Re: 2nd law of thermodynamics

On Jul 16, 11:59 am, "Ross Langerak" <rlange...@xxxxxxxxxxxxx> wrote:

"Disorder" is not a scientifically defined term, at least not in
thermodynamics.

Yes it is. Its the sum of combinations of possible states. Or degrees
of freedom.

Imagine a large square box called (Box A).

Firstly we put a smaller box, called (Box B) into (Box A).

(Box B) is 1/3 the length of any of the sides of (Box A).

(Box B) has 27 possible states in (Boc A).

Now take (Box B) out of (Box A)

We wil now put a larger box, (Box C) into (Box A).

(Box C) is 1/2 the length of any of the sides of (Box A)

(Box B) Had 27 possible states. Yet
(Box C) Only has 8 Possible states.

Therefore (Box C) has less freedom, and is thus more organised, due to
its larger volume! ;-) Kapische??

Being more ordered it has LESS entropy!






Take your most basic system of entropy.
2 atoms. (a & b)
Atom (a) is in energy level 1, and Atom (b) is in energy level 2.
Atom (a) in more highly ordered. (smaller volume)
Again, you are using an undefined, and therefore meaningless, term.
Atom (b) now transferres a photon to Atom (a).
According to thermodynamics, because of the transfer of thermal
energy, the entropy of this system *MUST* increase. But it CANT!


Classical thermodynamics deals with the transfer of heat in macroscopic
systems, not microscopic systems consisting of one or a few atoms. For your
system, you need to use statistical thermodynamics.

So;


I assume you mean that the transfer of a photon from atom (b) to atom (a)
results in a change in the energy levels of the electrons in the atoms,
rather than the energy levels of the atoms.

Actually its both (but anyhows) Well concentrate on the electron.
After the photon is emitted, it has a shorter wavelength due to the
loss of EPE.
EPE is twice the KE of the now faster orbital speed, the photon is the
diff between the 2.

Anyhows!

Our Atom was in a more highly organised state, due to its Larger
volume (as proved by the boxes) before emission.

After emission, it is less organised, yet the other atom absorbes the
photon, and becomes more ordered.


In other words, the entropy of the system hasnt changed!


Assuming both atoms are of the
same element,

Derrr!!!!


according to statistical thermodynamics, the entropy remains
the same.

Good, you agree with what ive been saying all along!



Atom (a) receives the photon from (b). (Transfer of thermal energy
therefore increased entropy), but at the COST of rearranged
organisation between the two atoms.

Again, "organisation" is not a scientifically defined term.

Ive just defined it for you!

According to statistical thermodynamics, there is no change in entropy.

Objection, your honour, ther witness is repetetive!



Atom (a) is now in energy level 2, and is thus more *DISORGANISED* as
you would expect!

Again, "disorganised" is not a scientifically defined term. What equation
are you using to calculate "disorganisation"?

The equations for the box's! For a fusion event (say 2 hydrogen
atoms) we use degrees of freedom. Same diff!


HOWEVER & MORE IMPORTANTLY!!!!!

Atom (b) is now in energy level 1, and has become more organised. Due
to its (NOW) smaller volume.

Volume is only relevant to the macroscopic, classical thermodynamics.

No, It isnt!

And for particles with no volume you use their wavelength to show its
amount of freedom, in its 4 vectors!



On a whole. Entropy, like energy, momentum, mass is conserved! :)
Enjoy!

No, entropy is not conserved. Entropy, like temperature, is not a thing
that can be moved from place to place.


Temperature can be moved from place to place!

If I want to increase the
temperature of a room by two degrees, I can't just go outside and grab two
degrees and bring them inside. Instead, I have to add sufficient energy to
the room to raise the temperature by two degrees. The change in temperature
is the result of the movement of energy.

And the movement of energy, is the result of the
"rearrangement" (movement) of matter. This rearrangement in order
compensates for the transfer of thermal energy.

And the entropy stays constant!


Likewise, if I want to decrease the entropy of a system by two joules per
degree Kelvin, I can't steal two joules per degree Kelvin from another
system and add them to the first. Entropy is a state function. Whatever
state a system may be in, it has a particular entropy. If I want to change
the entropy of the system, I must change the state of the system by
rearranging the energy of the system. As with temperature, the change in
entropy is the result of the rearrangement of energy in the system.

You cant rearrange the temperature, (without) rearranging the matter!


.

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