A important property of all systems in thermodynamics and statistical mechanics. Entropy characterizes the degree to which the energy of the system is *not* available to do useful work
2
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1answer
113 views
free energy and entropy of 2D soap froth
This is a (exploratory) computational project. The soap froth was created by injecting bubbles into a chamber formed by two rectangular plates which are 0.16cm. From the moment the soap froth was ...
5
votes
3answers
558 views
Entropy and the principle of least action
Is there any link between the law of maximum entropy and the principle of least action. Is it possible to derive one from the other ?
1
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1answer
45 views
How does quantum entropy scales with the size of the sample?
Suppose i have a 3D bulk of physical matter with no black holes enclosed in a sphere of radius $R$. What is the scaling law of all quantum entropy in function of $R$?
If the scaling is not $R^2$, in ...
3
votes
2answers
446 views
Can entropy be equal to zero?
I've searched for it but I only found contradicting answers from "scientists":
Mr. David Balson, Ph.D. states: "entropy in a system can never be equal to zero".
Mr. Sam Bowen does not refutes the ...
0
votes
0answers
93 views
Is it possible to add heat to a monoatomic ideal gas without increasing entropy? [closed]
The Sackur-Tetrode equation expresses the entropy of a monoatomic ideal gas:
[Equation from HyperPhysics]
11
votes
5answers
680 views
Why does the nature always prefer low energy and maximum entropy?
Why does the nature always prefer low energy and maximum entropy?
I've just learned electrostatics and I still have no idea why like charges repel each other.
...
4
votes
1answer
85 views
name of experiment
I'm seeking the name of or reference for an experiment I once saw in a college physics class. At the beginning of one class the instructor repeatedly wound a wiper that spread a blot of some type of ...
0
votes
1answer
217 views
How much energy Maxwell's demon will earn?
Suppose we have one mole of one-atom ideal gas at temperature $T$.
Suppose Maxwell's daemon has separated molecules into two sections, one with speed below mean and another with speed above mean.
...
2
votes
4answers
353 views
How does the introduction of living things into a closed system affect the rate of change of entropy?
Does the introduction of living things into a closed system increase or decrease the overall rate of change of entropy of a system?
3
votes
2answers
241 views
How would we perceive time going backwards?
I haven't taken Physics in University. Lately, I've been reading about some of the branches of physics through Wikipedia. I read several times that many of the theoretical models do not explain why ...
2
votes
1answer
282 views
Physics-based derivation of the formula for entropy [duplicate]
Possible Duplicate:
Proof of $S=-\sum p\ln p$?
I am looking for a derivation of the formula
$$S~=~-\Sigma_ip_i \log (p_i).$$
for entropy, from first principles. I only wish to assume the ...
3
votes
2answers
279 views
Can entropy be explained in terms of a cleaning/keeping your room clean?
I'm trying to relate the concept of entropy to keeping my room clean as suggested by my high school teacher ~1993...
Comparing the two scenarios:
Every day I come home and throw an empty can on the ...
1
vote
2answers
145 views
Activation energy and entropy
First assertion
If a system is already in a high temperature, adding energy, will increment the entropy in a low amount (compared with a system in a lower temperature).
Question (if assertion is ...
0
votes
1answer
337 views
Does the Higgs Mechanism contradict Entropic Gravity?
Does the Higgs Mechanism contradict Entropic Gravity?
It seems like it probably does. But then again, one is a microscopic theory and the other is macroscopic. Can they live together in harmony? or ...
2
votes
2answers
328 views
The definition of entropy in quantum mechanics
I have seen entropy with several different definitions. Like Von Neumann entropy and Rényi entropy, etc.
So I am curious why there are so many different definitions in quantum mechanics while only ...
1
vote
0answers
116 views
An explanation for the Landauer's principle
Has anyone understood the Landauer's principle? What is the current status?
In specific, is there a theoretical derivation of the Landauer's Principle?(not the heuristic one based on Salizard's ...
3
votes
1answer
186 views
Do laws of thermodynamics have a place in Theory of Everything? [closed]
I am having a difficulty understanding why second law of thermodynamics is still a valid universally accepted concept. I understand it works on paper for describing isolated heat systems. However, I ...
2
votes
1answer
116 views
Minimal Maxwell's Demon
I would like to understand where the waste heat is generated in the Maxwell's demon problem. To this end I've come up with the simplest scenario I can think of. If my scenario is workable I am hoping ...
2
votes
3answers
420 views
Does high entropy means low symmetry?
According to Bogolubov postulate (various texts name it differently) in Non-equilibrium thermodynamics, the number of needed parameters to describe our system is decreasing with time, and finally at ...
3
votes
3answers
308 views
Formal demonstration that minimizing the free energy equals maximizing the entropy
I never had great intuition when it came to thermodynamic concepts and potentials even though reading a textbook and completing the exercises has never been a huge problem.
In one of them, I was ...
2
votes
1answer
296 views
Why does the law of increasing entropy, a law arising from statistics of many particles, underpin modern physics?
As far as I interpret it, the law of ever increasing entropy states that "a system will always move towards the most disordered state, never in the other direction".
Now, I understand why it would ...
2
votes
2answers
122 views
Speed of Entropy change
If time in systems moving with different speed goes differently, does speed of entropy change differ in these systems?
(is "speed of entropy change" a valid term? can we compare them?)
3
votes
4answers
241 views
Does entropy decrease through measurement?
For an electron in its rest frame, we have an entropy
$$
S = \log 2,
$$
which comes from the 2 possible spin directions along z-axis.
If the measurement $S_z$ changes its state to $\left| + ...
0
votes
2answers
103 views
Qualitative discussion about entropy and disorder
Many discussions about entropy and disorder use examples of decks of cards, pages of books thrown in the air, two gases being mixed in a container, even the state of a nursery at the end of the day ...
1
vote
2answers
232 views
Entanglement Entropy
I needed some references which involves, the basic definition and motivation for Entanglement Entropy, and its one or two applications to many-body physics/black holes.
5
votes
2answers
957 views
Why do reversible processes not increase the entropy of the universe infinitesimally?
The book Commonly Asked Questions in Thermodynamics states:
When we refer to the passage of the system through a sequence of internal equilibrium states without the establishment of equilibrium ...
5
votes
2answers
161 views
Information Loss in annihilation
The concept of information loss is usually discussed with respect to a black hole. My understanding is that whatever matter you put into the black hole, it has only 3 "hairs" and so one doesn't know, ...
2
votes
1answer
143 views
Black hole entropy
Bekenstein and Hawking derived the expression for black hole entropy as,
$$
S_{BH}={c^3 A\over 4 G \hbar}.
$$
We know from the hindsight that entropy has statistical interpretation. It is a measure ...
2
votes
1answer
85 views
Zero entropy change
If you put a object in contact with a heat reservoir that is infinitesimally higher in temperature than the object and allow equilibrium to be reached the entropy change is zero right?
2
votes
2answers
552 views
Was the Universe's entropy equal to zero at the Big Bang? Is zero-entropy state unique?
It is postulated by many cosmologists that at the Big Bang time the universe was in an unusual low entropy state.
Does this claim specifically mean that the entropy of the initial universe was zero?
...
0
votes
2answers
171 views
Simplifying the explanation of a low-entropy Big Bang
The claim that the young universe was in a low-entropy state seems at odds with
maximal entropy being thermal equilibrium, and
the young universe being in thermal equilibrium.
I've looked at some ...
0
votes
0answers
37 views
Relation between maximum entropy thermodynamics and entropy bounds
Here is a question which I've been thinking about, I'm sorry if it's little too vague, maybe you could point me to some source to read, if there's no clear direct answer.
The whole concept of ...
1
vote
2answers
155 views
Fluid Dynamics - Water Bottle Drink Mix: Air or No Air?
If you take an ordinary sized plastic water bottle full of water and pour a packet of powdered (or liquid) drink mix into it, Will shaking the bottle with the cap screwed on to dissolve the mix into ...
3
votes
2answers
192 views
Entropy: two explanations for the same quantity?
I studied thermodynamics and I saw the following definition for entropy:
$$
\Delta S = \int_1^2 \frac{\text{d}Q}{T}
$$
that we use to calculate $\Delta S$ for different types of transformations.
In ...
15
votes
7answers
610 views
How is $\frac{dQ}{T}$ measure of randomness of system?
I am studying entropy and its hard for me to catch up what exactly is entropy.
Many articles and books write that entropy is the measure of randomness or disorder of the system. They say when a gas ...
2
votes
0answers
130 views
Entropy of a de Sitter horizon
The cosmological event horizon found in a de Sitter universe has some interesting similarities to that of a black hole. For example, since we can find a temperature at the horizon, we are able to use ...
6
votes
4answers
353 views
Second Law of Thermodynamics and the Arrow of Time: Why isn't time considered fundamental?
I've come across this explanation that the "arrow of time" is a consequence of the second law of thermodynamics, which says that the entropy of an isolated system is always increasing. The argument is ...
1
vote
1answer
86 views
Where is the critical moment where the microcanonical ensemble enters the justification for the equilibium state?
As explained in many books, for the microscopic justification of the second law of thermodynamics (lets formulate it as the total entropy takes maximum among all possible exchanges of two systems), ...
3
votes
0answers
63 views
Kolgomorov entropy issues
I am long been confused by these entropy terms. Would be obliged if an explanation is provided in less technical jargon
What are the differences between Shannon's entropy, topological entropy and ...
1
vote
2answers
159 views
Question about entropy and “smart materials” (that remember shape)
We all know that entropy is the measure of chaos in the system, and it's always increasing in the system.
Now comes my question - how does entropy work in smart materials? Here is a youtube video ...
2
votes
1answer
101 views
Reference request for low entropy big bang
There is a somewhat widely accepted argument that the second law of thermodynamics exists because the universe began in a low-entropy state. I'm writing a paper that mentions this (and must be ...
3
votes
5answers
1k views
Will adding heat to a material increase or decrease entropy?
Does adding heat to a material, thereby increasing electrical resistance in the material increase or decrease entropy?
Follow up questions:
Is there a situation were Heat flux ie. thermal flux, ...
1
vote
1answer
100 views
Can entanglement be used to decrease entropy of two systems?
I know that entanglement can create correlation between systems. Would it be true to say that entanglement create constraints between systems? Can constraints be used to lower the total entropy of ...
4
votes
1answer
724 views
What is the relationship between Energy, Entropy, and Information?
What is the relationship between Energy, Entropy, and Information?
I read this - What Is Energy? Where did it come from? - and the top answer says that 'energy' is an abstract number that is a ...
-2
votes
1answer
237 views
Loschmidt's paradox - really a paradox? [duplicate]
Is Loschmidt's paradox a paradox even today?
In other words, is the paradox resolved or not?
3
votes
3answers
807 views
Does radiation change entropy?
Are there entropy changes associated with the transmission of energy from the sun to the earth? Does radiation differ from other modes of heat transfer with respect to the entropy changes?
Are the ...
3
votes
1answer
223 views
Wasn't the Hawking Paradox solved by Einstein?
I just watched a BBC Horizon episode where they talked about the Hawking Paradox. They mentioned a controversy about information being lost but I couldn't get my head around this.
Black hole ...
3
votes
2answers
543 views
About Susskind's claim “information is indestructible”
I really can't understand what Leonard Susskind means when he says that information is indestructible.
Is that information really recoverable?
He himself said that entropy is hidden information. ...
1
vote
0answers
44 views
What other factors effect the ability of a propigating field of pressure in a gaseous medium to predict gravitational collapse?
What other factors effect the ability of a propigating field of pressure in a gaseous medium to predict gravitational collapse?
Will the only factor influencing the Speed of Sound in this medium be ...
7
votes
1answer
203 views
Area law for Entropy in Loop Quantum Gravity
In connection with the long saga of the (claimed) microscopic
calculations of the Hawking-Bekenstein entropy in (3+1) Loop Quantum Gravity (LQG) and related approaches I have the following question: ...
