Quantum Theory...help!

[John W. Kelly]

Whats heating it? a_uk

Heat left over from the Big Bang?

[i blame blame]

hi Blame,
I think I'm getting this thanks. So if the gate was removed no Work would be done due to no mechanical harness(by the definition of Work I suppose) but the Heat would still flow from Hot to Cold. Is a flow some kind of Work? In fact whats a "flow" in this sense?

Mechanical work can vaguely be defined as orderly motion of atoms in one direction (like a piston inside a cylinder, or a weight being lifted...). Heat going from hot to cold is essentially a statistical process. Fast (hot) particles will migrate to cold (slow particled) regions more likely and transmit some of their heat (kinetic energy) to the slower particles. I don't see how this can be turned into useful work, but it may not be impossible!

"homogeneous" and "information " are new and I get the homogeneous.

The "information"-approach is another way of grasping the concept of entropy. Like work, information can be useful...

The way I'm thinking about it is, say the hot side is twice as hot as the cold side. When the gate is removed the hot side gives the cold half its heat, this means that the resulting fluid is hotter than the cold was but cooler than the hot, TE I assume.

That's right.

But why would Entropy increase in this situation? As Entropy is the possible Work lost through Heat to the outside but we are in a perfect insulator so all Heat is retained?

No, entropy is not necessarily work lost through heat to the outside. Otherwise, nobody would claim that the entropy of the universe (the ultimate insulated system) is increasing, which it is. The work is lost because there is no longer a pressure difference between the two systems (referring to my simple model of equal number of equal particles in equal volumes, but with different temperatures).

I think I understand why no Energy would be lost in this example as the volume of the two fluids should make up for the lower Heat available for Work.(Shit sorry, this is beginning to sound like I'm blagging an intro to basic Physics )

Could they be anywhere? Only at TE I'd have thought. The removal of the gate is the start of the process to reach TE. Is TE instantaneous?

Correct. No, it's not instantaneous.

If not there must be an interface of some kind between the two fluids that mediates(?) the process. I'd originally thought of the exchange of Heat as having to be a two-way flow but know think that I need to think about what a transfer of Heat is.

It is indeed a two-way flow. But since the cold part has less heat to hand out, it inevitably receives more.

"particles"(page 20) are yours the same as Maxwells Molecules?

I'm not sure. I was thinking of the perfect gas model, where particles are hard spheres that only interact with each other when bouncing elastically against each other.

Because Heat is causing the particles to move faster, yes?

That's right. These particles will bounce more frequently and with more kinetic energy on the container's walls than the particles of the colder gas.

Stay tuned for more.

[John W. Kelly]

Because Heat is causing the particles to move faster, yes?

That's right. These particles will bounce more frequently and with more kinetic energy on the container's walls than the particles of the colder gas.

A good example is on the bottom of page 16.

[Arising_uk]

Hi Blame,

...Mechanical work can vaguely be defined as orderly motion of atoms in one direction (like a piston inside a cylinder, or a weight being lifted...).

I thought Joule had precisely defined what Mechanical Work was? A definite amount of Heat. I'm not sure what you mean by the "orderly motion of atoms in one direction".

Heat going from hot to cold is essentially a statistical process.

I thought it was a fact that could be understood by Maxwells assumptions about Diatomic Molecules and the statistical mathematics used to model it.

Fast (hot) particles will migrate to cold (slow particled) regions more likely and transmit some of their heat (kinetic energy) to the slower particles. I don't see how this can be turned into useful work, but it may not be impossible!

I thought the useful work occurs when a mechanical harness is introduced into the 'migration'? I also do not understand how heat(kinetic energy) is transmitted as Maxwell says that these 'particles' conserve Energy in their collisions(pgs 20/21). Are your 'particles' like my super-superballs? In that they swap heat but do not radiate any heat to the outside?

No, entropy is not necessarily work lost through heat to the outside. Otherwise, nobody would claim that the entropy of the universe (the ultimate insulated system) is increasing, which it is. The work is lost because there is no longer a pressure difference between the two systems (referring to my simple model of equal number of equal particles in equal volumes, but with different temperatures).

Is it not? I thought Clausius based Entropy upon the idea that "...there is always some degradation of the total energy in the system, some non-useful heat in a thermodynamic process" (pg 18 ). I understand this if the "dynamic" in thermodynamic means a physical harness in the system but in the flow of Hot to Cold without a harness in an totally insulated system, where is the Entropy? As no Heat can be lost? I agree that no Work can be produced within my system as there is no pressure differential once TE has been achieved but the total Energy can not be less than the combined containers as no Heat has been lost, so no Entropy?

"particles"(page 20) are yours the same as Maxwells Molecules?

I'm not sure. I was thinking of the perfect gas model, where particles are hard spheres that only interact with each other when bouncing elastically against each other.

Thems the ones, although I'm not sure about the "bouncing elastically " bit, superballs again?
a_uk

[John W. Kelly]

Is the trough and crest of a wave (oscillation) a change from magnitism to electricity and vice-versa?

[Arising_uk]

Is the trough and crest of a wave (oscillation) a change from magnitism to electricity and vice-versa?

fuck me! What page is this?

[John W. Kelly]

Ha! I've been dusting off some classical physics books to reinforce my shaky foundation. I didn't get "D's" in physics-class for nothing...

[i blame blame]

Is the trough and crest of a wave (oscillation) a change from magnitism to electricity and vice-versa?

No, an electromagnetic wave has 2 components, is composed of 2 waves. One for the oscillating electric field, and one for the oscillating magnetic field.

Ah! So could Work be described as the difference in pressure between two fluids?

It's change in volume multiplied by external pressure.

So Flow is instantaneous? How can that be? As it must take time for Heat to flow from hot to cold.

It's not instantaneous, no. I should have phrased it "less work can be done when reinserting the gate after a short time".

Are you saying that when the gate is closed the same process continues within each container? And when settled to TE because they were the same fluids they will be at the same temperature therefore no Work possible as no Heat difference?

Indeed.

Okay I might have deserved the razz(if this is a raspberry? Or is razz some Yank slang?)
You said it was absorbed by the ground. Do you mean that the 'waste' Heat is radiated out somewhere? Some to the ground, some to the 'air', some back into the superball. Does this explain why a superball is a super ball? As it retrieves more Heat than the other bouncey substances?
a_uk

That's almost correct. It doesn't necessarily retrieve more heat than other objects made of other substances, it just emits less.

...Yes, cavity or blackbody. The known universe is the closest thing to a "perfect black body" we know of. I may reply to the rest tomorrow.

How is the known universe a cavity? Whats heating it? Sorry if I miss the point.
a_uk

Well the universe isn't losing any energy or radiating anything to anywhere not in the universe.

Hi Blame,
I thought Joule had precisely defined what Mechanical Work was? A definite amount of Heat. I'm not sure what you mean by the "orderly motion of atoms in one direction".

Work is the energy used to cause "orderly motion of atoms in one direction".

I thought it was a fact that could be understood by Maxwells assumptions about Diatomic Molecules and the statistical mathematics used to model it.

Okay diatomic molecules are a little more complex as the internal energy of the system will be determined by the energies of rotational and possibly vibrational degrees of freedom in addition to translational.

I thought the useful work occurs when a mechanical harness is introduced into the 'migration'?

Pretty much.

I also do not understand how heat(kinetic energy) is transmitted as Maxwell says that these 'particles' conserve Energy in their collisions(pgs 20/21). Are your 'particles' like my super-superballs? In that they swap heat but do not radiate any heat to the outside?

The system of particles conserves kinetic energy and the total kinetic energies of every two colliding particles will remain identical but the kinetic energy of each particle may vary upon each collision.

Is it not? I thought Clausius based Entropy upon the idea that "...there is always some degradation of the total energy in the system, some non-useful heat in a thermodynamic process" (pg 18 ).

Maybe he means a non-insulated system, that can exchange heat with its surroundings, or a system that does work on its surroundings, or both.

I understand this if the "dynamic" in thermodynamic means a physical harness in the system but in the flow of Hot to Cold without a harness in an totally insulated system, where is the Entropy? As no Heat can be lost? I agree that no Work can be produced within my system as there is no pressure differential once TE has been achieved but the total Energy can not be less than the combined containers as no Heat has been lost,

Yes

so no Entropy?

And no. If you had introduced a "harness" into your system before TE was reached, it could have done work. After it has been achieved, it can't.

Thems the ones, although I'm not sure about the "bouncing elastically " bit, superballs again?
a_uk

Pretty much. Ideal gas particles emit no heat upon collision and conserve the total kinetic energy of the sum of particles participating in collisions.

[John W. Kelly]

Light takes time to travel. Is this limit tied to entropy? Heat?

[i blame blame]

Light takes time to travel. Is this limit tied to entropy? Heat?

One instance of thermodynamics, in which the speed of light comes into play is the concept of a photon gas.

In physics, a photon gas is a gas-like collection of photons, which has many of the same properties of a conventional gas like hydrogen or neon - including pressure, temperature, and entropy. The most common example of a photon gas in equilibrium is black body radiation.

A massive ideal gas with only one type of particle is uniquely described by three state functions such as the temperature, volume, and the number of particles. However, for a black body, the energy distribution is established by the interaction of the photons with matter, usually the walls of the container. In this interaction, the number of photons is not conserved. As a result, the chemical potential of the black body photon gas is zero. The number of state functions needed to describe a black body state is thus reduced from three to two (e.g. temperature and volume).

In a gas with massive particles, the energy of the particles is distributed according to a Maxwell-Boltzmann distribution. This distribution is established as the particles collide with each other, exchanging energy (and momentum) in the process. In a photon gas, there will also be an equilibrium distribution, but photons do not collide with each other (except under very extreme conditions) so that the equilibrium distribution must be established by other means. The most common way that an equilibrium distribution is established is by the interaction of the photons with matter. If the photons are absorbed and emitted by the walls of the system containing the photon gas, and the walls are at a particular temperature, then the equilibrium distribution for the photons will be a black body distribution at that temperature.

A very important difference between a gas of massive particles and a photon gas with a black body distribution is that the number of photons in the system is not conserved. A photon may collide with an electron in the wall, exciting it to a higher energy state, removing a photon from the photon gas. This electron may drop back to its lower level in a series of steps, each one of which releases an individual photon back into the photon gas. Although the sum of the energies of the emitted photons are the same as the absorbed photon, the number of emitted photons will vary. It can be shown that, as a result of this lack of constraint on the number of photons in the system, the chemical potential of the photons must be zero for black body radiation.

[Arising_uk]

Hi ibb,
Thanks for the time.
I get the idea that Energy can be described as the product of Heat and Work. Work being some harnessed measure of difference in Heat. I also think I get the idea of Entropy as being the possible Work lost due to the action of the harness in producing Work, i.e. Heat is lost to the harness that is not converted to Work. What I still don't get is that two fluids, with different Heats in an perfectly insulated container would according to you attain maximum Entropy? Is this Entropy zero? As all the possible Heat available for Work would still be within the container. What am I missing?
a_uk

[i blame blame]

Hi ibb,
Thanks for the time.
I get the idea that Energy can be described as the product of Heat and Work.

For the internal energy of a system in term of thermodynamics, yes. the mathematically correct expression would be "sum of heat and work" though, because "product of x and y" means "x times y".

Work being some harnessed measure of difference in Heat.

Not necessarily difference in heat, but difference in pressure (which can be caused by a difference in heat). If you have a large container with particle density rho, pressure P and a much smaller container with the same density and pressure, it will have a lot less heat energy stored, even though it has the same pressure and no work will be done. However, if the small container has higher pressure, it can do work on the larger container (let's assume they're separated by a tunnel in which there is a movable wall). So you could say that it's energy density that matters.

I also think I get the idea of Entropy as being the possible Work lost due to the action of the harness in producing Work, i.e. Heat is lost to the harness that is not converted to Work.

Yes, but entropy can also increase (work can be lost) if there's no work-harness, and only heat flowing from colder to warmer system.

What I still don't get is that two fluids, with different Heats in an perfectly insulated container would according to you attain maximum Entropy?

If you somehow prepare the container such that one fluid is on the right side and one on the left, and a definite interface between them then the one with more pressure (if volume and temperature are equal, then it also has more heat) could be used to push into the other part of the container if a harness is introduced between them. If however there is no harness then the two would just, the energy will distribute across the container after a while and no more work can be done if a harness is introduced. However, if the chemical composition causes the fluids not to mix (water and oil for example), then entropy would increase at a slower rate because heat could only be conducted through the interface, and radiated. There would be no convection as would be the case if the two substances were prone to mix.

Is this Entropy zero?

You could define maximum entropy as zero and then work with negative entropies. It's kinda arbitrary. Thermodynamics is mainly concerned with differences in entropies, so where you set the zero-value is a matter of convenience.

As all the possible Heat available for Work would still be within the container. What am I missing?
a_uk

Ah, the container itself could still do work on its surroundings, but no more work could be done within the container.

[Cerveny]

The (accidental) quantum process - the process of a point "now" we can understand as a phase border between the growing (ordered, causal) history and less ordered, oddly causal the future. There is some probability how a history, its new time sediment, new “crystal” layer of the history will look like, but there it is not any certainty concerning this shape...