Time travel has long captivated imaginations, inspiring countless stories and theories. While movies like Avengers: Endgame depict it as a feasible concept, the reality is far more complex. In fact, true time travel as we envision it may never be possible, even though aspects of it may already exist. To illustrate this, we can turn to the well-known grandfather paradox.

Being alive without ever having existed is the crux of this paradox. Imagine traveling back in time to a moment before your grandfather had children and eliminating him. This act would mean one of your parents never came into existence, which implies you wouldn't either. Yet, if you never existed, how could you have gone back to commit such an act? This situation creates a perplexing loop of logic.

Before delving into potential solutions, it's crucial to understand the mechanisms behind time travel. It's important to note that this is a theoretical exploration and not a scientifically validated explanation, as no consensus exists on how time travel to the past might actually function.

Traveling to the past differs significantly from advancing into the future. A common belief suggests that altering an event in the past can reshape the future. For instance, something as minor as disturbing a stone could theoretically set off a series of significant changes. However, the reality is that you wouldn’t observe any substantial butterfly effect. Instead, you would be adding to an already modified version of the past rather than rewriting history.

In essence, if you travel to a past moment, you must originate from a future point relative to that moment. To effect change in the past, the alteration would need to occur before you reach that future point; otherwise, the potential change remains untriggered. Thus, the timeline must progress linearly.

To visualize this, consider a number line where each number represents an event in time. The zero point indicates your birth, negative numbers signify moments before, and positive numbers reflect events after. This personal timeline does not correlate directly with universal time, making it unique to each individual.

If we were to represent a shift in the timeline through time travel, it might look like this: - Original sequence: 0, 1, 2, 3, 4, 5, 6, 7, … - Altered sequence: 0, 1, 2, 5", 3, 4, 5', 6, 7…

In this model, two instances of the number five appear. For example, if you exist at point 2 and travel back to point 5", which displaces 3 and alters the subsequent numbers, you wouldn't be aware of those changes until you reach point 5'. This implies that your past self at 5" has influenced your future self at 5'.

However, a critical aspect to remember is that if you exist at 5", you must also be alive at 5'. This means that traveling to the past while alive at the moment of departure is essential—a detail often overlooked in discussions about backward time travel.

Revisiting the grandfather paradox, we see that traveling to eliminate your grandfather before he had children means you would have to be alive when making the journey. For instance, if you traveled back from point 6 to -9, you would have to still exist at point 6 upon returning. Hence, the act of killing your grandfather would be impossible.

Consequently, the only logical resolution to the paradox is its non-existence within our established understanding of time travel. Rather than finding a flaw in the reasoning, we must dismiss the notion of such a loop occurring in the first place.

While this reasoning holds a degree of logic, it remains largely speculative. Currently, we lack mathematical proof that time travel to the past can occur, and even if we identified a theoretical framework, the energy required to facilitate such travel is beyond our capabilities. Therefore, returning to the past, especially with the intent to modify it, is practically unfeasible.

Nevertheless, this doesn't eliminate the potential for experiencing time travel—specifically, traveling into the future, not the past.

Consider the film Interstellar, where the concept of time dilation is pivotal. Although the future may appear fixed based on our current scientific understanding, it is not unreachable. In fact, we can demonstrate that you have likely experienced it already.