Apple patents something to do with hydrogen fuel cells

[NotAllThere]

Anti-matter factories is what we need.

[Doggy Styles]

Rockets will always be inefficient because most of the energy goes into lifting the fuel itself.

Given the problem, how are you measuring efficiency?

[TimberWolf]

Given the problem, how are you measuring efficiency?

Maximum efficiency is when the total mechanical energy equals the energy used.

Because rockets are so grossly inefficient, rocket travel will always be expensive economically too.