This is the idea that, today, enables scientists (including many past and present Members of the Institute) to understand the afterglow of the Big Bang and to see the universe as it was 380,000 years after it formed.Astrophysics first had something to add to the question of ages with the discovery of thermodynamics in the late 1800s.
It began with Edwin Hubble’s discovery that galaxies are all flying away from one another.
If galaxies are flying apart now, they must have been closer together in the past, and we can keep turning the clock back until all galaxies lay on top of one another.
Last night a spokesman for Jones said: “Priscilla Presley and Tom have known each other for many, many years.” Priscilla, who starred in hit US soap “Dallas” and the “Naked Gun” films, married “Are You Lonesome Tonight? Sir Tom — who once admitted to sleeping with 250 groupies — was left heartbroken last April when his wife of 59 years died of cancer at age 75.
“How big” is almost always an easier question to answer than “how old.” Though we can measure the sizes of animals and plants easily enough, we can often only guess at their ages. The ancient Greeks Eratosthenes and Aristarchus measured the size of the Earth and Moon, but could not begin to understand how old they were.
The young Earth was a hot and violent place, and even now, the Earth’s surface is constantly changing as rocks are deposited, eroded away, and subducted into the mantle.
The solution lay in space, where asteroids have remained essentially unchanged since the formation of the solar system.With space telescopes, we can now even measure the distances to stars thousands of light-years away using parallax, the same geometric technique proposed by Aristarchus, but no new technology can overcome the fundamental mismatch between the human lifespan and the timescales of the Earth, stars, and universe itself.Despite this, we now know the ages of the Earth and the universe to much better than 1 percent, and are beginning to date individual stars. These estimates were not seriously challenged until the emergence of modern geology in the eighteenth century.We can measure the ages of tiny grains in meteorites, called chondrules, to just 100,000 years out of 4.6 billion.The measurement of the age of the universe is a similar triumph.By measuring these rates, and the relative amounts of parent and daughter atoms in a rock, scientists could measure how long it had been since the rock solidified.