In this puzzle, you could observe that when the speaker was only emitting at small frequencies, all beads jumped from one side to the next. This has very much to do with the interaction between the beads. While initially distributed nearly evenly, one side will always have a little more beads than the other. On the side with more beads, there are obviously also more interaction between the beads. However, with every collision, the beads lose some energy. This slows them down slightly. This means that the side with fewer beads will on average be faster. Moreover, the faster a particle, the more likely it becomes that it jumps to the other side. So, it is more likely for a bead from the side with fewer beads to jump to the side with more beads. Of course, this effect is self enhancing. Once more beads have jumped to one side, the ratio between the two sides becomes higher and therefore it once again becomes more likely that more beads jump. However, this effect is only possible at sufficiently low frequencies. At higher frequencies, the slowing of the beads due to collisions does not affect whether or not they are still fast enough to jump over the barrier.
