On Shell And Off Shell
In physics, particularly in quantum field theory, configurations of a physical system that satisfy classical equations of motion are called on shell, and those that do not are called off shell.
For instance, in classical mechanics in the action formulation, extremal solutions to the variational principle are on shell and the Euler-Lagrange equations are on shell equations (i.e., they do not hold off shell). Noether's theorem is also another on shell theorem.
Read more about On Shell And Off Shell: Mass Shell
Famous quotes containing the word shell:
“How then can we account for the persistence of the myth that inside the empty nest lives a shattered and depressed shell of a woman—a woman in constant pain because her children no longer live under her roof? Is it possible that a notion so pervasive is, in fact, just a myth?”
—Lillian Breslow Rubin (20th century)