According to our current understanding of physics, an object with mass cannot travel at the speed of light. As an object with mass accelerates, its energy increases, and as it approaches the speed of light, its energy becomes infinite. This means that it would require an infinite amount of energy to accelerate a massive object to the speed of light, making it impossible to achieve.
Furthermore, as an object with mass approaches the speed of light, its relativistic mass increases, and time dilation effects become significant. Time dilation means that time appears to pass more slowly for objects moving relative to an observer at rest. As an object approaches the speed of light, time dilation becomes more pronounced, causing time to pass slower for the moving object compared to a stationary observer. However, the object does not move backward through time but experiences time differently than an observer at rest.
It's worth noting that there are theoretical particles called tachyons that are hypothesized to travel faster than the speed of light. However, these particles have not been observed in nature, and their properties and behavior, including the possibility of backward time travel, remain speculative.
In summary, based on our current understanding of physics, objects with mass cannot travel at or exceed the speed of light, and the notion of moving backward through space-time or time itself is not supported by our scientific knowledge.