Friday Ephemera
The Monster Wears Red

Quote of the Day (3)

I began my work at a time when invisibility was not fashionable at all.

Physicist Ulf Leonhardt, quoted here, in a piece noting how research into cloaking technologies has become popular and very nearly respectable. Needless to say, there are still one or two problems.

It’s difficult to find anybody in the know who expects there will ever be a device that hides itself and its contents at all wavelengths - if you can’t see it in visible light, then perhaps radar, infrared, ultraviolet or X-rays would reveal it. But optimism for practical uses is growing.

And there’s an issue I don’t recall being acknowledged in Star Trek

If a cloak were to make an object fully invisible to the outside world, then the outside world would be invisible to the object within the cloak. A thing (or person) inside a perfect cloak is not only invisible. It is blind.



Yes, that's certainly a potential real-world problem with cloaking fields and the like. The other one is the problem of waste heat... you do not want your cloaked starship's antimatter reactor to be visible on scanners after all, but if you can contain that heat instead, it'll be like living in a furnace :) .


How did the invisible man see? His retinas and lenses were invisible too.



“How did the invisible man see? His retinas and lenses were invisible too.”

I think Wells mentions something about Griffin’s experiment on an unfortunate cat, whose eyes remained partially visible. Maybe the same thing was supposed to have happened to Griffin himself?


Here we are...

“After I’d given the stuff to bleach the blood and done certain other things to her, I gave the beast opium... And after all the rest had faded and vanished, there remained two little ghosts of her eyes... The bones and sinews and the fat were the last to go, and the tips of the coloured hairs. And, as I say, the back part of the eye, tough, iridescent stuff it is, wouldn’t go at all... I remember the shock I had when striking a light - there were just the round eyes shining green - and nothing round them.”


An objection from a Trekker: the issue is actually acknowledged at least in TOS. In the Balance of Terror, the cloaked Romulan ship is unaware of and unable to track the Enterprise when running with its cloaking device enabled.


Counter objection from another trek(kie) . The Romulan ship COULD detect the enterprise but Kirk being the slippery customer that he was KEPT PACE with the Romulan vessel so deceiving them into thinking that the enterprise was merely a sensor 'shadow'. The Romulan ship was detecting them warts and all.

A Third Trekker

But what about cloaked Romulans not being able to see other cloaked Romulan or Klingon ships? Sooner or later wouldn't they smash into each other?


Hmm, that problem could be circumvented by having strictly agreed areas of patrol prior to going out for a spin.


Anyhow, the Captain of the Romulan ship was really Spocks father deep under cover as an agent of the federation so he was actually on our side and not a baddy.



You are somewhat right Jones, dismissing it as a sensor shadow seems to imply some sort of degradation of sensor performance when cloaked if perhaps not a complete blackout when cloaked. After all I assume that uncloaked a Romulan ship can scan things with sufficient detail to be able to distinguish a Federation vessal from a Klingon or Romulan vessal or just s shadow or anomaly. Otherwise they need to put some serious work into the quality of their sensors.




Hoping for technical consistency from "Balance of Terror" is a bit of a lost cause, since it was based on the novel The Enemy Below, where both ships used radar and sonar, and the writer never actually took the time to work out the physics of the cloaking device or its effect on sensors.

Regarding the problems of a cloaking device rendering the thing inside it blind: this depends on what kind of cloaking device, and what kind of sensors, you're talking about. The classic Romulan-type cloaking device renders an object invisible by bending light waves (of whatever wavelength) around it. This would certainly cause trouble for any sensor device that depends on incoming light waves. But sensor devices that use other methods of gathering information wouldn't be affected -- such as the "mass detectors" that both the _Enterprise_ and the Bird of Prey carry. You could also make the "light-bender" cloak less than 100% effective -- allow say, 5% of the light in and that might be enough for your own sensors, while still making outside sensors effectively useless.

But there are other ways of cloaking an object. For example, instead of a field that bends light, a 'one-way transparent' field: EM radiation can come through in one direction only. Light sensors are just electronic eyes, after all -- they work by detecting light that was reflected off an object. If the object isn't reflecting any light, a light sensor won't see it -- but sensors inside the cloaking field will still see the incoming light from Outside. There's also the "camouflage cloak" which detects incoming light on one side and projects an image on the other side that exactly matches what a sensor Over There should see if the ship wasn't in the way.

The problem of how to burn off trapped EM radiation is an entirely separate one. I've yet to see a good answer for it.

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