eclectic`

Historically - - -

Planck: We have now to seek a physical quantity whose magnitude shall serve as a general measure of the preference of nature for a given state. ...... R. Clausius actually found this quantity and called it "entropy". ..... Conduction of heat to a body increases its entropy, and , in fact, by an amount equal to the ration of the quantity of heat given the body to its temperature. Simple compression, on the other hand, does not change it entropy. ......In the limiting case, a reversible isothermal cyclical process, the sign of the (heat) equality holds, and therefore the work consumed is zero, and also the heat produced. This law plays a leading role in the applications of thermodynamics to physical chemistry. ..... The second law of thermodynamics imposes further limitations to the first law, allowing only certain types of transformations subject to certain conditions. in accordance with this law,

the some of Q/T is equal to or greater than zero. Heat is produced and work is consumed. In the limiting case, the work consumed is zero, the produced is zero, and the equality holds." Q = heat.

Planck's equation for the general law of entropy is S - (U + pV)/T = phi = dU +pdV where phi is the phase of the system and is linear and homogenous in S, U and V. S in the entropy, and U is the energy.

Entropy is "... a measure of the preference of nature for a given energy state". Planck used this concept to define the energy states of chemical reactions, which was the foundation of the development of his radiation equation. It is not clear to me as to how you can apply the concept of entropy to an engine.

There are some conventions here.

 

Generally I would say that classical physics is any physics in which [math]\hbar[/math] plays no role. That is anything that is not quantum in nature. So here I would include special and general relativity as well as many other things.

 

Non-classical would be any physics in which [math]\hbar[/math] does play a role. This may be true quantum phenomena or things a little more subtle like semi-classical or quasi-classical.

 

Sometimes by classical people also include theories that do not obey "Einsteinian relativity"- so they exclude special and general relativity.

What is "classical physics"? That is a very good question, and I have yet to find a good answer.

As to the role of h or har, n my opinion, the work of Max Planck in developing his radiation equation was all based on classical physics. There was no other physics at that time as far as I know. Therefore, his radiation equation was developed using classical physics. His model of the atom was based on the atom as an "oscillator", and the concept of energy states was based on chemical reactions and thermodynamics. Your last sentence is probably the best definition, which relates to the Minkowski interpretation of "space/time". Certainly, the concept of time and space varying as a function of the velocity of an observer is not easily analyzed using classical physics.

Air is a poor conductor of electricity but how does an electric current pass through air during lightning?

 

Thanks,

 

Ron

Electrons flow through a perfect vacuum unimpeded. The difference with air is that it is filled with oxygen, nitrogen and other gases that impeded the flow of electrons. To make electrons flow through non-conducting substances, a sufficiently high voltage is required to draw an electron from an atom. Add up the number of atoms an multiply by the voltage of ionization for each atom, and you will have the overall ionizing voltage to create lightning. Once that occurs, you now have a conducting path for the lightning, and a very high current is generated during discharge.

E=mc^2

where

E=energy

M=mass

c= the speed of light

 

What value of c is used in a rotating frame?

http://www.fourmilab...tein/E_mc2/www/

Excellent question!

Einstein's theory of relativity was based on spherical radiation. I question that assumption, but for spherical radiation, there is a radius and and angle that affects what you see at various points along the frame. In addition, this variation is not constant but varies with distance.

Such a field exists indeed next to a vibrating dipole (along its axis) but this variable field does not propagate too far - it decays rapidly with the distance and is called a "near field". Anyway it's an axial (radial) electric field E = -grad(V).

The field of an electric dipole exists throughout all space. When you vibrate a dipole, a very strange effect occurs. You can prove this to yourself by considering the zero-field plane of the dipole, which must change shape with vibration.

Entropy：A concept that is not Physical Quantity

shufeng-zhang china

Email: email removed

 

We define heat engine efficiency η as: η= W/W1, that is, replacing Q1 in the original definition η=W/Q1 with W1, W still is the net work of the heat engine applied to the outside in one cycle, W1 is the work the heat engine applied to the outside in the cycle, then, we use Stirling cycle as the element reversible cycle , if ∮dQ/T =0 is tenable, we can prove ∮dW/T =0 and ∮dE/T =0.

If the formula ∮dQ/T=0, ∮dW/T=0 and ∮dE/T=0 can really define new system state variables, it comes to the absurd result of such a definition.

In fact, during the process of obtaining "entropy", ∑[(ΔQ)/T)] become∫dQ/T is untenable, therefore, the formula ∮dQ/T=0, ∮dW/T=0 and ∮dE/T=0 are untenable.

The"entropy"defined by Boltzmann is used to interpret "entropy" by Clausius, so, it is at the same time denied.

 

 

http://content.yudu....ysical-Quantity

Let me see if I understand what you are saying.

Considering that the sum of dQ/T = 0 for a given temperature, then there is no heat loss nor any work yielded. In this case

∑[(ΔQ)/T)] is also zero,

as is ∮dQ/T=0, ∮dW/T=0 and ∮dE/T=0.

This means that ∑(Q) = 0 for any isothermal cyclic process. No heat is produced and no work is consumed, so this is a reversible process, such as the charging of a capacitor or inductor. Why do you claim that this is "untenable"?

Ref: "Planck's Columbia Lectures", 2005 (ISBN 0-9659176-3-0)

I thought for any new members that we have, it might be nice to introduce yourself. feel free to do so here

I am a retired engineer/scientist who has practical experience in various fields of science. Graduate degrees, former professor, and worked for various companies large and small. Have spent the last 23 years in trying to solve some of the great mysteries of science and written five books on the subject. Would like to debate some of these important subjects with those who are interested and even those who think they know better and claim that it is "pseudoscience" (a word that most of them cannot define).