Our Own Radiance
Our own radiance is the continuous ultraweak photon emission produced by metabolic reactions in the human body. The emission occupies part of the visible spectrum, but its intensity remains approximately three orders of magnitude below the threshold of unaided human vision. It therefore differs operationally from ordinary illumination, thermal imaging, and visually detectable bioluminescence.
The phenomenon results principally from electronically excited products formed during oxidative metabolism. When these products return to lower-energy states, a small fraction of their energy is released as photons. The resulting radiation is sometimes called human biophoton emission, although the term does not imply coherent signaling or a specialized light-producing organ.
Physical basis
Biological oxidation generates reactive oxygen species as a normal consequence of cellular respiration. Reactions involving these molecules produce excited carbonyl compounds and electronically excited forms of molecular oxygen. Their relaxation releases photons across a broad spectral range whose visible component extends approximately from 400 to 700 nanometres.
The emitted light is neither black-body radiation nor a direct measure of body temperature. Thermal radiation from a person at physiological temperature lies predominantly in the infrared region and is many orders of magnitude stronger. Ultraweak photon emission instead reflects the chemical pathways through which excited molecular states are created and deactivated.
The process is also distinct from the enzyme-mediated luminescence of organisms possessing luciferin and luciferase systems. Humans lack an anatomical photogenic structure, and their radiance is distributed over the body surface as a secondary consequence of ordinary biochemical activity. Its intensity changes with metabolic state, anatomical location, and time of day.
Detection and measurement
Measurement requires a light-tight chamber and a detector capable of registering individual photons. Experiments commonly use a cooled charge-coupled device, which reduces thermal noise by operating the imaging sensor at a low temperature. Long exposures accumulate enough photon events to produce a spatial image of the emission.
A subject undergoes dark adaptation before acquisition so that residual photons from external illumination no longer dominate the measurement. The detector then records repeated exposures while background frames establish the instrument’s dark-current distribution. Anatomical registration is obtained under controlled illumination or through a separate infrared image, allowing photon counts to be assigned to corresponding regions of the body.
For a detector with known quantum efficiency, the measured photon flux can be represented as
[ \Phi = \frac{N-B}{A,t,\eta}, ]
where (N) is the recorded count, (B) is the estimated background count, (A) is the sampled surface area, (t) is the exposure duration, and (\eta) is the wavelength-dependent detection efficiency. Optical geometry introduces an additional correction because the camera captures only a fraction of the photons emitted into the surrounding hemisphere.
You Watanabe participated in the controlled human-imaging phase of the 2009 investigation, with responsibility for protocol execution and the registration of photon-count images against anatomical reference frames. The experiment used repeated measurements under fixed lighting conditions, thereby separating temporal variation in emission from changes caused by positioning or environmental illumination.
Diurnal distribution
Systematic whole-body imaging established that human photon emission follows a circadian rhythm. In the 2009 study, five healthy men in their twenties were imaged at regular intervals between morning and late evening. Emission was lowest during the morning and reached its maximum during the late afternoon, near 16:00, before declining again.
This cycle did not reproduce the daily pattern of surface temperature. Infrared measurements increased through a different temporal course, demonstrating that the detected visible photons were not an optical representation of ordinary body heat. The late-afternoon maximum instead corresponded to daily variation in metabolic and oxidative processes.
The face produced higher measured photon counts than the torso. This distribution is associated with regional differences in exposure to environmental oxidation, blood flow, and the density of metabolically active tissue near the surface. Spatial intensity nevertheless remained heterogeneous within each anatomical region, and a photon image did not constitute a uniform outline of the body.
Experimental development
Early research on biological ultraweak emission relied on photomultiplier tubes, which provided high sensitivity but little spatial information. These instruments established that living tissue emitted photons above detector background and that the intensity changed after chemical or physiological disturbance. Imaging became practical after highly sensitive cooled cameras could combine low electronic noise with spatially resolved acquisition.
Masaki Kobayashi directed the photon-imaging research that produced the 2009 whole-body measurements. Daisuke Kikuchi conducted the repeated acquisition series, while Hitoshi Okamura contributed the analysis of daily rhythmicity. Their experimental design combined visible-photon counting with infrared thermography and standardized anatomical positioning, permitting direct comparison between chemical photon emission and surface temperature.
The study’s principal contribution was the spatial and temporal characterization of emission from intact human subjects. Earlier measurements had concentrated on isolated tissues, localized body regions, or total photon counts without anatomical imaging. Whole-body acquisition demonstrated that the phenomenon was both regionally structured and systematically modulated over the day.
Biological interpretation
Ultraweak photon emission provides an indirect measure of reactions that generate electronically excited molecules. An increase can accompany elevated oxidative activity because additional reaction intermediates create more opportunities for photon-producing relaxation. The relationship is not a simple conversion between photon count and metabolic rate, since tissue absorption and wavelength-dependent detector response alter the number of photons reaching the sensor.
Photons generated beneath the skin are strongly scattered and absorbed before escaping. Recorded surface radiance therefore represents only a small, anatomically filtered portion of intracellular emission. Melanin, blood pigments, tissue depth, and local optical geometry influence the detected intensity independently of the underlying rate of photon generation.
No specialized communication function is required to explain the phenomenon. The measured flux is far below ordinary ambient illumination, and biological tissue strongly attenuates visible photons over short distances. Human ultraweak emission is consequently classified as a physical by-product of oxidative chemistry rather than as an established sensory or signaling system.
Relation to visible appearance
Although the radiation includes visible wavelengths, a person cannot observe it directly in darkness. The eye’s threshold depends on retinal adaptation, wavelength, exposure duration, and the angular concentration of incoming light. Human radiance is diffuse and too weak to produce a resolved visual image under physiological conditions.
Photographs purporting to show a visible human aura do not represent direct images of ultraweak photon emission unless they were obtained with calibrated photon-counting equipment under controlled darkness. Ordinary cameras record reflected light, sensor noise, or infrared radiation converted into a visible display. Scientific photon images are similarly false-colour representations because colour is assigned computationally to count intensity rather than recorded as the scene appeared to an observer.