• piareround
In summary, the conversation is centered around the relationship between the entropy of a system and the properties of sound and light waves. The speaker is wondering if there is a quantitative or formulaic relationship between the measured properties of these waves and the change in entropy of a system. They mention an article they read about the heating effects of sound waves and the existence of Kirchoff's Law, which relates sound to heat transfer. This prompts the question of whether there is a similar relationship between sound and entropy. They also mention Planck's Law for black body radiation and wonder if there is a way to derive a relationship between the intensity of light and the entropy of a black body.

#### piareround

First I apologize if this has been asked before; however, did a google search of the archives and could not find anything talking directly about my question about entropy of light and the entropy of sound. Also, it been bothering me for quite some time:

1. Is there a quantitative or formulaic relationship between the measured properites of sound wave and the change in entropy of a system? If so can you give a common example?
2. Is there a quantitative or formulaic relationship between the measured properties of a light wave and the change in entropy of a system? If so can you give a common example?

Entropy of what system?

dx said:
Entropy of what system?

First thanks for the fast response, ^_^. I honestly thought it was going to take longer XD. Unfortunately, I personally don't know what system either, although I would assume that it would be somewhat isolated. Maybe a better way would be to talk about what really sparked this train of thought...

About ... 3 maybe 3.5 years ago I found a certain article written in 2000 by Seth Putterman and K. R. Weninger called "http://arjournals.annualreviews.org/doi/abs/10.1146/annurev.fluid.32.1.445" [Broken]" I found the very article interesting (so interesting I decide to go as a major in physics); however, to get to the point, one of the things that struck me odd about this article was the following quote on page 447:

"The local heating, which is 15 orders of
magnitude greater than follows from Kirchoff’s law for the attenuation of sound,
is strong enough to lyse cells. In fact this device is regularly used for the surgical
procedure called ultrasonically assisted liposuction (Weninger et al 1999a). In
that case a small hole up the center of the probe is used to remove the emulsified
fatty tissue." pg. 447

What I found odd was not the magnitude of heat at all, rather the simple fact that a formula called "Kirchoff's Law" (see footnote 1) existed that related sound to heating and vis versa for a certain set of conditions. (I don't know this law so I am not really sure what those conditions are ><; ) This made be wonder... if we can draw a relationship between the properties of sound wave and heat transfer in a system then is it possible to go deeper ... and draw a relationship between sound and entropy of that same system? Is there an academic example in physics relating the sound emitted on and entropy of a system? I am really not sure so that why I asked the questions I did.

Then Beyond that I remember that http://en.wikipedia.org/wiki/Planck%27s_law" [Broken] for black body radiation related the temperature of a black body to the intensity of light. In the same manner, I wonder if its possible can one derive a relationship between the intensity of light and the entropy of the black body? Unfortunately I wasn't sure what would be a valid method of showing such a relationship.

footnote 1: When I searched for the term "Kirchoff's law for the attenuation of sound", found it was Helmholtz-Kirchhof formula for the attenuation of sound not just Kirchhoff

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## 1. What is entropy?

Entropy is a measure of the disorder or randomness in a system. In scientific terms, it is the amount of energy in a system that is unavailable for work.

## 2. How is entropy related to the second law of thermodynamics?

The second law of thermodynamics states that the total entropy of a closed system will always increase over time. This means that as the system becomes more disordered, its entropy will increase.

## 3. Can entropy be reversed?

No, entropy cannot be reversed. The second law of thermodynamics dictates that entropy will always increase over time, and it is impossible to completely reverse this process.

## 4. How does entropy affect chemical reactions?

Chemical reactions tend to increase the entropy of a system, as they involve the movement of particles and the formation of new substances. This increase in entropy is a driving force for many reactions.

## 5. What are some real-life examples of entropy?

Some common examples of entropy include the melting of ice cubes, the burning of a piece of wood, and the rusting of metal. These processes all involve an increase in disorder and a release of energy.