Superman's powers are almost NEVER completely explained in the DC Universe. The last time anyone made an effort to explain his powers scientifically was during the Golden Age of Comics.
To be perfectly honest, there have only been a few efforts to effectively describe the SOURCE of his powers in any reasonable manner. His flight is only one aspect of his amazing suite of powers.
But if I were to try, I would have to reconcile his origins, the changes in how his powers were described and how they seem to have changed and more recently stabilized over the decades.
Let's go back to the Beginning:
This is Kal-L, also known as the Golden Age Superman.
He ran everywhere and could reach speeds up to a hundred miles per hour.
He didn't fly. Superman jumped 1/8 (700 feet) of a mile when he needed to reach someplace higher than sea level.
He couldn't be hurt by anything smaller than a bursting shell from a howitzer.
He was a strong as a locomotive, and this meant very few things could resist his incredible strength in 1939. This was the power level Superman started his career at.
The source of his ability was his genetic perfection harnessed by science on Krypton. In some early depictions, Kryptonians had their superhuman physical prowess on their own world. (This would later be changed.)
- The scientific explanation for the source of Superman's powers published in Action Comics #1 also compared Superman's great strength to an ant's ability to carry hundreds of times its own weight and a grasshopper's ability to leap great distances.
A Little History on the writers of Superman
Jerry Siegel and Joe Shuster created a number of characters named Superman before they settled on the one most people know today. Both were inspired by the writers and stories popularized in pulp magazines when the two creators were growing up. They were both interested in scientific ideas as well as religious ones.
Siegel and Shuster created multiple characters named Superman. The first was a bald villain with telepathic powers, published in the short story "The Reign of the Superman."
A tribute was made to this first evil telepathic Superman during a recreation of the DC Universe almost 60 years later with the introduction of the Tangent Universe Superman, Harvey Dent.
This Superman had incredible mental, telepathic and telekinetic powers making him one of the most powerful beings on his world. He would even take his show on the road and try to bring order to other parallel Earths, eventually bringing him into contact with classic Superman with explosive results.
~Tangent Comics: The Superman #1 (September, 1998)
Why is this relevant?
Superman's powers have grown significantly since the Golden Age. His host of physical abilities include increased strength and durability, super-speed, super-senses and the power of flight. The less than ideal explanation was his powers were expanded by his exposure to the light of a yellow star and some aspect of his Kryptonian biology.
In the Post-Crisis reboot of Superman written by John Byrne, his origin expounds only on the premise baby Kal-el who is currently hidden within the birthing matrix safe from the tainted atmosphere of his homeworld would develop on a world where his cells would give him the powers of a god.
Depending on the continuity, his powers vary from being slightly more powerful than his Golden Age appearances (Superman: The Animated Series) to being an immortal cosmic force for goodness (Kal-El: DC One Million).
- We are never informed as to the source of these benefits. We aren't told if it is some aspect of his biology, whether it is an organ or group of organs unique to Kryptonians. Even when they had the chance during their reboot after Crisis on Infinite Earths, the language remains vague and unspecific as to whether the source of his sun-powers was molecular, genetic or other...
From the Man of Steel Series, 1986
- There are several continuities which indicate his powers are linked to his DNA in some undisclosed fashion. Lex Luthor attempts to clone him in the Post-Crisis Universe creating Bizarro and later the Post-Crisis Superboy.
It is the Post-Crisis Superboy where we get the only answer which makes any sense. Luthor's attempt to create his own Superman lead to the Post-Crisis Bizarro. His later attempt to clone Superman was mixed with his own DNA. This Superboy is later revised in the Young Justice television series. Post-Crisis Superboy did not have the same powers as Superman. Or he did, but they were manifested as psychic-oriented abilities.
He had a measure of strength and a degree of increased durability. He lacked the visual powers (like Kal-L) and had to learn to fly. Most importantly, he could lift objects without them falling apart under their own stresses (in the same manner Superman does, notice no ocean liners snap in half when he lifts them out of the water).
The ability to lift objects without falling apart (as well as performing any number of other feats) was called "tactile telekinesis." (And they would say it again and again, until you understood it and could repeat it to your friends.)
This is another clue to an explanation of how Superman's powers worked. They were in some degree, genetic and could be replicated, however limited with Luthor-level (read that as highly advanced) technologies. This implied whatever the source for metahuman capacity possessed by the alien from Krypton, Luthor had managed to isolate some level of the power and bond it to Human DNA and control it.
When the New52 Universe rebooted Superboy, he was still genetically engineered by the mysterious NOWHERE and he retained limited versions of Superman's powers. He still had to learn to utilize his powers including his tactile telekinesis in new and varied ways.
Now Byrne's attempt to put limits and at least a degree of explanation on Superman's powers was not the last time the DC Universe would NOT explain how Kryptonians and to a lesser degree, Daxamites could possess these fantastic powers. Bot races share a suite of abilities unique to these two species in the DC Universe. No other aliens have exactly the same degree of superhuman capacity in every member of their species. Some continuities had other aliens fear Kryptonians though none had been seen in some 10,000 years.
Are we any closer to an explanation?
No. Nor will we be. Because no one wants to make an explanation for how Superman's powers work. It would cause a rift in how they have been explained, and a question as to whether it could be right, or possible scientifically.
Most scientists take the idea of a person the size of a man being able to store sufficient energy to perform even one superhuman feat performed by the Man of Steel.
I also suspect scientists enjoy the possibility of trying to explain his powers and to make them sensible in any degree using what we know about science. For example: The light from a yellow star is supposedly the source of Superman's powers. But the color of a star has very little to do with the energy it outputs. All stars are technically pretty much the same in their luminous stage. A red one or a yellow or a white are not much different from each other in any any way outside of their base temperature, luminosity and the lifespan of the star.
If Superman's draws his powers from stars, somehow metabolizing that energy and storing it in a form he can psychically access within his body, enhancing him to be able to survive without food or water, survive the vacuum of space, ignore and absorb radiations, become nearly invulnerable, lift the weight of the entire Earth, and fly faster than light, he completely violates the laws of physics as we understand them and he technically would be putting out more energy than he could ever take in!
What does this mean specifically for Superman's power of flight?
Superman's power of flight has been described as the manipulation of gravitons (an as-yet undiscovered particle associated with the forces of gravity), OR;
the redirection of his molecular activity in a single direction, pushing his way through the fabric of space-time, OR;
having access to a personal field of energy which alters fundamental forces allowing him to instinctively redirect the nature of the universe and allowing him to defy the laws of physics.
They could all be true or none of them could be true. But the fundamental aspect which all of these descriptions (save the very first one for Kal-L whose powers were purely an aspect of being a creature from a heavier gravity world) is their source in Superman's mind.
Which brings us back to John Byrne
Byrne's explanation of the Post-Crisis Superman powers as being derived from his mind's interaction with his "biologically-generated electromagnetic field" explanation was one which wandered into the DC Universe from the Marvel Universe.
The alien, Gladiator, was one of Marvel's homage/parodies of Superman. His powers are almost exactly the same and his capacity makes him one of the most formidable beings in their Universe.
In a battle with the Fantastic Four, Reed Richards determines Gladiator is a specimen of significant physical capacity, a great deal of Gladiator's powers are psychically-driven and to some degree require a conscious effort on his part. A momentary distraction allows the foursome to defeat Gladiator when an attack penetrates his personal field. (Fantastic Four #249; 1982)
- Gladiator could do everything Superman could, including lifting buildings without them falling apart (ala "tactile telekinesis) and the later explanation when ported to the DC Universe, went over well enough it became, at least for a time, an accepted canon in the DC Universe.
How Superman flies, like any other power he possesses, is linked to his cell structure, gene structure or perhaps some molecular aspect of his body. But I present one last nugget of evidence which may make the lack of an explanation less difficult to accept.
Welcome to the Source
DC had, for a time, indicated all metahuman capacity was linked to the GodWave, a manifestation of the New Gods mystical energy well-spring, called The Source. If you had a metahuman power, and indeed, it was theorized all living beings had some degree of connection to it, no matter how small, you could manifest superhuman abilities.
The major manifestation of the Source is the Source Wall, a barrier between our Universe and powers of an unknown but even greater capacity than those within the DC Universe.
- A power so great, Darkseid spent his existence trying to harness even a fragment of such power, he believed would make him unable to be defeated. Unfortunately anyone who attempts to harness such power is ultimately imprisoned in the surface of the wall by the Source itself. Those who fail become a guardian should the Source desire it.
Other local concentrated manifestations of the Source included:
The Green: a mystical source of life energy supposedly connected to growing things, discovered and used by the Swamp Thing. People connected to the Green have the ability to manipulate plants, alter their growth, change or even mutate them, giving them capacities they previously didn't have including movement. They can also take on properties of plants if their connection is strong enough.
The Red: another mystical source of life energy linked to living things in the Earth's ecosystem. The Red was a source of energy to those people who were linked to it. They could either shapechange, or aspect-change, giving themselves the physical capacities of animals, such as speed or the power of flight. Two known users of the Red were Animal Man and Vixen using a magical animal totem.
The Clear or the Blue: is a force which connects and pervades all aquatic life and oceanic themed elements in general within the universe. It is intended to be the force from which a number of aquatic-themed heroes or villains acquire certain abilities. The Clear is heralded by the enigmatic Parliament of Waves, an ensemble of former avatars who now reside as a counselling order to the Clear.
The Speed Force: The source of all speedster powers, this force allows anyone who can manipulate its energies the ability to run faster and perform feats of increase reflexes and temporal awareness. Most Flashes access this ability innately with time and experience offering them the capacity to perform even more spectacular feats of speed and energy manipulation.
Why this matters:
If indeed the Godwave and by proxy the Source are responsible for metahuman capacities in the entire DC Universe (whether through mystic or technological interfaces) then Superman (and every other metahuman) are overriding the fundamental forces of the Universe.
Since users of the Source's power (the New Gods and the Gods of Apokalips) tap this energy for their metahuman capacity as well it may be metahuman capacity is a side-effect of the Source's existence and could explain why metahumans can defy the laws of physics if they are linked to an energy more potent than anything in our much younger Universe.
Does this stand in the Rebirth Universe?
The ideas of metahuman capacity linked to the Source is from the Post-Crisis, Pre-Flashpoint Universes.
I don't know if any of it has survived the demise of the New52 Universe or whether anyone even cares to explain how metahuman powers work in any detail, let alone for Superman.
Since the Rebirth Universe has some underlying secrets, especially the source of its new existence, we will have to wait to see if any information is revealed around Superman's powers, how they work, and whether there will be any real explanation given beyond the fundamentals we already know.
We do know: In the Rebirth Universe, humanity can create and transfer metahuman capacity, giving people powers. We know this because the Chinese New Super-Man gains his powers from a secret branch of his government which studies metahuman capacity.
While New Super-Man's genesis destroys the technology necessary to give him powers and there is a degree of mortality using this technology, the implications are vast.
- If this is an experiment which can be replicated, there may be more metahumans than ever thought possible in this new DC Universe. We may also finally get an explanation for how superhuman capacity works and the underlying physics, biology or mechanics of the transformation.
Outside the DC and Marvel Universes:
The writer Mark Waid created a Superman-analogue called the Plutonian. As so many others have done, Waid's Plutonian had nearly the same powers and decided he would explain them as a form of powerful psychic ability allowing the Plutonian to alter reality to his benefit.
Waid description of Superman's powers and the rationale for their function was both elegant and masterful and may be the closest thing you ever get to see explaining how Superman's powers COULD work on the comic page. If Irredeemable #25 (2011) did nothing else, these pages were worth their weight in gold.
In Summary
Given the nature of Superman's powers and the lack of physical explanation for the vast range and capacity of them we are forced to deduce what other writers have speculated on for some time.
Superman's powers have both a physical and mental component to them. The physical aspect is linked to some either genetic, molecular or technological element which allows him to absorb, store and manipulate a vast energy supply which is able to be manipulated by Kryptonians and Daxamites intuitively when under a star that is not red or orange.
Superman's body does have some limited durability (depending on continuity) but if he resembles a normal human male under a red star with no enhanced abilities due to gravitational differences, HIS POWERS ARE PRIMARILY MENTAL IN NATURE!
Superman's powers are a form of limited reality-alteration, allowing himself to perform impossible feats which are similar to other manifestations of the Source including abilities such as super-speed and flight. This would explain how he could defy singularities, either holding them in his hands or escaping from their gravity wells against all laws of physics.
His powers are a literal manipulation of fundamental forces, allowing him to redirect the force of gravity, kinetic or electromagnetic energy away from or toward him, giving him the power of flight as well as to damage anything in his way.
Because he does this intuitively, it appears to the onlooker as if he is utilizing his body to perform these feats but they are actually manifestations of his energy projection, which are invisible to the naked eye. Even he considers his powers to be physical and uses them without a complete understanding of how they work, only that they do.
Because his powers are belief and psychologically-driven in nature, it may explain why he does not do well against magical forces whose very nature is based in belief. It may also be they derive their underlying energy from the same source he does making him as vulnerable as anyone to magical forces.
He is affected by exotic radiations like Kryptonite because they prevent him from utilizing his innate manipulation of reality, driving the catalyst energy (yellow sun radiation) from his body, sundering his connection to his powers violently.
We have seen him absorb other energies such as the energy of the Firepits of Apokalips, so we know his cells can be made compatible with energy from the New Gods Universe which are also patterned on the Source.
If I were to guess, Superman is a fuse to a far greater capacity, an energy (possibly even a conduit to the Source itself) which makes him capable of performing those incredible feats, but it is his access to yellow sun radiation which opens the portal to the greater energies. When his yellow radiation is depleted, he loses access to the more powerful energies because he cannot manipulate them without solar energy support.
Ultimately, I do not hold my breath any writer will be so bold as to try and create a unified theory of metahuman capacity in the DC Universe, which would try to put a name to how many, if not all metahumans, perform their feats but I would love to see someone try. Defining the fundamental aspect of flight for Superman, the Martian Manhunter, Wonder Woman and many others would be the least of the things such a work could encompass.
For anything to do this, it would have to have something to push against or to eject some kind of propellent.You mean like if he farted?