==Growing at the Speed of Gaia==
===The Misinformation of Science Fiction ===
Science fiction has taught us that planets are where everything happens, and that space is small and fast. Captain Kirk beamed down to a planet almost every week. The formats of television shows, movies and even novels force directors and authors to make space seem small and fast or come up with 'magic' reasons why space might seem smaller than it is. Kirk and Spock beam down to Sigma Iotia II and all the action takes place in a single city that looks like Chicago in the 1930s. Luke Skywalker crash lands at a seemingly random point on Degoba and it turns out that he is just a few hundred meters from Yoda. Of course, they were drawn together by the 'force'. Without it Luke might have spent his whole life looking for Yoda without success; Degoba was an entire planet covered in swamp. The imaginations of most science fiction writers seems to be limited. Instead of describing whole new planets, they describe planets as expanded versions of a tiny part of Earth; swamp planets, tundra planets, city planets, desert planets. But every planet we go to will be a whole world of its own, with a whole selection of Earth-like climates, and ecosystems we have never imagined.
Planets, especially Earth-like planets orbiting Sol-like suns are a vanishingly small fraction of what is out there. Scientists estimate that on average each star in the galaxy will have 1.6 planets but only maybe 2 in one thousand are likely to be Earth-like. On the other hand there are likely a trillion worlds orbiting each star in the galaxy. So for every Earth-like world in the galaxy there are likely a thousand trillion non-Earth-like worlds. I use the term world because the vast majority of these will not be planets but what astronomers call minor planets, asteroids and comet-nuclei. In addition there are vast clouds of dust and gas, nebula, so huge that light takes hundreds of years to cross them. A lot may be happening on these worlds and in these clouds. Just because we, and the other members of our biosphere, are not well adapted to living in these places does not mean that there is no action or never will be action in these places.
So space is an much more alien and varied and rich place than science fiction tells us. But it is also a very slow place. Space is so vast that light takes centuries, millennia and even eons to cross it. Science fiction has invented many 'technologies' in order to get their characters from one planet to another quickly so that a single human drama can be painted across the many stars. These technologies are effectively just magic to us here in the 21st century. We have no technology and no idea how to build technology that folds space or digs worm holes through it. Hyperspace might exist but so may pixies. There is no evidence for its existence. We cannot make plans around its existence. If we are going to travel to other stars using technologies we at least have some conception of how to create then the trip will take a long time. The nearest star is 4.4 light years away. At one tenth the speed of light it would take 44 years to travel there. To travel for so long, you would want a large ship to travel in; you would need to be able to raise children on board because those who started the voyage would be senior citizens by the time they arrived. You would need to carry enough people to establish a colony; it would hardly be worth making an 88 year round trip unless you were establishing a permanent presence. You would need food, supplies, equipment and supplies to maintain the space craft, equipment and materials to establish your colony. Lets imagine that somehow you managed to make do with 500 000 tons. The energy needed to accelerate that mass to one tenth the speed of light would be about equivalent to the total energy consumption of every human being on Earth for a year. And then you would need that much energy again to stop. If you carried that energy with you in the form of fuel then you would need even more energy in order to carry the fuel needed to slow down at the end. The project will be a massive one far beyond our reach for many decades. And even then it will be a slow one by human standards.
Sometimes science fiction uses Einstein's relativity to get around the problem of the time it takes to travel between stars. Star ships accelerate to close to the speed of light; time dilation means that the crew experience barely any time while the ship crosses the vast distances between stars. For instance, if we go 99% of the speed of light then we will experience only one seventh as much time as the spacecraft takes to travel. To go to the nearest star we will take only about 4.4 years but the crew would only experience about 7 months. The problem is that it will also take 70 times as much energy to accomplish the trip. Science fiction also usually uses some kind of magic 'technology' called inertial dampers to allow the spacecraft to reach these velocities in a reasonable amount of time without the crew being crushed by g-forces. We don't have that kind of technology. To reach such speeds in reasonable comfort would take a year with another year needed to reduce speed at the other end. In effect despite spending 70 times the energy we might only reduce the apparent duration of the trip for the crew from 44 years to about three. Still a very long time to live in a small ship; for 3 years one might find even a 100 000 ton ship rather small shared with 500 other colonists. For three years you would be dependant on complex systems, the failure of which could leave you stranded in space light years from the resources needed for your colonists to live. Another lie that is often told in science fiction is that if your engines fail in space, your spacecraft will grind to a halt and stop. But objects in space, due to a lack of air resistance, will continue coasting forever. Traveling at 99% the speed of light, the crew would be trapped, passing stars every few years but unable to slow down or get off.
===The Speed of Gaia ===
The more realistic and safer option is to travel slowly, living off the land as we go. To travel slowly in interstellar terms might mean measuring your speed in tens of kilometers per second but your travel times will be measured in tens of thousands of years. To 'live off the land' for such a long time requires that we bring a world with us. Earth is the most reliable space craft we have ever travelled on. We would be well advised to try to replicate its robust nature for our trips between stars. Again, contrary to all of our instincts and direct experience, objects in space will continue coasting forever once given a solid push, providing the push imparts enough speed to escape the local gravity. It doesn't matter if the object is a mote of dust or a galaxy or anything in between. To move a small world between stars might seem like an impossible task but in actual fact it should be quite doable with only minor improvements in reliability of technologies we already possess and dogged determination over generations. Two technologies are necessary. One is gravitational tractors and the other is gravitational sling shots.
====Gravitational Tractors====
Gravitational tractors are space craft that use their engines over long time spans to maintain their positions. This is harder than it sounds but still doable. Again the fact that once given a push objects in outer space continue to move and the fact that the gravity of Sol and all the other objects in the Solar system are continuously pulling at spacecraft make it harder to stay still in space than to move. However, in the vicinity of a small world in the outer solar system gravitational pulls are quite small. Ion drives would be quite capable of station keeping a space craft there. The key would be to use reflectors to concentrate distant Sol's light onto solar collectors in order to provide the power necessary. Then the minute but ever present gravitational pull of the spacecraft on the world would slowly change the orbit of the world in which ever direction we desired. Could a gravitational tractor pull a world right out of the solar system? Probably, if we were patient enough but that much patience isn't necessary. Instead let us consider how the Oort cloud was discovered.
====The 'Discovery' of the Oort Cloud====
No object in the Oort cloud has ever been seen. We have seen more than 1200 objects in the much closer Kuiper belt and one object in the intermediate scattered disk. But the objects in the Oort cloud are much too faint and too slow moving to detect with modern technology. At the rate telescopes are improving it might be possible to detect them in a few decades. So how do we know they are there? The answer is the statistics, long period comets and solar system modelling. Periodic comets don't last long. At best they may last millions of years. Repeated close passes to Sol melt them away. So, the question was asked, why are there still comets after billions of years of Sol's life. The answer is that there must be a source of comets. There must be a massive pool of icy objects in the outer solar system. As time passes, their orbits are perturbed, perhaps by passing stars, perhaps by close passes with each other and some of them fall toward the centre of the solar system. For centuries, astronomers have carefully measured the number of comets that appear each year and their distribution and their speeds and sizes and directions. From this data and based on the same computer models that are used to accurately predict the orbits of space probes and asteroids, we have worked out the sizes and shapes and make-up of the multiple pools that are out there. We knew the Kuiper belt was there before we detected the 1200 objects we have seen to date. We knew the scattered disk must be there before we detected Sedna. We know the Oort cloud is there based even though we have yet to detect an object. But the same models that tell us the current shape and size of each of these clouds also tell us how they got there and how they have been thinning these billions of years. Early in Sol's life all those icy worlds were much closer to her, still far enough to be icy but closer never-the-less. They made regular passes close to the young gas giants, Jupiter, Saturn, Uranus and Neptune. The gravitational pulls of these planets threw all the worlds in these clouds out into the orbits in which they revolve today. Many more crashed into the Gas Giants as we saw Comet Shoemaker–Levy 9 do in 1994. Others crashed into the smaller rocky planets and the moons of all eight planets leaving the craters that in many cases can still be seen today. But, most intriguing of all, Jupiter threw many worlds right out of the solar system and continues to do so today. The effect that Jupiter used to do this is called the gravitational sling shot.
====Gravitational Sling Shots====
We have already used the gravitational sling shot effect to launch space craft on interstellar voyages. The NASA space probes, Voyager I and II are on their way to the stars courtesy of momentum stolen from these planets. We could simply wait for the next world to make its final pass by Jupiter and jump on board in order to get a free lift to the stars. But if we use gravitational tractors to shift the orbit of a likely world we won't have to wait nearly as long. The gentle push of a gravitational tractor can push a near miss into the perfect trajectory and we will be on our way. The long gentle push of a gravitational tractor can steer that world toward the star of our choice so that our trip need not be millions of years but perhaps only tens of thousands. The speed gained by a pass with Jupiter can be as much as 26 kilometers per second, almost a ten thousandth of the speed of light. As we pass Jupiter we can add energy to the pass with the use of a gravitational tractor or a mass driver. In theory we could make two passes by Jupiter, one on the way in and one on the way out, and add to that more gas giants and we might make a thousandth of the speed of light. We could travel to the nearest star in just thousands of years and to anyone of thousands of stars in just hundreds of thousands of years. Although this is a much longer time than we would need if we tried the tenth the speed of light scenario or 99% the speed of light scenario, the energy required is much less and the crew would have an entire world with them, with all the resources they need to survive for millions of years.
====Gaia Time====
A well-adapted biosphere living on a world can survive for hundreds of millions of years. Gaia took billions of years to conceive of multicellular life. Once she did, she conserved it for hundreds of millions of years despite asteroids crashing into the Earth, solar variation bringing about intensely warm periods and freezing cold periods, super-volcanos releasing massive clouds of poison gas. She creates species at a rate of one per lineage per million years. The pulse of a biosphere is slow and if we learn to live on Gaia's time scales and forget about the myths of science fiction, we might find that travel between stars is easy. To succeed we need to practice growing biosphere's and living on frozen worlds for hundreds of thousands maybe millions of years. But as we learn to understand the pulse of Gaia and our place in the biosphere this will become natural to us.
===The Icy Outer Worlds of Solar Systems ===
The vast majority of the solid surface area in the universe seems to be airless ice. Since the demise of Pluto, Neptune has been the eighth of eight planets orbiting the Sun, the coldest and the furthest out. But Pluto didn't cease to exist. It wasn't even demoted from Planet status to something lesser. Instead it became the type object for a whole class of worlds, the Trans-Neptunian Object or TNO. Pluto was the first TNO to be discovered (in 1930). Since 1992 over 1200 other TNO's have been discovered. We are discovering them so quickly, that for the most part we aren't naming them, we are numbering them. But the largest ones and those that were discovered earliest have been named. They include, Eris, Makemake, Haumea, Sedna, Quaoar and Orcus. Each of these is a unique world, as yet unexplored except by artists imaginations. Each has been no more to us, yet, than a faint dot on a photograph taken by telescope. But just the eight largest discovered to date have a combined surface area almost as large as the land surface of the Earth. Scientists believe that we will eventually discover a trillion worlds out there with a combined surface aread of 10000 Earths. There is room in the solar system beyond imagining.
Terraforming Mars will be a beautiful project but after huge amounts of effort it won't even double the living area for the Biosphere; Mars is smaller than the Earth. Mars has a unique environment. Relatively little of the learning that we gain from the experience of terraforming Mars will be applicable elsewhere.
===Dyson Trees ===
On the other hand, if we create life forms that can live on the surface of TNO's then we can follow them there with relatively little effort. Although the surface of each TNO is likely to be unique, they will at least be similar. A tree adapted to living on one TNO will probably be able to adapt itself to living on another. And TNO's are mostly low gravity worlds without atmospheres. Except on the largest of them, the equipement needed to launch a seed into space from one world so that it lands on another would be no more powerful than a mideval catepult. With no atmosphere to slow down the seeds or divert them from their courses, from most TNO's just bending back a seed laden tree branch and then letting it go would be enough to sow a thousands worlds. As these trees adapt to each world they colonize, they will diversify. We will create animals adapted to living amongst their branches. We may teach these trees to create living spaces inside themselves for us. In return we will help them launch their seeds accurately toward new worlds and help them to grow. We will become symbionts with them. As they diversify, so will the animals and even the humans that live with them. Imagine the diversity of life in the solar system with a trillion worlds with the surface area of 10000 Earths.
===Living Seed Catapults ===
As these trees spread through the cloud of TNO's in the outer solar system (the Oort cloud) they will eventually reach its edge. There they may wait. But eventually, every few million years a star will pass close enough to Sol that its outer cloud of objects may come close to the edge of the Oort Cloud. When the first one comes by, our trees may be able to catapult seeds into that other solar system. A few more million years and both that system and ours will each colonize another system each. And so on it will go, doubling the number of stars colonized every few million years. In that way within a few billion years we may colonize a thousand stars. And within a few dozen billion years we may colonize the whole galaxy. And all we have to do to start this process irrevocably, is create one well adapted species of tree.
===Getting to Know Our Neighbours at the Speed of Gaia ===
Many of our fears about the harm we could do to other biospheres can be relaxed when we consider the strategy of focusing on small icy worlds. Life taken from Earth and transplanted directly to other Earth-like worlds might conceivably be adapted to other similar worlds. But life adapted to living on Trans-Neptunian objects will not be well adapted to living on naturally evolved worlds. If our life spreads to other stars' cold outer object clouds, it will not then be well placed to land on the inner worlds of those stars. It will be adapted to low gravity, zero atmospheric pressure (vacuum) and frigidly low temperatures while those inner worlds will be have high Earth-like gravity, high Earth-like atmospheric pressure and high Earth-like temperatures. Even enterring such an atmosphere, would mostly burn their seeds up. With luck they might colonize vacant inner worlds after millions of years of trying but anything already living will be safe from them; the well-adapted native organisms would rapidly out-compete the invaders as the invaders colapsed under their own weight in the high gravity, were crushed by the high pressure and baked in the high-temperature.
Imagine our TNO-trees meeting an meeting a similar but alien ecosystem coming the other way; the slow dance of cold outer worlds will give the two biospheres lots of time to adapt to one another. There will be predators and prey, parasites and unwilling hosts, and disease but nothing much more serious than what occurs in a biosphere normally. Invading organisms may outcompete natives and force them to extinction but even on Earth there is a normal rate of extinction. Over the course of millions of years species go extinct. Oort cloud objects take millions of years to orbit their suns just once. Our TNO-trees will take similar amounts of time to cross an alien solar system. The extinctions caused by the colisions of space-borne biospheres will be so slow that they will blend into the background extinction rates of both biospheres. In the meantime, each biosphere will present the other with millions of niches to adapt to. In combining they will increase their total diversity. Diversity is the advantage of moving at the Speed of Gaia.
===Diversity Through Sluggishness ===
===Imagining a human culture with the patience of Gaia ===