As you read this, you are glowing - weakly, faintly, but glowing nonetheless. Chemical reactions within your body, besides liberating energy and producing heat, are also emitting small numbers of photons, elementary particles of light. The glow is strongest in the late afternoon, and around the lower part of your face.
Many living creatures, including fireflies, jellyfish, squid, glow-worms and deep-sea fish, are known for producing their own light often through the help of bacterial accomplices. But virtually all living things emit some degree of light, albeit so weakly that it's very hard to detect. Our own biological glimmer is a thousand times less intense than the sensitivity of the human eye so our only hope of detecting it is with sophisticated instruments.
That's exactly what Masaki Kobayashi from the Tohoku Institute of Technology has done. Searching for our inner light is usually the province of hippies and new age followers. Kobayashi is neither - he has actually managed to photograph the dim glow of humans using an incredibly sensitive camera, able to detect the dimmest of lights.
Previous cameras took more than an hour to record a decent image but Kobayashi's camera is so sensitive that it can detect light at the level of a single photon. Even so, using it is tricky. The camera needs to be kept at -120 degrees Celsius and sealed in a completely light-tight room. The person being filmed also needs to be in complete darkness, as well as naked and very clean, lest clothing or grime obscure the photons they emit.
Kobayashi recruited five volunteers and allowed took photos of them every three hours between 10am and 10pm, for three days. Aside from the brief forays into pitch-blackness, they experienced normal light and dark conditions and slept between midnight and 7am.
The glow is a rhythmic one, brightening and fading over the course of the day with a peak around 4pm. Kobayashi thinks that this rhythm is driven by an internal body clock, for he managed to break the cycle and suppress the volunteers' bodily glows by keeping them awake in constant light and disrupting their sleep patterns.
The stream of 'biophotons' isn't just a reflection of body heat. An infrared camera showed that some of the hottest body parts like the side of the neck above the collarbones give off very few photons, and the total light emissions didn't match variations in body temperature in any meaningful way.
Instead, Kobayashi thinks that the glow comes from chemical reactions that produce free radicals - atoms or molecules that have a lone, isolated electron. Electrons usually dance in twos, but in free radicals, one is bereft of its partner. That makes these radicals incredibly reactive and they set off a series of energetic chemical reactions as they bump into the various fats and proteins in our cells. Our glow is produced when these reactions involve fluorophores - molecules that give off photons when they shift form a high-energy "excited state" to a low-energy "ground state".
His photos reveal that our faces are the shiniest parts of our bodies, with our mouths and cheeks glowing particularly brightly. With just five male volunteers, it's not clear if this distribution of brightness applies to all people, ethnic groups or even genders, although Kobayashi's camera certainly provides a way of finding out in the future. Nor is it clear if some particular bright sparks really do have lights shining out of their bums - the volunteers will have to be standing up for us to work that out...
For more on biophotons, see this New Scientist article.
Reference: Kobayashi, M., Kikuchi, D., & Okamura, H. (2009). Imaging of Ultraweak Spontaneous Photon Emission from Human Body Displaying Diurnal Rhythm PLoS ONE, 4 (7) DOI: 10.1371/journal.pone.0006256
If the camera has an exposure time of an hour, wouldn't they need to stay reasonably still, naked, in pitch blackness, for an hour? Unpleasant.
Note the word "previous"...
do you reckon biophoton are the source of light enabling dreams to be visualized?
Sorry, but I'm not buying this without more skeptical controls. The only "evidence" provided that we aren't just seeing infrared is that the sides of the neck, which are warm, don't show high intensity in the photographs. But the sides of the neck are at a very low angle to the camera, so their intensity would be greatly reduced in the forward direction.
Can't the camera determine wavelength? or be fitted with an IR filter? Can photos be taken from the side ... maybe with thermocouples in strategic locations to control for temperature?
Peer review certainly would have pointed out all these factors.
I imagine holopathic hacks will leap on this as proof that we all have "auras" or crap like that.
Wouldn't it be interesting if the "glow" of pregnancy turned out to be visible on that camera?
Ah, an important word to have missed!
Um yeah. These researchers have not seen this video. You don't even need a camera. http://www.youtube.com/watch?v=tjecYugTbIQ
Regrettably, this is probably going to spawn a minor scam industry.
"Kobayashi thinks that the glow comes from chemical reactions that produce free radicals"
Interesting. I wonder if he'll have antioxidant makers coming to him asking to take "before" and "after" pictures of their supplement users.
Less glow would indicated less free radical activity, right?
Hmm ... that makes me want to experiment on humans.
First of all, humans all emit quite a bit of thermal photons so we all glow nicely in the dark as you can verify with an infrared camera sensitive to the 8-12 or 8-14 micron wavelength range.
The first question that comes to mind is what wavelength photons are actually being picked up? To answer that question we can use filters or a monochromator + photon counting apparatus.
The next question is: what is the source of this radiation? Answering that question will also help answer the question: Is there really a periodic biological fluctuation which occurs daily?
I've always associated free radicals and glows with oxidative processes; for example the glow of luminol when exposed to ozone or to peroxides. I don't know if the free radicals on their own power any glowing, although it is possible to create free electrons (not really classed as 'radicals') in liquid napthalene and this makes the napthalene a beautiful green color (but it isn't a glow). :)
@Mike Holyoak: I doubt it. That would be an actual experiment with actual results; woo peddlers hate results because they never support the woo-woo claims.
Re infrared thermal emissions: did Kobayashi take into account that there are asymptotic "tails" for the BB radiation spectrum? It means that in principle, much higher frequencies than the peak are being emitted by warm bodies, even if at low intensity - per the idealized formula at least. (I don't think there's even a cutoff per se - but in practice, it would be very hard for a room-temp. body to happen to give off an X-ray photon.) So that means, bodies at 300 K should be emitting a very few visible photons anyway from the extended thermal curve. It certainly should be calculated, to check against the purported human emission of natural light. Anyone check on this? (I could - too lazy/no time, sorry! ;-)
Why cant i print this its so cool
Regarding the possible source of the fluorophores, and why they appear to be so abundant around the face and mouth... Facial moisturisers and toothpastes often contain optical brighteners or other additives (e.g. plant-derived polyphenolic compounds) which happen to be fluorescent, and which can hang around in the skin for days after application. These photons can't truly be called bio-photons if they are the result of oxidation of an exogenous compound. This would have been easy to test.