[tarice]

People couldn't lift the weight without consuming energy from food. Doesn't mean that it's powered by food.

The machine converts gravitational potential energy to electromagnetic radiation. People generate the gravitational potential energy by lifting the weight using kinetic energy, which was likewise created by converting chemical energy.

It's easier just to say "Gravity" because, without gravity, it wouldn't work with its inanimate weight.

[tjic]

> People couldn't lift the weight without consuming energy from food. Doesn't mean that it's powered by food.

Actually, it does, and that's the perfect way to analyze this. Food is good for keeping humans alive, but it's a pretty foolish fuel to burn in a human engine to accomplish things. It's perishable, it's eaten by rodents, it's hard to transport, and more. I chuckle darkly when someone tells me that something is "green" because it's human powered. Growing food isn't free - it uses conventional energy sources to harvest, transport, etc., and it's a ton less efficient than just burning that fuel directly.

[DanBC]

Food gets its energy from the Sun, so we may as well just call this device solar powered?

[jconnop]

Ad bigbangeum.

[emiliobumachar]

I suppose it all ultimately comes from solar energy, which, in turn, comes from nuclear fusion.

[njharman]

And the nuclear fusion is started if not powered by the heat and pressure caused by, wait for it...

GRAVITY!!!

[tinco]

Which is induced by the intense pressure gravity creates in large lumps of mass :) so yeah..

[sterna]

That is not entirely true. Nuclear fission is not powered by the sun, nor are nuclear fusion plants on Earth (when they arrive). However, fission is only possible because of the existence of heavy nuclei that were initially created during super novae explosions in massive stars billions of years ago so you could argue that is is also at least star powered.

The ingredients needed for fusion on the other hand are thought to have been created during the some of the early stages of the Big bang so fusion is truly independent of stars.

[libria]

When I think "powered solely by gravity" I think of something like a hydro electric plant which can generate more energy than is required to operate it.

At any rate, the phrase was written by Enpundit, not GravityLight. Their indiegogo page is less dramatic and more scientific about what powers their lamp:

http://www.indiegogo.com/projects/282006