0 Members and 1 Guest are viewing this topic.
Mike, 1) To have a perpetual motion machine, you have to get free energy out of a system without putting any energy in.2) I've demonstrated above that with Newtonian gravity, you don't gain energy--you break even on each loop.3) In reality, since there's resistivity in an actual system, you actually lose energy as the current runs.4) So it's not perpetual motion.QED.If you disagree with this, please tell me which point you disagree with. By the way, "perpetual motion" might be a bit misleading. In the absence of friction or other losses, a current can move forever without stopping. This is purely theoretical, though, since there are always some losses in reality, even in the best superconductors. But in theory, even if there is no resistance in the above wire and the current moves forever, it's not a violation of the second law of thermodynamics unless it gains energy with each loop.
Quote from: MikeS on 14/07/2011 08:45:02It could be argued that photon blue-shift which is usually interpreted as a gain of energy is nothing more than an effect of observing the photons from a dilated time frame.These are the same thing. They have the same physical meaning, all that changes is the particular means of description that one is using.Quote Photons do not gain energy falling within a gravitational field, they only appear to.If by "appear to" you mean, "behave in absolutely all interactions as if they have a higher energy", then yes. But that's a funny "appear to".
It could be argued that photon blue-shift which is usually interpreted as a gain of energy is nothing more than an effect of observing the photons from a dilated time frame.
Photons do not gain energy falling within a gravitational field, they only appear to.
Quote from: MikeS on 16/07/2011 07:11:32“Consider the following experiment.We use a given amount of energy to create pair particles at a high gravitational potential at the top of a tower and let them fall. In falling they gain kinetic energy which we use to operate an electric generator at the bottom of the tower. The electricity generated is used to produce more photons at the top of the tower which are then used to create pair particles which fall gaining kinetic energy and so on.Why would we think that it is possible to harvest energy from these particles? These particles either self-annihilate or one of them annihilates with another particle. (This is essentially how black holes lose mass and energy.) In any case, the net energy that they introduce into the system is zero. If they fall and gain energy, then they annihilate that energy, too. No detailed thinking about gravity or time dilation required.
“Consider the following experiment.We use a given amount of energy to create pair particles at a high gravitational potential at the top of a tower and let them fall. In falling they gain kinetic energy which we use to operate an electric generator at the bottom of the tower. The electricity generated is used to produce more photons at the top of the tower which are then used to create pair particles which fall gaining kinetic energy and so on.
I guess, it depends from what reference frame you mean gain energy. I maintain that from the reference frame of the photons, they do not gain energy.
Not so, They contain the energy of their creation and even if annihilated the energy still remains.Wrong. Energy can neither be created or destroyed, it can only be transformed into another kind of energy.
We use a given amount of energy to create pair particles at a high gravitational potential at the top of a tower and let them fall. In falling they gain kinetic energy which we use to operate an electric generator at the bottom of the tower. The electricity generated is used to produce more photons at the top of the tower which are then used to create pair particles which fall gaining kinetic energy and so on."
Quote from: MikeS on 16/07/2011 15:52:33We use a given amount of energy to create pair particles at a high gravitational potential at the top of a tower and let them fall. In falling they gain kinetic energy which we use to operate an electric generator at the bottom of the tower. The electricity generated is used to produce more photons at the top of the tower which are then used to create pair particles which fall gaining kinetic energy and so on."Ah, but to create more photons at the top of the tower you have to spend at least as much energy as you just gained by having their decay products fall to the bottom. Still not perpetual motion. Still Newtonian gravity.
Quote from: MikeS on 16/07/2011 16:09:09I guess, it depends from what reference frame you mean gain energy. I maintain that from the reference frame of the photons, they do not gain energy.Then you mean absolutely nothing, since there is no coherent way to define the reference frame of a photon.Quote from: MikeS on 16/07/2011 16:25:11Not so, They contain the energy of their creation and even if annihilated the energy still remains.Wrong. Energy can neither be created or destroyed, it can only be transformed into another kind of energy.Here you appear to be contradicting yourself. Either the pair has no net energy or it has the energy of its creation, not both.If we consider that the pair contains the energy of its creation, then we must take this energy into account gravitationally. The pair does not simply fall towards the surface of a planet, the planet also falls towards the pair. Given the equivalence of mass-energy, the same would have happened if that energy has not generated a pair of particles.If we consider the energy of the pair to be zero, then there is no creation of energy with regards to the pair and there is not destruction of energy when the pair is destroyed.
This does not mean 'nothing' simply we do not know how to define the reference frame of a photon. Not being able to define a reference frame for a photon does not mean it hasn't got one. Actually, I can't see why we can not define a reference frame lets say the reference frame is travelling along with the photon.
I don't understand what this is saying.
Why would we consider the energy of the pair to be zero?
Quote from: MikeS on 17/07/2011 05:15:28This does not mean 'nothing' simply we do not know how to define the reference frame of a photon. Not being able to define a reference frame for a photon does not mean it hasn't got one. Actually, I can't see why we can not define a reference frame lets say the reference frame is travelling along with the photon.Well, can you use your photon reference frame to do any calculations of the energy of a photon?QuoteI don't understand what this is saying.In general relativity, the action of gravity depends on the presence of mass and energy. The energy that goes into creating the pair also interacts with gravity. It doesn't matter whether that energy is in the form of energy or in the form of particles. You are introducing a difference where there is none.QuoteWhy would we consider the energy of the pair to be zero?If we are talking about virtual particles, then the net energy of those particles is zero. The come into being and are then annihilated.
No but I don't think the photon cares. I use reference frame of the photon to differentiate it from all other reference frames.
Are you saying that both energy (photons) and mass interact with gravity in the same way?
Quote from: MikeS on 17/07/2011 16:02:54No but I don't think the photon cares. I use reference frame of the photon to differentiate it from all other reference frames.Only in a poetic sense. You are not doing anything that we can make sense of physically. QuoteAre you saying that both energy (photons) and mass interact with gravity in the same way?Photons are not energy, but, yes, energy and mass interact with gravity in the same way.
A photon is a type of particle in the quantum mechanical sense. Some particles have mass; all particles have energy. Particles can transfer energy between each other.
I believe all known particles have mass with the exception of the photon.
All particles have gravitational potential energy as by definition they are all within a gravitational field.I believe that a photon is pure energy as in E=mc2.
Going back to your previous post, if you are saying that photons and mass interact with gravity in the same way then I would have to disagree.
Quote from: MikeS on 17/07/2011 19:44:14I believe all known particles have mass with the exception of the photon.You are free to believe that. Those of us that believe in gluons will have to disagree.[/color]QuoteAll particles have gravitational potential energy as by definition they are all within a gravitational field.I believe that a photon is pure energy as in E=mc2.[/color]Contemporary demonstrations of this theorem begin with proving something similar with regards to the momentum of a photon.e.g., http://terrytao.wordpress.com/2007/12/28/einsteins-derivation-of-emc2/QuoteGoing back to your previous post, if you are saying that photons and mass interact with gravity in the same way then I would have to disagree.Well, you are free to disagree, but those of us that believe in the general theory of relativity will have to disagree.
Gravity does not affect the geodesic of a photon which continues on a straight line in curved space time.What part of that does not agree with general relativity?[/color]
Quote from: MikeS on 18/07/2011 07:14:04 Gravity does not affect the geodesic of a photon which continues on a straight line in curved space time.What part of that does not agree with general relativity?[/color]Gravity is what determines the geodesic of a photon!
Gravity is what determines the warp of space time. A photon travels a straight line in curved space-time. The photon is is not directly affected by gravity, space time is.
Quote from: MikeS on 18/07/2011 12:35:16Gravity is what determines the warp of space time. A photon travels a straight line in curved space-time. The photon is is not directly affected by gravity, space time is.Well, you are free to have your own theory of gravity. Good luck.