Quantum Theory Allows To Travel Back In Time!
Quantum Theory Allows the Travel Back In Time
A travel back in time, so far, appears possible only in science fiction stories and movies. However, scientists strive to reach a resolution for the possibility of time travel through physics.
Can time flow backward? Why is it only moving in one direction – towards the future? Why do we remember the past and not the future?
Stephen Hawking makes it clear in his book “A Brief History Of TIme” that there are at least 3 different arrows of time pointing in the same direction:
Thermodynamic Arrow of Time:
According to the 2nd Law of Thermodynamics, there are more disordered states than ordered ones. For example, suppose you have a jigsaw puzzle in which it makes up a completely clear portrait in a closed box. Let this ordered state be state 1. When you shake the box the puzzle enters state 2 which is a disordered state. The probability that you open the box to find the puzzle forming a clear picture is extremely small. Then, the more you shake the box, the more the pieces will get into disordered states.
Psychological Arrow of Time:
The direction of the psychological arrow of time is the same as the thermodynamic arrow. It describes the fact that humans remember events in one direction: from the past to the present and the future is unknown. It can never be the opposite where we remember the future and predict the past.
Cosmological Arrow of Time:
This type shows that the universe is expanding. Scientists have long thought about the beginning of our universe. They reached the conclusion that the universe started in a tiny ordered state and started to expand after the Big Bang leading to the suitable conditions to occur therefore making the intelligent life possible.
The Speed Of Light:
Suppose the 2 following events: Event A – a party on Earth. And an event B – Football match on Mars. Observers to both events agree that A happened before B if a spaceship traveled from earth to Mars at a speed below the speed of light. But suppose the spaceship travels faster than light. Then, it is possible that event B happens before A. But, according to Einstein’s theory of relativity, nothing can travel faster than light.
Thus, all the above facts show us that time goes only in one direction like a railway. But a question of concern arises: Can there be a branch of this railway that takes us back to a point in the past?
Quantum Theory permits to Travel Back in Time!
General Relativity allows the occurrence of “bridges” between event A and B. Such bridges are wormholes which are thin tubes of space-time connecting 2 nearly flat regions apart. However, wormholes are not available in nature. Thus they require being created artificially by warping space-time. Moreover, this requires a space-time with a negative curvature which can be achieved only through matter with negative energy density.
The good news is that “Quantum Theory” allows the travel back in time, but only on a microscopic scale. The reason behind this is the radiation by black holes. A pair consisting of 2 virtual members particle/antiparticle, can have one member fall into a black hole. But scientists claim that the virtual member that fell into the black hole can also travel out of it thus traveling back in time.
But is it allowed to travel back in time on a macroscopic scale?
Hawking claims that there is a “chronology protection conjecture” which means that the laws of physics conspire to prevent humans and macroscopic bodies from traveling into the past. This is what Hawking believes in but he says that time travel is still an open discussion.
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