At first I didn't know what I have to do. I've tried to merge some boxes or kick them out of the map. Because you said spamming action in the middle would crash the game (It didn't) so I tried and then I found out that these boxes disappear and make new stars. Maybe add an indicator in the middle, maybe a bigger white point that represents the big bang or something. But it was a really chilly game, I liked it.
A little hint for the boxes. If you change the rigid mode to "Character", you can push them easier because they don't rotate anymore if you try to push them