Traditional rockets work by expelling mass at high velocity, which is
scattered into space. What if we could avoid scattering?
To avoid the scattering, take two non-overlapping beams of collimated
particles or light that shines into black-box-like setup inside another of
them, and use
the collected energy to power the collimated particles projector back to
the
source.
The idea is that the process set up this way would accumulate the
intensity
of particle beam as we add more energy, in a way similar to how would
how
wave interference creates increasingly stronger standing waves between
two surfaces, creating increasing pressure as we do not let the energy
scatter.
This would mean that the rocket pair would avoid having to be subject to
the tyranny of the rocket equation.
Credits: Mindey of HalfBakery.