Hubble’s Constant is a measure of the rate at which the universe is expanding. It is named after astronomer Edwin Hubble who first observed and calculated this rate. The value of Hubble’s Constant changes over time because the expansion of the universe is not constant, but rather it is accelerating due to the force of dark energy.
Hubble’s Constant is measured using a variety of techniques, including observations of the cosmic microwave background radiation, the brightness of supernovae, and the distribution of galaxies. The current accepted value of Hubble’s Constant is approximately 70 kilometers per second per megaparsec (km/s/Mpc).
The changing value of Hubble’s Constant has significant implications on our understanding of the universe. It provides evidence for the expansion of the universe and the existence of dark energy. It also affects estimates of the age and size of the universe, as well as the fate of the universe.
No, the rate of change for Hubble’s Constant has not always been constant. In the early universe, the expansion of the universe was slowing down due to the gravitational pull of matter. However, in the last few billion years, the expansion has been accelerating, causing Hubble’s Constant to increase.
Scientists use various models and theories, such as the Big Bang theory and the theory of dark energy, to explain the changes in Hubble’s Constant over time. These models are constantly being refined and updated as new data and observations become available.