How do scientists estimate the age of the universe?
Quick Answer
They combine the expansion rate of the universe with measurements of the cosmic microwave background and the amounts of ordinary matter, dark matter, and dark energy. The best current estimate is about 13.8 billion years.
The Full Story
The universe’s age is inferred from cosmological measurements rather than from a single clock. One major input is the Hubble expansion rate, while another is the detailed pattern in the cosmic microwave background, the afterglow of the Big Bang. Space missions such as WMAP and Planck measured this radiation with high precision, allowing scientists to fit the standard cosmological model. Under that model, the universe is about 13.8 billion years old. The same model also explains the large-scale structure of galaxies and the observed abundance of light elements.
Key Facts
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