> Abraham Lincoln is said to have originated this joke:
>
>     X.  How many legs does a dog have,
>         if you call a tail a leg?
>     Y.  Five.
>     X.  Wrong!  _Calling_ a tail a leg doesn't _make_ it a leg.

I thought that was Mark Twain.  No matter...

> An object can respond to a #mass message, but it can do that as
> often as you please, and it still will NOT have physical mass.

Really?  All my objects have some representation, be it electrons in a 
computer, graphite/ink on paper, etc.  So they all possess mass.

> Again, just because an object SAYS it has a volume doesn't mean it
> DOES have a volume.

See above...

>  I'm not sure whether you are confusing
> *talking about* properties with actually possessing them
> (but no matter how often I _say_ "I have $1000000" it still isn't true)

That was the funny thing about the new-economy bubble:  there it 
was/became true.

> or whether you are confusing *simulating* properties with actually
> possessing them (but not matter how often I *pretend* to have a
> million dollars it still isn't true).

Good thing you used money as an example, because money is just such a 
fiction.  It only exists / has value because everybody (or a 
sufficiently large percentage) has agreed to pretend that it does have 
value.  If people stop pretending, it loses its value.  Same with 
banks.  They (can) only work because people believe that they work.  If 
people stop believing, there is a run on the bank and the bank fails.

So the distinction is not nearly as clear-cut as you make it out to be, 
pretending and reality can be closely related, or even very much the 
same thing.

>
> 	> do not emit or absorb photons (so don't have colour);
> 	
> 	Any in the rainbow, or in any spectrum::
> 	
> 	Transcript show: myColourfulObject color.
> 	or
> 	myColourfulObject emitPhoton.
> 	
> The computer's screen can emit real photons.
> An object in the image can only talk about or simulate emitting
> photons.

Really?!  Now it seems to me that my morphs emit photons very nicely.  
True, they use the computer's screen to do this, but this doesn't 
really make a difference, does it?  I mean, we generally think of 
ourselves as talking to each other even when there are implements 
inbetween, such as a telephone.

> Was it Drew McDermott who wrote "Just because your AI program has
> a procedure called UNDERSTAND that doesn't mean it understands
> anything."

But just because it has a DNU handler doesn't mean it doesn't 
understand... ;-)

> The whole POINT of simulation is that it is NOT REALITY, only LIKE it.

Hmm...I though the POINT of simulation is that it is a LOT like 
reality, particularly in the aspect you are interested in.  And such 
'simulations' are also part of reality, and can interact rather 
forcefully with it.

> And my point is that vast amounts of computation are not about
> simulating the physical world, so that for lots and lots of objects
> there is no point in even trying to simulate physical objects.

Hmm...I am not sure about that conclusion, and I actually think you are 
completely missing the point about a lot of OO.

Just like high-level languages, OO is not necessarily about the 
problem, and certainly not about the computer.  The problem and the 
computer would be just as happy with bit-sequences toggled directly 
into the console.  However, giving a textual representation makes it 
easier for *humans* to deal with the problem.  And so do objects.  So 
even if the problem itself is not about objects in the physical world, 
it can still make a lot of sense to 'simulate' objects with 
characteristics like the those in the physical world in order to make 
it easier for humans (programmers / users) to deal with the problem.

Marcel

-- 
Marcel Weiher				Metaobject Software Technologies
marcel at metaobject.com		www.metaobject.com
Metaprogramming for the Graphic Arts.   HOM, IDEAs, MetaAd etc.