Interstellar Flight: Perspectives and Patience

I worked this table out with ChatGPT (with all the caveats that implies):

https://gridwhale.com/program.hexm?id=GCJ5TL7Z&file=GCJ5TL7Z...

Basically, nothing short of antimatter rockets will get you a self-contained interstellar ship.

Ion propulsion, even with nuclear reactors, can't get you enough speed.

Fission-fragment reactors can get you up to 1% lightspeed, but that's still 400 years to Alpha Centauri--I'm not sure I would trust a generation ship to last that long. Advanced fusion might cut that down to 100 years. Antimatter can reach 20% lightspeed, which means 20 years to Alpha Centauri.

ChatGPT kept asking to design a laser sail (external power source) to avoid the tyranny of the rocket equation, but I just don't think that can scale to crewed travel.

If we assume 100 colonists on the ship, with 10 tons of mass per person, accelerating to 0.2c over 2 ly and then back down, the energy required is quite substantial. Multiple centuries of the total output of the whole planet.