← Mathematical compendium

Published equation contexts

S=0S=0

Why this formula appears here

The derivation behind this trade-off runs through the ten generators of the Poincaré algebra rather than through anything special to a particular particle. The boost generator K\mathbf K is one fixed physical object for a given one-particle state; writing it as a symmetrized combination of a position candidate and the energy only closes the algebra’s commutation relations correctly if either the position candidate absorbs a spin-momentum term, yielding commuting components and frame dependence, the Newton–Wigner choice, or that term is left attached to the boost generator itself, leaving the position candidate free of it but noncommuting, the covariant choice. Both are legitimate solutions of…

Read the full article-specific guide →

Read the representative guide

How to interpret it

Read it with the definitions, units, and assumptions supplied by the article.

Research cited beside this formula

Published contexts (1)

A symbol can carry a different meaning in another article. Each occurrence keeps its own guide and term definitions.

S=0S=0

Equation 62 · Evolutionary Physics

The Atlas That Refuses to Close

This equation states an equality: the expressions on both sides have the same value under the article’s assumptions.

The derivation behind this trade-off runs through the ten generators of the Poincaré algebra rather than through anything special to a particular particle. The boost generator K\mathbf K is one fixed physical object for a given one-particle state; writing it as a symmetrized combination of a position candidate and the energy only closes the algebra’s commutation relations correctly if either the position candidate absorbs a spin-momentum term, yielding commuting components and frame dependence, the Newton–Wigner choice, or that term is left attached to the boost generator itself, leaving the position candidate free of it but noncommuting, the covariant choice. Both are legitimate solutions of…

Equation guide → · Article →