Astronomy Column

What's The Age Of The Universe?

It is estimated that the universe is 13.7 billion years old, but discrepancies in the measurement of this figure could open the door to a new revolution in physics.

One of the great triumphs of modern astrophysics is the determination of the so-called fundamental parameters of the universe, a group of numbers that indicate their basic properties such as their age, geometry, size, among others. One of these parameters is the Hubble constant. It comes from the discovery, almost a hundred years ago, that the more distant, faster galaxies move away from us and, therefore, that the universe is expanding. The rate of increase of this rapidity is the Hubble constant-and its inverse, with a multiplicative geometric factor - tells us what is the age, and therefore the size, of the observable universe. That is why determining its value has become for astronomers an obsession for almost a century.

Fortunately there are several ways to measure the Hubble constant, which allow us to check its value and thus measure it with great precision. Edwin Hubble himself was the first to try to measure it, but its result indicated that the universe's age was only about two billion years, much younger than the estimates of the age of the Earth existing even at that time. It was clearly a dilemma! We now know that this was caused by a problem in calibrating the luminosities of stars used by Hubble and that the universe is actually about 7 times older and larger. We now know the Hubble constant with an impressive precision of 2.4%.