Backwards time travel is physically impossible. You would need to travel at truly negative speed to achieve it, but the magnitude of speed is always positive.

[–] FlyingSquid@lemmy.world 14 points 2 years ago

Stop trampling on our hopes and dreams, it's all we have left.

[–] Chrobin@discuss.tchncs.de 5 points 2 years ago (1 children)

Correction: You'd need to travel with a speed higher than the vacuum speed of light.

[–] Karyoplasma@discuss.tchncs.de 2 points 2 years ago* (last edited 2 years ago)

Thinking about it, it's even more complicated than that. You're right that a negative speed would not work since the square of a negative number is positive anyway. But a speed higher than c would result in a negative square root, so no real solution. Also, traveling at exactly the speed of light would divide by zero lol

But maybe our formula is wrong. Or it's just impossible, who knows?