How do scientists estimate how old the universe is?
A) They look up the answer in a book.
B) They measure the abundances of radioactive elements in meteorites, and use their half-lives to calculate the age.
C) They measure how fast the Sun is losing energy, and how much energy it has to lose.
D) They make a guess: no one really knows how old the universe is.
E) They measure the speeds and distances of galaxies, and calculate the time it took for them to travel that distance.

Question

Quizplus · Accepted Answer

Scientists use the method of measuring the speeds and distances of galaxies, and then calculate how long it took for them to travel that distance, to estimate the age of the universe. This method is known as the Hubble's law or the cosmological redshift. By measuring the redshift of light from distant quasars and galaxies, scientists can determine their distance from us and their recession velocity. From this, they can calculate the rate of expansion of the universe and estimate its age.

How Do Scientists Estimate How Old the Universe Is