It’s nothing to do with old light. It’s to do with the relativity of simultaneity. Have a look at the Wikipedia article I linked to. Or read these posts on Ask

It’s nothing to do with old light. It’s to do with the relativity of simultaneity. Have a look at the Wikipedia article I linked to. Or read these posts on Ask a Mathematician / Ask a Physicist: - this one explains the basis of the phenomenon: https://www.askamathematician.com/2010/12/q-according-to-relativity-two-moving-observers-always-see-the-other-moving-through-time-slower-isnt-that-a-contradiction-doesnt-one-have-to-be-faster/ https://www.askamathematician.com/2010/12/q-according-to-rel... - this one explains the implications for FTL travel (and why it can result in time-travel): https://www.askamathematician.com/2011/09/q-hyperspace-warp-drives-and-faster-than-light-travel-why-not/ https://www.askamathematician.com/2011/09/q-hyperspace-warp-...