Dennis Whyte

So, all the atoms that make us up and this water and all that, the electrons are in tightly bound states and basically they're extremely stable.

Once you're at about 5,000 or 10,000 degrees, you start pulling off the electrons.

And what this means is that now the medium that is there, its constituent particles mostly have net charge on them.

So why does that matter?

It's because now this means that the particles can interact through their electric charge.

In some sense, they were when it was in the atom as well, too.

But now that they're free particles, this means that they start, it fundamentally changes the behavior.

It doesn't behave like a gas.

It doesn't behave like a solid or a liquid.

It behaves like a plasma, right?

And so why is it disappointing that we don't speak about this?

It's because 99% of the universe is in the plasma state.

It's called stars.

And in fact, our own sun at the center of the sun is clearly a plasma.

But actually the surface of the sun, which is around 5500 Celsius, is also a plasma.

Because it's hot enough that it's that.

In fact, the things that you see, sometimes you see these pictures from the surface of the sun, amazing, like satellite photographs of like those big arms of things and of light coming off of the surface of the sun and solar flares, those are plasmas.

Let's go to how a gas works, right?

So the reason a gas—and it goes back to Feynman's brilliance in saying that this is the most important concept.

The reason actually solid, liquid, and gas phases work is because the nature of the interaction between the atoms changes.