Is it possible that dark energy is not a constant, but rather is changing over time? Sean Carroll talks to us about how our understanding of dark energy evolved in recent history, and what is still left unknown. For exclusive ask-us-anything episodes, join us for just $3 a month on Patreon: https://patreon.com/whythisuniverse. Our merch is available here: https://www.shalmawegsman.com/why-this-universe