Here’s an article borne of one who likes to nitpick for others who nitpick. If you’re of the persuasion “It’s just a movie!” when you see things that don’t make sense, be warned. I’m going to examine implications of Superman’s powers, where they come from according to the comics and movies, and where that requires some real suspension of disbelief according to actual science.

This is a long piece, but if you’re ready to examine Superman’s powers, come along on a journey with me.

To begin, I want to start with a great video The Film Theorists did that examined the groundwork for this:

This video talks about how Superman apparently gets his powers, namely:

  • Storing non-ionizing radiation from our sun (like a plant), which is younger and brighter than Krypton’s and therefore gives him comparatively more energy than those from Krypton are used to.
  • Earth’s gravity is far weaker than Krypton’s, so his body built for a high gravity world seems really powerful to Earth.

The math The Film Theorists come up with shows that Krypton’s gravity would have to be 406 times stronger than Earth’s to account for the feats of strength we see Superman perform in the most recent movies. The problem with that? Our sun’s gravity is only 274 times more powerful than Earth’s, so trying to imagine a life-sustaining planet with gravity that massive gets a bit wonky.

The gravitational difference could more or less explain the feats of strength and jumping incredibly high, but not necessarily full-out flying or the laser beam eyes. At that point I guess we look to the solar powered explanation — Superman evidently absorbs and stores energy from the sun, allowing his body to do other things gravity doesn’t account for.

But hey, let’s try to accept those explanations as they are. Those in mind, do these explanations jive internally or even with science?

Relative Gravity and Muscle Atrophy?

On Krypton, Superman would simply be an average dude. This is something we actually see in the Man of Steel movie when he enters General Zod’s ship, which has a Kryptonian atmosphere. It weakens him from mighty demigod to bodybuilder that just got hit in the face with a shovel. That is, of course, until he gets back outside to Earth’s atmosphere.

The reverse of this is how our astronauts can jump easily on the moon even when carrying several hundred pounds of equipment. That’d be impossible on Earth, but the moon’s gravity is roughly 1/6 that of Earth’s. So a 180 pound man would only weigh 29.9 pounds on the moon. If that man’s body became accustomed to the 29.9 pounds, suddenly weighing 180 again (or more) would feel debilitatingly heavy.

That extra pep may sound awesome, but what would happen if the astronaut stayed on the moon for a prolonged amount of time?

We’ll put aside other environmental considerations like radiation, temperature, and lack of oxygen for the moment. When you don’t use muscles they atrophy. On the moon your muscles don’t have to work nearly as hard to sustain movement or carry your weight. Over time, they’d atrophy because they’re not being exposed to normal Earth gravity and aren’t being used to the same degree.

This is why those in the International Space Station must exercise rigorously in a zero gravity environment to preserve muscle mass. And even then there is slow degradation of skeletal muscle without Earth’s gravity constantly pulling on the body. The exercise can only replace that to a certain extent.

Relatively speaking, Superman’s body would be experiencing something similar. Earth’s comparatively puny gravity might make his Kryptonian muscles seem super strong for awhile, but the longer he resides on Earth the weaker he’d become, right? He’s not lifting huge objects constantly, and the rest of the time he’s Clark Kent writing news stories in weak gravity.

Unless there’s something in the Kryptonian DNA that prevents muscular atrophy or deals with the gravity differently. Certainly to have a body capable of withstanding the enormous gravity of Krypton we’re talking different bone density and muscle tissue. Not simply denser than ours, but perhaps composed of something else entirely. (He is an alien, after all.)

His relative super-strength could explain leaping to incredible heights, but how do we explain straight up flying? More on that further in.

Breathing and Pressure Vacuums

If Superman’s own lore insists that he’s not some magical being, that his apparent powers are largely the result of a relative difference in planetary atmosphere, then he’s just a man. He’s mortal. Maybe it’s incredibly hard to kill him on Earth given his relative strength and durability, but he theoretically still needs air and food, right? His skin may be super-resistant to damage in our atmosphere, but it’s not indestructible.

That should make him vulnerable to suffocation and atmospheric pressure, presumably.

Breathing and Atmospheric Pressure

Let’s look a deep sea diving for insight here. Every 10 meters (or 33 feet) you descend into water you experience an additional Earth atmosphere of pressure (14.7 pounds). At depths of 10,000 feet, you’re talking 4400 pounds of pressure pushing against your body. Not only is that lethal to humans, but it creates an interesting challenge in reverse.

Sea creatures that live at those depths have adapted to the pressure. That means their bodies can provide enough outward force to resist thousands of pounds of pressure, and as a consequence never survive for long after being brought to the surface where the pressure is comparatively very weak. The deeper the animal is accustomed to living, and thus the more pressure, the more pronounced this effect is.

Atmospheric pressure and gravity also seem related, which is why it’s harder to breath at high altitudes. Slightly lower gravitational forces mean the air is less dense (less oxygen per breath).

Since Superman can breathe on Earth we can assume the composition of air is fairly similar to Krypton’s. If Krypton’s gravity is significantly greater than Earth’s the air pressure at any given elevation would also be higher. Maybe we can explain the fact that it doesn’t seem to bother Superman by him growing up on Earth and becoming accustomed to it. Still, it doesn’t explain General Zod’s ability to shrug it off in less than 15 seconds in Man of Steel.

(Other than plot necessity because if the main bad guy was debilitated, final fight over.)

Zod gets flooded with a head rush of sounds, radio signals, etc. when he steps outside his ship in Man of Steel, to which Superman remarks that it took him years to learn to block it out and focus. Aside Zod’s unexplained ability to focus insanely quickly…

The sudden enormous difference in atmospheric pressure would probably have a similar effect on Zod’s body as a deep sea fish surfacing quickly, yet he seems fine and otherwise able to keep fighting Superman.

The Vacuum of Space

Both in the Christopher Reeve Superman movies and in the Henry Cavill ones Superman flies into space for one reason or another. This creates two interesting questions:

  • How can he still fly in space with nothing to “push” against?
  • How does he survive the vacuum of space and the lack of oxygen?

According to Wikipedia’s article on space exposure, a human body exposed in space (without a pressure suit) suffers the following:

  • Ebullism – body fluids bubbling up from reduced exterior pressure
  • Freezing solid due to evaporative cooling as water is leeched out of the body
  • Nervous system failure due to CO2 and nitrogen levels changing within the body
  • Cellular mutation from high exposure to x-ray, gamma rays, and other high energy photons

Superman doesn’t seem to be holding his breath while in space, which makes it seem like he doesn’t always need air. Perhaps that again goes back to his solar energy storage; maybe in the absence of air his body can rely on solar energy somehow to support bodily functions? If solar storage is a major component of his existence, maybe his body doesn’t require a constant supply of oxygen the way humans do. But…

Given that Superman’s body is built to withstand the extreme gravity and air pressure of Krypton, you’d think the utter lack of pressure would pose at least as much an issue for him as for humans. How does his body resist space’s vacuum? How is water not rapidly pulled from his body, and how does his body maintain its form?

For example, Wikipedia mentions that Joseph Kittinger experienced decompression on his hand at 31km elevation in a helium-driven gondola. His hand expanded to twice its normal volume in the time it was exposed, and took 3 hours to return to normal once re-pressurized. He wasn’t even in space and parts of his body were expanding out of control in just a few minutes.

Even if we allow that Superman’s suit is some type of Kryptonian pressure suit, his head, neck, and hands are still exposed.

And the exposure to ionizing radiation?

We know that Superman is susceptible to at least some forms of ionizing radiation because in Superman lore that’s supposedly how Kryptonite works. The radiation from Kryptonite interferes with Superman’s ability to draw energy from the sun, sundering his normal powers.

Is his body only weak against that particular kind of ionizing radiation but immune (or highly resistant) to others? Science buffs: is that even theoretically possible? Or is being susceptible to one of those pretty much being susceptible to all?


In Batman v. Superman we see him struck with an atomic bomb. Though he’s unconscious for several minutes, his body remains intact and he’s back to fighting form shortly thereafter. I guess from that we can assume that not only can his body withstand that degree of explosive force, but that the gamma radiation from the bomb doesn’t hurt him.


Flying, and Flying in Space

The difference in gravity between Earth and Krypton may explain the strength, and his absorption of sunlight for power may explain eye lasers and heat vision. But how does Superman fly?

Neil deGrasse Tyson discusses this on StarTalk Radio and points out that in the original Superman stories he actually didn’t fly. Superman could jump incredibly high and far, which is where the “able to leap tall buildings in a single bound” saying came from. Tyson agrees that while huge jumps seem plausible within laws of physics, straight up flying does not.

So how does Superman fly? Does his body emit some sort of physical force that propels him any direction he wants to go? We could explain that again with the solar power, that perhaps he can channel that stored energy away from his body like a jet engine pushes air. But how would that be affected by high altitudes, or even space? Jets have a maximum altitude they can safely fly, and their engines are useless in space.

Superman has flown through both, and with less and less air pressure to push against, that could become problematic.

One of the more plausible sounding theories is that all Kryptonians developed anti-gravity organs to withstand the immense gravity of their planet. On Krypton, that would supposedly allow inhabitants to safely survive the intense gravity. On Earth, this could give Superman the ability to create a gravimetric field around himself and defy Earth’s gravity, essentially allowing him to fly.

Physics buffs, feel free to weigh in here.

That’s probably the only theory I have read that also seems plausible in space. He could theoretically still manipulate gravity around him in space even with no air to “push” against. His gravity field would “pull” or propel him in whatever direction he desired.

Solar Energy Absorption

Since so many of our theories on Superman rely on this explanation, how could it escape the magnifying glass?

Most areas of the world receive about 150-300 watts of solar power per square meter each day, or 3.5-7 kWh/m2 (kilowatt hours per square meter). Let’s take the median and go with 225 watts (5.25 kWh/m2). But how many square meters of surface area does the average person have then?

Wikipedia’s Body Surface Area article says that the average man has 1.9 square meters of surface area. That would mean that, if we’re optimistic and say that Superman can absorb solar energy even through clothing, he can absorb 427.5 watts of solar energy during the day. If Superman could store all the energy his body receives all day, assuming 12 hours of daylight, he’d have stored :

(5.25 kWh/m2 x 1.9 m2) x 12 hours = 119.7 kW

To take off from the ground and lift a 203 pound (92 kg) man to the height the average jet cruises at (30,000 feet or 9144 meters):

Energy = mass x gravity x height

92 kg x 9.81 N/kg x 9144 m = 8,252,642.8 joules

So if my math is correct, it would take a 203 lb (93 kb) Superman (established in the first video) 8,252,642.8 joules to ascend to a jet’s cruising height against Earth’s gravity. To calculate how many watts that takes we have to factor time.

Superman lore says he can fly “faster than a speeding bullet”. The average bullet travels 762 meters per second. If true, he’d have to be flying at least that fast. To reach our proposed height of 9144 meters at even that speed, it’d take 12 seconds for him to ascend.

Rapid Tables joules to watts converter says that in that time span it’d require 687,720.2 watts.

Here’s the problem with all that. Our solar absorption calculation says that Superman, even in pretty optimistic conditions, can store 119,700 W (119.7 kW) per day. But to take off from the ground and reach the height of a jet in 12 seconds, which he’s done many times, would require 5.7x that amount of energy. So he’s expended more energy than he can even absorb in a day in 12 seconds, let alone all the other stuff he’s done.

Note also that this only takes into account energy needed to elevate to that altitude without air resistance, and not the energy needed to stay there or continue flying somewhere else.

Phew.. well this was by no means an exhaustive look at Superman’s powers, but certainly creates some perspective for the things we see on-screen. Have some thoughts or critiques of your own? Share below!