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zeroing in

Data, Data, and More Data

Your race-timing approach is indeed similar to the technique cosmologists today use to calculate the age of the universe. But is making this calculation as simple as taking those distance and velocity measurements for just a single galaxy? More specifically, if every galaxy in the universe started at the same place as our galaxy, can’t we simply choose one other galaxy, measure its velocity and distance relative to us, and insert those numbers in our time equation to give us the age of the universe?

Unfortunately, cosmological reality is a bit more complicated. To see why, let’s go back to the 1920s when astronomer Edwin Hubble was studying the motion of galaxies. Hubble measured how fast different galaxies moved away from our own Milky Way by detecting a characteristic of galactic light known as redshift. Examining his data, he discovered that more remote galaxies seemed to be receding from our galaxy faster than nearby galaxies were.

Since (as Hubble found) galaxies have different velocities relative to us, using velocity and distance data for one galaxy would not be sufficient to give us an accurate figure for the age of the universe. Rather, scientists need data from hundreds of nearby and distant galaxies to calculate the age of the universe. The broader the sample of data collected, the more accurate the calculation. (Box o' Math: The Hubble Constant gives a more detailed mathematical description of how scientists are zeroing in on the age of the universe.)

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