absence of light

On Wed, 5 Dec 2001 09:03:33 -0600,  patachon <phsov@xxxxxxx> on
Subject: absence of light mentioned, in part, the following:

>>if there is no light, there can't be a shadow. Neither in front nor
behind the "object" causing such " appearance" of a shadow.

RESPONSE:
You are correct. Light actually both leaks around the observer's back, when
the observer is facing the shadow, and the plane or surface receiving the
shadow also receives some light. The latter light reflects back and into
the penumbra. Therefore, the penumbra is a space of darkness, but it does
have some dim light.

 If there is light in front of an object, and if such object is absorbing
all the energy of the light ( not translucid or transparent, like a white
colored glass or a plastic bottle) a shadow , who is then a state of no
radiated energy, will be detectable by our sight. Only behind such object.
Also the energy "reflected" by any object will make it "visible" to our
sensors,eyes, body (heat).

RESPONSE:
Correct.

>>there are various forms of "light" a.k.a "electro-magnetic radiation"
and some are not visible with our eyes, but they exist...we can actually
"see" - better said detect - with our body the I.R. radiation, and others
like neutrons beams don't cause any shadows to appear. And we don't detect
those.  So a definition of "Light" would be necessary.

RESPONSE:
Of course the shadow discussion was in respect to fire light.

>> penumbra means "quite black " or better said "quite shadowed"...( like
in spanish "apen-as en la s-ombra" >>apenombra<>penumbra) so instead of
writing about such a space "between the light and the shadow" that doesn't
exist, because any "light level", eventually very dimm, actually exists per
se, we could describe the penumbra as a partially irradiated place.

RESPONSE:
A penumbra actually exists---with a very dimm light.

The point here is trying to define the "partially". Also interesting is
trying to understand why we can see dimmed objects trough the "shadowed
"spaces : because of the radiation-light from the objects is dimmed or
filtered by the shadow, or just because our detectors (and our central
brain system) analyze and do a difference between light levels in the whole
place ??

RESPONSE:
This discussion is going towards a very scientific interest. Suffice it to
say, we are concerned with the connection between darkness and light.  It
is this difference that seems to free us to imagine all kinds of
possibilities, almost like dreaming, that are possible in the act of
design.  It is in this condition that "The observer "lives" between light
and shadows with BACK to light, and FRONT towards shadow."


>>>but we don't talk here about the diffusion/diffraction of the light
...if the hole is small, the image(shadow) is more or less a good
reproduction of the observer. But if the hole is too big, there is no
shadow at all........

RESPONSE:
This is the concern of lenses; and my concern is with light and shadow
alone. It is related to Plato's cave notions.

Any optics specialist to explain why a very "small" hole is better to
reproduce an image/shadow than a bigger one ( even if the small hole means
much longer timing to adapt our sensors, or produce a picture in
photografic cameras - where the better quality in results is paid by a
longer time exposure>>always a similar total energy level used, at the end
of the process. (I mean the film "sensitivity" is the energy manager there,
as in our eyes.)

RESPONSE:
I tried to point out that we may actually "see" more in dim light than in
bright light. I was, of course, referring to the mind's eye, perhaps the
human heart as well.

Finally should we conclude all we see is an illusion ?

RESPONSE:
Buddhists do. The virtual world is perhaps closer to an illusion.  But we
actually manifest design artifacts in a physical world. Both have
value.  The former is sufficient to be of its own being; and the latter is
desirable for the making of design artifacts.  There is a potential for a
mathematical connection between each, the former in the representative
support of the latter.

Thank you for your discussion.

.H.