With information and energy, anything allowed by the laws of nature is possible. The confluent emergence of robotics, artificial intelligence, and nuclear fusion power brings this within our sight. In the centuries to come human beings will reach unprecedented levels of prosperity and welfare. The natural environment will be healed and restored. And humanity will spread throughout the galaxy.
Nuclear power is inevitable, because that’s where the energy is. Hydrogen is the most abundant element in the universe. The fusion of hydrogen atoms into helium powers stars. The reservoir of hydrogen on Earth alone is sufficient to meet the needs of any conceivable human civilization into the indefinite future. For more than fifty years, the pursuit of practical energy generation through fusion has failed. But in recent years there has been rapid progress using a number of novel techniques. It seems likely that within a decade or two at least one of these approaches will come online as a practical means of generating electrical power.
By the end of this century most of our power generation will be by means of nuclear fusion. The cost of electricity will drop. Abundant and cheap energy has almost endless implications for solving human problems. If energy is inexpensive, desalination can provide limitless amounts of fresh water wherever it is needed. Global warming and the planetary climate can be modulated by pulling carbon dioxide directly out of the air. Inexpensive energy will also enable the cost-effective synthesis of chemical fuels, where the use of these remains appropriate, as in aviation and rocket ships. It will be feasible to manufacture hydrocarbon fuels directly from carbon and water. Gasoline will become a renewable source of power storage and utilization.
Artificial intelligence combined with robotics will provide a means of channeling and utilizing energy to achieve anything that is possible. These technologies are sufficiently advanced to be on the verge of producing an autonomous self-driving automobile. The rapid maturation of artificial intelligence is demonstrated by the fact that computer programs can now easily defeat the best human chess players. Industrial robots are replacing human beings in a number of roles where they can perform many tasks more reliably and accurately.
The James Webb space telescope is an awesome achievement. But future telescopes will not be laboriously pieced together on Earth and then transported into space. The raw materials will be gathered in space or transported to the appropriate location and then assembled by robots guided by artificial intelligence. The process will be much more robust, as the assemblers will remain on site after completion to effect any needed repairs or correct any malfunctions. Telescopes with mirrors a kilometer or more in diameter can be used to scout nearby stars for Earth-like planets suitable for colonization.
If human life can be prolonged, colonization of the Milky Way galaxy will be inevitable. The average distance between stars in the galaxy is about five light-years. Even if the speed of light remains an insurmountable obstacle, interstellar travel is theoretically possible. Rockets can be accelerated to some appreciable fraction of the speed of light using nuclear pulse propulsion. If the average human life expectancy at birth can be increased to say, a thousand years, then a trip taking a hundred years becomes feasible.
Eventually, humans will not search out Earth-like worlds, but construct artificial worlds. This process has already been foreseen. The 1970 novel Ring World by Larry Niven describes an artificial world rotating like a ring around a star. Niven’s Ring World has a diameter equivalent to that of Earth’s orbit, a width of one million miles, and provides three million times the living space that Earth does. Such a world could be roofed by solar panels that open and close, alternating day and night, moderating temperature, and generating large amounts of electrical energy.
Construction of such a prodigious artificial world could be accomplished effortlessly by pushing a button. A probe will be launched, reach a distant solar system, and scout to see if sufficient raw materials are available. If so, the machine will proceed to duplicate itself and construct other machines, until a massive army of robots is assembled. This process of exponential growth and replication mimics nature. Nature utilizes seeds that contain information and a limited amount of stored energy. The seed uses its programmed instructions to unfold and grow, utilizing energy and raw material from the surrounding environment. Nature is capable of assembling a living organism vastly more complex than any artificial world from the information coded by only the four nucleobases that compose DNA.
The diameter of the Milky Way galaxy is about 100,000 light years. Human civilization will spread slowly, leapfrogging from star system to star system. Colonizing other galaxies is an entirely different challenge. The nearest large galaxy, Andromeda, is 2.5 million light years distant. Assuming, again, that the speed of light is an inviolate limit, trips of more than a million years are impossible, with any possible human lifespan. But a truly advanced and visionary civilization with sufficient resources could spread life throughout the cosmos by sending seeds on unmanned probes capable of making voyages through inter-galactic space lasting for millions of years. This is the old theory of panspermia, the idea that life has spread throughout the cosmos by the dissemination of seed material. What this seed material would consist of is unclear, but it would have to be capable of surviving for millions of years and have the potential to spring into some form of life when it reaches a suitable environment. Nature offers a suggestive model in the form of spores, which can remain viable for tens of millions of years. It’s entirely possible that Earth has been already seeded repeatedly by alien civilizations living in distant parts of the cosmos. This would help explain the incredible diversity and abundance of life on Earth, as well as anomalies in the fossil record such as the Cambrian Explosion. If the seeding of life on Earth seems implausible, consider that if it only happened once every 100 million years, it would have already happened 45 times in terrestrial history.
With humans moving to artificial worlds, the home planet can be turned into a park. Robotic labor can remove blemishes left by human activity, dig up landfills, and remediate all environmental damage. Contaminants will be removed from the oceans, lakes, and streams. Concrete and other materials will be ripped up, broken down into their constituent elements, and recycled. Vast herds of bison will once again range through the prairie grasses of the American midwest. The environment will be restored to a pristine state, or perhaps improved if our understanding of the science of ecology becomes sufficiently advanced.
The preceding speculation may seem fantastic, but it is simply an extrapolation of a long-term trend. Since Homo habilis first walked the Earth, about 2.3 million years ago, the history of the human race has been a history of accelerating technological progress. From the first stone tools, the utilization of fire, writing, and the harnessing of artificial power sources, our lives have become longer, richer, and more satisfying. Yet human beings have barely begun to fulfill our potential. We have reason to be optimistic about the future.