MadSci Network: Biochemistry
Query:

Re: Is it possible for the human body to discharge or project it's own energy?

Date: Mon Jan 1 19:50:17 2001
Posted By: Chris Larson, Research Scientist
Area of science: Biochemistry
ID: 972278348.Bc
Message:

Dear Ryan,

Not only is it possible for the body to emit a portion of its energy, the 
second law of thermodynamic requires that the human body as a machine must 
always be emitting some of its energy.

As you may know, there are basically 5 types of energy: mechanical, 
chemical, electromagnetic, heat, and nuclear, and these are all utilized 
in the human body. I will try to address which are emitted from the human 
body and/or what keeps them contained within the body, starting with the 
easiest.

The nuclei of every atom in the body are held together by the nuclear 
force (one of the fundamental forces of the universe), and this is 
contained within the body because it is almost always a more stable state 
for the nuclei to stay together than to come apart. The most common 
exception to this is probably potassium, which has a reasonable high 
incidence of unstable, and hence radioactive, isotopes as it is found in 
the body (foods like bananas have high amounts of it), and thus breaks 
down to emit radiation. However, although I am not a physicist I think 
that emitted radiation would be considered electromagnetic energy and not 
nuclear. Hence the body has and uses nuclear energy but doesn't really 
emit it because it is "contained" by atomic nuclei.

Next is chemical energy. The body is constantly using chemical energy to 
run every reaction that ever occurs in it, and any molecules that leave 
the human body that were synthesized in it could be considered to be 
emitting that energy. For example you breathe out carbon dioxide 
constantly, and if the chemical energy in those molecules are used by a 
green plant during its respiration, then you have emitted that energy. So 
I would say that the physical barrier of skin that keeps your body and 
hence all its molecules intact is the barrier to that energy not being 
emitted.

Next is electromagnetic energy. One thing that you often hear is how the 
human body has a weak electric and weak magnetic field associated with it. 
To the extent that we are made up of ions and thus are probably a charged 
object we would have a very weak electric field, and to the extent that we 
are a charged object subjected to the earth's magnetic field we would 
probably have a weak magnetic field in reponse to the earth's magnetic 
field, but although I don't know I would think these would have to be very 
weak since none of us attracts iron shavings or generates a current when 
we touch metal. However, we do emit electromagnetic radiation. From your 
physics you may remember that the spectrum of electromagnetic radiation 
from high energy to low energy consists of gamma rays, X-rays, 
ultraviolet, visible light, infrared, microwaves, and radio waves. Any 
physical object at any temperature emits thermal radiation, or what has 
been called black body radiation, and this is true for the human body. The 
wavelength of this radiation is determined by the temperature of the 
object.  Given the temperature of the human body, we emit infrared 
radiation, and in fact infrared detectors can "see" a human body even in 
total darkness (in contrast, night vision instruments basically collect 
the tiny amounts of visible radiation that is reflected off a human body 
over intervals of hundreds of milliseconds and convert that into a 
picture, like a camera, and hence cannot work in total darkness). So we do 
emit electromagnetic radiation, and it is completely not contained.

Next is heat energy. Heat is essentially energy transfer between objects 
at different temperatures, and this happens via conduction (direct 
contact), convection (warm air currents), and radiation. The human body 
emits heat energy via all three pathways, and there is really no 
containing it. 

Finally there is mechanical (kinetic and potential) energy. Kinetic energy 
is the displacement of an object over a distance, and as you can see every 
time we move our bodies we emit kinetic energy.

I hope that answers your question. Feel free to email to me directly if it 
does not.

Chris



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