Stephen Hawking once said, “If time travel is possible, where are the tourists from the future?” This question encapsulates the mystery and inherent failures of time travel. On June 28, 2009, he conducted an anomalous experiment. He hosted a time travel party for time travelers with the catch that invitations were sent out after the party was over so that only people capable of time travel would be able to attend. Unfortunately, no one attended the party. However, this did not annihilate Hawking’s belief in time travel.

There are some existing theories contradicting this event and highlighting the possibility of time travel still existing. These include the idea that no time traveler wants to visit our age, preferring more intriguing or distinct periods in time, or that a time traveler could land in the wrong location due to miscalculation. The concept behind this is that the Earth orbits the sun at around 67,000 mph, and our solar system drifts through the Milky Way at around 450,000 mph. If someone were to travel in time without knowing the specific location of Earth at every moment, it is quite likely they would end up light-years away from the desired destination.

There are two paradoxes contradicting the idea of time travel: the grandfather paradox and the Hitler paradox. The grandfather paradox states that if a time traveler goes back and prevents their grandfather from meeting their grandmother, the traveler would never have been born. This means the time traveler could never have gone into the past to prevent their grandparents from meeting, creating a loop where cause and effect are indistinguishable. Similarly, the Hitler paradox suggests that if someone were to travel back in time and kill Adolf Hitler before he started WWII, no knowledge of Hitler would exist, and it would obviously stop all the things he caused from happening, which removes the need for the time traveler to travel back in time to kill him. On the other hand, Hitler's impact on our history is so profound that it has likely affected the circumstances leading to the birth of nearly every person alive today. Thus, if the time traveler goes back in time to kill Hitler before he could create the sequence of events that led to the birth of the time traveler, the time traveler wouldn’t have been born to have come back in time to kill Hitler. This concept does not make any sense.

The idea is that if advancements in technology somehow enable us to travel in time, we probably should not, because of how easily anything could be destroyed or how minuscule changes in the past could have massive, unforeseen effects on the future. One small action could alter the course of time.

The speed of light is the maximum speed any signal can travel, putting a fundamental limit on how soon we can access what is going on elsewhere in the universe. However, accelerating a human being to the speed of light would require infinite energy, and even if it were possible, time wouldn’t run backward. Creating a unified theory that merges quantum mechanics with Einstein's theory of gravity is one of the greatest challenges in theoretical physics.