Our Universe 2: Redshift, Expansion & Dark Energy (Everyone's Guide Series Book 16)

This book continues our exploration of cosmology, the science of the universe as a whole.

One of the most profound questions in cosmology is: Has our universe existed forever, or did it have a beginning? Philosophers, theologians, and scientists have argued both sides of this debate, for millennia. The first observational evidence came in 1929 when American astronomer Edwin Hubble announced his discovery that the universe was expanding, and therefore had a beginning. This was one of the most important discoveries of the 20th century.

This eBook examines the key steps leading to Hubble’s discovery, including the contributions of Henrietta Leavitt and the understanding of supernovae and redshifts, color changes of starlight that reveal motion. We explain what “expansion” means, what is expanding and what isn’t. We then explore the accelerating expansion of our universe and dark energy.