Cat Sci writes:
I've never seen anyone working on an explosion model.
Explosions slow down, the expansion of the Universe is speeding up.
Just to mention a few details about the explosion analogy, the Big Bang wasn't an explosion of matter into existing space. It was a rapid expansion of space itself. That's why the 2d expanding balloon surface analogy is so apt, because the expanding balloon surface creates new 2d space, in a way analogous to the expanding universe creating new 3d space. The expanding raisin cake analogy is good, too.
Explosions on Earth slow down because they encounter air.
Explosions in a vacuum will speed up or slow down according to the force of gravity. An explosion in our solar system but not near a planet's gravity will speed up in the direction of the sun and slow down in the direction away from the sun.
The universe's expansion was originally assumed to be slowing because of gravity. Dark energy is just a name for an unknown phenomenon working against gravity to cause the acceleration of the universe's expansion.
--Percy