AaS! 106: How Do We Measure the Expansion of the Universe?

What's the deal with redshift? How can we actually interpret velocities when it comes to cosmic expansion? And what's with the recent tension over measuring the expansion rate? I discuss these questions and more in today's Ask a Spaceman! Support the show: http://www.patreon.com/pmsutter All episodes: http://www.AskASpaceman.com Watch on YouTube: http://www.youtube.com/PaulMSutter Read a book: https://www.pmsutter.com/books  Keep those questions about space, science, astronomy, astrophysics, physics, and cosmology coming to #AskASpaceman for COMPLETE KNOWLEDGE OF TIME AND SPACE! Big thanks to my top Patreon supporters this month: John, Matthew K, Helge B, Justin Z, Matt W, Justin G, Kevin O, Duncan M, Corey D, Kirk B, Barbara K, Neuterdude, Chris C, Erik M, Steve C, Digitalneo, Erik M, Tim R, Neil L, Gordon M, Joe R, Neil P, Gabriella G, Tom S, Bryan D, Irene P, Dustin R, Matt C, Iothian53, Steve P, Debra S, Ken L, Alberto M, Ron W, Chris L, Mark R, Alan B, Stephen J, David P, John F, Maureen R, Frank T, Craig B, Jesse A, Ron S, Steven L, Mark R, Ulfert B, Dave L, Stace J, S Stark, Richard K, Vladimir Z, Carol S, Stephen M, Grace M, Jeremy K, Russell W, Thomas S, David B, Tamara F, Robert B, Fr Bruce W, Catherine R, Nicolai B, Sean M, Nate H, and Edward K! Music by Jason Grady and Nick Bain. Thanks to Cathy Rinella for editing. Hosted by Paul M. Sutter, astrophysicist at The Ohio State University, and the one and only Agent to the Stars (http://www.pmsutter.com).