How Traveling Back In Time Could Really, Physically Be Possible
“Satisfyingly, we discover that this form of time travel also forbids the grandfather paradox! Even if the wormhole were created before your parents were conceived, there’s no way for you to exist at the other end of the wormhole early enough to go back and find your grandfather prior to that critical moment. The best you can do is to put your newborn father and mother on a ship to catch the other end of the wormhole, have them live, age, conceive you, and then send yourself back through the wormhole. You’ll be able to meet your grandfather when he’s still very young — perhaps even younger than you are now — but it will still, by necessity, occur at a moment in time after your parents were born.”
So, you want to travel back in time? It’s long been considered as a trope in science fiction movies, television, and literature, but the laws of physics make traveling backwards through time very difficult. In special relativity, it’s impossible, as you can only control the rate you move forward through time; the direction is non-negotiable. But in General Relativity, the curvature of space and time opens up additional possibilities. You can create a stable, traversible wormhole if some type of negative mass/energy exists, with a supermassive black hole connected to its negative mass/energy counterpart. Now, move one end of that wormhole close to the speed of light, and the two mouths age at different rates. Travel through the fast-moving end, and discover you’re back at the stationary end way in the distant past… but still in the future compared to when the wormhole was created.
It’s a brilliant way to achieve time travel, and as a bonus, it makes it impossible to go back in time and kill your own grandfather before you were conceived! Come learn how time travel could really, physically be possible after all.