Other potential energy conversion schemes are being investigated by
scientists and engineers. Those listed in the Energy Conversion Matrix
(Figure 2) only scratch the surface.
In particular, we are just learning how to manipulate photons. There are
photochemical, photoelectric, and even photomechanical transformations.
These have hardly been tapped.
Consider the reaction when an electron and its antimatter equivalent,
the positron, meet. They mutually annihilate each other in a burst of
energy! This energy will be harnessed someday.
What energy conversion device are we going to use to completely convert
mass into energy? The energy requirements for interstellar exploration
are so great that these voyages will be impossible unless a new device
is found that can completely transform mass into energy.
Then again, we haven’t the faintest idea of how to control gravitational
energy, but we may learn.
The panorama is endless.