Time travel has long been a favorite literary device of science fiction writers and a dream of many scientists. Some of them are sure that the possibility of time travel, at least in the past, is not so far from reality.
New Horizons
Today science is developing so dynamically that it is extremely difficult for an ordinary person to keep track of all kinds of theories and attempts to prove them. More recently, Einstein predicted in his General Theory of Relativity the existence of black holes - gravitational singularities that change the laws of physics so much that it was difficult for Einstein to believe in them. Today, the existence of black holes is not only proven, but also actively studied by astrophysicists around the world. In addition, even gravitational waves were recently noticed with a laser invented by the same Einstein.
His Special Theory of Relativity gave rise to quantum physics - a field of science that allows you to take a fresh look at the laws that govern our world, and even question the fact that we are alive in a single reality.
The idea of multiple worlds
Promotional video:
The many-worlds theory was formulated in 1958 by Hugh Everett. In quantum physics, this theory does not at all consider the collapse of the wave function of particles, which happens every time an attempt is made to measure one of the parameters of a particle, be it velocity or mass. The quantum explanation of the many-worlds theory is quite complicated, so for the sake of simplicity it is worth concentrating on its effect.
Everett's theory assumes the existence of parallel worlds, each of which shares the physical laws of space-time. This is not a multiverse theory that suggests the possibility of universes in which the laws of physics work in a completely different way.
Several interpretations
The many-worlds theory resembles the theory of “branching” of reality, when any choice made between A and B leads to the fact that our reality is divided into the one where the choice was made in favor of A and the one in which B was chosen. Thus, the worlds and there are infinitely many realities. According to several theories, they closely interact with each other, but according to the opinions of other people, they are not related in any way.
However, in quantum mechanics, this theory looks a little different. It implies reality for each of the observed states of the particle, where each of them is watched by a separate observer. Thus, what we call the collapse of the wave function, Everett's theory calls the "splitting" of the observer. For each parameter of a particle (be it mass, speed, size, charge, etc.), its own reality “splits off” with a separate past, present and, accordingly, future.
Interaction of universes
Quantum mechanics does not see this splitting as the formation of separate worlds that do not affect each other. She sees them as a single universe, united by a quantum superposition of a huge number of states.
Several scientists at Griffith University have suggested that superposition of states does not necessarily preclude "parallel universes" interacting with each other. This theory not only turns quantum mechanics upside down, but heralds entirely new possibilities for time travel.
Travel to the past
According to the new theory of interacting universes, scientists assume the likelihood of one-way travel in time. This will most likely turn out to be a journey into one of the parallel states. How exactly transitions into the past can be carried out and how they will affect the states of parallel worlds is still unknown to scientists.
