As you begin to understand the outer limits of science one of the things that you must learn is that “anything not expressly forbidden is compulsory”. What this means in the discussion of time travel is that we must examine the concept of time travel with the question of possibility and the understanding of the two types of time travel, moving forward in time at an accelerated rate in comparison to the rest of the universe and moving backwards in time.
For the concept of moving forward in time this discussion becomes very simple. Not only is there no law of physics which forbids the accelerated forward movement through time but there are laws which require it. This is the case of relativity that defines time space and explains that as an object nears the speed of light time will slow down. This leads to the “Twins Paradox”.
The concept of the “Twins Paradox” is that if you have twins and one stays on earth while another goes on a space voyage at near the speed of light for twenty years when they meet at the end of that twenty year voyage the one on earth will be twenty years older than the twin from the spaceship. This may feel unnatural but it appears to be completely natural and these effects have been measured.
Moving backwards in time is more problematic from an a perspective of achievability. But there are theoretical ways to do so. The simplest in concept, and likely most difficult in achievability is physically moving faster than the speed of light. The concept is that as you approach the speed of light time would slow down and as you passed it would actually begin to reverse. Sadly the same laws of physics which state that this could happen also deny the ability to do so stating that it would take an infinite amount of energy to move any object at the speed of light.
A second theory is that of wormholes. This concept states that because wormholes are tunnels across time-space they would allow for a shortcut not only across galaxies but across time. Some evidence that mico-wormholes may exist has been found in recent years and the laws of physics typically make no distinction between space and time meaning that it is possible that there is no law of physics that forbids time travel through wormholes. Yet even if they exist it is unlikely that one could be created large enough to send even data through let alone a person.
A third possibility that has also not been proved impossible is that of using a singularity to create distorted time-space. this would require either the ability to enter the distorted area around the black hole or an area of material 100 Km long with a density just over that of a neutron star that is rotating 2 times every millisecond and though no known understanding would allow for the creation of this matter or the survival of any crew that entered the distorted area around a black hole there is no scientific law that forbids it.
It is exceedingly unlikely that time travel will be made possible in the next ten thousand years(assuming that it is not given to us by a time traveler). It is in fact quite possible that it will nevert be achievable simply due to the restrictions caused by the amounts of energy in the universe compared to the amount of energy required to create the bends in space time, but it is not by definition impossible, only overwhelmingly difficult to achieve.
