> It is also trivial for them to hop worlds - either wait for a flyby How so? The gravity well of a gas/ice giant would be absolutely massive. Even if you coul

> It is also trivial for them to hop worlds - either wait for a flyby How so? The gravity well of a gas/ice giant would be absolutely massive. Even if you could get away from the planet, waiting for a flyby in interstellar space could well take millions of years between encounters.