GC: n

CT: Radiant Energy.
Atoms absorb energy from an outside source and release (or “emit”) this energy as electromagnetic radiation. This radiation can be in the form of waves of many different wavelengths or frequencies.
Many energy sources emit radiant energy. The sun and other stars are luminous or “light-giving” objects that produce radiant energy from nuclear reactions. Luminescence may result from biological processes (e.g., fireflies), from chemical reactions like burning kerosene in a lamp, from friction, or from electricity, as in a light bulb.

S: http://www.energyeducation.tx.gov/energy/section_1/topics/forms_of_energy/radiant_energy.html (last access: 11 February 2015)

N: 1. radiant (adj): mid-15c., from Middle French radiant and directly from Latin radiantem (nominative radians) “beaming, shining,” present participle of radiare “to beam, shine” (see radiation). Of beauty, etc., first attested c.1500. Related: Radiantly.
energy (n): 1590s, “force of expression,” from Middle French énergie (16c.), from Late Latin energia, from Greek energeia “activity, action, operation,” from energos “active, working,” from en “at” + ergon “work, that which is wrought; business; action”.
Used by Aristotle with a sense of “actuality, reality, existence” (opposed to “potential”) but this was misunderstood in Late Latin and afterward as “force of expression,” as the power which calls up realistic mental pictures. Broader meaning of “power” in English is first recorded 1660s. Scientific use is from 1807. Energy crisis first attested 1970.
2. Any form of energy radiating from a source, as electromagnetic waves, sound, heat, light, X-rays, gamma rays, etc.
3. Radiant energy is the energy of electromagnetic waves.
The term is most commonly used in the fields of radiometry, solar energy, heating and lighting, but is also used less frequently in other fields (such as telecommunications).
The quantity of radiant energy may be calculated by integrating radiant flux (or power) with respect to time and, like all forms of energy, its SI unit is the joule.
In applications involving transmission of power from one location to another, “radiant energy” is sometimes used to refer to the electromagnetic waves themselves, rather than their energy (a property of the waves).
Because electromagnetic (EM) radiation can be considered to be a stream of photons, radiant energy can be viewed as the energy carried by these photons.
Alternatively, EM radiation can be viewed as an electromagnetic wave, which carries energy in its oscillating electric and magnetic fields.
These two views are completely equivalent, and are reconciled to one another in quantum field theory.

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=radiant+energy&searchmode=none (last access: 11 February 2015). 2. GDT. 3. http://www.sciencedaily.com/articles/r/radiant_energy.htm (last access: 11 February 2015).

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CR: energy