Question

[Ja'chyra]

Some time ago there was a thread here concerning alternative power sources, I'm sure it was aimed at perpetual motion, with links to a project that has either started or are planning to build a prototype.

Does anyone have a link to the information that was in the thread? I have tried search and can't find anything.

Thanks

[Lemur]

Perpetual motion should be filed next to the Philosopher's Stone, just across from the Elixir of Life. If you reach cold fusion you've gone too far, and should turn back.

[Uesugi Kenshin]

So long as there is something other than the perpetual motion device it will not be possible.

[Kralizec]

Perpetual motion should be filed next to the Philosopher's Stone, just across from the Elixir of Life. If you reach cold fusion you've gone too far, and should turn back.

If I remember right, there's one (theoretical) instance of perpetual motion: when one celestial object circles around the other, ignoring the gravitational pul from other objects. Since there's no friction of atmosphere, it could move on forever- it's impossible to make it into an energy source though, because that would slow down the orbit.

[Avicenna]

It's impossible to ignore gravity though, and the movement will inevitably cause heat, causing it to lose heat and therefore eventually run out of energy.

Perpetual motion is impossible.

[Duke of Gloucester]

It's impossible to ignore gravity though, and the movement will inevitably cause heat, causing it to lose heat and therefore eventually run out of energy.

Perpetual motion is impossible.

Please describe the mechanism by which gravity generates heat.

Perpetual motion is possible in theory, but you can't harvest any energy from the system because this would slow it down.

[macsen rufus]

There's three laws of thermodynamics that need to be broken before perpetual motion has a chance.

1 - you can' t win
2 - you can't break even
3 - you can't get out of the game

By definition it'll never be an energy source, soon as you extract any energy it ceases to be perpetual (sheesh, why is perpetual so difficult to type??!)

If you reach cold fusion you've gone too far, and should turn back.

What?? You mean all that stuff I'm building in the attic won't work after all, damn you Lemur, and your bad news

[Avicenna]

Please describe the mechanism by which gravity generates heat.

Perpetual motion is possible in theory, but you can't harvest any energy from the system because this would slow it down.

Like macsen rufus said, if you make a perpetual motion machine it wouldn't be an energy source. Also, Gravitational Potential Energy converting to kinetic is an energy loss, is it not? There are also inevitably some particle scattered here and there, and friction between the object and particle converts, and hence loses energy.

GC: interesting idea, I'll look into it. Even if it is though, how would we extract energy? It will also not be for long, because eventually the Sun is going to engulf the Earth I think. Even if it doesn't and stops expanding at Mars, it's going to be far too hot for us to live here.

[Kralizec]

It's impossible to ignore gravity though, and the movement will inevitably cause heat, causing it to lose heat and therefore eventually run out of energy.

Perpetual motion is impossible.

The gravity is what makes it circle. I should have added "in a theoretical vacuum". A better way to put is that in a vacuum, an object that is once propelled will keep moving forward. A space ship traveling through vacuum doesn't need fuel to move forward, just to accelerate and decellerate. A perpetuum mobile is theoreticly possible in vacuum (therefore absolutely impossible in practice), but as said before will never be usuable as an energy source.

[Uesugi Kenshin]

If I remember right, there's one (theoretical) instance of perpetual motion: when one celestial object circles around the other, ignoring the gravitational pul from other objects. Since there's no friction of atmosphere, it could move on forever- it's impossible to make it into an energy source though, because that would slow down the orbit.

Not correct. There are some particles scattered through the near vaccum of space, so even then the friction caused by these particles would slow you down. This is pretty negligible most of the time, but if you're talking about a long enough period of time then it can cause quite a significant effect and would eventually stop the object.