The “Age Paradox”
How can the stars be older than the Universe????


Galaxy M-100 - Kopernik ImageIn 1994 Dr. Wendy L. Freedman, using the Hubble Space Telescope, observed individual Cepheid Variable stars in spiral galaxy M-100. Seeing these “standard candles” allowed her to estimate a distance to M-100 (and the entire Virgo group) of 51 million light years. This was much less than the previous estimate of 60+ million light years, and created great controversy in that it also led Dr. Freedman to estimate that the Universe was only 8 billion years old. For many years theories of star evolution based on particle physics and star distance estimates predicted that the oldest stars were 12 to 15 billion years old. There is an obvious paradox here!! One can’t have stars older than the universe they are in!
Kopernik image of M-100!

Other Astronomers strongly disagreed with Dr. Freedman’s results, but they were good enough to send many astronomers, physicists, and cosmologists, “back to the drawing board” to examine both the Big Bang Theory and stellar evolution. Some even said that there might be errors in particle physics theories.

More recently(1997), data from the Hipparcos satellite gives better distance and brightness estimates for a few close Cepheid Variables. Direct measurements by Hipparcos imply that the Cepheids are more luminous and more distant than previously imagined. This adjustment to the “standard candles” means that M-100 and the other galaxies are about 10% further, and that the Universe is about 13 billion years old. Other Hipparcos results which give better data on another type of variable, revised the distances and ages of Globular Cluster stars. These oldest stars are now estimated to be 9 to 12 billion years old, younger than the new 13 billion year estimated age of the Universe.

So, the “Age Paradox” is solved!!! Well, maybe not!

Even the nearest Cepheid Variables are at the outer limits of Hipparcos’ measurement abilities. Some scientists now claim that there is still a large margin of error in the Hipparcos data and that certain statistical quirks could cause an over-estimate of Cepheid distances. While other results support the new distances and ages, the “Age Paradox” could return to challenge scientists to further refine their theories. Of course that is the way science has always worked.



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George Normandin, KAS

July 7th, 1998