When scientists set out to measure what they expected to be a slow down in the expansion of the universe, they discovered the exact opposite: the expansion of the universe isn't slowing, but accelerating. The unknown forces behind this acceleration have been dubbed 'dark energy' - and Dr. Paul Sutter breaks down what we know about it, what we don't, and where current research is leading us. Find more with Dr. Paul Sutter here: Website: https://pmsutter.com/ YouTube: null Twitter: https://twitter.com/PaulMattSutter Facebook: https://facebook.com/PaulMattSutter Instagram: https://instagram.com/PaulMattSutter Tiktok: https://tiktok.com/@paulmattsutter Connect with Ars Technica: Visit ArsTechnica.com: http://arstechnica.com/ Follow Ars Technica on Facebook: https://www.facebook.com/arstechnica Follow Ars Technica on Google+: https://plus.google.com/+ArsTechnica/videos Follow Ars Technica on Twitter: https://twitter.com/arstechnica