How do we know the age of the universe?

Scientists have developed various methods to estimate the age of the universe. One of the primary ways is through the study of the cosmic microwave background radiation (CMB), which is the afterglow of the Big Bang. By analyzing the temperature fluctuations in the CMB, scientists can extrapolate back to when the universe was just a hot, dense soup of particles.

Cosmological Models

Another method involves using cosmological models based on the expansion rate of the universe. By measuring the rate at which galaxies are receding from us (Hubble's law), scientists can work backward to determine when all matter and energy were concentrated in a single point.

Nucleosynthesis

Nucleosynthesis, the process by which elements are formed in the early universe, also provides clues to its age. By studying the abundance of light elements like hydrogen, helium, and lithium, scientists can infer how much time has passed since the Big Bang.

Combining these and other methods, scientists have estimated the age of the universe to be approximately 13.8 billion years. As our understanding of cosmology advances, these estimates may be refined to provide an even more precise age of the universe.