WWWHis method of calculation was the use of the Hebrew Bible genealogy, and an in-depth study of Greek, Roman and Chaldean history which represented all of known European history at the time. His conclusion? The first day of creation occurred on Sunday, October 23, 4004 BC, therefore, Earth was 6000 years old. From what I could understand, his calculation was the beginning of everything—man, the Earth and the universe—since there were no eye-witness accounts for the period preceding man, he assumed the literal interpretation of Genesis. He was not alone. He was supported by the great Sir Isaac Newton, astronomer Johannes Kepler, scholars Venerable Bede and Scaligar; all coming to similar calculations.
On February 8, 1969, a stone approximately the size of a car, and traveling at ten miles per second, exploded over Allende, Mexico, breaking up into thousands of fusion encrusted pieces. The Allende stones became one of the most widely distributed meteorites, providing scientists a wealth of material to study. They are the oldest known matter at 4.567 billion years old, 30 million years older than Earth, and 287 million years older than the oldest rock known on Earth.
We live in an ever expanding universe. The vast majority of galaxies are moving away from each other and they’re all moving at different speeds depending how far away they are. The galaxies further away are moving faster than those that are closer. In other words, not only is the universe expanding, it’s doing so at an accelerated pace.
WWWA great analogy I’ve come across is to consider a loaf of raisin bread, the raisins representing galaxies, and the dough being the fabric of space. As the dough rises, it carries the raisins with it, pulling them apart from each other, the raisins on opposite sides of the loaf will move further from each other than the raisins that were nearer each other. Stated simply, the speed of their motion is proportional to the separation between them.
WWWAstronomers determine a galaxy’s motion by observing its light spectrum, galaxies moving away make it appear redder, called the red shift, and used to calculate the velocity of many galaxies and then plotted. This is called the Hubble constant or the rate of expansion. Then it’s a matter of dividing the distance by the velocity to give them the time, or age. It’s like playing time backwards. WWWAnother technique is the measurement of Cosmic Microwave Background (CMB) from the faint glow left by the Big Bang—the radiation that streamed into space when the universe was 300,000 years-old, showing up as hot and cold spots on temperature maps. The older the universe, the farther these spots lie from Earth, and the smaller they appear on the sky. From the size of the spots, scientists can calculate the age of the universe.
WWWFrom these methods of measurement astronomers have precisely calculated the age of the universe to be 13.75± 0.13 billion years-old.