The thinking, and science, behind hydrogen-powered cars is beautifully demonstrated in this episode. Spangler shows how, by itself, oxygen is not combustible. However, when some hydrogen gas is added, that changes! His assistant scoops us some bubbles that have been created in a soapy solution that has oxygen and nitrogen added to it. When Spangler puts a match to the bubbles, they explode in a loud "Bang!" due to the release of energy.