Initial formation of clumps in nebulae?

okay, so i was watching the science channel and they were showing how an astronaut playing with salt and sugar in bags in outer space discovered that they will clump together without any help at all, and thus nebulae form stars and, in turn solar systems, with no help from any other events. my question is this. what causes the initial clumping. in the presence of absolutely nothing else, i suppose the tiny amount of gravity that a particle of dust would have would in tern, eventually pull it towards another particle, causing a cascading snowball effect where clumps of particles "consume" other ones to become larger clumps. but I keep thinking that gravity wouldn't be that powerful at that small a scale. is it possible that there's some electrical charge at play here? when they showed the video of the clumping salt and sugar it looked very much like static electricity was the main factor there. possibly the plastic bag was giving off an electrical charge via friction? any explanation would be appreciated.