The SCIENCE of Green Lantern: Embracing the Yellow

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.

Doppler who?
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!


Ryan Haupt hopes he made sense. Hear him keep trying to be understood on his podcast Science… sort of. (WARNING: Listening while jogging may cause Doppler shift.)


  1. Intriguing as always, Ryan. As a scientifically challenged amatuer writer, your columns always make me realize how handy a tool science can be when writing capes and tights comics. It’s a well that I feel too few writers tap into (with the exceptions of Morrison, Ellis, Hickman, etc.).

    Your idea of Mogo as the only color-shifting lantern holds tremendous story potential IMO. Just like the possibilty of the Blob’s hypothetical second mutation from a few weeks ago. I haven’t been able to get that idea out of my head.

    Particularly when it comes to power sets and space operas, science can expand and enrich the environment these characters dwell in. With the ability to control gravity in all directions, Blob could go from the last villain to get picked for dodgeball to a Magneto-level threat. And with the ability to change between colors and abilities, Mogo could become an even greater asset to not just the GL Corps but all the corps. There’s definitely a story there.

  2. Here’s my thoughts on the subject. Any interior designer can tell you that the definition of “yellow” could be either very broad or very strict, depending on your own opinion (or gender — just kidding!). So if something is just “yellowish” does the impurity apply?

    Remember in the JLA story “Tower of Babel” where Kyle is hypnotised into thinking that he’s blind, and the Ring makes it so because his own subconscious, tempered by his willpower, believes it to be true? I think the yellow impurity works kind of the same way. Whatever the individual Lantern considers to be “yellow”, the Ring is ineffective against.

    That was also my theory about how the impurity worked in the first place. Yellow isn’t inherently immune to the Power Rings; the Lanterns just think that it is, and thus the Rings make it so, because they react to the Lanterns’ willpower and imagination. This could be something placed into the Lanterns’ minds by Parallax upon recruitment; like a self-fulfilling prophecy.

    This would explain why, in Geoff Johns’ Green Lantern: Secret Origin, Hal is capable of affecting that yellow bulldozer: In a moment of anger, he isn’t considering the impurity and thus it does not translate into the Ring.

  3. RapidEyeMovement….you are my hero. That is an awesome no-prize theory!

  4. OK, I’m confused. Wasn’t this already explained in the books? First, I don’t think Kyle overcame anything, his ring was never affected by yellow so he never had to worry about that limitation. This was later explained by Geoff Johns as being because Parallax had already been released from the power battery by the time Kyle got his ring. It wasn’t actually the color yellow that affected the rings but the concept of what yellow represented in the entity of Parallax that was the cause. Which is why now that they know about Parallax and the impurity they can over come it. Which to me, was a great explanation to what was always a stupid rule.

  5. This is one of those moments I want to…gloat?  Well, perhaps not gloat, but I would sure like to feel special.

    @Ryan, look again at your Dr. Light article, and you’ll notice my comments from last August about this very Green Lantern story.  Oh yeah, I’m the cool one!! Oh yeah! Oh yeah!  I’m a science comic geek!  🙂  LOL!


  6. @RapidEyeMovement 

    I don’t know if you’ve read the story about F-Sharp Bell?

    It’s an Alan Moore Green Lantern story about a new recruit from a species who has no “sight“, and thus the recruit doesn’t understand the concept of color or even know what a “lantern” is.

    So he thinks of his ring as a sound generator, specifcally F-Sharp, and thus instead of being a Green Lantern, he’s an F-Sharp Bell.

    This of course opens a whole can of strangeness, since sound isn’t like light.  Sound is matter vibrating, and thus is F-Sharp okay with yellow, but he’s powerless in the void of space

    Don’t forget, HYPER-CONTINUTITY applies!  🙂


  7. @powerdad  Well I’ll be damned. Bravo, good sir.

  8. I have no idea what this article is about.

  9. It’s about “What does star color can tell us?”

  10. Okay, now I’m curious.  Does Green Arrow have any “paint arrows“?  I would imagine during the time Lantern and Arrow were hanging out together a few black or purple or red or anything-other-than-yellow arrows would really have helped the cause. 

    Okay, thinking about the “paint arrow” question, I found myself writing this little dialog between Green Lantern and Green Arrow in the vein of how a silver age story should have dealt with this.

    “Look, Green Arrow, there is an alien YELLOW robot from outer space destroying the city! But I can’t do anything to it because its YELLOW!”

    “No problem, Lantern!  Although my arrows by themselves would be pointless against that menace, my [some color other than yellow] paint arrow will allow you to take care of it!”


    “Thanks, Arrow!  By working together we saved the day!  Now it’s time for a big glass of milk and a plate of freshly baked cookies!”

    “Hurray! Great idea, Lantern!  And after that we can go read to the blind children at the local orphanage.”

    “And after that, Arrow, I can see about recruiting severely COLOR blind individuals to become lanterns. That way they won’t know if something is yellow, and thus they’ll never be powerless to it!”

    “Fantastic, and after that, I’ll buy you a pair of [some color other than yellow] colored glasses, making it so you’ll never be able to see the color yellow again in the course of combat, and thus you’ll never be powerless again!”

    “What a great idea, Arrow! But first, milk and cookies!”

    (This silver age story was brought to you by the color Green, and the letter F.)

  11. @Haupt  Hey, bravo to you for writing this great article!

  12. @powerdad  I am indeed familiar with Rot Lop Fan and, if my idea is correct, then he would be able to affect yellow, since he would have no idea what it is.

    However, your coloured glasses idea renders my theory null. Unless of course, the Guardians were just too pompous to allow the Lanterns to wear John Lennon specs. No THAT would have been an amazing story!

    (You have an excellent handle on Silver Age stories, by the by.)

  13. @RapidEyeMovement  I definitely like your idea. I seem to recall Frank Miller implied a similar one in All-Star Batman, when Batman was hypothesizing on why Green Lantern couldn’t affect yellow objects. Batman decided it must be some sort of mental block (or  something like that).

    The issue with the yellow color problem is more indicative of having an easily graspable “short-coming” for a character (or thing or situation). The rule of not being able to effect yellow is a nice one on the surface because it’s easy to state, quick to grasp, and easy to remember and thus recognize in the future. (When marketing a mass consumed product, these are often important sought after characteristics.) But it falls apart on more detailed and longer inspection, probably due in part to lack of thought at “design” phase.  (That’s just how things are sometimes.)

    This is like the problem with Lt. Commander Data on Star Trek: The Next Generation. He’s an android who can speak all sorts of languages, but is unable to form contractions when he speaks American-Style-Future-Space-English. So he can only say the more formal versions of “is not”, “they are”, and “cannot”, instead of “isn’t“, “they’re“, and “can’t“; just to name a few.

    His short coming is easy to communicate (“Hey, he can’t use contractions“), easy to understand, easy to remember and recognize. And I can completely understand why they would want this too, because it demonstrates to us in the audience that with all his computing power, his physical abilities, and whatever; he still can’t do something as simple as a contraction. (No wonder this guy wants to be human.)

    Unfortunately the whole “contraction problem” falls apart on closer inspection, because if Data really wanted to contract “cannot”, he just needs to say the last name of the German philosopher who wrote Critique of Pure Reason while speaking in a Southern American accent.