[C210N]

I forget the exact numbers, but they are known... but the ballpark is correct:

Only thing needed is an engine with constant acceleration of, say, a tolerable 1.1g. Aim the craft towards Alpha Centauri, and go. After about a year stop the engines. you’d be going 50% the speed of light. After 2 years, maneuver the craft around, light up the engine again, and start “braking”.

For someone on earth, time elapsed is about 7 or 8 years. For someone on board the craft, time elapsed is about 2-3 years.

There are online calculators where one can plug in various numbers for time, distance, speed, with constant acceleration in mind, to determine how long the traveler ages versus earthlings.

[jmacusa]

Well at about four and a quarter light years from Earth a trip to Alpha Centuari is around....(my math is not so good) 800 million light years? So, the travelers will be kind of ... old.

[Lurker]

“Only thing needed is an engine with constant acceleration of, say, a tolerable 1.1g”

How would you fuel such an engine?

L