The Sunday Opinion section contained an astrophysical essay called Darkness on the Edge Of the Universe. (I urge you to read the essay. You may enjoy discovering why this piece belongs in the opinion section.) The author, Brian Greene, explains an oddity that devolves from our current understanding of the composition of everything we can see: the universe appears to be expanding at an accelerating rate, such that, a hundred billion years from now, if astronomers can point their telescope at the skies, they will see: nothing. Because no light from the ever-distancing stars and galaxies will reach us.
Through no fault of the author, the essay has a subtitle that, in my opinion, is just wrong. It says: The day will come when most stars will disappear from the night sky. (And by the way, this subtitle does NOT appear in the essay online.)
There’s a simple problem with the subtitle: What is a day? Leaving Shakespeare out of this, we must note that the concept of a day is defined by our relationship to our sun, and it has to do with how the earth rotates as it chugs along in its orbit. Long, long before a hundred billion years, the sun will be gone. If there are astronomers to observe the darkest sky, they will have some other vantage point than earth, a place where there may not be days at all, but certainly, not what we regard as days, Thus, our sort of day will not come when most stars will disappear from the sky.