I've often thought, when watching fictional TV shows and movies, about the feasibility of various superheroes/aliens/spellcasters/etc and their super powers. Some of them would conceivably be possible in a variant or other of our universe and its physics, but others don't seem like they'd make much logical sense no matter how you bend the laws of physics.
Of course, some of these claims are not just relegated to works of fiction. Charlatans the world over are happy to make claims about mind reading, spoon bending, spirit talking, future telling, yogic flying and other fantastical abilities.
Here's a work-in-progress collection of my thoughts on the ins and outs of some popular supernatural traits.
Traditional X-Rays work via use of a photographic plate and an X-Ray source (e.g. something radioactive)
Some shows, such as Hollow Man, The Invisible Kid and Invisible Sister, understand that invisibility wouldn't affect someone's clothing, so they'd have to be naked to be properly invisible.
In The Incredibles there's a suit that is able to turn invisible along with its wearer.
However, for any invisibility power, if invisibility is happening at a cellular level all cells on our bodies that are not ours would still be visible. That includes not only the food that we eat, and the water that makes up a lot of our bodies, but also bacteria that live inside us. And it turns out there's a lot of bacteria that hitch a ride.
Magneto's an interesting case of flying - as he can control ferrous metals with his mind, he's able to wear metallic clothing or accessories and lift himself via these supports. I guess he'd want to make sure that he's wearing a tight-fitting (but breathable, so that he doesn't sweat too much) metallic body suit. If he was just wearing metallic underwear (such as these crazy things), he'd end up giving himself a wedgie every time he flew.
Levitation is, I guess, a limited form of flying.
Despite what some shows will tell you about humans' ability to tap into super strength when a crisis occurs, like needing to lift a car off of someone, there are limits to how much strength someone has. Pushing one's strength to the limit usually ends with rapid damage to the muscles, and this would not be sustainable.
I would imagine shape shifting involving the rapid change of cells in the body between different types - a rapid rearrangement and reassignment. Howerer, often shape shifting - especially to different animals - involves forms that are either much lighter or much heavier than the initial form. This would require destruction of cells for morphing into a smaller creature, which is possible if strange, but for morphing to a larger form would require the creation of extra biological material. Where does this material come from?
The Hulk is a kind of shape shifter.
It would be fun to see a shape shifter who had to nip to the bathroom to lose a few pounds before morphing into an eagle, or stuff their face with pizza to become a large mammal like a horse or a bear.
This super power has some interesting consequences for causality.
In the TV show Misfits, a bit part character has the ability to physically control dairy products such as milk, cheese and yoghurt with his mind. The show does a good job of treating this silly sounding ability realistically, showing that this power gives you the option of killing anyone who has consumed dairy products.
Realistically, although I can't think of anything that would allow someone's mind to do this in our universe, I could imagine a universe where dairy products have a property like being ferrous, and where someone could use their mind to create the dairy equivalent of a magnetic field (cheese rays?) and control dairy products.
Recently I've been playing a lot of Fallout 76 with my friend Aaron. In the game, I have a perk card (ability) called Pannapictagraphist which allows me to detect (via a sound) when I'm close to a magazine. Magazines are handy to find because they give your character a temporary boost to one of their abilities.
Aaron likes to ask silly questions, and asked me while we were playing the game and I was hunting for a nearby magazine if I thought that this perk was in any way plausible. I responded that I thought it was. I could imagine someone with a sense of smell, for example, that could pick up certain chemicals at very low concentrations. If one of these chemicals were used by the printing industry as a gloss coat for magazine covers, this would make the detection of magazines fairly straightforward.