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GravityLight: Generate light with gravity

gravitylight.org

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Re: GravityLight: Generate light with gravity

#43

Post by avian »

Confusion wrote: post #39
avian wrote: post #35

Earlier quoted context omitted.

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

The fusion persists because gravity forces hydrogen sufficiently close together.

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

Re: GravityLight: Generate light with gravity

#44

Post by Someone »

dragonwriter wrote: post #20
IshKebab wrote: post #7

Earlier quoted context omitted.

A battery powered LED torch is far superior for emergencies. The only reason you'd really want to use this is if you really can't afford a solar-rechargable battery. (But for some reason can afford this, which I'd expect to be more expensive.)

> A battery powered LED torch is far superior for emergencies. The only reason you'd really want to use this is if you really can't afford a solar-rechargable battery. Rechargeable batteries can be reused, but still need to be replaced; this may prove lower maintenance, which means once you can get it, you are more secure with it with a less secure distribution system. In many of the places where people are without e…

That's true, but the statement was as to its usefulness in emergencies. This thing is fixed to the wall, limiting what you can use it for in an emergency. For example, if you have to find your car keys in a different room, make emergency repairs to your water mains after an earthquake, or figure out how to get a friend out from a collapsed wall in the dark, a torch is more useful.

For emergencies, I would prefer a mechanically powered flashlight with a supercapacitor over this thing.

Re: GravityLight: Generate light with gravity

#46

Post by brianpan »

ajuc wrote: post #37
mdturnerphys wrote: post #33

Earlier quoted context omitted.

If we're playing that game: - Human muscles get energy from food. - Food is or gets its energy from plants. - Plants get energy from the Sun. - The Sun's energy comes from gravity-forced fusion. So gravity :)

Good point, but it's not the end. Fusion uses up energy put there by the Big Bang :)

The Big Bang came from....gravity?

Re: GravityLight: Generate light with gravity

#47

Post by dear »

mdturnerphys wrote: post #33
ajuc wrote: post #24

Nitpick, I know, but: it's not powered by gravity it's powered by human muscles, so in the end - by food.

If we're playing that game: - Human muscles get energy from food. - Food is or gets its energy from plants. - Plants get energy from the Sun. - The Sun's energy comes from gravity-forced fusion. So gravity :)

So by your logic fossil fuel is solar energy.

Re: GravityLight: Generate light with gravity

#48

Post by daveloyall »

romaniv wrote: post #30
ajuc wrote: post #24

Nitpick, I know, but: it's not powered by gravity it's powered by human muscles, so in the end - by food.

I don't think it's a nitpick. I think this is a very important point. Is the hypothetical fuel more expensive than food?

I think your muscles are pretty energy efficient.

The kinetic potential battery (the weight lifted against gravity) is also very efficient.

Food is very energy dense. https://what-if.xkcd.com/128/ (sandwich vs battery)

Uh, change of topic: isn't the caloric value of a food how much heat can be released by burning it (probably when it is dehydrated)? Plenty of energy stored in a sandwich, sure. But a car battery could power a small spaceheater-like thing for... a while. There's a lot of potential for heat production in a car battery (even without BURNING it). Did Mr. Munroe get this one wrong?

Re: GravityLight: Generate light with gravity

#49

Post by bnegreve »

achr2 wrote: post #31
pavel_lishin wrote: post #28

Earlier quoted context omitted.

But this isn't for charging a phone; it's for having light, right now.

I get it, I am just saying that there are a lot of ways to make a single LED light shine, potential energy from a weight is likely the least sensical.

> potential energy from a weight is likely the least sensical.

potential energy is very easy to produce, keresene is not always available. I think this is the #1 benefit.

Re: GravityLight: Generate light with gravity

#50

Post by andrewstuart2 »

dear wrote: post #47
mdturnerphys wrote: post #33

Earlier quoted context omitted.

If we're playing that game: - Human muscles get energy from food. - Food is or gets its energy from plants. - Plants get energy from the Sun. - The Sun's energy comes from gravity-forced fusion. So gravity :)

So by your logic fossil fuel is solar energy.

By causality, it kinda is.
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