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Science

People Emit Visible Light 347

Posted by timothy
from the lots-of-girls-I-know-glow-visibly dept.
An Anonymous Reader writes "The human body literally glows, emitting a visible light in extremely small quantities at levels that rise and fall with the day, scientists now reveal. Japanese researchers have shown that the body emits visible light, 1,000 times less intense than the levels to which our naked eyes are sensitive. In fact, virtually all living creatures emit very weak light, which is thought to be a byproduct of biochemical reactions involving free radicals."
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People Emit Visible Light

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  • by Anonymous Coward on Thursday July 23, 2009 @03:14PM (#28798739)

    Shouldn't that be invisible light?

  • by Anonymous Coward on Thursday July 23, 2009 @03:19PM (#28798813)

    Er. Your argument is that because something emits enough photons, then some are bound to be inside the visible spectrum?

    That is not how light works. If you want a different wavelength, you need photons with different energy, and you need a different process.

  • by dgatwood (11270) on Thursday July 23, 2009 @03:22PM (#28798865) Journal

    Just to be pedantic, you'd have to move it into a colder room or it won't be distinguishable from the background emissions of everything else. The only things that could possibly be distinguishable would be things that produce their own heat, whether electrically or chemically.

  • Mood rings! (Score:5, Insightful)

    by scubamage (727538) on Thursday July 23, 2009 @03:39PM (#28799107)
    So, since this light is directly related to biological processes, that means in theory it should be tied to mood. For instance, clinical depression is tied to a general depression of all physiological processes. So, it would stand to reason that if you're down, you would emit less light. Someone who is euphoric should look (relatively) like a lightbulb in comparison. I know in the article it says that the amount and color of light varies, I wonder if this would lead towards a mood-ring style ability to read emotions. For instance, someone who is emitting a "pensive" light spectrum, along with other biological cues like sweat, and fidgiting may be a good suspect for scrutiny.
  • Re:Biblical? (Score:5, Insightful)

    by Tubal-Cain (1289912) on Thursday July 23, 2009 @04:00PM (#28799397) Journal
    I'm not sure halos are even part of Christian canon.
  • by Tubal-Cain (1289912) on Thursday July 23, 2009 @04:10PM (#28799507) Journal

    So what process creates the other half of the bell-curve, the photons at a lower energy than infra-red radiation?

    /me checks electromagnetic spectrum

    Looks like extremely low-energy photons are radio.

    Assuming it actually is a bell curve [slashdot.org].

  • Uh, duh. (Score:3, Insightful)

    by pi_rules (123171) on Thursday July 23, 2009 @04:30PM (#28799793)

    Anybody that's ever taken LSD could have told you that!

  • Re:Biblical? (Score:4, Insightful)

    by gilleain (1310105) on Thursday July 23, 2009 @04:54PM (#28800105)

    it's entirely possible that extremely sensitive individuals can see the light coming off the extremely bright individuals.

    If there are people who have vision that is 1,000 times normal, then they must get blinded by the sun really easily...

    There may be something to metabolism ... which could easily generate 10 or 100 x the intensity observed in this study, and thus be observable by many people.

    Conversely, the 'brights' (don't tell Dawkins about this!) would be producing lots more free-radicals than normal. I sure hope they also have more efficient repair mechanisms in place to mop them up.

  • by Chris Burke (6130) on Thursday July 23, 2009 @05:24PM (#28800465) Homepage

    Whatever researchers may use it to mean, the majority of people will probably be inclined to use the dictionary definition, and the most common one, if you don't clarify:

    1 a: capable of being seen <stars visible to the naked eye> b: situated in the region of the electromagnetic spectrum perceptible to human vision < visible light>

    Wait. You're telling me that the majority of people will use definition 1a, and only 1a, without even considering 1b, even though 1b specifically and directly refers to the exact phrase being used -- "visible light"?

    You're telling me that the majority of English speaking people do not ever consider the multiple definitions that nearly every word in our language has, and choose based on contextual clues what the most likely intended meaning is? I don't buy that for a second. You know why? Because just now, without even thinking about it, you automatically processed the word "buy" and based on the contextual clues chose meaning number 5 [merriam-webster.com].

    This has nothing to do with people choosing the first definition from a dictionary as opposed to the second, because nobody was looking in a dictionary. This has to do with people not knowing a scientific term so common and non-obscure it's definition 1b in said dictionary.

    So basically, if you mean "light in the visible spectrum", just say that. "Visible light" will be interpreted by most people according to the 1a definition of "visible", not the 1b definition. It comes first because it's common...

    Okay, once again I'm surprised, and again I admit it must just be the fault of my perception.

    I would never have guessed that people who have no idea what "visible light" means would find the phrase "light in the visible spectrum", or even just "spectrum" meaningful. I wouldn't have thought those people even knew that the stuff outside the visible spectrum was light. So you're telling me that people know that the colors in a rainbow and X-rays and radio waves are all the same thing, they're all light, but at the same time have no idea what "visible light" could mean? I really never would have expected that.

    I guess this illustrates one of the difficulties of writing about technical material for a layman audience -- remembering what it was like to be a layman, and thus what a layman would understand, when that could have been a long time ago. As far as I can remember, I learned about the EM radiation spectrum that includes X-rays, radio waves, infrared, and the light our eyes are sensitive to along with the phrase "visible light" to describe the latter section of the spectrum in a single class session in high school physics. So it would never have occurred to me that you could expect your audience to know one and not the other.

  • Re:Mood rings! (Score:3, Insightful)

    by merreborn (853723) on Thursday July 23, 2009 @06:13PM (#28801033) Journal

    So, since this light is directly related to biological processes, that means in theory it should be tied to mood. For instance, clinical depression is tied to a general depression of all physiological processes. So, it would stand to reason that if you're down, you would emit less light. Someone who is euphoric should look (relatively) like a lightbulb in comparison. I know in the article it says that the amount and color of light varies, I wonder if this would lead towards a mood-ring style ability to read emotions. For instance, someone who is emitting a "pensive" light spectrum, along with other biological cues like sweat, and fidgiting may be a good suspect for scrutiny.

    To actually detect this, wouldn't you need the subject to be in a completely dark room?

    Otherwise, how do you differentiate their 'trickle' of emitted photons, from the flood of ambient photons reflecting off them?

    And once you have them alone, in a room so dark that they can't see their hand in front of their face... Well, that's probably going alter the subject's mood a little.

  • Re:Biblical? (Score:2, Insightful)

    by Magic5Ball (188725) on Thursday July 23, 2009 @07:09PM (#28801591)

    While most cows aren't spherical in real life, within a species the height of cows, their mass, horn length, volume of milk production, girth, colour, etc. all vary within known ranges, with most members of the population being distributed about the middle. It's also possible that the luminescence phenomena is mostly quantized--cows have a whole number of legs and not 3.6 +/- 0.4 legs, nor 1.1 +/- 0.1 brains--but the fact that luminescence appears to vary within each day (at least within their sample) in individuals of a species with a lifespan of 10e5 days suggests that it's not a binary or quantized trait.

    So, this isn't assuming a spherical cow as much as assuming (until we have better evidence) for this discussion that this instance of a previously unobserved kind of animal (new physiological trait or process) fits into the same pattern in which the vast majority of all other known traits also fit. Scientists have been wrong in the past on this kind of confirmation bias assumption (see ring species, for example) but we always have to start with what we know and can show from available evidence.

    If you have evidence that we need a new sub-field of biochemistry or physiology or genetics to deal with dimly glowing human faces which offers a more robust model of the intensity of glowing faces and/or ocular light sensitivity than we have in this discussion (for which we have really big piles of circumstantial evidence from many different circumstances and models which seem to have worked for the last few decades at least) please present it so that we may discuss your new model instead. Otherwise, your attempted counterpoint amounts to a claim without evidence that much of what we know about evolutionary biology is wrong (possible, but you didn't specify why you think that).

  • Re:Biblical? (Score:2, Insightful)

    by Magic5Ball (188725) on Thursday July 23, 2009 @07:26PM (#28801755)

    That's great. If you're right and halos are completely explained by historical pragmatic industrial design, glowing faces doesn't tell us much that's new. However, if there could be a physiological basis for some of the spiritual things for which we don't yet have a fully satisfying explanation--potentially individuals like shamans, diviners, etc.--we'll have gained some important insights into the human religions which have shaped so much of our world. We might also learn more about how we sense and perceive other people, which would be useful for such things as clinical and behavioral psychology, the treatment of mental illness, and the performance arts industries.

    While your old tech explanation is cool, I'd get more new tech toys out of understanding if and why human faces glow (and also, what else glows?).

  • Two Theories (Score:3, Insightful)

    by DynaSoar (714234) on Thursday July 23, 2009 @09:32PM (#28802717) Journal

    1. The rods of the human retina can react to a single photon. However, to be consciously perceived between 5 and 10 photons must be detected within 100 milliseconds. To pick up light that's 'visible', but "1,000 times less intense than the levels to which our naked eyes are sensitive" ('Which is, of course, impossible. -- Hitchhiker's Guide) the researchers in TFA are claiming to detect small fractions of a photon (repeat HHG assertion here).

    As stated, the above applies to conscious perception. A normally non-conscious perception via an alternate visual channel has been proven to exist. This 'blindsight' has been discussed here previously http://science.slashdot.org/article.pl?sid=08/12/24/2330245 [slashdot.org] . It has been shown to not only exist in the sighted, but can be trained in them so to become functional. There was a school for this in New Mexico that was written up in Co-Evolution Quarterly almost 20 years ago. In the discussion thread here, more than one person admitted to having developed or noticed having this ability.

    2. The spirit of we two legged can become attuned to the spirit of the four legged, and so the hunter can find prey in darkness, and one can also avoid becoming hunted. Likewise, we can feel the spirit of the standing people (trees) and so find our way between them with surprising speed. Although it works as though it were sight, because it is a working of the spirit, the impressions received are not detected as visual images to the mind, but only to the spirit.

    I've got a lot of academic training in #1. I've got some training, and have ancestors with a lot more in #2. They may be incompatible, but since no viewpoint perfectly and completely describes reality, none can be said to be the only truth. In any case, learning to use dark sight doesn't require believing either.

    Still, there ain't no such as pieces of photons.

  • Re:Biblical? (Score:5, Insightful)

    by reboot246 (623534) on Thursday July 23, 2009 @09:59PM (#28802839) Homepage
    No, what I'm saying is that the proposition, "People Emit Visible Light", is a crock. I take words seriously. When they say "visible", I take it to mean "VISIBLE". If they meant to say, "people emit light in the visible part of the spectrum", then they should have said exactly that. Words have meanings.
  • Re:Biblical? (Score:3, Insightful)

    by rumith (983060) on Friday July 24, 2009 @12:34AM (#28803611)

    especially when referring to a qualitative attribute such as visibility; what's visible to one person may not be visible to another

    Right. That's why the definition of "visible light" should rely more on some species-wide feature than on some feature that varies wildly from one person to another.

    It would be accurate to say people emit some light within the wavelength range that is normally visible. It would be inaccurate to say people emit visible light.

    This statement is exactly what I wanted to hear when I posted my first reply. :-)

  • Re:Biblical? (Score:3, Insightful)

    by clarkcox3 (194009) <slashdot@clarkcox.com> on Friday July 24, 2009 @12:45AM (#28803645) Homepage
    Visible light, just means light within the visible spectrum. Even if everyone closes their eyes, and nobody actually sees it, visible light is still visible light (as distinct form Infra-red, Xrays, radio, etc.)

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