Q: If energy is quantized, what is the least amount of energy possible? And how did they measure it?
First the flow of electricity smacks the electrons into higher energy levels, then the light is created when the be-smacked electrons drop back down into lower energy levels. The discrete colors indicate that the electron energy levels inside the atoms are also discrete. In nice controlled quantum mechanical systems, like individual atoms or resonant chambers (e.g., microwave ovens), you’ll find that the energy levels are always quantized. However, the energy levels (and the method of measuring them) depend on what system you’re studying. When the ground state is low enough the chance of seeing something in that state becomes lower and lower.