[haxiomic]

I take your point, but the food ultimately gets its energy from the sun, which gets its energy from collapsing under gravity. I don't think there's a clear place to stop, but I'd say the name Gravity Light gets the idea across anyhow

[avian]

Sun is powered by fusion. Gravity just holds it together.

[Confusion]

The fusion persists because gravity forces hydrogen sufficiently close together.

[ajuc]

So gravity is a catalyst, not the energy source.

[jheriko]

its a symbiotic relationship. stars exist generally at an equilibrium point where gravity is trying to make it collapse, but the pressure produced from the constituents pushing outwards balances it out.

this is because if something is collapsing from gravity it will stop once some other force is pushing out harder.

this explains a lot of phenomena and is a key piece of understanding the modern theories of stellar phenomena, e.g. via the pauli exclusion principle, why neutron stars can form during a supernova (from the extra inward pressure combining with the gravitational collapse exceeding the degeneracy pressure of electrons in the plasma)... its also why beyond a critical mass the collapse doesn't stop at all and produces a black hole.

in any case energy is always conserved... but the ultimate place it is being extracted from to power a star is the gravitational field. everything else, e.g. the nuclear fusion, the light pressure from temperature etc. is a result of that energy being transferred into the star as it forms and continues to evolve.

[avian]

By that logic my car is powered by steel, because that's what keeps the fuel-air mixture sufficiently close together.

[scott_s]

Close, but not quite. The steel of your engine did not cause your engine to exist. But gravitational collapse of interstellar gas is the process that formed the sun. So, in that sense, gravity comes before the fusion.

[Confusion]

It's common to say a car is powered by fuel. It's also common to say a car is powered by its engine. The latter is indeed is a device that brings fuel and air close together (and does some more important things). It's less common, but certainly not wrong, to say a car is powered by combustion.

Similarly, I think saying both 'the sun is powered by gravity', 'the sun is powered by hydrogen' and 'the sun is powered by fusion' is reasonable.