Most of us have received a bit of information at one time or another that seemed too bizarre to be true. If we hear the information from only one source, skepticism is the appropriate response. However, if multiple, unrelated sources provide corroborating information, the reliability of the information increases dramatically. Similarly, any claim for dating the creation of the universe seems incredible at first glance because no humans existed then. However, when multiple techniques give the same date for the beginning, that date becomes eminently credible.
The most popular dating technique models the history of the universe based on measurements of various cosmological parameters and uses the model to calculate the time since the big bang. Using precision measurements of the cosmic microwave background from the WMAP this technique gives an age of 13.73 +/- 0.15 billion years.
Alternatively, one can measure the ages of the oldest globular clusters or the oldest white dwarfs in the Milky Way Galaxy to determine an age for the universe. The oldest globular clusters date between 8.5 and 13.3 billion years old with the most likely date around 12.1 billion years. Adding the formation time for globular clusters gives a date consistent with the WMAP results. In the case of the white dwarfs, astronomers have determined an age for the universe of 12.8 +/- 1.1 billion years—also matching the WMAP results.
Recently, an article in the Astrophysical Journal provided another date for the universe using radioisotope dating on very old stars. The first stars formed with only hydrogen and helium because the big bang produced only those two elements in abundance. After a first generation of massive stars formed, burned, and exploded as supernovae (in a rather short time of a few million years), a second generation of stars formed with detectable amounts of elements as heavy as uranium and thorium. The star described in the article matches just such a second-generation star. The abundances of detected elements match predictions of the elements formed in supernovae. The only variance is that the radioactive elements such as uranium and thorium are depleted because of decay over the billions of years since the star’s formation.
Using the measured abundances of the heavy elements, the international team of astronomers dated the birth of the star at 13.2 +/- 2.7 billion years ago. Since the time required to form these types of stars is about half a billion years, this technique provides a fourth independent measurement of the age of the universe. Since all four techniques are consistent, we can be confident in the 13.7-billion-year age they give for creation.