Could time travel become a reality? Cosmic strings may hold the answer

So far, time travel has only become reality in the realm of science fiction, yet modern physics is posing ever bolder questions about the nature of space-time. According to some theories, cosmic “scars” left behind from the earliest moments of the universe — known as strings — may not only tell the story of the birth of the cosmos, but could also hint at the possibility of travelling back into the past.

The idea of time travel has fascinated humanity for centuries. While most people regard it as mere fantasy, some physicists argue that the universe may contain structures which, at least in theory, could allow a return to the past. These peculiar phenomena are known as cosmic strings and are described as “scars” dating back to the universe’s earliest moments.

Cosmic strings and the Big Bang

At the dawn of time, the universe existed in an extremely hot, dense, and high-energy state. When the Big Bang occurred some 13.8 billion years ago, the released energy split into four fundamental interactions: gravity, electromagnetism, and the weak and strong nuclear forces.

As Popular Mechanics notes, this transformation is believed not to have occurred without leaving a trace, as permanent imprints were formed in the very fabric of space-time.

These are the so-called cosmic strings, whose behaviour is difficult to imagine at first glance, but which may resemble stretch marks on human skin or cracks that form in ice during freezing. Some physicists believe that these structures may still exist in the universe today, seemingly passive, yet studying them could prove crucial to understanding how the early universe functioned — and, according to certain theories, even to the realisation of time travel.

Time loops and Einstein’s theory of relativity

According to Ken Olum, research professor at Tufts University, two cosmic strings moving parallel to one another could together bend space-time in such a way that a closed timelike curve is created. This concept essentially describes a time loop: if someone were to pass through it, they would return to their point of departure — but at an earlier moment in time. In this sense, cosmic strings could theoretically function as a kind of natural time machine.

This form of time travel is particularly intriguing because it is consistent with Einstein’s general theory of relativity, which states that massive objects can distort space-time and, under certain conditions, even allow the usual rules of time to be overridden. Cosmic strings belong to this same conceptual framework and provide a theoretical foundation for other ideas related to time travel.