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The laws of Physics don’t care whether time moves backwards or forwards: nothing prevents time travel. But according to a new study, those same laws imply that time travelers would have their memories erased… and their clocks wouldn’t work.
First, the good news for time travelers. Physicists have long recognized that Nothing in the laws of Physics specifically prohibits time travel.
As far as we know, these laws don’t care whether time is running forward or backward; work equally well anyway.
This recognition has given rise to numerous studies, some of which are surprisingly serious, to test the limits of causality.
In this demand, physicists have tried everythingfrom bending the fabric of space-time to exploiting quantum uncertainty to travel backwards and forwards in time. They even tested some of these ideas.
But nothing seems to work. In fact, some of the schemes require decidedly unphysical conditions that make them unlikely to ever be tested.
However, highlights , the most enthusiastic always remember that has not yet been proven that time travel is impossible.
Memory loss
Now the bad news, which comes from Lorenzo Gavassinoa mathematician at Vanderbilt University in Nashville, who discovered some side effects of time travel has never been addressed until now.
The Milanese mathematician maintains that the laws of Physics may not prohibit time travel, but if time travel is possible, these same laws lead to some strange consequences — one of which is that any human being who made the journey wouldn’t be able to remember her.
The laws of physics suggest that that person’s memory would be erased as soon as she returned to the present. So how do the laws of Physics lead to this disappointing conclusion?
Only one law is responsible — the Second Law of Thermodynamicsaccording to which the entropy, or disorder, of any system always increases with time.
Unlike the other laws of thermodynamics, the second law distinguishes between time running forward and backward. Broken eggs never mendcoffee with milk it will never go back to milk and coffeeand so on.
In a series of theoretical experiments, Gavassino showed the significant consequences of the laws of Physics for a spacecraft carrying a time traveler in a circular path through spacetime — in other words, a trip return to the same moment in time.
A fundamental characteristic of this circular journey is the fact that the entropy have to be the same at the beginning and end — because the traveler returns to his original state. Thus, if entropy increases over time, there must be a point on the circle at which reaches its maximum before returning to its original value.
Gavassino considers that the consequences for the time traveler in the spacecraft that passes beyond this point of maximum entropy are clear: “all thermodynamic processes, including biological processes such as the formation of memory and aging are reversed“.
“The memories of an observer inside the spacecraft are necessarily erased at the end of the trip“, concludes Gavassino, in a recently pre-published on ArXiv.
A particularly fascinating aspect presented by the Italian mathematician in his article involves the behavior of watches during time travel. Gavassino demonstrates that clocks would not work as expected.
For a watch to return to its starting point after a complete journey, it must operate at a frequency that produces an integer number of “ticks” during the trip.
This requirement may introduce subtle “defects” in watches designed for standard linear time, making their measurements unreliable on a closed time curve.
And since the same argument applies to the normal vibrations of molecules and atoms, this raises the possibility of a widespread disturbance of the normal existence of matter in a time curve.
Gavassino’s findings have significant implications for our understanding of time and causality. Although the study does not determine whether time travel is possible, sheds light on the stringent conditions that must be satisfied in such scenarios.
In a universe with close temporal curves, time travel would not resemble the gratuitous adventures of science fiction. Instead, travelers would be confronted with a world governed by rigid self-consistencyerased memories and interrupted causality.
Naturally, would-be time travelers will look for potential gaps in Gavassino’s reasoning. One possibility is that although the second law of thermodynamics applies to a system as a whole, it need not necessarily apply to its parts.
For example, there may be a form of some parts of a thermodynamic system their entropy decreases while the remaining entropy increases, in order to guarantee that the total entropy maintains the conditions required by the laws of Physics.
Naturally, the real time travelers, who walk among us from other centuries, will have long ago concluded that Gavassino must have missed something.
