Dating on the earth
The measurement of the age of the universe is a similar triumph.
It began with Edwin Hubble’s discovery that galaxies are all flying away from one another.
“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.
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.
The Sun must be shrinking for this explanation to work.
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.The rate of nuclear reactions goes up as the core temperature rises, and the Sun shines more brightly.It is about 30 percent brighter today than when the Earth was young.The problem was that even the oldest rocks were not as old as the Earth itself.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.
Search for dating on the earth:
We take a star’s worth of gas held together by gravity, calculate its structure, and then follow its evolution over millions or billions of years.