It sounds like a perfectly typical, baseless, first-year philosophy student proclamation: “You see — time … doesn’t exist!” Cue the smoke bomb and rapturous facial expression. Well, it’s time to blow everyone’s minds and confirm that, yeah, that statement is kinda-sorta true. Except, it’s only true because time isn’t time. Time is space, which means time travel is really space travel.
In his 1905 theory of special relativity, Albert Einstein noted that as objects approach the speed of light, they experience time more slowly. As Live Science overviews, this is referred to as “time dilation.” But to that fast-moving object, everyone else is slow. Hence: Time is relative and not the same for all observers.
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Four years later in 1909, German mathematician Hermann Minkowski coined the term “space-time” to refer to the unified spatial and temporal nature of reality. Time, he concluded, is just another aspect — a dimension — of space. You can move through space at the expense of time, or vice-versa, like how you can turn right at the expense of turning left, per Big Think. To the perspective of light particles — the massless, fastest objects in the universe — time doesn’t exist, as Forbes explains.
So, if you want to time travel? You’ve got to travel through space at near-lightspeed. And as the rest of reality zips by, you slow down. Presto: You’re in the future. But you can’t go back, as Live Science details. Past physical space no longer exists.
