On ray shields and their transparency

[Zor]

This is a general observation that involving shields that am suprised that people have overlooked.

Lets take the starship Enterprise (please not note that this applies to a variety of other sci-fi series where shields are used as well, i am just using Trek as a general reference point) as it floats through space with her shields up. Now imagine you are in a spacesuit and are floating in space as it goes by, by everything that has been established about these spacecraft is that you can see through these craft's shields. To get into more detail, light is reflecting off the Enterprise's hull towards your eyes. Now lets take a spacecraft comes in and fires at the enterprise a laser cannon and the enterprise is with a beam of highly focused and intence light, the same type of electromagnetic energy which passed through the shields TWICE when you take a causal glance at it. If a ship had ray shielding up, what it should look like is an opaque bubble, but as it stands it looks like that apparently the exact oposite of the Infamous "No Lasers" argument would happen if a Laser Beam was fired at a spacecraft with shields up.

Has this ever been adressed in fluff?

Zor

[Stormin]

When it is addressed (can't give specific examples, was a long time ago) it's usually passed off as the shields blocking the higher energy of weapon-strength light.

Back when I did a little bit of writing I had weapons that took advantage of how the ship behind the battlescreens would need to see out so the lasers were built to shift a wide range on the spectrum instantly.

[Ender]

You want a shield to be transparent to longer wavelengths so your sensors work - if radar is absorbed, and IR can't get through how will you see? And you only need to block the shorter wavelengths, E=hv and v=c/lambda, so E=hc/lambda. Raise the energy of the laser you raise the energy of the photons, which since c and planck's constant are, you know, constants, means lambda needs to go down.

So shields being invisible to long wavelengths and opaque to short wavelengths is perfectly sensible.

[Lord of the Abyss]

Another possibility is that the shield is transparent to non-coherent energy, but reflects or absorbs coherent energy like lasers. There are real world materials like that.

[Ender]

Another possibility is that the shield is transparent to non-coherent energy, but reflects or absorbs coherent energy like lasers. There are real world materials like that.

That would mean that it wouldn't stop things like nuclear explosions

[TheLostVikings]

Another possibility is that the shield is transparent to non-coherent energy, but reflects or absorbs coherent energy like lasers. There are real world materials like that.

That would mean that it wouldn't stop things like nuclear explosions

I guess that is technically forgivable as you will hopefully see them coming. Unless the enemy have relativistic missiles, then you are indeed screwed.

[Uraniun235]

I remember reading a short story about a space battle which actually grappled with this issue - the shields blocked incoming light and radar, so ships had to rely on scout boats and extendable sensor arrays, and hope that your antennas weren't all burned off before the other ship's were (and also hope that the other ship didn't pummel your shields into total collapse first).

[Stormin]

http://en.wikipedia.org/wiki/Langston_Field

Sounds like this, from Jerry Pournelle's works.

[Lord of the Abyss]

Another possibility is that the shield is transparent to non-coherent energy, but reflects or absorbs coherent energy like lasers. There are real world materials like that.

That would mean that it wouldn't stop things like nuclear explosions

Well, yes. But the OP did use the term "ray shield", which implies resistance to, well, "rays". Not bombs. And it would still be useful, even if you don't have a second type of shield that stops matter; you can shoot down missiles, unlike lasers.

[Mad]

That would mean that it wouldn't stop things like nuclear explosions

Well, yes. But the OP did use the term "ray shield", which implies resistance to, well, "rays". Not bombs. And it would still be useful, even if you don't have a second type of shield that stops matter; you can shoot down missiles, unlike lasers.

A nuclear explosion would emit gamma radiation. Or, rays.

[Lancer]

That would mean that it wouldn't stop things like nuclear explosions

Well, yes. But the OP did use the term "ray shield", which implies resistance to, well, "rays". Not bombs. And it would still be useful, even if you don't have a second type of shield that stops matter; you can shoot down missiles, unlike lasers.

A nuclear explosion would emit gamma radiation. Or, rays.

A nuclear explosion wouldn't be stopped by ray-shields that worked by blocking coherent radiation.

[Uraniun235]

http://en.wikipedia.org/wiki/Langston_Field

Sounds like this, from Jerry Pournelle's works.

Yeah, that was it.

[Mad]

Well, yes. But the OP did use the term "ray shield", which implies resistance to, well, "rays". Not bombs. And it would still be useful, even if you don't have a second type of shield that stops matter; you can shoot down missiles, unlike lasers.

A nuclear explosion would emit gamma radiation. Or, rays.

A nuclear explosion wouldn't be stopped by ray-shields that worked by blocking coherent radiation.

True, but that has nothing to do with Lord of the Abyss' argument.

[Ford Prefect]

It seems fairly ovious that he is suggesting that 'rays' is a word here that implies 'coherent beam weapons', and you are being a pedantic ass.

[Batman]

I find it much more likely that Lord of the Abyss thought bomb=matter thus ray shields don't figure into it, really. And sorry, Mad is right.
Lord of the Abyss doesn't get to redefine radiation just so his conception of ray shields works.

[PunkMaister]

Aren't' ray shields the ones used in Star Wars to trap Anakin and Obi Wan?

[Nyrath]

The earliest example of a "force field" in SF that I am aware of is William Hope Hodgson's The Night Land (1912)

However, the second earliest that I know of is in E.E. "Doc" Smith's THE SKYLARK OF SPACE (1928). In that, "ray screens" stop deadly weapon beams, but have no effect on material objects.

"Attractor" rays pull material objects closer and "repulsor" rays push material objects away (this later appeared in ST:TOS under the name "tractor beams"). Repulsor ray projectors were specially treated pieces of copper. So bands of such copper were placed around one's spacecraft to create a "repulsor field." This provided protection from missiles, shells, and other material weapons.

[Cykeisme]

Is a non-coherent directed energy weapon physically inconceivable?

If it was possible, then the hypothetical shields (that block only coherent em radiation) would not prevent the passage of such a beam..

[Teleros]

As I understand it, the point about laser beams being coherent is so they don't look like flashlights - ie all the energy goes from emitter to target with the minimum possible lost. I suppose you could make a really powerful flashlight, but it'd be horribly inefficient, never mind whether or not it worked against such shields.

[Fingolfin_Noldor]

Is a non-coherent directed energy weapon physically inconceivable?

If it was possible, then the hypothetical shields (that block only coherent em radiation) would not prevent the passage of such a beam..

No. Because the beam quality of such a laser weapon would be so bad that the dispersion rate will weaken the beam by the time it arrives at its target.