🚀 go-pugleaf

In article <dwarner.18@milo.ub.com> dwarner@milo.ub.com (Dave Warner) writes:
>
>Okay, so suppose the existance of an object that does not emit or reflect 
>anything in the visual spectrum.  The object is not transparent or 
>translucent.  Let the object assume the mass and dimensions of a 4 x 8 sheet 
>of marine plywood.
>
>What does it look like?

a 4 x 8 sheet of marine plywood painted matt black.  Next.

								-- K.

In article <dwarner.18@milo.ub.com>, dwarner@milo.ub.com (Dave Warner) writes:
=
=Okay, so suppose the existance of an object that does not emit or reflect 
=anything in the visual spectrum.  The object is not transparent or 
=translucent.  Let the object assume the mass and dimensions of a 4 x 8 sheet 
=of marine plywood.
=
=What does it look like?

It looks like a black body attached to a 0K heat sink.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.

The object would look like a 4 x 8 rectangle of absolute blackness.

-----------------------------
random punchline of the day:
"The theoretical physicist says, "Ok, assume we have a can opener..."
----matt
mrice@eniac.seas.upenn.edu

dwarner@milo.ub.com (Dave Warner) writes:


>Okay, so suppose the existance of an object that does not emit or reflect 
>anything in the visual spectrum.  The object is not transparent or 
>translucent.  Let the object assume the mass and dimensions of a 4 x 8 sheet 
>of marine plywood.

>What does it look like?

If it is non-reflecting, it cannot also be non-emitting UNLESS it is
cooled to absolute zero.  In that case, you wouldn't see it for the
layers of frozen oxygen, nitrogen, carbon dioxide, and water that
would quickly form on it.

If it is a perfect absorber, then at any temperature above absolute
zero it will radiate some light.  But if it is at room temperature
(or not too much warmer than that) this radiation will be invisible
to the human eye, and it would look like a sheet of plywood painted
matte black.

Dave Warner (dwarner@milo.ub.com) wrote:

>Okay, so suppose the existance of an object that does not emit or reflect 
>anything in the visual spectrum.  The object is not transparent or 
>translucent.  Let the object assume the mass and dimensions of a 4 x 8
sheet 
>of marine plywood.

>What does it look like?

1 x 4 x 9 looks much nicer... 8-)

--
Geoff, Sysop Equinox (equinox.gen.nz) +64 (3) 3854406 [4 Lines]
                               Voice: +64 (3) 3852101
        "Hi. You have just entered the fourth dimension. Small isn't it?"

In article 18@milo.ub.com, dwarner@milo.ub.com (Dave Warner) writes:
>
>Okay, so suppose the existance of an object that does not emit or reflect 
>anything in the visual spectrum.  The object is not transparent or 
>translucent.  Let the object assume the mass and dimensions of a 4 x 8 sheet 
>of marine plywood.
>
>What does it look like?
>

It is black, like my heart.

:-)

> Non-reflecting object: visual appearance? (Shaped like a 4x8 sheet 
of marine plywood.)

If held against a white sheet; a *black* 4x8 sheet of marine plywood.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Brian Milner, The Computer Centre, Brunel University , West London, UK   |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|brian.milner@brunel.ac.uk | Failed films #27 -  The Sound of Mucus       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Or, empty space. Once when it was necessary to have a very
dark background for some high-speed flash photography, we
waited until night and used an open window as the background.
It worked great. Of course, it's necessary that there be no
light sources or nearby objects (anything is a potential 
reflector) visible through the window; what constitutes a 
source or "nearby" will depend on your application.

In article <schumach.725151168@convex.convex.com>, schumach@convex.com (Richard A. Schumacher) writes:
>Or, empty space. Once when it was necessary to have a very
>dark background for some high-speed flash photography, we
>waited until night and used an open window as the background.
>It worked great. Of course, it's necessary that there be no
>light sources or nearby objects (anything is a potential 
>reflector) visible through the window; what constitutes a 
>source or "nearby" will depend on your application.

I'm afraid that "empty space" is anything but.  Were your claim even close to
accurate, there'd be a lot of astronomers out of business.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.

carl@SOL1.GPS.CALTECH.EDU (Carl J Lydick) writes:

>In article <schumach.725151168@convex.convex.com>, schumach@convex.com (Richard A. Schumacher) writes:
>>Or, empty space. Once when it was necessary to have a very
>>dark background for some high-speed flash photography, we
>>waited until night and used an open window as the background.
>>It worked great. Of course, it's necessary that there be no
>>light sources or nearby objects (anything is a potential 
>>reflector) visible through the window; what constitutes a 
>>source or "nearby" will depend on your application.

>I'm afraid that "empty space" is anything but.  Were your claim even close to
>accurate, there'd be a lot of astronomers out of business.

Why?

In article <mcampbel.725383855@eola.cs.ucf.edu>, mcampbel@cs.ucf.edu (Mike Campbell ) writes:
=carl@SOL1.GPS.CALTECH.EDU (Carl J Lydick) writes:
=
=>In article <schumach.725151168@convex.convex.com>, schumach@convex.com (Richard A. Schumacher) writes:
=>>Or, empty space. Once when it was necessary to have a very
=>>dark background for some high-speed flash photography, we
=>>waited until night and used an open window as the background.
=>>It worked great. Of course, it's necessary that there be no
=>>light sources or nearby objects (anything is a potential 
=>>reflector) visible through the window; what constitutes a 
=>>source or "nearby" will depend on your application.
=
=>I'm afraid that "empty space" is anything but.  Were your claim even close to
=>accurate, there'd be a lot of astronomers out of business.
=
=Why?

Well, the original question dealt with what a perfectly black object would look
like.  Now, though for a photographer the view out an open window might look
"black," to an astronomer (remember, these guys deal with exposures on the
order of HOURS), there's LOTS of light out there.  Hell, even for combat troops
with passive night-vision goggles, there's lots of light out there.

And that's not even considering the infrared.
--------------------------------------------------------------------------------
Carl J Lydick | INTERnet: CARL@SOL1.GPS.CALTECH.EDU | NSI/HEPnet: SOL1::CARL

Disclaimer:  Hey, I understand VAXen and VMS.  That's what I get paid for.  My
understanding of astronomy is purely at the amateur level (or below).  So
unless what I'm saying is directly related to VAX/VMS, don't hold me or my
organization responsible for it.  If it IS related to VAX/VMS, you can try to
hold me responsible for it, but my organization had nothing to do with it.