Time travel revolution in physics: Gravity protects the universe from paradoxes

“What happens if we go back in time and change the past?” The question is considered one of the biggest paradoxes to which scientists and theoretical physicists have been seeking answers for decades. The "chronology preservation hypothesis", put forward by Stephen Hawking in 1992 and arguing that the laws of nature make it impossible to travel to the past, was waiting to be proven at the theoretical level. Theoretical physicists Moustafa Ismail and David Mattingly from the University of New Hampshire mathematically demonstrated that gravity can act as a natural shield that prevents time paradoxes. The research, the details of which were shared in Physical Review D, opened a new window into the mechanism of the universe protecting its own fabric.

ALTERNATIVE TO EINSTEIN'S THEORY: METRIC-AFINE GRAVITY

Albert Einstein's Theory of General Relativity mathematically allows for the existence of "closed timelike curves". This makes it possible, in theory, to travel to one's own past by creating a path backwards in space-time. However, researchers Ismail and Mattingly went beyond Einstein's equations and applied the "Metric-Affine Gravity" model, which handles gravity with a more flexible mathematics.

Using this model, scientists have constructed a theoretical system that requires time to always flow forward within the space-time fabric. This new mathematical infrastructure, called "MAGIC" (Metric-Affine Gravity Enforcing Chronology), prevents universal paradoxes by preventing time from forming a backward loop.

THE SOLUTION BRINGS A NEW BIOCHEMICAL AND PHYSICAL INSTABILITY

Although time travel paradoxes were mathematically prevented, the developed model faced physicists with a new obstacle. While in general relativity gravitational waves propagate in two different modes, the MAGIC model produces a third type of fluctuation called a "scalar mode."

Simulations showed that these scalar fluctuations, instead of remaining stable, lead to a "gradient instability" that grows exponentially in the space-time fabric. This makes it difficult for the model to present a completely stable structure in the universe in its current form.

STUDIES CONTINUE FOR THE FINAL THEORETICAL SOLUTION

The research team emphasizes that the MAGIC model is not yet a finished theory, but is a vital first step in demonstrating gravity's potential to protect the universe. Experts are working on new mathematical arrangements to stabilize this gravitational formula that prevents space-time from breaking.

Theoretical physicists state that when this instability in gravitational waves is resolved, it will be definitively proven how the laws of nature protect the universe from disasters caused by time travelers.