Superman has super-strength, super-speed, flying powers, can shoot laser-like things from his eyes, and has some type of X-ray vision. Comic book scholars have debated Superman’s vision before, but Wired decided to consider how it could work.
First, how do normal non-superheroes see? In order to see an object, light has to go from that object to the eye– either reflected light or light that the object emits itself. The key fact idea is that the eye is only a receiver of light.
What about X-ray vision? We can make X-ray images by taking high speed electrons and shooting them at a metal surfaces. X-rays are just like visible light except they have a much shorter wavelength. Because X-rays have a different wavelength and frequency, they interact with matter differently than visible light. This means that some materials are partially transparent.
How could this work with Superman’s vision? If his eyes could detect X-rays like humans detect visible light, he would still need an X-ray source. Could these same X-rays come out of his eyes? Sure, but in that case he would be detecting X-rays that are deflected from these human tissues, not the ones that pass through. But aren’t there natural sources of X-ray radiation? Yes, there is an X-ray background radiation—cosmic X-rays. However, the intensity is so small it could hardly be useful for superheroes.
What if Superman could see into a human body like the MRI (Magnetic Resonance Imaging does? How does an MRI even work? The simplest explanation is: a proton acts like a tiny magnet because of nuclear spin and when you apply a very large magnetic field, these protons will have their “magnetic poles” align with this field. The protons can be excited to higher energy states by applying another external radio frequency—but when they relax back to their lower energy, they emit radiation. The MRI then detects this radiation and uses it to make a 3-D map of where all the hydrogen is in the body. Different tissues have different amounts of water—so different amounts of hydrogen.
There are two key points to the MRI if it were to be adapted as super-vision. First, you need a large magnetic field. Second, an MRI image isn’t created all at once—instead, it takes time to vary the magnetic field, detect different signals and finally use algorithms to process the data into an image. The only way to make this work with Superman would be to very rapidly move around an object to observe the radiation at different locations all at the same time he is creating large magnetic fields. No, it wouldn’t work.
There are some other ways that Superman could see more than a normal human. What if he could see in the infrared region? That would be just like using a thermal cameras. The same could be true for ultraviolet light. Not only would you see different details in UV light, but there is already plenty of it around—especially if you are outside. What if Superman could see cell phone signals? This type of radiation is just about everywhere on the surface of the Earth and this frequency of radiation can “see through” many different materials.
Nice try, Wired- but we still believe in Superman’s X-ray vision!