Sources of EM radiation in organisms?

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Discussion Overview

The discussion revolves around the sources of electromagnetic (EM) radiation in organisms, focusing on the mechanisms by which energy is emitted, particularly in relation to blackbody radiation and the contributions from biological processes such as chemical reactions and electrical activity in the nervous system.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that the brain and nervous system emit EM energy due to electrical currents, but question the extent of this radiation.
  • One participant notes that while a 'wave of depolarization' travels down neurons, the energy radiated from this activity is minimal compared to energy lost through conduction and infrared radiation.
  • Another participant suggests that the majority of EM radiation from organisms is due to blackbody radiation.
  • It is mentioned that the peak wavelength of emitted radiation from humans is around 9.5 micrometers, indicating that most radiation is in the infrared spectrum.
  • There is a question regarding the implications of a non-perfect blackbody on the power equation and whether it affects intensity.
  • One participant speculates that if a body is not a perfect blackbody, its surface temperature may be higher for the same rate of energy loss compared to a blackbody.

Areas of Agreement / Disagreement

Participants express differing views on the extent and nature of EM radiation emitted by organisms, particularly regarding the contributions of blackbody radiation versus other mechanisms. The discussion remains unresolved with multiple competing perspectives on the topic.

Contextual Notes

There are assumptions about the definitions of blackbody radiation and the conditions under which organisms emit EM radiation. The discussion does not resolve the implications of non-perfect blackbody behavior on energy emission.

KingNothing
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Organisms radiation EM energy. I am aware of the brain and nervous system as a source (because of electrical currents, etc) and that we have a lot of IR radiation.

Is the majority of the energy due to blackbody radiation, a by-product of chemical reactions, or something else?
 
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A 'wave of depolarisation' travels down a neuron cell. This causes (very) small currents at the body surface. Therefore very little energy is radiated due to the electrical activity of the brain and nervous system.
Most of the energy lost by the body is due to conduction from the skin to the air around us, and some is lost by infrared radiation also.
 
BruceW said:
and some is lost by infrared radiation also.

Which is exactly what I am asking about. Where does that come from?
 
Blackbody, primarily.
 
Yep. Due to blackbody radiation, the peak in emitted radiation wavelength is at 9.5*(10^-6) meters. So most of the blackbody radiation given off by a human is infrared.
This radiation is given off by all parts of the person (but radiation given off by internal parts of the person may be absorbed by other parts of the person on its way out).
If the person can't be approximated as a blackbody, then I have no idea what will happen.
 
What effect does having a non-perfect black body have on the power equation? Does it lower the intensity by some constant factor? (After all, there's only one Halle Berry)
 
If a body is not exactly black - i.e. it is frequency selective in its emissivity, then i think its surface temperature will always be higher than for a black body, for the same rate of energy loss.
 

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