"Empty space" when seen at the subatomic level is far from empty but instead
seethes with energy, the rapid appearance and disappearance of all sorts
of elementary particles, and fluctuations in the fabric of spacetime
itself. It is the source of zero point energy
which is seen as the potential basis for radically new forms of propulsion
and "free energy" in the far future.
| Quote by John A. Wheeler
"No point is more central than this, that empty space is not empty.
It is the seat of the most violent physics."