Both images are animated GIFs.  Please wait to see the images move.

There are 2 great forces in space.  The negative force and the positive force.   The negative force contacts the positive force by electric charge, which formed thunder between the 2 forces.

Thunder between the 2 forces generates large amount of energy.  Energy causes space to expand.  When our space, our universe, was hit by the thunder (became a path for the thunder), our universe expanded.  Billions of years later, our universe will shrink again to its original size.  Then it becomes a black hole. 

Expanding universe is a hot universe.  It is hot because it was hit by the thunder (became a path for the thunder).  Shrinking universe is a cold universe, which is a black hole.  Shrinking universe becomes cold and awaits one day to be hit by the thunder again.  When one day shall it be passed by the thunder again, it will once again become an expanding universe.