Iroh's mystical explanation of lightning bending matches with real world physics Though not exactly the same, it's close enough. 

He talks about all energy being "yin and yang, positive energy and negative energy" which correlates to atom nuclei and their orbiting electrons. He then goes on to say how only a few firebenders can separate the energies and create an imbalance which want to be restored to balance. And obviously this describes how lightning and any electrical arc is creating, by separating positive and negative charges to create a high enough voltage, i.e. an imbalance, which wants to be restored to no voltage, so the negative electrons rush towards to positive nuclei and create an arc, aka lightning.

As a physics major and general science buff I love this easter egg of showing how complex scientific ideas were indirectly understood by ancient thinkers. Such as how the ancient Greeks conceived of the necessity of the atom thousands of years before it was discovered.