[AccessD] SERIOUSLY OT: Re: An Interesting question

 From a physical science perspective, light is a measurable quantity, a number of photons of a given 
frequency.  Absolute (visible) darkness does exist (in caves) and is zero photons of any visible 
frequency.

Of course when discussing "light" you have to discuss the eye and what frequencies can be seen. 
Infrared is "light", it is photons of a frequency below(?) red.  But it cannot be seen.  Thus it can 
be absolutely dark (in a cave) and yet there can be infrared "light" (heat) photons bouncing around. 
  Likewise ultraviolet.  Just because we cannot see them doesn't mean "there is no light".

In fact that is the whole point of a bunch of the sensors on telescopes, to allow humans to "see" 
frequencies that the eye cannot perceive.  And of course night vision goggles sense infrared and 
convert that to a frequency that our eyes can see.  By shining an infrared light, night vision 
goggles can "see in total darkness".

So "darkness" in its most common usage has a very specific definition based around what frequencies 
the eye can see.

John W. Colby
www.ColbyConsulting.com


Drew Wutka wrote:
> So?
> 
> Darkness is just the opposite... no (known) bottom limit...
> 
> Drew
> 
> -----Original Message-----
> From: accessd-bounces at databaseadvisors.com
> [mailto:accessd-bounces at databaseadvisors.com] On Behalf Of Gustav Brock
> Sent: Monday, March 30, 2009 10:04 AM
> To: accessd at databaseadvisors.com
> Subject: Re: [AccessD] SERIOUSLY OT: Re: An Interesting question
> 
> Hi Drew
> 
> Because a light stream is energy with a defined zero level and no
> (known) upper limit.
> 
> /gustav
> 
>>>> DWUTKA at marlow.com 30-03-2009 16:42 >>>
> ..  We measure brightness in units of light.  Why don't we measure it in
> units of darkness?
> 
> 
>