What will the future of space travel look like? What will the future of humanity look like? These are big questions, and it’s outrageous to attempt to answer them in a short column like this, but they are interesting questions nevertheless. However, there is another question that this column could hope to broach: how amazing will the future be? There is a subtle difference between this question and the previous ones. It is very hard to guess what technologies, social trends, political changes, or unknown events will define the next century, much less millennia. It may be that there are true visionaries, both ancient and contemporary, that have successfully gleaned the future. However, it is probably surmountable to try to separate the visionary from the lucky guesser, and the lucky guesser from the crazy fool.
Instead, consider this: why isn’t humanity now living in the future? Where are the flying cars and the jetpacks? The answer is this: the future is here, just different than anticipated. There are no flying cars, but there is a hyper-efficient taxi service called Uber that can turn almost any car on the road into a service vehicle, and the service is accessed by a universal communication device the size of one’s palm which (depending on the model) costs about as much as any other major appliance and a cable subscription. There are jetpacks: they only operate over water, but they are absolutely here. In the same way, this column cannot hope to guess at what the future will be; it can only talk about what other visionaries or loonies have talked about, with the hope and confidence that the future will have a similar store of amazement.
The Kardashev Scale
In 1964, a Russian astrophysicist looking for extra-terrestrial intelligence (work which continues today through the Search for Extra-Terrestrial Intelligence (SETI) Institute), came up with a scale that could be used to classify different civilizations that humanity might discover. This scale is based on the concept of the energy use of a civilization increasing with technology, and therefore energy use being a good proxy for technological advancement.
This scale can be thought of, in the most broad sense, the kinds of things that different civilizations, including humanity, might be able to do as they reach different levels of energy consumption.
The initial scale included three types of civilizations: I, II, and III. Other theorists and dreamers have since expanded it.
A pre-type I civilization like modern humans, relying on finite and limited sources of energy like dead plant matter.
Type I – Planetary Civilization
A civilization that is so advanced, it requires all the energy that its host planet can provide. The majority of this energy comes from the nearby star, so this requires covering almost all of the planet in solar-harvesting technology, or possibly filling the local space with solar panels. Humanity is currently on-track to reach this state in 100 to 200 years, and will then control 10^16 W of power. Such a civilization would probably have control over all the energy on the planet, including the ability to control things like the weather, volcanoes, and earthquakes.
Type II – Stellar Civilization
The obvious next-step for a civilization that has exhausted new power sources on its host planet is to move on to its host star. If all this energy could be harnessed, the civilization would control 10^26 W. There are many theories of how this could be done. For instance, a gigantic sphere or networks of satellites could be built around the star, known as a Dyson sphere or Dyson swarm respectively. This Dyson swarm was first proposed by physicist Freeman Dyson, who argued that SETI-type alien-seekers should try to seek a type II alien civilization by looking for a relatively cold (0°C) but very large object using infrared light, the characteristic signature of such a device no matter its construction.
Initial (obviously high-preliminary) estimates suggest that there could be enough mass in the solar system to construct a Dyson swarm, but there are a multitude of other technical challenges that are currently impossible to solve, much less unknown technical challenges that presumably exist.
A type II civilization would be essentially indestructible, at least from outside forces: an object such as a comet or asteroid on a collision course with the homeworld could be vaporized with ease. If that was not an option, the type II civilization could probably move the endangered planet out of the way, or move another large planet into the way to intercept. However, given the large material requirements that constructing and maintain a Dyson swarm would take, it is probable that the offending asteroid would have been long-ago disassembled by armies of autonomous mining drones.
Type III – Galactic Civilization
The last of Kardashev’s initial civilization types, this civilization would harness many billions of stars to attain power consumption on the order of 10^36 W. This stage of galactic civilization is significantly constrained by the speed of light, unless a faster-than-light (FTL) method of travel is discovered. Such a method of transport is not out of the question: there is some limited work into a theoretical device known as an Alcubierre Drive. This device, also known as a “warp drive,” gets around the speed-of-light limit by moving at sub-light speeds through space while making space warp at incredible super-light speeds.
The warp-drive is, of course, the method used by space ships in Star Trek to get around the galaxy in a reasonable time. The term came from the show, and the mode of operation is similar to the Alcubierre drive, except not rigorously mathematically-defined.
If it turns out that FTL methods are not forthcoming, it may still be possible to grow a galactic civilization. One proposal to colonize the galaxy is a generation ship, a large self-sustaining vehicle like the one seen in Wall-E that houses generations of sentient beings on a trip to the stars. The technical problems, like achieving a perfect recycling program, are significant, but the social issues that are associated with a generation ship seem far more interesting. Science fiction authors, in particular, have experimented with this concept. For instance, what kinds of cultural divergences could occur over generations of space travel. Would internal strife develop? Would the citizens of the micro-world forget their initial goal and purpose? Could the people aboard a generation ship technologically regress, possibly even to the point that everything from the ship they are on to the stars—none of which are close enough to be a sun—become mysterious and unknowable?
Type IV – Universal Civilization
Since a type III civilization would probably already need to supersede current physics limits to exist, some imagineers have decided to expand the Kardashev concept to an inter-galactic civilization, with power needs approaching the universal output of 10^46 W. A type IV civilization would be extracting energy from sources that are probably not yet known about. Its capabilities would probably approach that of the modern concept of omnipotence.
As unlikely as it seems, it could be possible for a civilization without FTL capabilities to achieve this state of being. Such a civilization would probably have the energy and material resources, and the technical know-how to turn a Dyson sphere—star and all—into a solar-system sized generation ship to sail across the vastness of space for millions of years. Given the massive surface area that a Dyson sphere offers, the population within the sphere could happily spread over the inside of this dome for thousands of generations without running out of space.
Type V – Maximal Civilization
As vague as the concept of a type IV civilization is, the concept can be extended (at least) one step further. A maximally-advanced civilization is so indefinite that it’s hard to even suggest the power limits of this civilization. This civilization would have to somehow transcend universal limitations, exploiting the power generation opportunities of parallel or alternate universes, assuming such concepts exist.
At this point, if not with a Type IV civilization, the purpose of this article—to imagine how wonderful the future may be—begins to break down because the concept of a maximal civilization, capable of maximally-advanced technical feats, is an asymptotic limit that will never be met. Nevertheless, the concept gives some sense of the limits of human imagination, and the goals that could someday be sought.
The closer, more modest predictions of planetary, solar, and galactic domination are probably more suitable for imagining the scale of discovery, science, engineering, and technology that might someday be attained. That does not even touch on the opportunities for artistic and cultural achievement. The connectivity of the Internet facilitating the Arab Spring, and visual masterpieces like the movie Avatar, are two off-the-cuff examples of the cultural and artistic advances that accompany modern technology. Imagine the things, horrible and spectacular, that could be done when stars are the playthings of the denizens of Earth.