Why Causal Connection? What does that mean?

It’s to do with a YouTube video I watched that’s basically a thought experiment on travelling to the edge of the universe. All theoretical of course: it talks about light speed and the expansion of space

“…the Earth lies beyond our cosmic horizon. We are no longer causally connected to it. To put it another way, it is now literally impossible to compare clocks to those back on Earth”

Professor David Kipping – “A Journey to the End of the Universe”

I found that both terrifying and beautiful. And I couldn’t get the thought out of my head for a few days.

Causally Connected.

Seemed like a fun name for a blog about networks.