*Stop reading this if you haven’t watched season 3 of LOST and are planning on it.*
Found this great theory on the powder/black smoke that was seen in the show LOST, when Ben takes Locke to visit Jacob. The producers/writers have always maintained that the mysteries would be explained through scientific means of some sort. Not to say this is 100% correct; just that it struck me as starting to be plausible.
“The Black Smoke is Jacob. I think his consiousness can travel sort of like an invisible spirit. Remember the ring of black powder Ben touched before they got to Jacob’s cabin? I think the Others circled the cabin with that stuff so that when Jacob leaves the cabin the black powder clings to the magnetic field that surrounds him. The Black Smoke can move trees, stones, etc, and in the cabin Jacob did similar things to the objects in there.” — TVSQUAD comment
If you want to read more about the Black smoke – Lostpedia has a huge write-up of every occurrence and possible theories.