Krazyhorse and other people with physics background please answer my question

[Dauphin]

I think he did understand. Which is why he said the timescale is billions of years (i.e. the sun expires and we have no more renewable energy from the sun, and the recycling becomes a problem because of the 2nd law). It's a nerdy answer.

That or he did actually misunderstand.

[Kidlicious]

Ah, of course, Kuciwalker.

[The Mad Monk]

If we filled a volcano with sand and afterwards it erupted, what would be the result?
Would it explode downwards, and what would be the result; or would it still blow up and what would be the result? If it explodes up, would it heat the sand to shards of glass raining down?

See nuée ardente.