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, cant 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,
lets 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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