RE: This is the best thing since sliced bread!

From: hal@finney.org
Date: Mon Jan 22 2001 - 23:21:25 MST


Denis Bider writes, regarding the stored light pulse:
> Might something like this eventually be used to produce a... Hollow Man?
>
> Or an invisible aeroplane? Or an invisible building?
>
> Photons could be absorbed at one side of the building, and the information
> carried over to the opposite side of the building, where the photons could
> be reproduced as they were.

An interesting speculation. A few problems with the experiment as it
is now are, first, the photons get captured in a gas, so I think you
would have to physically move the gas to the far side of the building
and then release it. And second, the freezing is of a discrete pulse,
so for continuous use you'd have to probably have a fast series of
pulses, storing each new "block" of light in a separate area of the gas.
I have no idea whether the current experiment could be adapted to deal
with these problems.

In a way this sounds more like Bob Shaw's "slow glass" described in some
of his stories including "Light of Other Days". Slow glass is glass
which light moves through slowly. This concept seems to resonate with
people and be remembered far more than you would think for such a simple,
even trivial, idea.

Back to invisibility, I've always loved the way the effect was presented
in the Arnold Schwarzenegger movie, Predator. Here Arnold plays the
leader of a band of mercenaries who, part way through their mission,
discover that they are being stalked and hunted by an alien using
super-advanced technology.

This includes a camoflage suit that makes the alien nearly invisible.
It works perfectly when he's holding still, but when he moves there
is a slightly noticeable shimmer. The implication was that the suit
took some time to react in terms of getting the emitted light to match
that which entered on the other side. This seems like a plausible
limitation of invisibility technology as well as making the alien much
more interesting visually as we gradually learn about his presence along
with the characters he is hunting.

Invisibility suits built with the technology Denis is describing might
have some similar properties.

Hal



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