Why Going Faster-Than-Light Leads to Time Paradoxes

I like to imagine that as soon as we discover FTL and break spacetime, the simulation crashes and the higher beings are annoyed they have another bug to fix

"The universe is not required to be in perfect harmony with human ambition." -Carl Sagan

I watched the entire video, and I get the sense you broke the rules of your own diagram. You drew two diagonal lines at the start, indicating the speed of light. You set the premise that any line between the time axis and this diagonal line is something moving slower than light (STL). Any line between the diagonal line and the space axis are faster than light (FTL). You then start speculating about FTL transmitters able to send a message instantaneously, meaning horizontally to the right. I'm with you so far. This is where you break every rule that has been set. You draw a line that goes downward. We've not established any reason why a line would do that. Your made up transmitter can only go up to a limit of a horizontal line (instantaneous messaging). These paradoxes start popping up because you've suddenly decided this message is being sent to the past. The FTL transmitter is now a time machine for no reason. Like I said there might be some physics I don't understand. However in the diagram you've been using, there has been zero explanation of why any line would ever go down. The established rules were that lines could only be in the STL or FTL directions. Once you start going downward you break your own rule set.

It's very rare and special when someone can explain such a complicated topic in an easy to understand and follow way. Thank you.

Does anyone realize how crazy it is that we can even theorize something like this

There once was a young lad named Mike. Who could run faster than the speed of light. He took off one day, In a relative way, And returned on the previous night!

Faster-than-light line source: youtube.com/shorts/qBqP3ZAGjT4?si=gNIdcC4WI8AYsTUf

The greatest explanation so far. I've been trying for months to understand this by reading forums and watching youtube videos. None were able to explain this. I still need to understand it more intuitively instead of through looking at lines, but this definitely opened my eyes. This is by far the best and most simply explained video so far on this. Thank you

"It almost seems like a cruel cosmic joke that the universe be arranged such a way that we are able to look out and glimpse its wonders and yet are trapped here by the speed of light." So well said:washhands:

Well, I don't know about time travel, but a fascinating thing to think about is that if you could travel FTL and have a way to look at earth from any distance, you could go far enough away from earth to see the past.

What I love here in the commentary is everyone having the freedom to express their thoughts in either direction or in neither direction. Where I stand, the whole thing is a big mind F – – K. I want “want” to believe we can break the Ftl barrier, but any basis for that desire does not include any scientific knowledge or fact at this point in time. But, it’s fun to talk about. Peace.

The universe doesn't care if it makes sense to us.

I like how Terry Pratchett said it better than the way Hawking did: Everything that happens, stays happened.

Omg this diagram finally explained why and how space and time are connected. Thank you so much. I always thought I understood this concept but I was just repeating info not fully grasping it.

Revisting this. Professor, I just saw an article featuring your terrascope idea, featuring you, of course 😊. I was so excited for you

This video is amazing. Thank you for this simple explanation of such complex issues. I have discussed your diagrams with a couple of colleagues last night and we had an amazing time 😊

"The cosmic speed limit, the speed of light is so diminutive compared to a galaxy. It almost seems like a cruel cosmic joke that the universe be arranged in such a way that we are able to look out and glimpse its wonders and yet are trapped here by the speed of light. Fated to only ever peer through the bars of our cosmic prison and dream." -- This is so beautifully spoken...

The speed of light should really be taught as the speed of causality. The speed of light is an incidental stenographer of the speed of causality.

There's a great scifi series on a subreddit where humans are using C+ canons that send projectiles using something akin to "slipspace" to travel faster than light to target, and in universe from the target's perspective they get hit before the canons are even fired.

Thank you Professor, very interesting. I myself think that the only reason we even discuss FTL travel is because SF writers had to 'invent' it in order to write space travel stories. One thing: I believe you pronounced the word albeit as 'al-bite'. Actually albeit is simply a contraction of 'although be it' or 'although it be', and so is correctly pronounced *all-be-it*.