Science:
The universe can expand faster than the speed of light.
Black holes exert the same amount of gravitation as it's equivalent in normal matter. They do not transport you to another universe, that's a wormhole.
The mysterious dark matter also lies in the visible universe, it is the name we give to the missing matter that should be there according to the observations.
Science-fiction:
I like to think of it as going on in infinity, without beginning, without end. We can try to look back as far as possible, but never reach the beginning.
And the same goes for the scale, on a proton/neutron level everything looks surprisingly like the empty voids of space. For comparison, our universe could be just a cell in another giant organism, and we are something like mini-bacteria. Also we keep on finding smaller and smaller things. First it was the atom (also called the undividible), then the proton, then the quarks, then the ..... Same here, no 'matter' how deep we go, there is always something new. This goes on and on and on.
At least thats how i like to think of it
The following video is very old and i watched it for the first time a loooong time ago, but it is beautiful and can recommend it to anyone with an interest in these things. It's called Powers of Ten.
