Dark energy and the accelerating expansion of the universe

In 1998, two teams of astronomers measured the distances to faraway galaxies using a type of exploding star, Type Ia supernovae, whose peak luminosity is predictable, making them standard candles. The distant supernovae were fainter, and therefore farther away, than expected if the expansion of the universe were slowing down. The surprising conclusion, recognized with the 2011 Nobel Prize in Physics, was that the expansion is speeding up. Astronomers call the unknown cause dark energy. Independent evidence from the cosmic microwave background and from the large-scale distribution of galaxies supports the same picture, and indicates that dark energy makes up about 68 percent of the total energy content of the universe. What dark energy actually is remains one of the biggest open questions in physics; some recent surveys even hint that its strength may change over time.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report