Unlimited Energy - Perpetual Motion Machine?, Gravity the answer?

One thing which has been puzzeling me for a long time is gravity. Ever since I've first heard the concept of gravity i've never truly understood it. I've asked how can it constantly be pulling the heavenly bodies together? Where is all this energy coming from? The introduction of string theory and the invention of the gravitron may find the elegant answer I've been looking for. However even today I wonder if you could some how harness and tap into this source of energy. Thus breaking the fundemental first law of thermodynamics.

The first rule of thermodynamics gives rise to the conservation of energy which states "energy can neither be created nor destroyed, only transfered". From this we can infer that there is a finite amount of energy in the universe as energy cannot be created. So in theory finding a way to harness a source of never ending energy we would be breaking the rule. You could gain an infinite amount of energy that must at one point break this finite limit.

Then it struck me, it's easy to gain energy from gravity. In fact were doing it as we speak and its almost definately not the only way, tidal power. Now to demonstrate how this all applies, consider this thought experiment. Imagine a perfectly spherical planet stationary on its axis and consisting of a core - much like our planet, yet perfectly uniform. Overlaying this core will be a mass of water, the lack of an atmosphere causes the water's surface to be impeccably still. Now we need to add two tidal generators on either end of this planet. Intentionally, the center of gravity will lie in the exact center of this planet. For the final step we need to add two spherical moons in a perfect orbit around this planet both exactly opposite with the same mass, speed and direction. Now, leaving this model undisturbed shouldn't it generate unlimited energy? The perfect nature of this model ensures that either moon will not stray from their intial orbit, as the main planet's center of gravity shouldn't move.

One question that has been posed is how will one store unlimited energy provided by this model. My solution to this would be to pool the energy into the spin of an object floating in neighbouring space. As newtons laws of motion ensures that it will keep spinning and in doing so store the energy. Einstein's E=MC^2 dictates that this spinning object will gain mass and therefore gravity, so it would be wise for this object to be slowly moving away from my model. So hypothetically all this should have created a perptual motion machine.

Now, what are your opinions? Anybody see any obvious loopholes in my logic?

Adam

No.

uhm...

When you store water (or whatever, you can also store little furry animals if you want to) that the gravity force of a moon brought to you and don't allow it (or the animals) to move with the moon (as it/they would because they are drawn to the moon), you create a force on the moon that is not exactly 90° to its movement (as it would if the water/the animals would always be exactly under it). So you pull the moon towards the water/the animals, therefore slowing it down, therefore reducing it's kinetic energy.
OK, this will only be reduced by a very small amount, but it's not perpetual.

(I'm a bit tired right now and I have no real knowledge about tidal power, so please correct me)

To make it clearer, replace the gravity by a solid piece of string. Tie it to the moon and twist the other end around a generator. As long as nothing creates a force on the generator, it will always be exactly under the moon (wrong, but who cares). Now, you jump in and grab the generator, so that the moon pulls on the string and the generator creates electricity. When you do this, you technically grab the string and hold back the moon a tiny little bit.

(oh god, I'd better go, I hope I'm not talking too much garbage)

[edit]oh and welcome to the forums. please read the FAQs and enjoy your stay.

+ gravity = force.
force != energy.
force * way = energy.
The energy "stored" in an object that has weight is only released when it moves closer to the object the gravity force comes from.

This post has been edited by URMEL on Mar 10 2005, 03:56 PM

Your model of planets and moons isn't very cost effective, considering nobody trying to create Perpetual Motion Machine isn't already a God and if so has already succeeded. One wierd thing you mentioned in said model was the addition of wave generators at the north andsouth poles of the planet. You wouldnt need to have the generators of you already had the perfectly orbiting twin lunar bodies. thier own gravity would be pulling at the surface of the planet and slightly contorting the planets spehical shape as the moons orbited. That motion alone would cause waves if it were also not for the fact that high and low tides are caused by the very same lunar gravity that contorts the planet.

But, as far as the core question of perpetual motion goes, you can look up such machines in the US patent office and find several good, but ultimately failing ideas. (the one about the sponges soaking up water to increase weight to be pulled down while other sponges are wrung dry to lighten themselves and be pulled up by the other wet sponges was a wierd one) I'm sure everybody has thought of the generator powering the motor turning the generator one.

I also saw something pnce about the second law of thermodynamics saying that the Universe is constantly cooling. And this process will ultimately mean that most forms of energy via fusion and fission will eventually be tranferred into nothing but kinetic energy.

There's anothier theory that the Universe will eventually be sucked into massive black holes and there is another topic that discusses black holes as a source of infinite energy. So, maybe that thread has the answer you're looking for.

methinks he means them perfectly opposite each other on the equator.

While i know the Conservation of energy rule the statement that energy cannot be greated or destroyed only transferred has led me to often think that there must be a hellva lot of energy in this universe for it to exist the way that it does. It would mean that in order for our sun, earth and the moon to exist the amount of energy that would be nessecary to create these 3 things alone would have had to be immense. Not only that but when you think about all the energy needed to make all out planets and all the stars in this universe the mind boggles!!

Correct me if im wrong but i think that you by tidal generators you mean generators that generate electricity by the movment of the water due to the tides as apposed to something that generates a tide.

If thats the case then that make sense lol. Seeing as how it is possible for 2 moons to have such an orbit i can only wonder why is there water with no atmostphere seeing as how heat would need to be provided to keep the water liquid and thats bound to create vapor and lead to clouds and so on but we will just stick to theory.

As far as your idea goes it would possibly create a perpetual energy source but i doubt that the level of energy generated would be large enough to be useful. Also in order to harness this energy people would have to live on the planet but thats not really an issue if we have the technology to do something like that.

I think that there are too many 'ifs' in this idea, such as the perfectly flat water and uniform planet. If you are going to say that, why not imagine that the laws of thermodynamics can be broken?

The moons would slowly be pulled towards the planet, because of the delay in the water not pulling uniformly on them.

Apart from this, it is the best perpetual motion idea that I have seen ^^

Well before you start the Keely Motor company you have a couple of obvious problems:

All orbits decay: Rougly four things influence orbital decay, in order of severity Atmospheric drag, EM drag, Tidal Forces and Gravitational waves.

i) It seems like you have tried to pretend that your planet doesn't have an atmosphere. The problem being that if your surface water is liquid then some of it is going to vaporise, which over time becomes your atmosphere.

ii) For some reason you have neglected to take into account the very thing you are trying to create. The tidal effect on the moon.

iii) Also in a weak sense gravity itself is going to decay your orbit.

All of these seem to point to the idea that your machine is far from perpetual.

It seems like you are trying to get around these issues by pretending that your orbits is "perfect" if that means it doesn't decay then all you are doing is pretending certian physical laws don't exist. If you were going to do that, why not just pretend that perpetual motion is possible from the start?

One of the ways you could keep the orbit from decaying i guess would to put rockets on the moons to stabilise their orbits every now and again to stop the decay.

But then it would not be a perpetual system, because the fuel would run out, and the mass of the moons would change as this happened

Thanks for your comments! You guys made some nice points and observations, some more nit-picky then others

First off, valid point about the atmosphere, in fact I thought of this flaw myself but decided there were numerous ways around this. To keep the model simple I decided to say liquid water, on the other hand it could be an ionic liquid, some of which, if I recall correctly, do not even evaporate.

Next, about the "perfect" orbit decaying. What really causes a perfect orbit to decay? As far as I understand it’s just a change in gravity acting between the two objects. This is what’s really happening in all of sarkeizen's cases. Newton defines mass, gravitational constant, and distance between centers as the only factors that affect gravity. Well Newton’s gravitational constant will remain well, constant (duh!). Also the masses of the moons and the planet will also remain constant. So we now only have the distance between the centers of the two masses. Infact here I have accounted for the tidal effect here: there are two moons exactly opposite creating two identical tides, with two exactly opposite tide machines acting exactly the same. Hence the center point of the planet will remain the same and consequently the distance between the two center points. Now the only thing I can see stopping this being a "perfect" orbit is something in space disturbing the system. This is just a thought experiment but nevertheless, theres an infinitely small chance that over infinite time it will remain undisturbed. But I care to remind you - theres still a chance!

Adam

But you haven't accounted for the fact that the shape of the water on a planet does not make a perfect ovoid.

Also, the ovoidish shape would not be directly in line with the two moons because of the delay in the moving of the water.

A moon is in orbit when the gravitational force between the planet and then moon is equal to the centrepital force needed to keep the moon moving in a circle of a given radius.

F[centrepital]=m[2]v^2/r
F[gravity]=Gm[1]m[2]/r^2

where m[1] is the mass of the planet, m[2] is the mass of the moon, G is the gravitation constant, r is the radius of the orbit, and v is the velocity

F[centrepital]=F[gravity], so
m[2]v^2/r=Gm[1]m[2]/r^2
the m[2]s and the rs cancel, so
v^2=Gm[1]/r
solve for r and
r=v^2/Gm[1]

So, the point is, if anything causes a moon to slow down, it's orbit will get smaller. Since the mass of your moon is constant, any way of harvesting its kinetic energy will do that. Since v=sqrt(Gm[1]/r), the moon has to speed up as its orbit is decreasing in radius. So, when you take kinetic energy away from the moon, it will fall, converting its gravitational potential energy into kinetic energy until it is at equilibrium again.

Any tidal generator will convert a tiny bit of the moon's kinetic energy into electrical energy, and that energy will have to be replaced by the gravitational potential energy of the moon. Yes, your generator does use the moon's kinetic energy, because it depends on the moon's motion. So, over millions of years, your generator would make the moons crash into the planet, making your machine unperpetual.

Edit: Clarity

This post has been edited by Coerade on Mar 13 2005, 03:53 PM

@Diorama42: It doesn't need to be a perfect ovoid, only a symmetrical one. Also, it doesn't matter whether the ovoidish shape would not be directly in line with the two moons so long as the center of mass of the planet remains in the same place.

@Coerade: Ok, nice. But you've failed to mention why a tide created by an orbiting body would draw kinetic energy from that body. In other words why would the generator use the moon's kinetic energy? The center of masses and the masses of both the moon and the planet will remain the same. Hence the force between the moon and the planet will remain the same and so theres nothing stopping a perfect orbit - correct me if i'm wrong.

Adam

The tidal generators would take energy from the movement of the oceans and convert it to electrical or whatever. Correct me if I'm wrong, but does this not mean that the system would slowly lose Kinetic energy and not be perpetual?

I suck at explaining things, so I'll point to URMEL, who said it better than I could.

Plus,There's nowhere else for the energy to come from. Elecricity comes from the movement in the oceans, which has to come from the movement of the moon.

This post has been edited by Coerade on Mar 13 2005, 05:54 PM

Ok I made a little diagram to show you what I think were all talking about.



I'm pretty sure the images are self explanatory, no time to label

Figure one shows a perfect orbit so to speak.

Figure two shows what URMEL is explaining. The object (fury animal’s lol) changes the center of mass and therefore the force of gravity acting between the planet and moon is no longer at 90 degrees.

Figure three shows my way of thinking, there are two moons exactly opposite acting exactly the same, therefore altering the planet exactly symmetrically. Like have two weights opposite, this is demonstrated by the diagram.

Adam

I believe that someone mentioned that in order for this to work the water (or whatever liquid) needs to remain a liquid, which requires a source of heat. This heat energy could only come from an external source, which would run our sooner or later, meaning that this isn't perpetual motion.

The heat source may run out but if enough energy is generated from the tidal generators this enegergy could be used to keep the liquid well....liquid

I'm pretty sure it's impossible to generate enough energy from those plants to heat the entire planet's water. As said before, this would also cause some of the water to evaporate off. This could cause any number of variations in the "perpetual motion device" which I couldn't be bothered going into here.

Anyway, even if that were possible, the generators would rely on mechanical energy, which always loses energy through heat caused by friction.

As I have already said:

Ontop of this I'm sure there's ionic liquids that remain a liquid at 0K. I already know that helium remains a liquid at 0K.

I hope this clears some things up.

Adam

So, figure 3 implies that if your oval of water is symetrical, then the center of mass of your planet will stay at the center of your planet? still, I don't think this'd work. See the block(I say block because that's what the diagram shows, and I'm too uncreative to thing of a better word) of water that's closer to the moon will still be pulling harder than the block on the other side, because it's closer. So, the gravitational force would still not be perfectly perpendicular to the moon's path of travel.

but there isnt just one moon, if you will look back at addit's origional post you will find:

so both moons are pulling with the same gravitational force and there wont be unbalance.
i swear some of you just arn't reading this guys posts thoughroly(sp?)

This post has been edited by _Littleman_ on Mar 14 2005, 11:30 AM

Do you guys realise that the water shouldn't even be needed in your "perpetual motion machine"? Simply a perfectly stable orbit without any outside interference would give (seemingly) perpetual motion. Unfortunately, you wouldn't be able to harness this as a power source in that case though.

If it were that easy to create perpetual motion though, scientists would have already figured it out. They say it's impossible, so there must still be some energy leaving a system like that. Either that, or it's impossible to keep an orbit from decaying.

The idea about gravity needing a constant input of energy in order to maintain its attraction is false under Einsteinian general relativity. The reason for this is that massive objects do not merely distort space, but they distort TIME as well (i.e. spacetime--time is regarded as simply another dimension of space in general relativity). Here is an example:

Imagine two planets, A and B, beginning perfectly at rest with respect to each other. Because of the distortion of spacetime caused by their mass, as time is added, space must be subtracted--in other words, as you go forward in time, the two planets must move toward each other (neglecting any motion from other sources).