At the beginning of our last episode, I mentioned that we’d just learned that new work by the Dark Energy Spectroscopic Instrument, or DESI, had provided hints that our universe has a changing density of dark energy, but I needed time to look over the research. Well, I’ve looked, and the news is kind of cool, especially if you like mysteries. As the story goes, back in 1998 two different supernovae research teams did a fit to their brightness versus velocity data and found the expansion rate of our universe, which is the source of that measured velocity, appears to be growing over time. This...