Irreversibility Definition and 21 Threads

Hi, as in a previous thread I would like to better understand the Feynman's analysis of brownian ratchet as described here: https://www.feynmanlectures.caltech.edu/I_46.html https://en.wikipedia.org/wiki/Brownian_ratchet Consider the case in which the two boxes (i.e. heat baths) are at the same...

"Reversibility means that we never lose information, that at a fundamental level we can always retrodict the past as well as predict the future in the laws of physics". Susskind in his Theoretical minimum Lecture 2 describes about the laws which are true and which are not. He tells the law of...

I was reading mehran kardar (books and lectures) it says the concept of irreversibility comes from an assumption (in which we increase the length scale by interaction disctance between two particles). So My question is the concept of irreversibility is still valid in the case of 1 particle...

Hi, I was revisiting my (high school level) understanding of thermodynamic cycles and I think I still have some doubts. Last year and more recently I posted a few questions which surely helped me, but I think I need more clarifications. In a nutshell, what I'd like to know is the following...

Homework Statement The change in entropy is zero for: A. reversible adiabatic processes B. reversible isothermal processes C. reversible processes during which no work is done D. reversible isobaric processes E. all adiabatic processes Homework Equations ## dS = \frac{dQ}{T} ## The Attempt...

Dear community, I stumbled upon this ecology article (https://www.witpress.com/elibrary/dne/4/2/402, page 4) and have some confusion about a statement in there: "Before further unpacking the formal defnition of entropy, one would be justifed in asking why not simply choose (1 – p) instead of...

Decoherence is when the system is entangled with the environment irreversibile... But when it is reversible.. is it still called Decoherence? However, the universe is said to be a closed system. Does the irreversibility in decoherence means it is just our ignorance that we can't track it. For...

For properly normalized extensive macroscopic properties (and this includes the center of mass operator), there is such a proof in many treatises of statistical mechanics. It is the quantum analogue of the system size expansion for classical stochastic processes. For example, see Theorem 9.3.3...

Consider a piston-cylinder arrangement with an ideal gas inside the cylinder. The region outside this arrangement or thermodynamic system is absolute vacuum. The piston has some mass and initially everything is in equilibrium. The inner surface of the cylinder is rough hence friction force comes...

I am trying to grasp the concepts of reversible work, irreversible work and irreversibility.(Last one is the difference between them if i am not mistaken.) Let us consider a rigid and evacuated container at volume V. Then, a valve opens and athmospheric air (P0, T0 is filling the tank. The wall...

I have a conceptual question that I am trying to clear up. A reversible process means that the net change in entropy is zero. If we have two scenarios, where case 1 has a ΔS= 0.1 J/K and case 2 has a ΔS= 0.5 J/K. Is it a correct statement to say that case 1 is "less irreversible (i.e...

I'd like some help to understand how to calculate "lost work" for irreversible heat transfer across a finite temperature difference. I'd also be grateful for any links to the derivation of a clear, general expression for lost work (in terms of entropy). Thanks

Hi,all My problem is following this picture! http://mykomica.org/boards/shieiuping/physics/src/1325318780058.jpg If the system is isolated, dQ is always zero. Sb-Sa ≥0 And it satisfies the requirement of spontaneousness in isolated systems. So ,I do wonder if irreversible process is always...

Homework Statement A mass m with heat capacity c at temperature T_1 is dropped into the sea at T_2. What is the irreversibility of the process? Homework Equations I = T_0 (\Delta S + \Delta S_E ) I = W_{\text{rev}} - W The Attempt at a Solution Heat in is Q=mc\Delta...

I've been writing a lot recently about whether the reason for the increase of entropy over time (i.e. the second law of thermodynamics) is the time irreversibility of the weak nuclear force. I would like to get some people's thoughts on this topic (perhaps links to important papers on this...

Hello, I would be grateful is someone could explain what the irreversibly temperature in type II superconductors is. I have just done some NMR experiments on MgB2 and get a lineshape change at the the irreversibility temperature as opposed to the field corrected Tc, so I believe it has...

Hello, Here is the Boltzmann collision term as it is expressed on http://en.wikipedia.org/wiki/Boltzmann_equation" : Deriving the H theorem from this equation is the way to usually prove of the irreversibility of this term. Of course, this collision term should not be symmetric by...

Reflection is not considered to be a measurement. Reflection, like using lenses is considered to be a time-reversible process. It is not a measurement and it does not erase the coherence (interference pattern) Here is what I don't understand What happens to the momentum of the photon? The...

A stupid couple of questions... In quantum computations, one typically starts with some initial quantum state on which an operator is applied. This operator must be unitary , right? (I guess that otherwise, it would not corerspond to an actual physical quantum setup). And this implies...

The thermodynamic explanation of irreversibility - does it include the microscopic view of a process, i.e. the expansion of a ideal gas (the random movement of the molecules) or the melting of an ice cube? Or is it only defined within the macroscopic world?

I'm a bit confused with this topic we're supposed to be writing a paper on: "Thermodynamical Irreversibility VS Mechanical Reversibility (Microscopic Nature of the 2nd Law of Thermodynamics)" I think I know the concept of the irreversible nature of thermodynamics...such as the flow of...