This will be speculation and therefore I don’t know what it is that I will be writing about but neither does anybody else. The future is impossible to predict, which is what makes it so difficult to be accurate. Perhaps it is best to follow nature’s way and to respond instantly to the evolving situation with which one is presently confronted. Gravity works that way, as do Newton’s other descriptions of basic reality, but we humans live in a social reality that is far too difficult to describe with mathematical equations and descriptive formulas. It is our future human history that will tempt us most to try to predict.
Thomas Malthus, back in the 1790s and early 1800s, was predicting that world human population would soon exceed its food supply and begin oscillating around a sustainable number of less than a billion people. The driving force for limiting population would be famine because of lack of food, disease because of the poorly fed sickly people, and wars fought to obtain fertile land and crops. We now have almost ten times as many people and the population is going up by the amount he predicted as the maximum in about ten years. Even predicting a gross thing like human population appears to be bounded by very broad error bars.
A decade ago the world was about to run out of oil to run our cars and airplanes, heat our homes, and create fertilizer to raise our food, but even so fixed a thing as the supply of oil in the ground that had been carefully mapped and known to be running out has gone up by as much as ten times. The oil-retrieving method named fracking has come to the rescue. Of course, that oil when burned ends up polluting the atmosphere and that brings on problems like global warming. It seems that new solutions have continued to be found to help us not only survive as a species but to continue to explode in population.
Who knows what will happen? But the human population can’t keep growing forever without eventually converting the whole planet Earth into human flesh. But wait, the computers and robots using advanced computers are taking over the jobs formerly held by humans. In our existing economy most people work to make money for themselves and their families, and with that money buy food and other necessities. At the moment few people are starving, but if many, most, perhaps all jobs are replaced by robots how will people make money to feed themselves, let alone their families? Will that bring on a famine, or will the robot community just keep feeding us so we can keep on reproducing more people and thus create more work for the robots? Let’s assume that all goes well and the human population is able to grow to even greater numbers because the robots are good at creating food which they themselves don’t consume while producing it. What then will be the limit on human population?
Perhaps the robots will run out of power, their food, and then be unable to sustain humans. The response would be to find new power sources. Ultimately that is the sun which we access directly as light energy, secondarily as wind energy, and tertiarily as stored energy like coal and oil. When that energy limit even approaches the robots will place more of their efforts into creating solar energy farms and wind farms. Ultimately that effort would go to sea and vast areas would be covered with solar panels and wind-gathering fields of windmills of various types.
All of that seems excessively speculative, but if the human population continues to double at the rate of the last one hundred years, 1925 = 2 billion, 1975 = 4 billion, 2025 = 8 billion, 2075 = 16 billion. What then? We will be forced to create energy and food using power generated in these new ways. A person born in 1990 can expect to see a population of 16 billion. To achieve those population numbers will require the creation of the energy technologies mentioned.
The evolving world view must include supporting vast new energy sources.