It’s about time for some long-range planning, considering how well we’re doing with the short-range stuff. If you don’t agree, come back in about ten minutes and see if it’s time then. I’m thinking of really long term, not like those geology folks who think 1,625 million years is a fair stretch. I want something big.
As you go out long enough, the Sun is going to continue shining. This might sound controversial, but remember that we’ve almost completely amortized the costs of constructing the Sun. All we’re responsible for now is basic maintenance and upkeep. Even if we wanted to replace it with a more modern design it’d hardly be economical. And besides, the contemporary zoning regulations would make it really annoying to build the necessary falsework for a replacement to the Sun.
Now the thing about the Sun shining is that all that light falling down exerts pressure on the ground. Light hasn’t got any mass, being possessed of low self-esteem as a child when it might have formed some. But it does carry momentum, being unable by temperament to say no when asked to carry some momentum somewhere. When the light hits the ground and is absorbed or bounces off it pushes the ground down as surely as hitting it with tennis balls would, only without line judges. This is never a lot of push, but it is there all across the daylight half of the globe, and that adds up to a fair-sized push.
Imagine the Earth to be made of Play-Doh. This is a metaphor: it is actually made of peanut butter. But if you take a gob of Play-Doh out of its can you can lose all focus while you absorb that strange plymer smell. Please try to be productive through that. While enjoying the smell roll the Play-Doh into a ball and then set it down. It will not stay a round ball forever. Even before other people in the house take it to build their own projects, the continual pull of gravity will spread it out. This takes time, but we have that time. There’s probably billions of years of time you haven’t scheduled anything for yet, but still won’t be able to get around to writing that novel you have in mind.
Earth isn’t sitting inactively on a table. This is a good thing as the temptation to hit it with a giant pool cue would be nearly irresistible. Nor is it sitting in a giant chicken nest, again good for everyone who worries about stuff hatching from underneath them. But while the pressure of sunlight is flattening the Earth, the Earth is also rotating. This implies all that sunlight has the same effect of rolling a ball of Play-Doh on the ground: it’s going to roll out into a long, thin pole.
There’s no denying this is a long-term fate, but I warned you about that four hundred words ago. As the rolling effect will continue eventually the Earth with be a pole world. Long enough at this and the Earth will just a few inches wide and enormously long swinging around the solar system like a baton. Imagine the size of the matching cheerleader.
What can we expect life on this Pole World Earth to be like? Narrower, for one. There will be evolutionary pressures towards plants with very shallow roots, which means we may at last be free of those impossible-to-remove lawn weeds. It will be difficult for trees to grow tall, but those which manage will find to their photosynthetic delight that spreading their branches even a couple inches to either side means they get sunlight all day long. Probably that’s good for plants. You can’t imagine them getting worn out from too much sunlight and sneaking off to a corner, exhausted and panting from all that sugar-making.
While burrowing life forms will find life difficult, those which are comfortable living on vines or branches will be in good shape. Two- and three-fingered sloths may find the climate most comfortable except when someone wants to pass.
Humans will need to adjust as well. Those with long experience in grabbing poles, as they may have on buses or subways, will have an advantage, of course. Thus we see in large-city mass transit systems as evolutionary pre-adaptations to the future Pole World Earth. Subtle foreknowledge of this fate and the privileged position city-dwellers will have may account for the smugness often held against the urbanized.
Yet subways will have long since ceased to run by then, probably by the time the world is a pretty long rod only about fifty feet in diameter since trains need more clearance than you would have guessed. Not a lot more, just like another two feet or so more. But that’s still more. Without subways we can expect the economy to be radically different and generally much more cylindrical. Strong but lightweight straps could reasonably be in demand, but on the other hand people may just grow steeper arches in their feet. This is why it is so hard to predict the distant future.