Paradoxes of time travel
One of the greatest challenges of time travel lies in the contradictions it creates. The grandfather paradox is only one of these contradictions. These problems arise because we assume that the laws of thermodynamics, the laws governing heat and energy, normally operate in a time loop. According to Gavasino:
In fact, the law of increasing entropy, a thermodynamic quantity that measures the degree of disorder of a system, is the only law of physics that distinguishes between the past and the future. As far as we know, entropy is the only reason we remember past events and cannot predict the future.
Entropy governs many of our daily experiences, from how our bodies age to how we process memories. Even simple tasks like walking rely on friction, which itself increases entropy; So how do these processes behave in a time loop?
A quantum solution to paradoxes
According to LiveScience, Gavasino’s research, published on December 12, 2024 in the journal Quantum and Classical Gravity, offers an interesting solution. Inspired by the research of Italian physicist Carlo Rovelli, he showed that thermodynamic behavior essentially changes in a closed time curve. In such a loop, quantum fluctuations arise that can wipe out entropy; A process that is fundamentally different from what we experience in everyday life.
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Quantum fluctuations can have dramatic effects on time travelers. For example, by reducing entropy, a person’s memory may disappear and aging may be reversed. Gavasino raises this question: the increase of entropy is the cause of our death. What happens when you turn death upside down? This phenomenon can even turn irreversible events like killing one’s grandfather into temporary events in a time loop, eliminating the paradox altogether. Gavasino says:
Most physicists and philosophers of the past have argued that if time travel existed, nature would always find a way to avoid paradoxical situations. According to the principle of self-consistency, everything must be coordinated to create a coherent and logical story. My work is to present the first rigorous argument of this principle of self-consistency that originates in established physics. Specifically, I applied the standard framework of quantum mechanics without additional or controversial assumptions and showed that the self-consistency of history follows naturally from quantum laws.
Theoretical and practical concepts
While Gavasino’s findings provide a compelling theoretical framework for time travel, the question remains: Do closed time-like curves exist in the real world? Most scientists are skeptical about this. For example, in 1992, Stephen Hawking proposed the famous “chronology conservation conjecture,” suggesting that the laws of physics might prevent time loops from forming in the first place. This assumption could include space-time being transformed or broken just before the loop is created.
Even if time loops do not exist, understanding and modeling them can provide insights into real phenomena. For example, by examining how the real entropy evolves and behaves along a closed path at the subatomic scale, we can reach surprising insights about the behavior of subatomic systems and their thermodynamics.