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Politics : Evolution
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To: koan who wrote (69267)2/24/2017 5:53:51 PM
From: TigerPaw  Read Replies (1) of 69300
 
I learned something new.
I went to an astronomy lecture about White Dwarf stars by Dr. Mike Montgomery of UT.

The premise was that when a white dwarf evolves it goes from a star like our sun, to a red giant, to the white dwarf. His theory and math showed that the outer layers of the red giant are thrown off at a characteristic temperature and then there is no longer a nuclear furnace to heat the star further. It begins to cool. The age of a white dwarf can therefore be determined with good accuracy by it's temperature. Temperature can be easily measured by it's color, adjusted for motion shifts.

With this knowledge, the next step was to make a survey of all known white dwarves, measure their age, and see such things as "do completely cooled white dwarves contribute significantly to dark matter" . The survey was started and as they plotted the age/temperature for each star they noticed something very odd. The temperatures fell from the predicted initial temperature in a steady line, until it hit a threshold (3000K I think he said). At lower temperatures there simply weren't any white dwarf stars. None!

They realized that the universe simply was not old enough for any white dwarf to have ever cooled below that temperature. The team realized that this cutoff temperature was actually a much better way to measure the time of the big bang, and therefore the age of the universe, than any previous technique. (previous best technique was to measure the relative speed and distance of all stars and try to compute when they were all together in one place).

I learned the universe is 13.7 billion years old.
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