Where does intensity collide?

In physics, intensity is the power a wave or field delivers per unit area, so a brighter light, a louder sound, or a stronger beam all carry more energy across a surface each second. Bouguer's 1729 Essai d'optique sur la gradation de la lumière founded the quantitative measurement of light's intensity and the law by which light fades through an absorbing medium, and later work carried the same power-per-area quantity over to sound and other waves. Here the referent is a measurable flux of physical energy, given in watts per square metre, and not the degree of a felt emotion, the rate of scattered events, or a philosopher's degree of a quality.[1]

Unit

One value of power per unit area, in watts per square metre

Recovery means

Not applicable

Measured by

Recorded with photometers, radiometers, or microphones that capture energy flux across a known area

In philosophy, an intensive magnitude is a quantity that has a degree rather than parts you can add up, such as warmth, brightness, or pressure, which can be more or less intense without being built from countable units. Kant's 1781 Kritik der reinen Vernunft, in the section called the Anticipations of Perception, defined intensive magnitude as what is grasped only as a degree, set it against extensive magnitude that is built from parts, and drew on an older scholastic debate about the intension and remission of qualities. The referent is a philosophical property of how much of a quality is present, argued in metaphysics, and not a physical energy flux, a statistical rate, or a personality trait.[2]

Unit

A degree on a scale of one quality, with no smallest part

Recovery means

Not applicable

Measured by

Argued conceptually, by whether a quality admits degrees, rather than read off an instrument

In statistics, the intensity of a point process is the rate at which events occur, the expected number of points per unit of time or space that governs models of random arrivals. Poisson's 1837 Recherches sur la probabilité des jugements en matière criminelle et en matière civile introduced the distribution of rare events whose rate parameter this intensity is, and Cox's 1955 Some Statistical Methods Connected with Series of Events set out the intensity function for series of events whose rate may change over time. The referent is a rate parameter in a probability model, estimated from counts of events, and it shares only the word with a wave's energy flux, a degree of a quality, or the strength of a person's emotions.[3][4]

Unit

Expected number of events per unit of time or space

Recovery means

Not applicable

Measured by

Estimated from observed event counts, for example by maximum likelihood under a Poisson model

In psychology, affect intensity is a stable individual difference in how strongly a person typically experiences emotions, whether positive or negative, apart from which emotion it happens to be. Larsen and Diener's 1987 Affect intensity as an individual difference characteristic defined and reviewed the trait and tied it to a self-report scale, the Affect Intensity Measure, on which some people report reliably stronger emotional reactions than others. The referent is a measured characteristic of a person's emotional life, and not the physical power of a wave, the rate of random events, or a philosophical degree of a quality.[5]

Unit

A person's average strength of emotional response, as a scale score

Recovery means

Not applicable

Measured by

Assessed by self-report, chiefly the Affect Intensity Measure