No new stars or other structures will be generated. Finally there will be just a bunch of rocks left. There was no comment from the philosophers Radio galaxies are typically the same size no matter where they are, allowing comparison of data. The amount of mass needed to tip the scales is just one hydrogen atom per cubic meter of space. That's a lot of empty space to fill - too much, it seems.
Calculations come in at a quarter of that.
But the way astronomers figured that the universe won't be throwing in the towel had to do with observations of various celestial phenomena. Type Ia. These supernovae are triggered when a dying white dwarf pulls too much gas off a neighboring red giant star, setting off a thermonuclear explosion that rips the white dwarf apart. The explosions can be brighter than an entire galaxy, but last only a month or so before fading away. The great thing about these supernovae is that they look identical no matter when they happen. They're easy for scientists to date accurately, since phenomena recorded from stars say, five billion light years necessarily occurred five billion years ago.