Traveling through time... between Hawking's optimism and Einstein's relativity

Physicist Stephen Hawking exits the stage during an announcement of the Breakthrough Starshot initiative with investor Yuri Milner in New York April 12, 2016. REUTERS/Lucas Jackson Hawking believed that we are unable to build a time machine under current technologies, but we may be able to do so in the future (Reuters) 12/11/2018 Time travel is the dream of many around the world, especially those who watch science fiction films and admire the many applications and effects of this type of travel. The writer, physicist Peter Millington, addressed the topic of time travel in his article published by the American “Science Alert” website, after reading the book “Brief Answers to Big Questions” by the late British physicist Stephen Hawking. In his book, Hawking believes that time travel is practically possible, but his optimism regarding its application is tinged with caution, given that we are unable to build a time machine with the technology available at the present time, but perhaps we can do so in the future. Relativity and the speed of light The writer referred to the theories of the German physicist Albert Einstein about space and time, which basically lead to saying that space and time are part of one thing called “space-time,” and that we must be prepared to think about distances in time in a similar way to our thinking about distances in space. Despite how strange this may seem, we happily answer that such-and-such city, for example, is two and a half hours away from us, meaning that the trip to it would take that long if we traveled there at a speed of eighty kilometers per hour, for example. The author of the article supports his argument with what was stated in a book by physicists Brian Cox and Jeff Forshaw, in which they reached the conclusion that time and distance “can be replaced by using something that has the properties of speed.” Einstein links our ability to travel through time with the theory of causality, that is, the law that states that there is an effect that always comes after the cause. From this standpoint, we find that causality represents an obstacle that prevents us from understanding what is happening in other regions of the universe. Science fiction films deal a lot with the issue of time travel (Getty) Science fiction films deal a lot with the issue of time travel (Getty) The theory of causality also stands in the way of the hopes of those who call for the feasibility of time travel and discourages it, especially since human travel through time and his return to dates that precede his existence in order to plan events that would prevent his birth from occurring, is in stark contrast to the principle of causality, which states that the effect comes after... The reason does not precede it. The author of the article stated that Einstein realized that the consequence of the speed of light - which exceeds 299 million kilometers per second - being absolute, is that space and time themselves cannot be absolute. Einstein's theory states that moving at the speed of light revolves around the principle of relativity, where time will pass normally for the person who is moving, but he will appear to onlookers as if he is frozen in time, while they will appear to him as if they are moving forward very quickly. Unfortunately, traveling faster than the speed of light will not be easy, as this will require an unlimited amount of energy. Even if we were able to achieve this, we would not be guaranteed that time would simply move backwards, as talking about moving forward and backward would not be logical. Wormholes Einstein's theory explains that the force of gravity results from the way mass bends the fabric of time and space, which means that as the size of mass increases in a region of space, the area of space-time increases and the movement of clock hands near it slows down. If the concentration of mass in one place increases, space-time will become so distorted that light cannot escape its gravity, which will lead to the formation of a black hole. In order to be able to travel through time, we need a passable wormhole that we can cross, but this leads us to the need to create negative energy zones to stabilize the wormhole. Regarding this perception, the physical laws of the nineteenth century indicate that it is impossible to apply, which, in contrast, is not excluded by modern theories of quantum mechanics. " String theory (known as M-theory) would offer a promising possibility for approaching time travel " The author shows that arriving at a stable theory that combines the data of quantum mechanics and Einstein's theory of gravity represents a major challenge for scientists specializing in theoretical physics, but string theory (known as "M" theory) would offer a promising possibility for approaching time travel. But string theory requires that space-time have 11 dimensions: one dimension of time, three dimensions of where we are moving, and seven other dimensions that are winding and invisibly small, which Hawking was optimistic about our ability to reduce space and time. Save the date Although our current understanding of time travel does not rule it out, it is highly impractical. This is due to the failure of Einstein's theories to describe the structure of space-time with sufficient accuracy, in addition to the fact that the laws of nature are consistent in a way that does not allow the occurrence of strange paradoxes based on tampering with cause and effect in the way that time travel seeks to do. The writer concluded that - whether our future includes time travel machines or not - we must not forget that we are time travelers in some way, as our movement at a high speed means that we contribute to changing the speed of the clock’s rotation around us, which means that we are time travelers, but Not in the way we aspire