We still don't know if we have to travel 22 light years to reach a point 22 light years from here.
Predicting what is impossible based on existing knowledge hasn't worked too well in the past.
Predicting what is impossible based on existing knowledge hasn't worked too well in the past.
http://www.daviddarling.info/encyclopedia/O/one-g_spacecraft... has other examples. They are round-trip, not one way, hence my describing my math as very rough.