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D&D 3E
Physics help 
25th-Jun-2009 02:09 pm
I've got a subterranean lizard-type race in a game that I've just introduced and I'm thinking of having an interesting method of vision for them. Instead of seeing in the visible light spectrum, they see radioactive wavelengths, specifically ionizing radiation such as gamma rays, x-rays, and ultraviolet. Objects that emit or reflect radiation are viewed as bright and objects that absorb it are viewed as dark (the more reflected/emitted and the more absorbed, the lighter or darker it appears).

In their normal habitat, the natural stone provides plenty of low-level radiation that allows them to see in that environment as if in bright daylight. Obviously, when travelling outside of this terrain, they will want to take with them a mildly radioactive substance as a "lantern" (they are more resistant to radiation than other species).

The primary benefit is that they would be able to somewhat see through any material through which radiation will pass, which means that it will be harder to hide from them. Also, it means that they could see in pitch black, given the right "light source".

What limitations can you foresee? I'm pretty sure a vision mode like this means that the race would not even be able to see something like a computer monitor or television (Bit of a long story on why this is relevant. In summary, there's an advanced alien species in my game that periodically experiments on the party by abducting them and forcing them to fight strange creatures and species that were also abducted. The party doesn't know it yet, but most of the dungeons they have gone through are purely mental simulations).

I'm asking this because I'd like to make them a playable race, but my knowledge of radiation is limited. I don't just want to give them darkvision and be done with it.

EDIT: I think I am going to include a cheap magic item that "translates" visible light into a form visible to the race. This should help overcome any of the major problems.
25th-Jun-2009 02:43 pm (UTC)
How far/near into the UV can they see? For one, even normal glass is a lot more opaque to UV. So is water. More penetrating radiation would get farther in, but it does interact with matter. There probably would be a distance delineation.

There's a lot of difference between near-UV (which some insects use) and gamma rays -- about as much as the difference between near-UV and far infrared. UV to gamma rays is a very broad range.

They also would have problems seeing surface features of things, except maybe using the wavelength as depth -- UV only penetrates your skin, while gamma rays can go straight through you. Writing of other races might as well not exist unless they use special dyes, or they see close enough to the visible range to pick up on the dye.
25th-Jun-2009 03:03 pm (UTC)
Ooh, writing, I didn't think about that. That bars things like scrolls from them and I don't want to do that.

I do know that a term like "radiation" is tricky to pin down. Radiation includes things like light, radio waves, microwaves, etc.

Mostly I'm meaning that they see in the form of radiation emitted by something like uranium. Wikipedia is what suggested that this is called ionizing radiation, which includes UV and gamma rays. Maybe I misunderstood the article.
25th-Jun-2009 03:16 pm (UTC)
Uranium generally emits alpha particles (high-speed helium nuclei) and gamma radiation. While UV is ionizing radiation, it's not generally emitted by radioisotopes. Normally, you get gamma rays, and maybe X-rays. UV is usually still in the energy rage where it's emitted by atoms/ions, not nuclei.

Your race could probably use a radioactive mineral in their dyes to read/write things. It would mean that anything not written with them in mind would be hard to make out -- think like invisible ink. Or else you could say that scrolls in your setting need to use a radioactive source, or the magic bound in them allows them to be read by anyone with a written language.
25th-Jun-2009 03:00 pm (UTC)
awesome concept.

i forsee a problem with depth perception, as well as walking into materials that pose no hindrance to radiation,a nd so wouldn't show up for the creature.
25th-Jun-2009 03:05 pm (UTC)
I'm thinking that the creature still perceives this, as the radiation is still hindered in some way. Basically, the same as humans seeing through glass. Unless it's exceptionally clear, we know the glass is there.
25th-Jun-2009 03:07 pm (UTC)
more like flesh. you an x-ray you can't see the flesh, so they will have a fun time walking into gelatinous cubes and other boneless beings.
(Deleted comment)
25th-Jun-2009 03:12 pm (UTC)
yea, and a negative to spot boneless creatures.
25th-Jun-2009 03:15 pm (UTC)
Depends...what happens if you X-ray a creature with an endoskeleton? I can see it for something like a gelatinous cube but I don't want that to extend to something like, say, a giant wasp.
25th-Jun-2009 03:17 pm (UTC)
that creature counts as having bones, they are just on the outside.

i would also give a negative to spot most thin objects, such as cloth and paper. they may resist x-rays a slight bit, but something that would be comparable to that is a human passably noticing a smooth piece of saran wrap. It's just more difficult.
25th-Jun-2009 03:13 pm (UTC)
Yet if you X-ray a bare skeleton, it is a much clearer picture. The flesh is translucent to it but not invisible. The species would still know that something is there that is even mildly absorbing radiation.

But you bring up an interesting point. This species would view living creatures mostly as skeletons and organs with a rough 3-D outline of its physical form. Might give them a bonus to Heal checks for that.
25th-Jun-2009 03:16 pm (UTC)
Bleh. This post goes up there. I deleted and re-posted to correct a word confusion on my part.
25th-Jun-2009 03:38 pm (UTC)
Maybe it's the gamist inme, but I'd suggest stepping back from the physics for a second and trying to figure out what kind of mechanics you're looking for.

Do you want it to act like normal sight, except that the "light source" needs to be a special kind of lantern? You could do that, and then just specify whenever necessary whether the creature has appropriate lighting or not. That might be easiest--"This room is well lit, both with normal light and radiation-light" or "This room is dark, but is considered dim-light for radiation". This would be somewhat simple to run (all normal rules apply), but requires you to do basically double the work. It also means you could get around writing and stuff by having ink just happen to contain slightly different kinds of radiation, etc.

Other options are to look at stuff like Blindsense/sight and Scent, and see if you want to grab one of those style mechanics for dealing with this. Check out the Grimlocks for a possible template.

Are you actually expecting your players to want to play this race? Cause if not, you might not need to worry about it, and just let the bad guys see or not see as required for the story :)
25th-Jun-2009 03:48 pm (UTC)
Very true, and this is actually how I plan to run them. But if one of my players happens to know a lot about radiation, I want to be able to know how this works. Even if none of my current ones do, this is my game world that I always play in.

Besides, all of the things brought up so far have created an interesting idea of describing what the vision makes things look like.
25th-Jun-2009 04:10 pm (UTC)
Actually, unless you're planning a science-fiction crossover, I'd suggest not getting too technical about hard-science stuff like ionizing radiation. This will let you avoid two big problems:

1) This is more knowledge than your players need to have (or should have) so you're doing way more work than you have to do. Their characters would not understand something like radioactivity anyway. (Even Marie Currie didn't understand it when she first found it, which is why she died young!) The characters would just see that some rocks (ones containing radium) have a soft "magical" glow. They would eventually discover that these rocks were "poisonous", and prolonged exposure caused a "sickness".

2) Unless you are playing only with very young children, you will eventually run across someone who knows more about radiation than you do. They will notice any details you've gotten wrong, which will really undermine the overall veracity of your campaign. It is unavoidably awkward when your players know more about how your world works than you do.

Instead, I'd recommend just inventing a new kind of Dark Vision. Members of your new race might call it "seeing the spirit rather than the flesh", or "knowledge of the Inner Light". You can still model it on radiation, but now you aren't locked into making the exact science work. So, if you predicate some aspect of your campaign on a detail that later turns out to be wrong, you won't have to backtrack and try to figure out a way to make it work. Also, you won't ever run across anyone who tries to Rules-Lawyer you because they know (or THINK they know) more about ionizing radiation than you do.

- Charles Carrier,
Olde-School Grognard
25th-Jun-2009 04:43 pm (UTC)
1) Did you know that radioactive things don't glow? The Straight Dope: If you were radioactive, would you glow?

2) You are right about taking a step back and being vague about how it works. I doubt they will call their vision mode anything but regular vision, for the same reason humans don't call our vision Lightseeing or something: We don't have another vision form which would necessitate naming to avoid confusion.
25th-Jun-2009 06:00 pm (UTC)
While most radioactive stuff (including organic matter) does not glow, radium actually does glow - it emits a blue light. Also, phosphorescent minerals in the rock with the radioactive material will glow, so a radioactive cave could provide quite a light show.

For a little information on radioactive stuff that does glow, check here:
27th-Jun-2009 02:51 pm (UTC)
Maybe they have different eye sheath coverings for different wavelengths that they can change lightning fast. If they ever get to a part where there is a lot of light you can see the sheaths as they look like the color that people associate the radiation with, Ex: Gama as a green film etc...

Is that Nixon hugging a ham?

For some reason that struck me as hilarious this morning,
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