Why stop at 50 cm? In the long term, if the children of humanity continue to inhabit physical bodies, there's no need for them to be larger than a millimetre in

Why stop at 50 cm? In the long term, if the children of humanity continue to inhabit physical bodies, there's no need for them to be larger than a millimetre in size. Plenty of room at the bottom. The benefits of reduced resource use don't stop on Earth. A 1 kg payload ought to be sufficient for an interplanetary or interstellar voyage.