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Conservation of Energy

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The terms 'conserved quantity' and 'conservation law' have specific scientific meanings in physics, which differ from the meanings associated with their everyday use. For example, in everyday usage, water could be conserved by not using it, by using less of it, or by re-using it. However, in scientific terms, a conserved quantity of a system stays constant, changes by a definite amount that is transferred to other systems, and is converted into other forms of that...

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The Uncertainty Principle

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When solving problems using the energy conservation law, the object (system) to be studied should first be identified. Often, in applications of energy conservation, we study more than one body at the same time. Second, identify all forces acting on the object and determine whether each force doing work is conservative. If a non-conservative force (e.g., friction) is doing work, then mechanical energy is not conserved. The system must then be analyzed with non-conservative work. Third, for...

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Related Experiment Video

Updated: Nov 24, 2025

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Generation and Coherent Control of Pulsed Quantum Frequency Combs

Published on: June 8, 2018

On conservation laws in quantum mechanics.

Yakir Aharonov^1,2,3, Sandu Popescu⁴, Daniel Rohrlich⁵

¹School of Physics and Astronomy, Tel Aviv University, Tel Aviv 69978, Israel; yakir@post.tau.ac.il S.Popescu@bristol.ac.uk.

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

|December 29, 2020

Summary

This summary is machine-generated.

We question the standard definition of conservation laws in quantum mechanics. Our work suggests these laws need to be revisited and extended to capture essential natural features.

Keywords:

conservation laws fundamental aspects of quantum mechanics quantum mechanics

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Area of Science:

Quantum mechanics
Theoretical physics

Background:

Conservation laws are fundamental in physics.
Standard definitions are widely accepted but may be incomplete.

Purpose of the Study:

To critically examine the meaning of conservation laws in quantum mechanics.
To propose an extension to the standard definition of conservation laws.

Main Methods:

Conceptual analysis of quantum mechanical formalisms.
Exploration of implications for understanding physical phenomena.

Main Results:

The standard definition of conservation laws in quantum mechanics misses essential natural features.
A revised and extended definition is necessary.

Conclusions:

The current understanding of conservation laws in quantum mechanics requires reevaluation.
Extending these laws is crucial for a more complete description of nature.