I finally get time travel (in theory)!

I was reading an article called ‘10 Strange Things About the Universe‘ and came across the next two paragraphs. The part that’s bold and italic actually finally made me understand how time travel would theoretically work. It’s interesting though as a thought experiment to imagine how fast you’d have to travel if you wanted to go back to any amount of time further than a few nanoseconds.

Here’s the excerpt:

The relativity of simultaneity is the idea that whether two events occur simultaneously or not is relative and depends on the observer. It is a strange consequence of the special theory of relativity, and applies to any events that happen that are separated by some distance. For example, if a firework is let off on Mars and another on Venus, one observer traveling through space one way might say they happen at the same time (compensating for the time light takes to reach them), while another observer traveling another way might say the one on Mars went off first, and yet another might say the one on Venus went off first. It is caused by the way different viewpoints become distorted compared to each other in special relativity. And because they are all relative, no observer can be said to have the correct viewpoint.

This can lead to very unusual scenarios, such as an observer witnessing effect before cause (for example, seeing a bomb go off, then later seeing someone light the fuse). However, once the observer sees the effect, they cannot interact with the cause without traveling faster than the speed of light, which was one of the first reasons faster-than-light travel was believed to be forbidden, because it is akin to time travel, and a universe where you can interact with the cause after the effect makes no sense.

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