Perpetual motion not possible ?. Answer this!.

[fteoath64]

So why is the earth spinning at constant speed around its axis ?. For billions of years! This questions goes for the moon spinning around the earth, and the planets orbiting the sun. Where do they get their energy from, how does that translate to the spinning force ?.

From our own definition, these motions would be perpetual motion, would it not ?.

 

[pcgeek11]

They will all stop ... eventually. We will not be around to see it however.

 

[The Boston Dangler]

planets, stars and galaxies are not closed systems. lots of motion is not perpetual motion.

 

[silverpig]

We haven't been spinning at a constant speed. The moon slowly slows us down and days are getting longer.

In space, you don't need energy to keep spinning because there is no friction. If there was only one object in the universe, and you started it spinning, it may in fact spin for next to forever.

 

[pcgeek11]

planets, stars and galaxies are not closed systems. lots of motion is not perpetual motion.

Perpetual motion doesn't exist.

 

[William Gaatjes]

We haven't been spinning at a constant speed. The moon slowly slows us down and days are getting longer.

In space, you don't need energy to keep spinning because there is no friction. If there was only one object in the universe, and you started it spinning, it may in fact spin for next to forever.

I think even then it will slow down.
Since the object is still part of the universe.
It would just take very very very long.

Brainfart :
If parallel universes would be possible, then hypothetically one could take an object from one (the other) universe and plant it in our universe.It would even then not be perpetual motion because there is still energy consumed from the other universe( to keep it in motion and to keep it in our universe). However, the object would act as a gateway to transport energy from the other universe to our universe. The other universe would be the source of the energy. But there is a price to pay for that energy, i would think. The other universe will be drained far more quickly then the universe the object is in. If there would be life in that universe life advanced enough to that level of physics, that life would not be all to happy about the object being here. Of course, this is just philosophizing for the lolz.

Perpetual motion does not exist. One can only hide the energy consumption. But the energy consumption will always be there...

 

[kevinsbane]

Hm.

How does the "many worlds" theory deal with thermodynamics? I mean, theoretically every time there is a decision point is reached, then the universes split off... and if somehow access between universes is achieved, and energy transfer between universes is possible, you could get "free" energy by forcing decision points to branch off the universe, ....

Actually, thermodynamics isn't violated when I think about it, even in that case. Thermodynamics doesn't state free energy isn't possible... it states that entropy always increases. Meaning that if you twin a universe... you twin its entropy as well. Thus entropy increases?

 

[JTsyo]

Hm.

How does the "many worlds" theory deal with thermodynamics? I mean, theoretically every time there is a decision point is reached, then the universes split off... and if somehow access between universes is achieved, and energy transfer between universes is possible, you could get "free" energy by forcing decision points to branch off the universe, ....

Actually, thermodynamics isn't violated when I think about it, even in that case. Thermodynamics doesn't state free energy isn't possible... it states that entropy always increases. Meaning that if you twin a universe... you twin its entropy as well. Thus entropy increases?

I doubt our laws of physics hold true for outside the universe. Contrary to fiction, if you flip a coin there's only one answer and the universe needs not split. Situations like Schrodinger's cat would result in a branch.

In the case of the OP, things in orbit have potential energy from being in the gravity field of another body. PE for the spin is from either formation of the body or from impacts. Since the inertia is so high it'll take billions of years to lose that PE.

First law allows for perpetual motion in a universe with only one object with a initial velocity. But in practical sense perpetual motion usually assumes you are overcoming "frictional" forces not just assuming them to be zero.

 

[SMOGZINN]

First law allows for perpetual motion in a universe with only one object with a initial velocity. But in practical sense perpetual motion usually assumes you are overcoming "frictional" forces not just assuming them to be zero.

If there was only one object in the universe how would you know if that object was spinning or not? Does this one-object-universe have a preferred frame of reference? If so that makes it considerably different then ours.
It would seem that for something to be spinning it has to have something to measure that spin against.
I'm not sure that in a one-object-universe that motion is possible at all.

 

[silverpig]

I think even then it will slow down.
Since the object is still part of the universe.
It would just take very very very long.

Brainfart :
If parallel universes would be possible, then hypothetically one could take an object from one (the other) universe and plant it in our universe.It would even then not be perpetual motion because there is still energy consumed from the other universe( to keep it in motion and to keep it in our universe). However, the object would act as a gateway to transport energy from the other universe to our universe. The other universe would be the source of the energy. But there is a price to pay for that energy, i would think. The other universe will be drained far more quickly then the universe the object is in. If there would be life in that universe life advanced enough to that level of physics, that life would not be all to happy about the object being here. Of course, this is just philosophizing for the lolz.

Perpetual motion does not exist. One can only hide the energy consumption. But the energy consumption will always be there...

In order for it to slow down it would have to dissipate energy somehow. If it's just a solid sphere at near absolute zero spinning around that is not charged, it won't dissipate much if any energy at all.

There might be some interaction with zero point energy somewhere, but I dunno.

 

[Biftheunderstudy]

The rules go something like this:

1. You can never win, only break even.
2. You can only break even at absolute zero.
3. You can never reach absolute zero.

 

[PsiStar]

There are forces that are constantly acting on every object in the universe. Some negligibly weak compared to others.

There is a thread somewhere in HT that beats to death why the earth is slowing down. Why the moon's rotation around the earth is slowing down. There are links in that thread to volumes of math discussing this ... all real science.

There are very few "somehows" left in that math. The ones that are left are the extremely weak forces from elsewhere. It is up to you to search in this forum to find those related threads.

 

[pandemonium]

The rules go something like this:

1. You can never win, only break even.
2. You can only break even at absolute zero.
3. You can never reach absolute zero.

Words of wisdom right there. Reminds me of Devil's Advocate: "Look, but don't touch. Touch, but don't taste. Taste, but don't swallow!"

 

[The Boston Dangler]

Perpetual motion doesn't exist.

let me rephrase that:

having a great deal of kinetic energy is not perpetual motion.

 

[Matthiasa]

Something about a superconducting coil in an area between galaxies.

 

[PsiStar]

Something about a superconducting coil in an area between galaxies.

Why stop there? Pick a place between universes. And uhhhh ... .. .

 

[Hulk]

Second law of thermodynamics basically states that you cannot have a process that creates energy. Basically all you can do is break even. i.e. perpetual motion.

But the Third Law of Thermodynamics states that you can't even break even. So no perpetual motion. The entropy of every process must increase. And that's that.

 

[CoachB]

By no means can I claim to understand quantum mechanics BUT I believe I heard the physicist Lawrence Krauss intimate that our particular universe, be nature of it's form of creation, would continue to expand forever. Would that not be considered "perpetual motion" .....if true?
And if true, could we not conceivable find a way to harness that expansion energy?

 

[Hulk]

By no means can I claim to understand quantum mechanics BUT I believe I heard the physicist Lawrence Krauss intimate that our particular universe, be nature of it's form of creation, would continue to expand forever. Would that not be considered "perpetual motion" .....if true?
And if true, could we not conceivable find a way to harness that expansion energy?

No there is energy driving every process. For example, isn't an electron orbiting the nucleus of an atom perpetual motion? No, not when you think about it. If you cool the atom to absolute zero all motion stops. So external heat is driving the atomic motion.

If the universe expands forever that just means that the initial energy of the Big Bang was large enough to overcome the gravitational forces that would tend to pull the matter back to the center of the original event. So the universe just achieved "escape velocity" in a manner of speaking. No more perpetual motion than a rocket accelerating to escape velocity, then the propulsion stops but the rocket keeps moving away from the Earth. Eventually if in the universe only the rocket and the Earth existed the rocket would end up crashing back into the Earth since space is curved.

The idea of the universe expanding is somewhat different because the universe isn't expanding into anything. It is in effect creating 3D space. It is more a 3D bubble expanding into a 4D multiverse.

To a 4 dimensional creature our universe would appear flat in a manner of speaking. Have you ever seen a hypercube? It's a 3 dimensional object that is the shadow of a four dimensional cube. Some people can project the hypercube back and visualize the 4D "thing" that created the 3D shadow. So when you get into the universe and what it is expanding into you enter a realm we can't comprehend because we are "trapped" in 3 dimensions. We cannot conceive of the idea that our space is being created as the universe expands. To us the universe is infinite. Always has been and always will be. Much in the same way to a 2 dimensional creature on a sphere their universe will seem infinite. But to a 3D creature viewing, it is easily seen simply as a sphere, not infinite at all.

So you have to be careful when applying 3d physics to 4d or higher problems.

 

[Matthiasa]

Why stop there? Pick a place between universes. And uhhhh ... .. .

Its more for a place cold enough to keep the thing superconducting without having to apply energy to keep it cold once there.
Yes I know you don't actually have to go that far out but it would also fail if something ran into it.

 

[CoachB]

Hulk,
I think I follow your line of thought. But, again according to Krauss, the universe is expanding at an ever increasing velocity.....which (to me) implies a perpetual input of energy. Granted this is bleeding edge QM theory and we may never be able to experimentally confirm this stuff (until we meet that 4D creature who can give us the 411) :>)
ON THE OTHER HAND, if perpetual motion were possible in our universe, there should be clearly observable examples of it....shouldn't there?

Thanks for the discussion!

 

[DirkGently1]

Hulk,
I think I follow your line of thought. But, again according to Krauss, the universe is expanding at an ever increasing velocity.....which (to me) implies a perpetual input of energy. Granted this is bleeding edge QM theory and we may never be able to experimentally confirm this stuff (until we meet that 4D creature who can give us the 411) :>)
ON THE OTHER HAND, if perpetual motion were possible in our universe, there should be clearly observable examples of it....shouldn't there?

Thanks for the discussion!

You are correct. For the rate of acceleration to increase there must be additional energy.

Look up 'Dark Energy' for more on this.

 

[Onceler]

Perpetual motion doesn't exist.

What about electrons around the nucleous?
I would say that if someone could build a device that kept in motion for a considerable amount of time that would qualify it to be a perpetual motion machine.
And there would have to be an ultimate limit to entopy as well.

 

[jhu]

Electrons moving around in a superconductor loop.

 

[SMOGZINN]

Hulk,
I think I follow your line of thought. But, again according to Krauss, the universe is expanding at an ever increasing velocity.....which (to me) implies a perpetual input of energy. Granted this is bleeding edge QM theory and we may never be able to experimentally confirm this stuff (until we meet that 4D creature who can give us the 411) :>)
ON THE OTHER HAND, if perpetual motion were possible in our universe, there should be clearly observable examples of it....shouldn't there?

Thanks for the discussion!

The universe is expanding, but it is not in motion (as far as we know). This is one of those places that things start to get weird in quantum physics. The universe expands with out actually moving. Remember that the laws of thermal dynamics pertain to everything in the universe, but not necessarily the universe itself.

What about electrons around the nucleous?
I would say that if someone could build a device that kept in motion for a considerable amount of time that would qualify it to be a perpetual motion machine.
And there would have to be an ultimate limit to entopy as well.

The idea of electrons spinning around a nucleus is a somewhat intellectually lazy shortcut. It is really a shame that they are still teaching it. Electrons are not actually some little dot zooming around the proton like earth is orbiting the sun. It is more of a shell, think of it like a force field surrounding the proton, but try to remember that even that is a bit of a shortcut. Really the electron is statistically distributed and exists in many places at once.

(What to get really weird? Wrap your head around this. It is even possible that there is only one electron in the entire universe, and our apparent observation of all the electrons is just one electron that is in all those different places and states all at once.)