Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Thermodynamic Processes

Thermodynamic Processes

A thermodynamic process is a path through a sequence of states that takes a system from an initial state to a final state. In a cyclic process, the system returns to its initial state, so the changes in state properties and state functions (ΔT, Δp, ΔV, ΔU, ΔH) over one complete cycle are zero. However, heat and work transfers can still occur during the cycle, and the net heat and net work over the cycle need not be zero.A reversible process occurs when the system is infinitesimally close to...

The Entropy as a State Function

The Entropy as a State Function

Consider an arbitrary process that moves between two specific states (A and B) in a cyclic manner. This process is reversible and broken down into smaller parts that each follow a Carnot cycle. A Carnot cycle has two isothermal (constant temperature) processes. During these processes, the ratio of the amount of heat transferred to their respective temperature remains constant. The other two processes in the Carnot cycle are also reversible but adiabatic, which means they occur without any heat...

Reversible and Irreversible Processes

Reversible and Irreversible Processes

The thermodynamic processes can be classified into reversible and irreversible processes. The processes that can be restored to their initial state are called reversible processes. It is only possible if the process is in quasi-static equilibrium, i.e., it takes place in infinitesimally small steps, and the system remains at equilibrium However, these are ideal processes and do not occur naturally. An ideal system undergoing a reversible process is always in thermodynamic equilibrium within...

Entropy

Entropy

Salt particles that have dissolved in water never spontaneously come back together in solution to reform solid particles. Moreover, a gas that has expanded in a vacuum remains dispersed and never spontaneously reassembles. The unidirectional nature of these phenomena is the result of a thermodynamic state function called entropy (S). Entropy is the measure of the extent to which the energy is dispersed throughout a system, or in other words, it is proportional to the degree of disorder of a...

Entropy

Entropy

The first law of thermodynamics is quantitatively formulated via an equation relating the internal energy of a system, the heat exchanged by it, and the work done on it. A quantitative formulation of the second law of thermodynamics leads to defining a state function, the entropy.
When an ideal gas expands isothermally, the disorder in the gas increases. From the molecular perspective, the gas molecules have more volume to move around in.
Consider an infinitesimal step in the expansion, which...

Second Law of Thermodynamics

Second Law of Thermodynamics

In the quest to identify a property that may reliably predict the spontaneity of a process, a promising candidate has been identified: entropy. Processes that involve an increase in entropy of the system (ΔS > 0) are very often spontaneous; however, examples to the contrary are plentiful. By expanding consideration of entropy changes to include the surroundings, a significant conclusion regarding the relation between this property and spontaneity may be reached. In thermodynamic models, the...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Compensating Random Transition-Detection Blackouts in Markov Networks.

Physical review letters·2026

Same author

Pedestrian's approach to large deviations in semi-Markov processes with an application to entropy production.

Physical review. E·2026

Same author

General theory for localizing the where and when of entropy production meets single-molecule experiments.

Proceedings of the National Academy of Sciences of the United States of America·2024

Same author

Estimator of entropy production for partially accessible Markov networks based on the observation of blurred transitions.

Physical review. E·2024

Same author

Nonequilibrium fluctuations of chemical reaction networks at criticality: The Schlögl model as paradigmatic case.

The Journal of chemical physics·2024

Same author

Time-Resolved Statistics of Snippets as General Framework for Model-Free Entropy Estimators.

Physical review letters·2023

Search research articles

Related Experiment Video

Updated: Jul 16, 2026

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids

Published on: December 4, 2017

Optimal finite-time processes in stochastic thermodynamics.

Tim Schmiedl¹, Udo Seifert

¹II. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart, Germany.

Physical Review Letters

|March 16, 2007

Summary

Researchers found the optimal control protocol to minimize work in small systems. This protocol, crucial for processes like moving colloidal particles, often involves sudden changes at the start and end.

Area of Science:

Statistical mechanics
Soft matter physics
Biophysics

Background:

Small systems (colloidal particles, biomolecules) interact with heat baths.
Controlling these systems requires external parameters.
Minimizing work is key for efficient state transitions.

Purpose of the Study:

Determine the optimal external control protocol.
Minimize mean work for finite-time state transitions.
Analyze protocols for specific systems like laser traps.

Main Methods:

Formulated the problem using statistical mechanics principles.
Derived an integro-differential equation for the optimal protocol.
Solved the equation for moving and time-dependent laser traps.

More Related Videos

Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection

Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection

Published on: February 18, 2014

Related Experiment Videos

Last Updated: Jul 16, 2026

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids

An Analog Macroscopic Technique for Studying Molecular Hydrodynamic Processes in Dense Gases and Liquids

Published on: December 4, 2017

Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection

Submillisecond Conformational Changes in Proteins Resolved by Photothermal Beam Deflection

Published on: February 18, 2014

Main Results:

The optimal protocol generally satisfies an integro-differential equation.
Explicit solutions reveal finite jumps in the protocol.
These jumps occur typically at the beginning and end of the process.

Conclusions:

Optimal control protocols for small systems are essential for efficient manipulation.
Sudden changes in control parameters are characteristic of optimal protocols.
Findings apply to systems like colloidal particles and biomolecules in heat baths.