Where does potential collide?

The stored energy a unit charge or mass has by virtue of its position in a field, measured relative to a reference point. In Introduction to Electrodynamics, Griffiths defines electric potential as the potential energy per unit charge, carried in joules per coulomb, or volts; gravitational potential is the analogous energy per unit mass. The referent is a location in a field, not a person and not an economy, and the quantity is a property of position that can be recovered as work when the charge or mass moves. What makes it potential is that the energy is stored and latent until released, and it is defined only up to an additive constant fixed by the choice of reference.[1]

Unit

Joules per coulomb (volts), or joules for potential energy

Recovery means

Not applicable

Measured by

Computed from charge or mass configuration and position, in volts or joules, against a chosen reference point

The voltage difference across a cell membrane, and in particular the fast, all-or-nothing swing of that voltage that carries a nerve signal. Hodgkin and Huxley, in their 1952 Journal of Physiology paper, measured the squid giant axon and gave a quantitative account of the ionic currents that drive the action potential, the brief spike from a resting level near -70 mV to a positive peak and back. The referent is a living membrane, the unit is millivolts, and the word potential here names an electrical difference maintained by ion pumps and channels, not the stored energy of position in the physics meaning and not any capacity for growth. The two natural-science meanings share the word and the electrical vocabulary, but one is a static field property and the other a dynamic biological signaling event.[2]

Unit

Millivolts across the membrane

Recovery means

The membrane repolarizes and passes through a refractory period before it can fire again

Measured by

Recorded in millivolts with electrodes across the membrane, as in a voltage clamp of the axon

A person's capacity to grow toward the fullest use of their talents, the drive Maslow called self-actualization. In his 1943 Psychological Review paper, Maslow placed self-actualization at the top of a hierarchy of needs and described it as the desire to become everything one is capable of becoming; humanistic psychology later built on this the idea of human potential as a latent capacity waiting to be realized. The referent is a whole person and their development across a life, not a charge in a field and not an economy's output. The unit is not physical; it is a capacity inferred from growth, and what marks this meaning is that the potential is a person's own becoming, shared with the physics meaning only by the metaphor of something latent.[3]

Unit

A person's latent capacity for growth (no physical unit)

Recovery means

Not applicable

Measured by

Inferred from clinical observation and self-report of growth toward self-actualization, not a physical measurement

The maximum output an economy can sustain when labour and capital are fully employed, without pushing inflation upward. Okun introduced potential GNP in 1962 in the Proceedings of the Business and Economic Statistics Section of the American Statistical Association, defining it as the output the economy would produce at full employment and estimating the gap between it and actual output. The referent is a national economy, the unit is real output in currency, and the construct is a ceiling set by resources and institutions, not the energy of a charge, the voltage of a membrane, or the growth of a person. It shares the word potential with the others only through the idea of a level not currently reached.[4]

Unit

Real output in currency at full employment

Recovery means

Not applicable

Measured by

Estimated statistically from full-employment output and the output gap, in real currency