Originally posted by buddhasystemI guess Mary's not going to answer, so...I'll comment on the temperature issue.
Mary, what do you think of that? What evidence points towards conversion of mass to thermal energy, and do you think it's true that high temperatures are only reached in larger aggregates of matter?
When I saw table showing a breakdown of the properties of interstellar matter in the Milky Way, I thought it was interesting that more matter within a given volume actually correlated with a lower, rather than a higher, temperature.
The least aggregated areas of interstellar matter, like the coronal gas, are actually the hottest according to that table:
That "Hot Ionized Medium" reaches temperatures of millions of degrees, which I'd say represents extremely high temperatures. But that may have only 100 atoms per cubic meter, so I don't see how that can be called a very large aggregate of matter, it's actually among the lowest aggregates of matter in the Milky way from a density perspective. So I can't agree with Larson that "Extremely high temperatures are reached only in very large aggregates of matter". Extremely high temperatures are reached inside stars, which are large aggregates of matter, that much is true. His use of the word "only" is the problem, and it makes that statement false.
Temperatures of millions of Kelvins are possible in both very large aggregates of matter like stars, and very small aggregates of matter like the hot ionized medium in the Milky Way.