If you’ve been keeping up with Green Lantern (and I’m sure many haven’t, so SPOILER WARNING) Geoff Johns has recently reintroduced the yellow impurity. This originally was the idea that the Green Lantern’s couldn’t affect anything colored yellow. This limitation was overcome by Kyle Rayner and later explained as an impurity within the power battery caused by the entity Parallax. The reintroduction surprised me, and being surprised is in and of itself a pleasant surprise is modern comics. But I mostly surprised because of the upcoming film. The way I see it, there’s no way a major motion picture would ever deign to include something as silly as a weakness to the color yellow, so reintroducing this concept to the comics seemed a bold move at best and foolhardy at worst. Regardless, it got me thinking. Just what is ‘yellow’? How limiting is that limitation? Time to turn on the science brain and figure this conundrum out!
What is color?
Color as perceived by the human eye is just a specific wavelength of light in the visible spectrum. Light extends far above and below what our eyes can see, as detailed in a long ago column concerning the powers of Dr. Light. And while I think it’d be pretty cool to have an Infrared Corps (emotion: inner rage), X-Ray Corps (emotion: honesty, nothing to hide) and a Ultra-Violet Corps (emotion: stoned) that’s not really the point I’m driving at in this article. What I really want to talk about is the fact that color is not static… sort of.
Has is been done before?
In the interest of full disclosure, when I first had this idea I thought it was new and unused. Looking into it a little further I found that Larry Niven and John Byrne had employed the idea I’m about to flesh out in their book Ganthet’s Tale, which I stumbled across at Kotaku. I haven’t picked up the book yet because it’s out of print but I’d be curious to see how they handled it after I use my iFanplatform to flesh out my own thoughts. Here goes.
Light, like sound, can be Doppler shifted. The way a lightsaber swooshes or the way an emergency vehicle sounds different coming at you versus going away from you are both examples of the Doppler effect. If the source of a sound (in this case the emergency vehicle) is moving towards the receiver (aka you) then the sound waves are seemingly compressed, whereas if the source is moving away from you they sound waves seem to stretch out. This is one of those really cool physics concepts that I simply cannot do justice to on a comics website so I encourage you to scope out some other sources, even the Wikipedia article is pretty well fleshed out.
What does star color can tell us?
At astronomical (i.e. cosmic) scales, the color of stars can indicate relative motion. In this case, the wave in question is light, not sound, so instead of hearing something different the observer sees something different. In the case of stars, a star moving away from earth is redshifted, whereas a star moving towards earth is blueshifted. Obviously it’s a lot more complicated than that, but the general principle is still good.
Members of various Corps should then theoretically be able to shift the color emitted from their ring relative to the observer. We know Oa is pretty far away, but travel between Oa and Earth with a ring seems like no big deal, so those rings must allow you to move very fast. With all that in mind, couldn’t Hal fly fast enough to make an observer see different colors coming out of his ring? I don’t see why not.
Example (Click image to embiggenate):
Hal wants to move a banana. With the impurity back he’d have a hard time moving said banana, unless he fired a beam at it from his ring while at the same instant he flew away from the banana fast enough to make that beam appear yellow to an observer standing behind the banana. Thus, the banana is moved. But that isn’t very convenient since Hal would be pretty far away from the banana by the time he moved it, so why not fly at the banana from very far way and move it when his light shifts? Because green would shift into blue, and as we all know blue lanterns can’t do anything without a green lantern around. I guess you could argue that Hal is his own green lantern and since the beam appears green to him as the source then maybe this would work, but I’m skeptical at best.
So why don’t the different Corps use this trick all the time during battles?
Well first of all it’d be a mess, it’s hard enough having the Indigo Tribe involved. But it’s also important to remember that we’re talking about the speed of light, which is no trivial thing. In a vacuum light travels a 3 x 10^8 m/s, that’s 300,000,000 meters every second! Fighter pilot or not, nobody’s reflexes are good enough in close quarters combat to think and react faster than light. (It’s actually a giant pet peeve that comic writers seem to love the phrase “faster than thought” which makes little sense, but that’s another article.) So for cosmic scale movements on very long time scales I can see this trick as being useful. The Guardians and Mogo could probably have some fun playing around with it, but I doubt it’s useful enough to be worth the trouble for the majority of the Corps.
So now a Green Lantern knows what to do if they want to ring sling against yellow. It's impractical and probably subject to some relativistic effects I'm going ignore for now. I think I can now safely read Ganthet's Tale and see if Larry Niven and I are operating on the same wavelength (Electro-Magnetic Spectrum joke!). How about you, iFanbase? Have you read Ganthet's Tale? If so, how'd I do? If not, are you now intrigued by the concept? If you're Geoff Johns, do you want a miniseries about Mogo as a rainbow lantern shifting around time and space? Call me!