Question

[doc_bean]

That's pretty interesting. Alright, forgive my physics noob-ism once more:

Would it not be theoretically possible to fashion some device that harnesses that same force which causes tidal changes and whatnot into a conventional energy you could use to power computers and heat homes?

Gravity ? There have been some experiments to use the energy stored in gravitational fields, but afaik none were a real success. I remember seeing a report once about some guy claiming he had build an engine that worked by getting energy from the motion of the stars

Gravity is very important for energy storage though, the way we do it here, and I imagine in quite a few other places, is to pump water from a lower to a higher tank, and then later use the energy from letting the water come back down again.

Tidal wave energy generation exist, I believe they use it in some parts of Britain.

BTW Does anyone know at what speed gravity 'travels' ? Is it instantaneous or is it, like light, limited in speed ?

[Atilius]

BTW Does anyone know at what speed gravity 'travels' ? Is it instantaneous or is it, like light, limited in speed ?

The theoretical quantum of the gravitational field is the graviton; a massless, spin 2 particle. Since it's massless, the graviton must propagate at the speed of light, just as a photon does.

[English assassin]

Nothing to do with perpetual motion, but I would like to take this chance to draw the org's attention to the awesomeness that is a Stirling Engine:http://en.wikipedia.org/wiki/Stirling_engine

[doc_bean]

Nothing to do with perpetual motion, but I would like to take this chance to draw the org's attention to the awesomeness that is a Stirling Engine:http://en.wikipedia.org/wiki/Stirling_engine

I have to understand this thing for an exam tomorrow...

/end escapism

[English assassin]

Good luck. Its probably annoying to say that I found it really hard to understand, and then when I got it, was impressed with how simple and clever it all was.

[yesdachi]

Wouldn’t the harnessing of the wind be considered using relative perpetual motion as an energy source? like the tital power?

[Papewaio]

Wouldn’t the harnessing of the wind be considered using relative perpetual motion as an energy source? like the tital power?

Perpetual motion refers to an object forever moving without outside interference. Also perpetual motion will not use energy from within the system, it is a kind of forever moving equilbrium.

Windmills are not a closed system, they rely on an external energy source:

Sun Fusion energy -> Photons -> Heat up Earths Atmosphere -> Creating Winds -> Move windmills.

The Universe, unlike humans, likes to share things, particular energy. As such the laws of thermodynamics mean that a perpetual motion machine is not possible. What most people refer to as perpetual motion is an object that is getting energy from some outside force to keep it moving.