Either by the ages of its oldest contents, namely stars, or by measuring the Hubble Constant, the deceleration parameter and the cosmological constant, and computing its age from the best cosmological model consistent with its rate of current expansion. As we look farther out into space, we expect to see the value of the Hubble constant to change because the universe was expanding FASTER in the past, and we see the light from galaxies as they were moving long ago. The measure of this 'deceleration parameter' is a fine correction to the Hubble Age estimate obtained from the local Hubble constant. It turns out that the Hubble constant, expressed as a velocity per distance, has the units of an inverse time ( 1/seconds) and Big Bang theory tells us that T = 2/3 x (1/H) as I noted in a previous question. For a value of:
...Value of H...................Age................
50 19.2 billion years
75 12.9 billion years
100 9.6 billion years
....................................................
The current estimates by Wendy Freeman seem to cluster around H = 75 km/s/mpc although a significant school of astronomers led by Alan Sandage consistently get numbers close to 50. Recently, however, values closer to a compromise value of about 70 have begun to appear. Stay tuned!
Copyright 1997 Dr. Sten Odenwald
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