@TimeFlipper @steven chiverton
As far as I can tell, the 3 6 9 thing originally comes from John Ernst Worrell Keely, a man who worked with vibration in the 19th century. Supposedly, he broke apart water molecules & other things using sound. First, he'd break apart the molecules, then the atoms, then the subatomic particles. He claimed there were 7 levels of subdivision achievable before they got too small to interact with, but that matter itself is infinitely divisible. When he found the resonant frequency, he would then superimpose on that vibrations at the 3rd, 6th, & 9th octaves of the scale.
There used to be a website called KeelyNet, but unfortunately its curator died a few years ago. The website doesn't seem to exist anymore, but you can probably find it on the Wayback Machine.
Keely also claimed that "time is gravity", whatever that means.
I am aware of the Tesla quote about 3 6 9 being a key to the universe or some such thing, but I'm not aware of him ever explaining it publically. If anyone knows his explanation, please tell me.