According to our current scientific understanding, time travel, particularly backward time travel, remains speculative and hypothetical. While there are various theories and ideas proposed, such as wormholes, black holes, or cosmic strings, that could potentially allow for time travel, they are purely theoretical at this point.
However, if we consider the concept of traveling close to the speed of light, as described in special relativity, some interesting effects related to time dilation can be observed. According to the theory, as an object approaches the speed of light, time dilation occurs. From the perspective of an observer on Earth, time for the moving object would appear to slow down.
If you were somehow able to travel at extremely high speeds approaching the speed of light, your subjective experience of time would slow down relative to the stationary observer. This means that, from your perspective, time would appear to pass more slowly compared to someone observing you from a stationary position. This effect is often referred to as "time dilation."
As you approach the speed of light, the time dilation effect becomes more significant. If you were able to reach the speed of light, time would essentially stop for you. However, from an outside observer's perspective, it would still appear that you are traveling forward in time, just at a much slower rate than the observer.
Regarding the effects on your body during this hypothetical journey, the theory of special relativity predicts that as you approach the speed of light, several phenomena occur. First, your mass would appear to increase, which is known as relativistic mass increase. Second, your length in the direction of motion would contract, which is referred to as length contraction. These effects are consequences of the Lorentz transformation equations of special relativity.
As your velocity approaches the speed of light, the energy required to accelerate you further also increases significantly. Furthermore, the immense energy and momentum involved in traveling at such speeds would likely have profound physical effects on your body, which are currently beyond our technological capabilities to fully comprehend or replicate.
It's important to note that these effects are based on our current understanding of physics and the theory of special relativity. The concept of time travel, especially backward time travel, remains speculative and subject to ongoing scientific exploration and debate.