From:	David Woods <david@*******.FREESERVE.CO.UK>
Subject:	Re: thermographic vision-question
Date:	Tue, 2 Feb 1999 23:20:00 +0000

David Buehrer wrote:
>
> For the mere cost of a Thaum, David Woods wrote:
> /
> / Perhaps I'm thinking of Predator II. That film had the alien looking
> / through wombs to see foetuses.
>
> ...oh yeah. Okay, you're right. That was pretty bogus.
>
> And another thing that was bogus was the fact that the Predators hunted
> during the hot season based on the idea that they came from a hot
> world. I'm sorry, but I don't think thermographic vision would evolve
> in a warm environment. It would probably evolve in a cold environment
> that would let you see your warm-blooded targets standing out against a
> cold background.

If irrc there are snakes with recessed pits containing IR sensitive
cells. They use them to sense small mammals. I'm not sure, but I think
they live in jungles.

Generally speaking an IR sensor has to be at a lower temperature than
the target. Modern passive IR cameras use semi-conductor devices that
break this. It's hard to imagine how a biological system could do
something similar.

Since Mother Nature hasn't come up with anything close to SR Thermo
Vision, it's probably impossible. Magic is a wonderful thing.

> In a hot environment critters don't have to expend as
> much energy to keep warm and would fade into the background, or
> cold-blooded critters (like lizards and snakes) would be damn near
> invisible.

Of course as I mentioned previously, with enough thermal resolution,
objects can be picked out even at ambient temperature.

- David Woods