Age of universe is often disputed.

What's a few billion years among friends? That's the gist of what Eric J. Chaisson says about the disputed age of the universe. Chaisson, a research professor at Tufts University, Medford, Mass., is a former director of science and education programs for NASA's Hubble Space Telescope program.

Ever since people have sought to calculate the age of the universe, disagreements have cropped up. At one time, the Earth was thought to be younger than people. More recently, the ages of stars in the Milky Way have been calculated to be older than the universe itself. These are temporary mistakes, according to Chaisson.

While the formula used to calculate the age of the universe yields an answer of 15,000,000,000 years, he maintains that this formula is correct only for "an unreal universe devoid of all matter." If the universe decelerates with time. the true age must be closer to 19,-000,000,000 years.

Meanwhile, ancient stars strewn throughout the galaxies, whose age is measured according to when they turn from blue to reddish, seem to be more than 15,-000,000,000...