Outer space is apparantly a pretty strange place.
Physicists theorize that in the vaccuum of outer space, energy pops into
existance from nothing, and then pops back again... ...into nothing.
"Dark matter" is the invisible and undetectable matter physicists
theorize must exist in order to explain the amount of gravity there is
in our universe.
One of the most promising ideas to explain "dark matter" is that it
doesn't exist at all. It's just that there are multiple universes, and
gravity from the other galaxies superimposes on our own gravity. That
is, gravity waves superimpose just like every other kind of wave.
If you're in an artificially lit parking lot at night, the amount of
illumination at any point on the ground is more than that caused by the
closest lamp alone. The contribution from the more distant lights adds
together to allow for better illumination than would be provided by the
closest light by itself. In the same way, gravity from other universes
may be causing our universe to expand more slowly than it otherwise
would, and cause our galaxy to rotate more rapidly than it otherwise
The world around us is comprehensible. Everything smaller than an atom
and bigger than the universe is incomprehensible.