There is a way to understand it guys, and it's really simple. In general relativity the source of gravity is

the stress-energy tensor, and Einstein said things like:

*"This space-time variability of the reciprocal relations of the standards of space and time, or, perhaps, the recognition of the fact that ‘empty space’ in its physical relation is neither homogeneous nor isotropic, compelling us to describe its state by ten functions (the gravitation potentials g*_{μν}..." Most people don't know what he meant here, and they miss the fact that a gravitational field is a region of inhomogeneous space. Whilst we tend to think of gravity as "negative energy", if you tested

the Casimir effect at any location in a gravitational field, the plates will move together. There is no location where the plates move apart, and that's telling us that the stress-energy is positive at all locations. People ascribe this to virtual particles, but you have to remember these are

*virtual*, and that vacuum energy is

*vacuum* energy. It the energy of the vacuum, it's the energy of

*space*. And since stress is the same as pressure, that means the "pressure" of space is positive at all locations. Think of a stress-ball, and squeeze it down in your fist. You put it under pressure, and when you let go, what happens? It expands. Now think of the universe as a ball of space. What happens? It expands, because space has this innate pressure.

The dimensionality of energy is pressure x volume, space has a pressure, and it certainly has a volume, so this means that dark energy is space itself. There's no energy outside the universe and so no space, so there's nothing to hold it in, hence it expands. There is the small matter of

the vacuum catastrophe, but you can think of this as the difference between an expanding stress-ball and an expanding ball of compressed gas. If space didn't have a connected "elastic" quality that supported light waves, the universe would expand far more rapidly, just as a ball of compressed gas expands far more quickly than the stress-ball.