Sound Science Bite: Sept 30. "Guess How Old I AM!" -- The Universe

Biblicists say around 6000 years. Early geologists put it at millions or even billions of years. In 1862 the physicist Lord Kelvin computed a 20 million year age for the Sun based on its energy ouput and available energy from gravitational collapse. This wasn't nearly enough for a lot of geologists and far too much for Biblicists.

In the 1920s Edwin Hubble was the first to notice the universe was expanding and his measure of the rate of expansion (given by the so-called Hubble constant) said the universe was two billion years old, younger than the 4.5 billion years physicists had determined for the age of the Earth from radioactivity. Oops! The problem was although the Doppler shift gave the rate of recession of galaxies very well, the distances to these galaxies was poorly known.

When the cosmic background radiation was analyzed -- the radiation left over from what is said to be the "Big Bang" -- cosmologists were confident they had nailed down the universe's age to 13.8 billion years. Other cosmologists have been trying to measure the Hubble constant to confirm that. There have been quite a variety of types of measurement, and they don't disagree wildly, but the age of the universe could still be as young as 12 billion years or as old as 14 billion years. The problem with the younger ages is that according to well-established models of the age of stars, the oldest ones approach an age of 14 billion years, but there could be some inaccuracy in the models. The problem with the range of ages continues to be measuring the distances to galaxies accurately. Personally, I think the universe doesn't look a day over 13.6 billion years.