> random: "Sound can be used to achieve the same effect ... My
> point is combustion is a gross form of energy, there are many
> subtle ones that pre-historic civilizations may have used
> Generally agreed - but what source of energy was used to
> produce the sound - there is no free lunch.
> Regardless of the means of delivery, the energy necessary to
> accomplish a task must be delivered, and since it cannot be
> created, it must be converted from some existing source.
> If not fossil fuel, then what?
Try The Ancient Solar Premise for a full answer. Megawatts of free power from an average sized pyramid.