[sudhirj]

Reminder that life can also make interstellar travel thinkable by slowing down - four years (or four thousand years) seem like a long time because our lifespans are short and we think fast. If we were tree-like, or immortal, our timescales would change.

Also a reminder that no time passes for a photon when it crosses the universe. i.e. to the people on a ship approaching light speed, not much time passes as they reach their destination. And less time passes the closer they get to light speed.