Potential Energy

[HydrogenBond]

There are different types of potentials, but all go from higher to lower potential if allowed to act on their own. In some cases, in the process of going from higher to lower potential, it is possible for the potential to first increase before it decreases, as long as the final potential results in a net lowering of potential.

The easiest example to see is connected to a gravity siphon. With a siphon I can use the potential in the water, to cause it to climb up hill, against gravity. This is only possible, if the final bottom height results in a net lowering of potential. If we add the height of all the water going up the siphon hill, the water gains more gravity potential and kinetic energy then it had before it began the climb, without us adding any net potential. Where the energy loss is, is at the end. The final water velocity is slower, since some of the potential is used up front at the expense of the end.

In chemistry there is a similar EM energy siphon hill called the activation energy hill. The reactants first have to climb up an energy hill before they are able to descend down to the bottom into a more stable energy state. They can't go directly down, but have to follow the siphon first. All we need to prime the EM siphon is one chemical reaction. We use a little of the reaction energy potential up front. The same is true of nuke reactions with a nuke siphon being used to get up an energy hill before reaction.

Another observation about the gravity siphon is the water also has to lower entropy so it can get into and travel within the siphon. In the pool, it is free to move about with higher entropy, but in the siphon it gets restricted and has to follow a very directed course to a particular spot. Part of the upfront potential being used by the siphon is being used to lower the entropy into a state of order to get the final affect.

The question becomes, can EM and nuke siphons also cause the entropy of the reactants to lower. The affect would be directed diffusion sort of like the water in the siphon tube. One chemical phenomena that shows this is fire. If we start a wood fire, the heat rises. The rising hot air alters the pressure near the fire, sort of pulling a vacuum near the fire. The fire is using some energy up front to start the siphon. This causes the air to line up and start to diffuse into the fire at a forced rate dependant on energy used. The result is the fire is able to grow and accelerate the lowering of potential. If the fire had to depend upon just diffusion it would reach a slower steady state rate for lowering potential. It is worth the energy up front.

With solar nuke reactions one might expect the same thing. The nuke siphon should not only push H up the activation energy hill for reaction but it may also cause the H to convect for burn.

[Jay-qu]

I think you are taking the analogy to its limits here.

The activation energy for reactions is provided up front by some means, then the reaction may be self-sustained. Look at this on a minute scale. Two particles [reactants] react after being supplied with a sufficient activation energy, the activation energy is incorperated into their chemical potential, they then release energy in an exothermic reaction down to the bottom of this 'hill'. Not all of this energy is realised because a portion of it is utilised to supply the activation energy to the next set of particle reactants.

[UncleAl]

Intensity, gradient, divergence, curl - know your field observables.

What about fields with no gradient but with divergence? A diamagnet or a paramagnet will move (in opposite directions) in such a magnetic field without there being "downhill" from gradient. What about a field with only uniform curl? Opposite chirality entities will have different energies of insertion with nowhere to go to change that.

[HydrogenBond]

The point I was making, is that potential doesn't always have to go directly from high to low potential, but can go from high to higher potential before going to low potential. In the case of the siphon, it works because we use some of the original gravity potential up front to prime the siphon.

In the case of the camp fire, the heat rising produces density differences which create pressure differences. This is made possible by gravity. In this case, the EM forces within the fire, recruits gravity, for the up front potential. This allows the fire to order the air into forced convection, thereby using some up front potential to overcome the air entropy. This gravity recruitment helps lower the EM potential.

Weather is an interesting example. The sun creates a potential in the atmosphere by evaporating water and heating the air. The process does not directly reverse itself, from higher to lower potential. It has to use some energy up front to get the siphon primed. For example, clouds are more likely to form in low pressure systems. This is paradoxical since we need to get the water in the air to condense, which is easier to do in the lab with high pressure. Nature prefers to climb the energy hill. Maybe this is important for allowing stability within potential gradients, which would not be able to exist if there was no energy hill needing to climb.

If you look at controlled fusion, the problem seems to analogous to trying to prime a siphon, but with air getting in, so there is a siphon break. One gets some of the water over the hump but the reaction is not sustainable. The thinking is cause and affect, but the siphon affect appears to go by affect, cause and affect. The affect of lowering potential is energy. Some this energy affect is used up front to prime the cause and affect.

[Qfwfq]

Originally Posted by UncleAl

What about fields with no gradient but with divergence?

Specify what you mean by "with no gradient", do you mean having gradient equal to the zero tensor (gradient of a vector)? If so, the divergence would be the trace of this tensor, how could it be other than zero?

Originally Posted by UncleAl

A diamagnet or a paramagnet will move (in opposite directions) in such a magnetic field without there being "downhill" from gradient.

Since when does a magnetic field have non-zero divergence in vacuo? The force on a dipole, such as that induced in the paramagnet or diamagnet, depends on the gradient of the modulus of the field.

Originally Posted by UncleAl

What about a field with only uniform curl? Opposite chirality entities will have different energies of insertion with nowhere to go to change that.

Which means that, if hypothetically they were such entities that could flip their chiralities in coupling with the environment, Boltzmann would determine the population of the two states at a given temerature. Sodann?

Lack of time prevented me from reading through and making sense of HB's post, lack of prolixity makes you an easier target when you are inaccurate or not making too much sense.