Found in 3 comments on Hacker News
Lewton · 2018-07-09 · Original thread
This book is the closest I’ve seen to ELI5ing general relativity

https://www.amazon.co.uk/Why-Does-mc2-Should-Care/dp/0306819...

And it makes it obvious why FTL travel implies time travel

It’s chock-full of a-ha moments and is a pleasure to read

thangalin · 2014-04-10 · Original thread
Chances are FTL communication is not possible.

http://curious.astro.cornell.edu/question.php?number=612

http://en.wikipedia.org/wiki/Superluminal_communication

The book, "Why E=mc^2" is an exceptional read. If I recall correctly, it explains why light-speed is a universal limit:

http://www.amazon.co.uk/Why-Does-mc2-Brian-Cox/dp/0306819112

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