We are at the weekend and there is no better time, once we have gotten out of all that stress that the week causes us, to talk about certain theories such as the one you just raised Amon Ori, a renowned physicist who is currently working within the Israeli Institute of Technology and who has just published in the magazine Physical Review D, an article where a theoretical model of a time machine capable of taking us to the past is exposed.
To get an idea, since we can consult the article through the website of Arxiv, what we have before us, as has already been commented, is nothing more than a theoretical model of time machine, that is, a series of equations that describe the conditions that, if they could be established, would allow the human being to build a time machine with which to move to any time.
Amos Ori shows that, theoretically, you can travel to the past
As established in the published article, the idea behind this kind of time machine would be to exploit the increased curvature of space-time. Basically what is explained is that this machine would have to take advantage of the fact that the arrow of time can twist itself into a loop. In the words of Amor Ori:
We know that the curvature of space-time occurs constantly, but we wanted to obtain a curvature strong enough to give it a shape that leads the timelines to form closed loops ... We have tried to discover if it is possible to manipulate space-time to develop it in this form.
Once the initial condition has been achieved, the time machine will work completely autonomously
A very interesting point of this document is when the physicist himself explains that, if the initial condition is achieved, the time machine would work by itselfIn other words, it would not need any type of intervention from any external actor. The example that he gives to understand this is based on the moment in which a ship fires a howitzer, once the shot has taken place there is nothing to do, the howitzer will go by itself towards its objective, driven only by the laws of physics.
Among the calculations that have been published it is literally shown that the space-time loop can be built with ordinary matter and positive energy density. The negative part, according to the physicist himself, is that it would still be necessary to solve a question as simple as the stability that a machine like this must have in order to become a time warp.
At this point and despite the fact that this theory, although does not involve the use of exotic materials, The truth is that very particular initial conditions have to be given that are very difficult to achieve if not impossible.
This time machine would always take us to the same point of return
This theoretical model may be difficult to believe, the truth is that Amos Ori is not the only physicist who has studied the viability and possibility of time travel since others have also identified other ways to achieve it, although the vast majority argue that exotic matter should be used to create a curvature in space-time capable of changing the orientation of the arrow of time.
With regards to exotic matter that we discuss is something that exists, or at least that is what quantum physics confirms, although in minute quantities, so small that a time machine could not be built as such, hence the solution proposed by Amos Ori has already attracted so much attention from the community. which would literally solve this problem.
Finally and when in doubt clear that the time machine that this physicist proposes to us is subject to the evolution of time. This means that it would not be a machine like the one shown in many movies where a certain person chooses the date they want to travel to, but rather a space-time tunnel that would always take us to the same date, that is, if We created this tunnel today, July 21, 2018 and decided to use it 20 years later, this would return us to July 21, 2018.
Further information: Arxiv