The processes at work in nebula formation and lava lamps are not similar. They are identical. Nebulae are nothing but the Galactic Overlord's version of lava lamps. And spiral galaxies are his/her/its version of toy tops. Black holes are sorta like huge cosmic Slinkies. You see, the Galactic Overlord gets bored pretty easily. He doesn't have a computer so he can't hang out at The Mudcat.