These days, astronomers think normal matter comprises just 5 percent of the universe’s contents. Meanwhile, dark matter makes up some 26 percent, and dark energy accounts for the final 69 percent. Dark energy, it turns out, seems to be the real-world force behind Einstein’s cosmological constant, which plays a major role in preventing a Big Crunch-style collapse.
Thanks to the expansion caused by dark energy, within a couple of trillion years, all but the closest galaxies will be too far away to see. Then, perhaps 100 trillion years later, star formation will cease, as dense stellar remnants like white dwarfs and black holes lock up any remaining material.
About a googol years from now — that’s a 1 followed by 100 zeroes — the last objects in the universe, supermassive black holes, will finish evaporating via Hawking radiation. After this, the universe enters a so-called Dark Era, where matter is just a distant memory.
The second law of thermodynamics suggests that entropy will keep increasing in a system (such as the cosmos) until it hits a maximum level. In real terms, that means that at some point, the universe will ultimately reach a state where all energy — and, hence, heat — is uniformly distributed. The final temperature of the entire universe will hover a smidge above absolute zero.
So, rather than mirroring Revelation, the death of our cosmos will likely resemble the beginning of Genesis: All will be empty and dark.