Talk:Second law of thermodynamics

CONFUSED AND MISLEADING

This is NOT a simple English explanation of the essential facts about the Second Law.. missing

The definition of of the term ENTROPY: "A quantitative measure of disorder" Cambridge Encyclopedia.

The meaning of disorder: A thermodynamically disordered state is the most probable state for the system which results in the even distribution of energy (temperature and pressure), electrical charge and chemical composition or mixing. A completely disordered state after which nothing more is able to happen is called equilibrium.

Even though the discovery of this law was in connection with thermodynamic processes of heat engines the driver of the Second Law itself is Probability NOT heat energy or any other form of energy. viz Boltzmann Equation s = k.log w has no energy term in it. W is just a number. The dissipation of energy is a RESULT of the decay of the state of the system driven by the probability that state can exist out of all the possible states it could be in.

Gravity mentioned in this context is completely out of place, out of context and irrelevant to the operation of the Second Law which in its simplest form says:

                Any state of matter will of itself tend to move to its most probable state

Vh mby (talk) 13:01, 17 May 2014 (UTC)

Entropy as a measure of spread

I have posted the intuitive idea of entropy as a measure of spread. This is better than the idea of 'disorder', which is widely quoted, but now recognized as not the best way to think about entropy.Chjoaygame (talk) 16:24, 6 March 2016 (UTC)

IP sockpuppet of banned user

I have corrected some serious errors that were introduced by an IP sockpuppet of a banned user, IP 110.147.139.222. That user persistently pushes those errors.Chjoaygame (talk) 16:19, 6 March 2016 (UTC)

The real Second Law is about entropy maximization, not heat transfer.

Entropy is a measure of progress towards the state of thermodynamic equilibrium. It is NOT a measure of disorder, whatever that means anyway. That state of maximum entropy occurs when all unbalanced energy potentials have dissipated. Those energy potentials need not only involve molecular kinetic energy, that is, temperature. They include gravitational potential energy of molecules as well. The Clausius statement is now understood by us physicists to be merely a corollary of the Second Law which only applies when only kinetic energy affects entropy - hence only in a horizontal plane in a gravitational field. When the world starts to understand entropy correctly, it will be realized that there can be an increase in entropy associated with DOWNWARD heat transfer in a planet's troposphere, and this also happens in other force fields, notably in a vortex tube along any radius as there is heat from the cooling central regions to the outer warming regions. There is no other valid explanation for planetary core and surface temperatures. It happens when a prior state of thermodynamic equilibrium (which DOES have a non-zero temperature gradient vertically in a planet's troposphere) is disturbed with the absorption of new thermal energy at the higher altitudes - as happens mostly in the morning. That's how the surface warms each morning even under thick cloud cover. The colder clouds do NOT raise the surface temperature with their radiation. The surface temperature cannot be explained with solar radiation, or any other radiation.

Why there MUST be a non-zero temperature gradient in a force field like gravity

The state of maximum entropy (which the Second Law says will be approached) is called "thermodynamic equilibrium" by physicists. In that state entropy is homogeneous and there are thus no unbalanced energy potentials. In other words, nothing can happen spontaneously as no net energy tends to move across any internal plane. But molecular gravitational potential energy is just as relevant as molecular kinetic energy, the mean of which is related to temperature. If you consider a horizontal plane in the troposphere, at thermodynamic equilibrium the pressure from above the plane equals that from below the plane. But, by the Ideal Gas Law, pressure is proportional to the product of temperature and density. At thermodynamic equilibrium there is also no net transfer of mass across any internal plane. It follows that there must be equal numbers of molecules passing upwards across that horizontal plane as there are crossing downwards. Hence, since the pressure is equal, the mean kinetic energy of the molecules passing upwards equals the mean kinetic energy of those passing downwards. Now, gravity increases the percentage chance that a molecule will move downwards after a collision, that probability thus becoming a little above 0.5. Hence there must have been a lower density of molecules above the plane than below it, and so we have a stable density gradient which results from the Second Law process of entropy maximization. Likewise, because gravity accelerates the motion of molecules between collisions, there must have been a lower mean molecular kinetic energy above the plane and a higher one below the plane. Hence the Second Law process of entropy maximization is what causes the stable temperature gradient in any planet's troposphere. Inter-molecular radiation between radiating molecules works against the gravitationally induced temperature gradient, reducing it by up to about a third of its theoretical magnitude, as we know happens in more moist regions. But the fundamental IPCC assumption that the surface temperature would have been the same as that found at the radiating altitude in the absence of radiating molecules is wrong.