Friday, March 6, 2009

More About Infinite Monkeys (Part 1): Fade to Black

My old friend Phil Rose writes me the following:

Hey Rich--

In your profile you say:

"....trapped in a world we never made (to quote St. Steve Gerber). We are infinite in the sense that we are also immortal and that essential thing that makes us individuals will still be around when the sun is a brown dwarf. (Whether we will be happy at that point in time is another question.)"


The sun will never be a brown dwarf. The sun will eventually be a black dwarf. Different things. Brown dwarfs (dwarves? :-) ) are objects midway in size between superjovian planets and red dwarf stars, never quite big enough to fully ignite but faintly glowing.

A black dwarf is a white dwarf that is so old that it has cooled down and grown dim.

Our sun will continue to burn brighter and brighter, as it has done since it formed(thus making global warming inevitable no matter how much we cut carbon emissions), until it runs out of hydrogen; after this it will undergo a process in which its core will shrink down to a small size, and give off a burst of energy as it does so -- becoming a white dwarf. But the white dwarf core will be obscured from view by what is called a red giant, since the energy burst from the core inflates the outer layers of the sun's atmosphere, which balloons out into a spherical shell, fading to red as it does so (still the same amount of energy, but averaged out over a much huger surface area). As the "red giant" continues to expand it eventually breaks up into tatters of gas, forming a "planetary nebula" (like the ring nebula). The white dwarf is now visible at the nebula's center. Eventually the nebula dissipates to nothingness. The white dwarf remains, and fades to black.

Disclaimer:

Loudon's Law (after the late, great Jim Loudon of the University of Michigan Exhibit Museum): Any statement made about the earth and space sciences MUST have this phrase appended to it: "But it's more complicated than that..."

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