loop. “Most physicists and philosophers believed that nature would always avoid contradictory situations, but my research shows that the logical sequence of history follows naturally from quantum laws,” Gavassino notes.
Practical implications
Despite the theoretical basis, the question whether closed time curves exist in the real universe remains open. In 1992, Stephen Hawking proposed the “chronology defense hypothesis,” suggesting that the laws of physics would prevent the formation of time loops. For example, spacetime can become singular before loop formation.
Nevertheless, Gavassino’s study is useful for expanding our understanding of the nature of entropy. Even if time loops do not exist, their modeling will help to better understand subatomic systems and their thermodynamics. “Entropy is one of the key topics in physics that shapes our perception of the Universe,” concludes Gavassino.
We have previously explained the mysteries of dark energy and infinite expansion.
According to livescience.com
