Transcript:

So, let's look at the energy efficiency of the Sun. Okay, the Sun is producing energy by fusion. It is fusing hydrogen to make helium at the core of the Sun.

And we can calculate — not calculate, actually measure — how much energy the Sun is radiating out. And we know the size of the Sun. So we can normalize it. We can say per unit volume of the Sun, this many watts of energy is being created.

Then, you can ratio it down. If you shrink the Sun down to a size of an average human being, very surprisingly, the average human being metabolizes food to make energy much more efficiently than the same volume of the Sun. When you shrink the Sun down to a human size, it does not make the same amount of energy that a human being is making by digesting food.

Let that sink in for a moment.