Yeah, I read the article. Posting it doesn't make it more applicable. You don't need to accelerate at 20 G, because your trip is going to be several years anyway. You accelerate at 1 G or less with an engine that can continue indefinitely. More than that is superfluous. Interstellar engines are things like photonics and ion drives. These things produce shit-all for thrust, but they're ideal because they're more efficient and more sustainable. Liquid breathing is a solution to a problem that does not exist.