The next talent on the list is Superman's X-Ray vision. I always thought this was a ridiculous power that couldn't possibly happen in real life, but several biological examples, the cinematography of the movie, and a recent class I took about satellites and remote sensing has changed my mind completely. You just need to suspend your disbelief for a few minutes and assume that Kryptonians have evolved to have retinal cells that respond to nearly every wavelength of electromagnetic radiation. I'll lead in with some Earthly examples that show this to be biologically possible. First, bees have an extended visual spectrum that allows them to actually see UV light. We've named this color "bee purple," and plants have evolved together with the bees to take advantage of another visual cue they can use to attract pollinators. In the picture of a cucumber flower below, the left image is what we see, and the right image is a false-color composite of approximately what the bee sees. The bees have a slight trade-off in that they can't see as far into the red end of the spectrum as humans can. The mantis shrimp, on the other hand, compromises nothing! Well, that's a little bit of an exaggeration. They also don't see as well in the red end of the spectrum since that is the first wavelength absorbed by water, but have been found to adapt their vision when raised in shallower environments. They have a complicated vision system that may reach far beyond human eyesight nonetheless. Humans have 4 kinds of photoreceptors in our retinas (rods and 3 colors of cones). Mantis shrimp have 16. We can't even imagine what they see! The shrimp see many colors we can't detect, but due to their smaller invertebrate brains they can't actually tell apart colors as closely as we can. They just group light stimuli of several wavelengths into a single category like one shade of green if that group of receptors is activated. Still, this is an amazing sensory system which I'm sure leads them to appreciate their colorful appearance. Additionally, mantis shrimp have incredibly strong limbs that they use to crack mollusk shells (no easy task as anyone who tried to eat a closed clam can tell you). These punching pincers snap with the speed and force of a gunshot, which is so fast that it momentarily boils the water near them and creates heat and light! They are sounding more and more like Superman... Their power is only exceeded by the similarly pugilistic snapping shrimp. Another animal that takes more advantage of the electromagnetic spectrum for locating food is the pit viper. These snakes are so named for the pits below their eyes that sense infrared radiation. So no, these sensors aren't actually retinal, but they are integrated well enough into the brain that the viper can use this extra sense to find its prey. In some cool research going on at the Grace laboratory at the Florida Institute of Technology, they are blindfolding the snakes to get a better measure of their heat-sensing accuracy. Those are the biological limits of electromagnetic sensing, but mechanically we have come much further in extending our range of "sight." X-ray machines, heat sensors, and satellites take advantage of different wavelengths of radiation to give us another point of view. The advantage of using different wavelengths of light is that we can "see" deeper than the surface of an object. X-rays that look at our bones are the best example of this, and it's usually what you see Superman doing with his heightened senses: looking through surfaces. Different wavelengths can also show differences between objects that can't be seen in only visible light. The infrared heat-sensing image below shows a stark contrast between the warm-blooded human hand and room temperature lizard. We can easily distinguish humans from lizards in the light, but IR vision becomes more valuable in the dark. It's also useful when trying to tell apart objects that appear the same visually. There was an episode of Buffy the Vampire that showed members of the high-tech secret government organization called "The Initiative" using a heat sensor to pick out cold-blooded vampires from crowds of normal humans because outwardly they look the same. Well, as normal as you can be when you live on a Hellmouth... IR spectra are also handy for picking out differences in vegetation, like different crops, the health and moisture content of plants, or AstroTurf vs. real grass. In the left photo of the University of Wisconsin, Madison stadium, the football field is indistinguishable from the green grass and trees of the area. The right image, however, is a false-color composite where high IR reflectance is displayed in red (plants reflect a lot of IR so that they don't heat up). The trees and grass light up in red, but the turf of the stadium remains dark, showing us that it's not planted with real grass. One of the coolest applications of "seeing" other electromagnetic wavelengths would be if Superman could see radio waves. Then he would literally have radar! This suddenly makes his reckless flying through clouds seem much less reckless when you realize that he knows exactly what's on the other side since his radar vision penetrates the atmospheric moisture. So why was he de-powered when dragged into a ship with Kryptonian atmosphere? Why did Zod become overwhelmed with all of these super-senses only when his breather helmet broke and he was exposed to Earth's atmosphere? This can also be explained through the science behind satellites! Satellites are limited to using wavelengths of light that can easily penetrated the planet's atmosphere, especially since the signal has to travel through this boundary twice: first to reach the Earth's surface, then to bounce up to the satellite. Here's a diagram of what parts of the spectrum are the most absorbed by the atmosphere: It is no coincidence that the range we can see, visible light, is also one of the ranges least absorbed by our atmosphere. Animal eyes evolved to take advantage of this abundant, but not very damaging, radiation. So now I'm going to take the evolution proposition from before one step further: Kryptonians came from Earth, but then developed on a different planet where their eyesight had to evolved to see beyond visible light because it didn't penetrate very well, and only after that did they move on to colonize Krypton. On Krypton, the atmosphere was very dense, and blocked out almost everything except visible light. So the enhanced sight that had previously evolved became a vestigial trait that wasn't used until Kal-El came to Earth where more radiation was visible to him. This is a good explanation for his super hearing as well. If Krypton had a dense atmosphere, it is possible that sound didn't propagate very well, and hearing senses had to be more acute to pick up anything.
What I really enjoyed about the movie was Clark's struggles as a child to understand and control these enhanced senses. He has the equipment to see any wavelength of light, but he doesn't know how to focus it on just one part of the spectrum. Hence his vision becomes muddled with overlapping images of his skin, his bones, and his thermal signature all at once. It's an overwhelming experience for any kid! My only scientific qualm with the vision examples used in the movie is the trick he did of reading someone's ID badge through a one-way mirror AND through his pocket. Seeing people on the other side of the mirror would have been easy with IR or X-rays, but unless the name on the badge is written with a radioactive tracer or something special, there's no way Clark should have been able to read it. The letters are only distinguishable with visible light, and those wavelengths simply will not propagate through cloth or mirrors. Nice try, alien.
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I'll start by saying that I really enjoyed watching the new Man of Steel movie! It was a very immersive experience, and I thought the character of Superman was explained better both physically and psychologically than previous adaptations had done. So the next series of posts are going to be a breakdown of how some of his amazing power can be made possible! Before we start, SPOILER ALERT: Superman saves the day! Let's start with his most obvious feature: super strength. For this, I'm going to cite James Kakalios' The Physics of Superheroes. He goes through some basic calculations in the first chapter and concludes that the planet Krypton had a force of gravity 15 times greater than that of Earth acting on the inhabitants, so Clark's Kryptonian body is adapted to withstanding much stronger forces than humans usually encounter. The chapter goes further to explain that this increased gravity can be caused by super high density neutron star matter at the core of the planet. Even better, this neutron star core would bring about the instability that caused Krypton to collapse just after baby Kal-El was shot into space! It is reasonable to think that Superman's DNA was wired to build a body with incredibly strong bones and muscles, but some will cite the counterargument of "Use it or lose it" in protest. Sure, Clark probably did not reach his full strength potential at first since his muscles wouldn't have overdeveloped in the weaker gravity field. Still, he would have been born naturally stronger than other kids, and once he realized that he probably started bench-pressing farm equipment to build up his body. What else would you do if you were an awkward super-powered adolescent? The super strength explanation spills over into a discussion of his flight powers. Super strong legs is the only explanation needed for the original Golden Age Superman that was "able to leap tall buildings in a single bound" because that was all he got: one bound. This style of flying is similar to the Hulk's galavanting around NYC in The Avengers. There was a subtle homage to this early Superman description in the Man of Steel movie when Kal-El is first testing the limits of his powers after discovering his true identity. He starts flying by making really really big jumps, but then after a few tries he learns the mysterious "double jump" skill and can change course in mid-air without any solid surfaces to push off of. So yeah, there's not really a good scientific explanation than that, sorry.
Stay tuned for X-ray vision Xplained! UPDATE:My first post about Batman's use of sonar in The Dark Knight talked about the similarities between echolocation and modern sonar used to navigate and locate objects underwater. The fictional application of Batman's sonar tool was the part where every cell phone in Gotham was turned into a receiver that fed into a giant computer to find the Joker. Well guess what? We are that much closer to catching the Joker, citizens! A recent paper designed an algorithm that can use recorded echoes from an array of microphones to measure the dimensions of a room. The figure below shows the set up of microphones in their controlled test area as well as the more complex Lausanne cathedral of Switzerland. What makes this a practical criminal catching tool? First, the microphones don't have to be placed in any specific geometry, you can use whatever arrangement is handiest. Second, it has been hypothesized that this algorithm could be programmed into a cell phone app. This echo algorithm can be applied to design more realistic virtual realities or make teleconferencing sound more natural. It would also be a much faster way to measure the dimensions of a room than physically getting out a tape measure. These dimensions would be useful for architectural planning, forensics, rescue missions, and finding criminals escaped from Arkham Asylum! Or at least right now you can accurately find all the walls of the room they're hiding in, which was a big component of the sonar use in The Dark Knight. Now how do we get that cell phone feed to display in some cool goggles... Interested in trying out the code yourself to start your vigilante career? You can find it available freely online! References:
Dokmanic, I., Parhizkar, R., Walther, A., Lu, Y. M., & Vetterli, M. (2013). Acoustic echoes reveal room shape. Proceedings of the National Academy of Sciences, 1221464110 |
Alanna DurkinExploring the realm of biologically inspired design one superhero example at a time, with some other natural sciences mixed in. Archives
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