Superman is one of those superheroes who has a whole constellation of abilities rather than a discrete superpower. But one fan theory suggests that all these abilities — from superstrength to heat vision — stem from a single superpower.
Ryan North, of Dinosaur Comics fame, asked his friend Ben Tippett to write a scientific paper-style analysis of Superman's powers after listening to Tippett describe his unified theory of the Kryptonian's abilities. Tippett, trying to understand Superman's powers from a physics perspective, has posited that Superman doesn't have multiple superpowers, but one amazing ability:
It is our opinion that all of Superman's recognized powers can be unified if His power is the ability to manipulate, from atomic to kilometer length scales, the inertia of His own and any matter with which He is in contact.
Tippett then proceeds to explain how each of each of Superman's abilities — his superstrength, his senses, his flight, his freezing vision — are simply a manifestation of that ability, and offers helpful equations and diagrams to illustrate his points:
The folks at Metafilter are already poking and prodding at the theory, with the key argument being that, if Superman can manipulate matter in this way, why bother with heat vision and freezing breath? Why not simply heat and freeze matter with any part of his body?