Now as to why his penetrating vision is blocked by glass (one has to pick a material, and I remembered how older X-ray machines were often foiled by crystal), goodness only knows. Mystical stuff, that glass.

I got no explanation for heat vision, since eyes are receptors, not emitters. I can go with the pyrokinetic notion; he can make things burn by looking at them, and the line-of-sight limitation makes it look like death rays from his eyeballs.

The other perennial explanation is, of course, that’s he’s psychic.

John Byrne or whoever would imply whatever up the wazoo as he or she wished, but the readers always had the option to believe that Superman emitted death rays from his eyes, and was not a pyrokinetic.

The explicit example that was counterintuitive to a public idea is the X-ray vision. Superman did not emit X-rays from his eyes Post-Crisis. He used his telescopic vision to peer between molecules that he was peering between using microscopic vision. He combined his two ’scopic vision powers in order to see through objects. Frankly I think is as awesome as it is ironic. Heat vision was born when X-ray vision was used to melt steel (i.e. guns) in early Superman comics, and microscopic vision as a specrtoanayltical instrument, a device to determine chemical make-up, was simply a better description at what point for what Superman would do to anaylize chemicals, which was “using X-ray vision” which makes no sense if you think about it.

Bah. too many big words.

There are so many logistic issues with considering these attributes as straight sensory perception — i.e., Superman’s super hearing lets him hear the sound of a trigger being pulled on the other side of Metropolis…but he also hears *every other sound* in Metropolis amplified to an equal degree…and somehow in this cacophony he can still find the precise location of that gun and get there faster than the speeding bullet can reach its target. Kryptonian clairvoyance is easier for me to swallow (for story purposes) than a more materialistic explanation.

By the same token, we can assume “x-ray vision” is just a quaint phrase and has nothing to do with the limitations of real x-rays or other medical scans. It’s more like “medical ESP” — and who wouldn’t want that?