Description
When light passes through the universe and is redshifted by the expansion of space itself, how is energy conserved? The stretched light has a longer wavelength and therefore a lower energy. Is energy conserved? If so, where does it go?
Support Physics Girl videos → https://www.patreon.com/physicsgirl
http://physicsgirl.org/
http://twitter.com/thephysicsgirl
http://facebook.com/thephysicsgirl
http://instagram.com/thephysicsgirl
Creator/Host: Dianna Cowern
Editor: Levi Butner