Popsugar Reading challenge category: A book with a parallel reality
Book: The Gods Themselves, by Isaac Asimov
The title comes from a Friedrich Schiller quote: "Against stupidity, the gods themselves contend in vain." Humans discover a new source of unlimited energy, via contact with a parallel universe. A scientist figures out that the new energy source will eventually destroy the sun. But other scientists and politicians won't listen - one notes that people will only believe what they're comfortable with. Written in 1972, it seems quite prescient around climate change.
In the parallel universe, we meet some aliens who are very alien, fluid in form, three-gendered, and able to fuse into solid form. They're well aware that the new energy source will destroy our universe - they simply don't care. And so it's up to one rebel on each side of the divide.