Yes, there is a hypothetical particle, called the tachyon, that could travel back in time. One catch: It almost certainly doesn’t exist.
Before we start talking about time travel, we first must talk about the speed of light. All objects in our universe are constrained to go no faster than the speed of light. The only particles capable of achieving light speed are massless particles, like light itself. Anything with even a tiny amount of mass will find it impossible to achieve light speed. That’s because the faster you go the more massive you become, and at light speed your mass becomes infinite, which would take an infinite amount of energy to accelerate.
But the speed of light isn’t just an expression of how fast objects can travel. It’s an expression of how fast objects can influence each other. Every single interaction in the universe, whether it’s your sibling hitting ...
