Riding the Torch

"Riding the Torch" is a novella by Norman Spinrad. The premise is that humanity has destroyed the Earth via nuclear war, and centuries later, humanity's remnants are still traveling in a convoy in search of another world to inhabit. Eventually, the realization sinks in that Earth was unique; there are no other worlds that can reasonably support life, there is no other life in the universe except humanity.

I think of that novella from time to time, particularly today, when I read that according to computer models, solar systems like ours are rare:

The researchers ran more than a hundred simulations, and the results show that the average planetary system's origin was full of violence and drama but that the formation of something like our solar system required conditions to be "just right."
...

The simulations suggest that an average planetary system's origin is extremely dramatic. The gas disk that gives birth to the planets also pushes them mercilessly toward the central star, where they crowd together or are engulfed. Among the growing planets, there is cut-throat competition for gas, a chaotic process that produces a rich variety of planet masses.

Also, as the planets approach each other, they frequently lock into dynamical resonances that drive the orbits of all participants to be increasingly elongated. Such a gravitational embrace often results in a slingshot encounter that flings the planets elsewhere in the system; occasionally, one is ejected into deep space. Despite its best efforts to kill its offspring, the gas disk eventually is consumed and dissipates, and a young planetary system emerges.

Now don't you feel special?