Dark Energy:Dark energy is a hypothetical form of energy that is thought to permeate all of space, causing the universe's expansion to accelerate. Its nature and origin are currently unknown, making it one of the biggest unsolved mysteries in physics.
Cosmic Microwave Background:The cosmic microwave background (CMB) is the oldest light in the universe, originating from the time when the universe became transparent to radiation, about 380,000 years after the Big Bang. Studying the CMB provides valuable insights into the early universe and the formation of large-scale structures.
Baryon Acoustic Oscillations:Baryon acoustic oscillations (BAOs) are small fluctuations in the density of the visible matter in the universe. These oscillations are imprinted on the cosmic microwave background and can be used as a standard ruler to measure the expansion of the universe and study the properties of dark energy.