Astronomy Cast Ep. 669: Challenges to Dark Energy by Fraser Cain & Dr. Pamela Gay Streamed live on Feb 6, 2023. It's been over 20 years since astronomers first discovered that the expansion of the Universe is accelerating thanks to dark energy. And in these decades, astronomers still don't have much evidence for what could be causing the increased expansion rate. Maybe there's something else going on to explain it. This video was made possible by the following Patreon members: David Burry Gowen Jeanette Wink Stephen Veit Jordan Young Venkatesh Chary Andrew Poelstra Brian Cagle David Truog Gerhard Schwarzer THANK YOU! - Fraser and Dr. Pamela