Time - Time Now let's try to get a feel for the time...

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Time Now let's try to get a feel for the time scales. I will use another scale model, but instead of reducing distances, I will shrink down time. The scale model is called the ``cosmic calendar'' in which every second in the ``cosmic calendar'' corresponds to 475 real years (so 24 cosmic calendar days = 1 billion real years). If you use the classical number of 15 billion years for the age of the universe, you can squeeze the universe's entire history into one cosmic calendar year (recent measurements place the age closer to 14 billion years). The universe starts in the early morning of January 1 at midnight in the cosmic calendar and our present time is at December 31 at 11:59:59.99999 PM in the cosmic calendar. Here are some important dates in this super- compressed cosmic calendar relevant to us humans: (see also the figure below) Origin of the Universe--Jan. 1 Origin of our galaxy--Jan 24 Solar system origin--Sept. 9 Earth Solidifies--Sept. 14 Life on Earth--Sept. 30 Sexual reproduction advent--Nov. 25 Oxygen atmosphere--Dec. 1 Cambrian explosion (600 mil years ago when most complex
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This note was uploaded on 12/15/2011 for the course AST AST1002 taught by Professor Emilyhoward during the Fall '10 term at Broward College.

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Time - Time Now let's try to get a feel for the time...

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