Age of the Universe
Written by John Carl Villanueva
"How old is the universe?", seems like a fairly logical question to ask unless you tend to believe that the universe has been here forever and will be here forever as well. There are a number of proofs that would indicate that that isn't the case but let me give you one first.
Scientists have much reason to believe that the composition of astronomical objects are the same as what we have here on earth. That is, the elements on the Sun and other stars, as well as other planets or asteroids and comets can all be found here on earth. Furthermore, there is no reason to believe that the manner by which they evolve differs from the way they do here.
To be more specific, uranium-238 found anywhere in the universe should undergo radioactive decay and eventually turn into lead after a finite period of time. Thus, if the universe has been around in an infinite period of time, then in the earth alone, you wouldn't hope to find any trace of uranium-238 … but then we still do.
That should tell us one thing: that the universe has been here within a finite period. And because that is so, it should be possible to measure how long it has been around. So far, there are 3 major methods by which we can determine the age of the universe. Although they do not directly match, their predictions lie within the same order of magnitude; all within a range of 10 billion to 20 billion years
The first method, called nucleocosmochronology, is like the one mentioned above, i.e., making use of the abundances of radioactive nuclide. Another method makes use of the Universe's rate of expansion, while the 3rd through the behavior of globular clusters, which are spherical collections of stars, the oldest of which have stars estimated to be no older than 18 billion years.
The Universe's expansion is an offshoot of the Big Bang theory, which also has led to the discovery of cosmic microwave background radiation, the source of data of the most precise measuring devices for the age of the Universe.
The most precise measurement of the age of the Universe so far, pegged at around 13.7 billion years, was made by NASA's Wilkinson Microwave Anisotropy Probe (WMAP). Anisotropy pertains to the uneven distribution of cosmic microwave background (CMB) radiation, the oldest electromagnetic waves in the Universe. With WMAP, NASA has been able to generate a full-sky map of CMB radiation and, subsequently, that said estimate.
We've got a few articles that touch on the age of the universe here in Universe Today. Here are two of them:
- 13.73 Billion Years – The Most Precise Measurement of the Age of the Universe Yet
- Age of the Milky Way
NASA also has some more:
Tired eyes? Let your ears help you learn for a change. Here are some episodes from Astronomy Cast that just might suit your taste:
Filed under: Astronomy
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