odor and humans

Clive Steward csteward at narration.cityscape.co.uk
Fri Dec 16 20:00:53 EST 1994

In article <3co0ao$5qi at rebecca.albany.edu>,
tivol at tethys.ph.albany.edu wrote:

>>Well, if you put  two pendulums (out of sync) in the same room, they will 
>>eventually swing in sync also.  I don't think they have pheromone receptors.
>Dear Jason,
>	The two pendulums may get in phase if (as is overwhelmingly likely)
>their frequencies differ by a small amount; however, they will then continue
>to change their relative phases (unless coupled appropriately) until they are
>out of phase again.  The same is apparently not true about human females; there
>*does* appear to be a coupling based on olfaction.
>				Yours,
>				Bill Tivol

It might be worth looking at the pendulums, though, since they can sync
with arbitrarily small amounts of coupling, and maybe there's a similar
biochemical 'balance point' arrangement which can explain how the tiny
energy change in odor differentiation can influence rather larger
biological happenings.

Pendulums in a room end up being influenced to match their swings because
they couple movement to each other, however minutely.  Likely the dominant
means is through the floor.  If this coupled movement isn't matched, it
influences each pendulum's acceleration, thus timing.  For complete
syncing, the simple model usually talked about, the pendulums need to have
the same 'natural' swing frequency.

The effect occurs throughout the swing, but is most influencing at each
'beginning':  the 'balance point' regime when the pendulum is near
stopping, stopped, and then returning.

If at this point, the other pendulum is moving rapidly at the bottom of its
swing, it is generating the most force against the floor because of the
angular momentum change (centrifugal force) against the constraint of its
pivot.  In our simple case, peaking at this time, the floor movement which
results will make the greatest change in the 'beginning' pendulum's timing.

You can see that if the pendulums are more nearly in sync, the net
vibrations will be more similar (ignoring transit time through the floor),
and especially, both will be going slowly at the more critical end points
of swing.  The very lowest influence will occur when both are exactly
matched:  zero, if matched swinging is possible because the natural
frequencies are the same.

It gets more complicated if the pendulums aren't the same in natural
frequency, but they will still influence each other, and this dynamic
complexity also is resultant in  greatest degree from the conditions around
'starting-again points' of balance.

The same kind of reasoning explains why predicting solar system orbits is
much more difficult (with multiple planets and to arbitrary precision over
time) than one might first expect.  Here mutual gravitation is the dominant
coupling factor, and moments where gravitations tend to cancel each other
out are the 'balance points'.

Clive Steward
csteward at narration.cityscape.co.uk

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