We shall outgrow the earth, and fill the solar system.
We currently utilize energy equivalent to less than one percent of the total solar energy falling on the earth, and it seems unlikely we can grow a whole lot further without stepping on each other’s toes so hard that we fall into a civilization ending war. We are currently at 0.73 on the log linear scale between Kardashev I and Kardashev II.
We are already running into political difficulties at our current size — Nimbyism against new data centers, and the current fighting over the straits of Hormuz. It is technologically feasible to become a Kardashev 1 civilization while restricted to a single planet, but we will blow each other up first.
We probably probably encounter similar difficulties in reaching energy usage levels of Kardashev 2 — and a civilization ending war in space would be a lot more final than a civilization ending war on earth. It would eradicate everything bigger than microbes.
Once we capture fair bit more than the total solar energy falling on the earth, (Kardashev 1 and a bit) then interstellar travel using beamed power becomes reasonable (trips take decades, rather than millennia) so we are going to settle other stars before solar civilization destroys itself.
We might destroy the solar system first, but probably not. It is big, and we probably get the interstellar capability before we get the total destruction capability.
Musk is already making a small start on harnessing useful amounts of off earth solar energy, correctly stating that there is no room for the proposed expansion of data center energy usage. Not literally and physically no room, we have ample physical and technological capacity to do it, but its getting short enough that people are quarreling over energy consumption and cooling requirements. And right now, in the straits of Hormuz, those quarrels have gotten seriously out of hand. Empty tankers are sailing to Iran, filling up with oil, and when they leave the US pirates them. As President Trump commented, piracy is very profitable. When space gets crowded, intercepting other people’s sunlight is going to become profitable. As long as people have room to grow in a single orbit in a single orbital plane, they can always just move their entire habitat away a bit to avoid conflict, but once we fill that plane, and need to use other orbital planes, which we would need to use to in order form a Dyson sphere rather than merely a Dyson ribbon around the sun, people are going to start temporarily cutting off each other’s sunlight. One could arrange for compensation — when one habitat cuts off another temporarily, it arranges for payment for energy to be beamed to the shadowed habitat for the duration, but people are going to argue over it, and as space gets more crowded, those arguments are going to become difficult.
How big can a Dyson ribbon civilization grow within a single orbit in a single orbital plane.
TLDR. Mighty big, big enough that there is no problem doing interstellar travel on beamed energy.
A single habitat can grow to any length along the orbit. Inwards and outwards from the orbit, which they will need for cooling, it is limited by tension caused by tidal forces. Above and below the orbit, which they will need to intercept sunlight, it is limited by compressive tidal forces, which tend to push stuff back towards the orbital plane. The inwards and outwards tidal forces are equal in magnitude, but opposite in sign. One is pulling, one is squeezing. Tension is easier to build against than compression, so the limit is going to be holding solar panels far above and far below the orbit.
Lets assume modest strength of materials, and we build well within those strength limits. Assuming very strong materials and building out to the absolute limit of strength does not change the picture all that much — super strong materials help with tension, but they do not help as much as you would expect with compression. The practical limit for steel skyscrapers is vastly below the theoretical limit for steel, and not as much above concrete skyscrapers as one would expect, while tensioned structures like suspension bridges routinely accomplish a good fraction of the theoretical limit.
Solar panels extending 70 000 km above and below the orbital plane, extending a width of about ten earth diameters, need resistance to crushing similar to that of a four story building on earth, so that is probably the practical limit of size of a habitat.
So the practical limit of a space habitat is about 10 earth diameters. Its practical volume however, is limited by cooling and power collection, so its actual practical contained volume is tiny in comparison to the earth. Its livable area, however, is about sixteen times larger than surface area of the earth, sixty times larger than the land area of the earth, a hundred and fifty times larger than the area of the earth that is not desert, covered in ice, or under water.
A single space habitat can get very very big before strength of materials under tidal forces becomes a concern.
And there is room in a single orbit for about seventy thousand such habitats, any one of which would control about a hundred times as much energy as our current earthbound civilization, any one of which would be capable of sending an interstellar mission. The primary limit on doing an interstellar mission in a tolerable amount of time is that it requires a lot of power.
I earlier said that there was no limit in extending a habitat along the orbit. This is not quite true. If a habitat extends further along the orbit that it does inwards towards the sun and outwards from the sun, it becomes unstable. However individual habitats can connect with drawbridges that can extend or contract to accommodate orbital perturbations, much as ocean liner makes connections to port facilities in ways that can accommodate the movements of the ocean.
They would, however, remain somewhat separate political entities, for if one unit did not like the consensus of the other units, it could disconnect and go someplace else, as if New Jersey could decide it did not like New York State governance and fly off to join Texas, or go it alone some place else. Each unit remains a space ship, a very big and very slow spaceship, but still a spaceship. It will have a captain, and the captain has to go along with the port authority when he is in port, but he does not have to be in any one port.
These spaceships will not look much like what we think of as a space ship, they will look more like plants or chandeliers. A plant wants to occupy a large surface area with a small mass and and small inner volume, so has lots of thin bits sticking out a long way, as slender as strength of materials allows. And with no wind, no gravity, and very mild tidal forces, that is long way.
Dyson sphere
I don’t think a Dyson sphere is feasible for us, due to moral limits rather than technology and availability of materials. We are fallen angels and risen killer apes.
A Dyson sphere cannot be one contiguous object, due to strength of materials limits. It has to be a vast number of ribbons, each at angle to each of the others, each composed of a vast stream of many vast chandelier space ships.
This angle involves a vast number of spaceships passing rather close to each other at rather high velocities, hence, Kessler syndrome: If someone throws a pail of garbage overboard, then years later it will hit something creating a large explosion.
If, on the other, the great preponderance of the material is in a single orbital plane in concentric orbits, we do not get Kessler syndrome.
Plus everyone is going to be occluding everyone else’s sunlight, leading to complicated political negotiations that are going to get tense. Plus, the technological advance necessary to and resulting from humans inhabiting space necessarily leads to each controlling a vast amount of energy, so the equivalent of a truck driver has the equivalent of nukes and rods from God.
Plus, the amount of material needed to build a comfortable Dyson sphere is well short of the amount of material in the solar system. If we did it, we would have to be rather stingy with matter. We are going to start quarreling over material resources well before we intercept a large portion of the earth’s sunlight, and we are going to be quarreling over sunlight well before we intercept a large portion of it.
Governance of solar civilization
People capable building a Dyson sphere are going to have to have to first build the Kingdom of God on Earth. Or the other extreme, Skynet, one entity with total control over everything and everyone. Heaven or Hell could do it. We, on the other hand, are going to blow ourselves up. A Skynet civilization could never reach the stars, partly because of its inherent rigidity, but mostly because Skynet will never be able to tolerate the existence of any entity independent of itself. When we reach the stars, we might well find a few Skynet civilizations that have been stagnant for geological time. We will not be able to talk to them, and they will shoot at us if we try to visit. You will recall how in the first couple of decades following the fall of the Soviet Union, the Globohomo empire became increasingly unable to tolerate the existence of any entity that was not converged to Harvard ideology — what Musk calls “the woke mind virus, Moldbug calls “the Cathedral”, and “Based Camp” calls “The urban monoculture” The Globohomo Empire was systematically cutting communication from Russia, interaction with Russia, and cooperation with Russia long before sanctions came into effect. What it could not control, it sought to isolate itself from.
When we get to the stars, we may find the ruins of rather more civilizations that destroyed themselves than silent, stagnant, senile, hostile Skynets, but Skynet is an obvious failure mode as we control more and more energy, and our extended phenotype becomes more and more fragile. The temptation is to try and fix war by concentrating power in the center. The UN became an instrument of Globohomo, and globohomo an instrument of the woke priesthood.
Practical governance of solar civilization would need to resemble the governance of the lands of Roman Empire after the Roman Empire in the West fell — to the extent that there was any, it consisted a bunch of independent chiefdom’s appointing Bishops, and the Bishops forming a Christendom wide consensus. Better, it could resemble the Holy Roman Empire before the Pope managed to get control of the appointment of Bishops — A Holy Roman Empire with little real power over its semi independent principalities, the principalities appointing priests, and the priests forming a consensus.
The Harvard consensus, the woke mind virus, or the urban monoculture, whichever you call it is rule by priests, an officially unofficial state religion, a theocracy. There is always an official religion and Christianity was the somewhat theocratic stater religion of Christendom, giving the many fragments of the Roman Empire unity, and enabling the harmony of Europe. Organised Christianity, that for all its frequent idiocies, heresies, and wicked acts, was a vastly saner and healthier religion than our current one. That consensus kept the peace, somewhat. You think it did not? Compare with the pagans. Compare with the the Muslims. We are less likely to blow ourselves up if everyone is forced to repeat every Sunday “Peace on Earth to all men of goodwill.” Which also has the effect of encouraging outgroups to display goodwill. The Cathedral doctrine of “sucker punch a fascist” created its own opposition, and the Disney policy of making the fans weep and humiliating the beloved heroes of their IP did not put bums on seats.
From the fall of the Roman Empire to the modern period, Christendom was a multitude of tiny states. But each of the tiny states was substantially theocratic, and in this respect, all one state, though the Papal power grab split that one state into two. There were wars, many of them terrible, but none assembled vast arrays of combatants, none of them was potentially civilization ending. Rather, there were sometimes a lot of small wars. But substantially fewer, smaller, and less destructive than the strife of Pagan against Pagan, and Muslim against Muslim.
The slow path to to the stars.
A nineteenth century workshop can reproduce another nineteenth century workshop, but silicon chips and all that need a full industrial civilization to build everything a full industrial civilization needs. This trend might continue to get worse, but threedee printing and direct contact lithography is running in the other direction.
And another thing on the cards is that AI has vastly improved our capacity to design very large molecules, which may open the door to nanotechnology, allowing radical miniaturization of everything we need to produce anything, via the path of radically and fundamentally redesigning existing microbes — the soft wet path to nanotech.
People are currently attempting to use this radically improve photosynthesis — so far with complete lack of success. If they succeed, which is far from clear, it is the first step on a very long road, and they have not yet succeeded in that first step.
If we wind up being capable of packing our entire industrial base into something reasonably small — and that is not necessarily a reasonable consequence of readily foreseeable tech developments, then settling interstellar space become possible power becomes possible. moving from one interstellar comet to the next as the fusible run out. We would spread at about sixty to a hundred kilometers. But we don’t actually know how to render a family sized settlement self sufficient in space, while we do know how to build a beamed power device — it’s just a very big project by the standards of a Kardashev 0.73 civilization.