Board Thread:General Discussion/@comment-76.126.125.211-20170831061704

The explanation of Saitama's abilities leaves it ambiguous, suggesting Dr. Genus's idea was merely a hypothesis, and not a fact. The trivia suggests the hypothesis is instead a fact.

Vacuum adaption is not needed, along with most of the subcategories in invulnerability. He is resistant to extreme pressures. That and heat resistance pretty much covers it.

A knife applies pressure over a small area. A punch applies pressure over a larger area. The gases/liquids/solids in his body apply pressure when he is in the near vacuum of space. Technically, they apply pressure when he is on Earth as well, it is just the pressure from within matches the pressure of atmosphere from without.

I have no idea what kind of damage type energy blasts have, but it could be lumped with heat resistance or have its own category. Cold resistance is not a thing. Cold is the absence of heat (in the general sense, not the physical one).

If you wanted to be technical, you could call both of the resistances, "resistance to gradients". A large pressure gradient is present when a human body is in a vacuum or at the bottom of the ocean. A large temperature gradient is present when a human body is in the center of the sun or in interstellar space.

Basically, he is invulnerable to gauge bosons. 