[Coda]

Originally Posted by Potironette

Or just that light can be felt as heat and humans can't see some lights?

This is exactly it.

Actually, is light just "photons" and heat is atoms moving around or something, so whatever the light is from the bulb that people just happen to not be able to see is, will transfer energy to say, a human hand, to be felt as heat?

Another correct deduction!

Or is it just that in the case of a lightbulb, energy just gets transferred into making a lightbulb's glass move around and that is felt as heat? Or a combination @_@?

It's a combination. The glass is still transparent to most of the light passing through it, even the infrared light, but obviously it absorbs SOME of the energy itself because you can't unscrew a hot lightbulb.

Oh, that makes more sense. Can I generalize all equations as describing an observed effect that may or may not actually happen?

Yes, exactly. Physics formulas are models that mathematically describe observed relationships. They don't assert that any particular thing is possible, only that if it were possible you would expect to see that result.

It's particularly important to remember that they're models, too, because they can be wrong -- especially at the level you're working at, the formulas are approximations that work out within an acceptable margin of error within the domains you're likely to be able to observe. They also describe ideal interactions, but no real-world experiment happens in a truly closed system with 100% perfect components and 100% efficiency.