YMMV / The Night Land

• Fanon: Because the idea of the Sun slowly going dark has been disproved by advances in astronomy, fan works like Awake in the Night Land assume that the death of the Sun was caused by an outside source.
• Scifi Writers Have No Sense Of Scale: The survival of the human race and of evolved predator races is based on energy and light provided by volcanism on the bottom of the Great Valley. It's explicitly said the upper surface of the Earth is frozen cold (and supposedly just as inhospitable as a cold planet like Mars today). However, the Great Valley is said to be more than 100 miles deep where the Great Redoubt lays and maybe 150 miles where the Lesser Redoubt stood. The highest mountain today is 5.5 miles high and everything above 5 miles is regarded as the death zone, where nobody can acclimatize, pressurized aircraft fly 8-9 miles above the Earth and the limit of space is 60 miles above us. Yet our hero walked in armor outside the controlled atmosphere of the Redoubt and descended 50 miles through the Valley? And nothing changed around him outside "a bit thicker air"!? Saying that air on the Earth surface nowadays is a bit thicker compared to air 50 miles above is like saying the Pacific is slightly wet. This is possibly more of a case of Science Marches On given when the story was written; the very term 'death zone' was coined 41 years after this was written, and much of the research took place after the author's death in 1918. Just like with The Time Machine this story was also written before the discovery of radioactivity and radiocarbon dating: back then the Earth and sun were believed to be only tens of millions of years old and the expected remaining lifespan of the sun was far shorter than the 4.5 billion years expected by modern science. Likewise, the internal structure of the Earth had not been well surmised at that point: a valley 100 miles deep would place most of it well into the Earth's upper mantle, which needs to have cooled considerably in the future to be made of solid rock at that point.