Sitting around a campfire, you can feel its heat, smell the woody smoke, and hear it crackle.
If you get too close, it burns your eyes and stings your nostrils.
You could stare at the bright flames forever as they twist and flicker in endless incarnations.
But what exactly are you looking at?
The flames are obviously not solid, nor are they liquid.
Mingling with the air, they’re more like a gas, but more visible--and more fleeting.
And on a scientific level, fire differs from gas because gases can exist in the same state indefinitely while fires always burn out eventually.
One misconception is that fire is a plasma, the fourth state of matter in which atoms are stripped of their electrons.
Like fire and unlike the other kinds of matter, plasmas don’t exist in a stable state on earth.
They only form when gas is exposed to an electric field or superheated to temperatures of thousands or tens of thousands of degrees.
