(CNN) — Hovering blue flames that flicker over bogs and marshes have inspired ghostly folktales for centuries. Known as “will-o’-the-wisp,” “jack-o’-lantern,” “corpse candle” and “ignis fatuus” ...

We’re still not sure exactly what dark energy is, but it may have played a key role in the early universe. The resulting dilemma is called the Hubble tension, and Niedermann and Sloth say they may ...