Frequently when forecasting how species spread out from their world of origin you will hear the term ‘Dyson Sphere’ as well as the Kardashev Scale.
Dyson Spheres are synonymous with K2, or Kardashev 2 civilizations.
This is where all, or a large portion, of a star’s energy is being used by a civilization, rather than the roughly one billionth of that light that tends to hit a planet.
Now people often picture this as a single giant hollow sphere around a star with an Earth-like surface but in reality what was pictured by Freeman Dyson and scientists in general is what is often now called a Dyson Swarm to avoid confusion.
Not one single rigid sphere but millions or billions or even trillions of smaller artificial bodies orbiting the star as a cloud of satellites.
These could be anything from simple, thin but large solar panels or mirrors to large rotating rings or cylinders whose interior mimics normal planetary conditions including gravity from the effect of centrifugal force.
This has a few advantages.
First it requires no advance science.
It’s a massive undertaking but massive in the way a highway system, canal and irrigation system, or long wall is.
It takes a lot of effort but not a lot advanced technology.
Second it can be built in stages, unlike a wall or dam a Dyson Swarm works perfectly fine even when just composed of a few hundreds objects absorbing a millionth of the sunlight, and you just keep adding to it with time.
Like a city or suburb.
And because artificial habitats or solar panels are far less massive then naturally occurring objects of a similar size, like asteroids, in much the same way house are less massive then hills, a solar system has enough material on hand to create a fairly impressive swarm.
Now it’s hard to guess exactly what these swarm objects would be like but the usual assumption is a good portion of them will be rotating habitats mimicking the conditions of the home planet and other will be ultra-thin power collectors.
Even without ultra-strong materials like graphene this spinning habitats can be individually the size of counties or medium-large islands.
Some might be intentionally left wild to be forest preserves, other might be sprawling suburban equivalent setups, and yet others might mimic dense cities or serve as massive hydroponics factories for food or biomass raw material.
Or the entire array might be used to power one enormous computer.
How this unfolds we can’t guess with much accuracy but we expect it to be an inevitable process if the following conditions hold:
1) A given culture tends to expand in numbers when they have the resources to comfortably support more people.
2) No power generation method is possible which is vastly superior to a star.
3) Faster-than-light travel or travel to parallel realities is not possible or not incredibly easy.
Now, even if one or more of those doesn’t hold completely true such englobements are still possible and likely in most cases, but we’ll get to how those exceptions would work later.
For the moment we are going to simply assume all three conditions are true and ask how they affect the Fermi Paradox.
And it’s quite straight forward.
If a civilization wishes to keep expanding it will slowly ‘Dyson
up’ it’s home solar system.
With all that extra power on hand it can launch interstellar colonial mission.
As it begins making a swarm around its own star its child star systems are going to slowly do the same.
With all that power on hand the original system and its spawn are going to keep sending out more colonial missions.
So you would expect to see stars slowly disappearing in a rough sphere around that homeworld and eventually absorb the entire galaxy, and even other galaxies.
This is the Dyson Dilemma because most models for even very anemic growth rates of population, far, far slower than the human norm, would allow this to occur in a mere million or so years and yet as best as we can tell the conditions for life have been solid for a long time, and civilizations should have been able to arise at least a billion years ago.
The Dyson Dilemma of the Fermi Paradox doesn’t ask why we can point radio dishes at distant stars and pick up no radio signals.
Rather it asks why we can even see any stars at all.
Why aren’t they all Dyson Swarms by now?
Now, we’ll take a moment to clarify something that confuses a lot of people interested in the Fermi Paradox who aren’t heavily-steeped in physics.
A very common question is ‘well maybe they are there and we can’t see them?
Maybe they’re the missing mass, dark matter, that people talk about?’
The problem is that Dyson Sphere’s aren’t dark.
Even a perfect and complete one with 100% light absorption still emits light.
When light strikes an object and is absorbed, it gets warmer and begins cooling itself by emitting light of its own.
This light – infrared - is usually invisible to the human eye, but is quite visible to our telescopes designed to see it.
Before very long an object being hit by light will reach equilibrium where it gives off just as much light as it receives, just at a different frequency.
So a system being turned into a Dyson Swarm will not get dimmer.
Rather it will begin getting dimmer in visible frequencies of light while getting brighter in infrared frequencies.
It’s total light given off will not change though.
There is no known way to hide this.
You can control which frequencies come off, but not the total intensity of emitted light, and your control is determined by the diameter of the swarm around the star and the star’s own power.
Or to be more accurate, it is determined by the power of the star divided by the surface area of the swarm.
One big enough to be cool enough not to stand out would also noticeably block light from other stars, and moreover it would still exert gravity on all its neighbors in a very noticeable fashion.
We’ll talk about this more later but for the moment we’ll just say it is not practical to hide a Dyson Swarm, let alone millions of them, and its hard to imagine why they would go to the effort.
So that is Dyson Dilemma in a nutshell.
If we assume most galaxies spawn a technological civilization that is growth oriented we would expect there to be very few if any stars visible to the naked eye.
Furthermore, unlike radio signals which we might miss even from a few hundred light years away, and expanding globe of Dyson Spheres absorbing galaxies should be visible hundreds of millions of light years away.
And we’ve no reason to think intelligent life couldn’t have existed that early elsewhere.
Particularly in such huge volume of space that contains nearly as many galaxies as there are stars in this galaxy.
From this logic the argument is as follows: Either technological civilizations capable of building Dyson Swarms are incredibly rare, to the point of occurring at less one in a quadrillion stars, or… one of our prior assumptions is wrong.
Now to repeat those, they are:
1) A given culture tends to expand in numbers when they have the resources to comfortably support more people.
2) No power generation method is possible which is vastly superior to a star.
3) Faster-than-light travel or travel to parallel realities is not possible or not incredibly easy.
There are a couple other assumptions in here too we’ll get to later but those three are the key ones.
The other 2 big ones are:
4) It is practical to build a Dyson Swarm
5) Intelligent life does not inevitably kill itself off and go unreplaced by other intelligent life.
We’ll be looking at how these 5 assumptions could be untrue, but also how many cases where they wouldn’t be true just don’t matter.
However if they are true then you have the Dyson Dilemma’s most probable explanation to the Fermi Paradox: Technological Civilizations almost never occur, they occur so rarely that not only are none visible to us right now, and in all likelihood none exist even right now within hundreds of million of light years, concealed by the time it takes light to get to us.
This does not mean life is rare.
It might be incredibly rare or occur almost inevitably on every planet of roughly Earth-size near a reasonably Sun-sized star.
It doesn’t even necessarily mean complex life like animals are rare, or even intelligent life like dolphins and elephants.
It specifically means technological civilizations are incredibly rare.
That evolution doesn’t necessarily favor intelligence nor intelligence favor technology.
The Dyson Dilemma doesn’t try to posit why technological civilizations are rare, just that they are.
Now all those exceptions we spoke of.
You’ve probably thought of a few as we went a long and we’ll get to them now, but we’ll do them backwards because #1 tends to be the most controversial.
1) A given culture tends to expand in numbers when they have the resources to comfortably support more people.
2) No power generation method is possible which is vastly superior to a star.
3) Faster-than-light travel or travel to parallel realities is not possible or not incredibly easy.
4) It is practical to build a Dyson Swarm
5) Intelligent life does not inevitably kill itself off and go unreplaced by other intelligent life.
#5 argues that technological species are hard to wipe out.
Natural events that can wipe them out generally occur less frequently then they would likely need to achieve technological safeguards against them.
You can shield yourself from asteroids, volcanos, and supernovae, and if you have a K2 civilization, one with a Dyson Sphere, you don’t have to worry about volcanos and all your asteroids were probably disassembled building the place.
You can quite literally use your own star as a weak rocket thruster to steer yourself away from expected supernova stars or even build dyson swarms around those stars to shoot them away from your civilization.
This is called a Shkadov Thruster, and is an innate ability of any Dyson Sphere as it relies on simply causing the light of that star not to emit uniformly and produce some thrust in one net direction.
This takes a very, very long time to move stars but supernova candidates live a very long time except compared to others stars and can be seen a long way off.
What’s more a supernova or Gamma Ray Burst is not as dangerous to artificial worlds like rotating habitats as they are to natural worlds with ozone layers.
So natural threats aren’t as big a deal.
That just leaves artificial self-destruction.
Things like nuclear wars or super-plagues.
It also leaves options like artificial Intelligence, genetic or cybernetic supermen, or similar but that’s an iffy case because a species getting replaced by another intelligence isn’t wiping out a technological civilization.
It’s just replacing it with a smarter one.
One that is more capable of creating Dyson Swarms and quite probably even more aggressive.
If it were relaxed and passive and not prone to growth it wouldn’t likely have replaced its dumber forebearers.
Even in the example of a single huge computer mind which wants no competition and thus doesn’t reproduce, it will still likely want to expand its processing power and a computer powered by an entire star, known as a Matrioshska Brain, is a type of Dyson Sphere.
It may not be content even with one star event though it wants no rivals or children and may send out dumber automated ships to gather matter, or even entire stars, to drag back to its home system.
Opting to become a massive single brain around millions of red dwarf stars packed together in tight orbits.
Red Dwarves are not just the most long lived stars, but also the most fuel efficient, converting virtually all their hydrogen into helium and light.
It is no more difficult technologically to steer millions of stars into an immense single dyson swarm of their own then a more classic swarm around a single star.
If every drop of hydrogen in a galaxy were forcibly steered into forming a single massive swarm of red dwarves only a hundred light years across, rather than a hundred thousand, and yet dim enough that a single immense swarm of computer processors that distance out could exist without melting.
So we see that even a singular intelligence with no desire to reproduce might eat entire galaxies if we only assume that it possesses the motive to think faster.
So that leaves us only catastrophes of an artificial nature that can wipe out all intelligent life.
A nuclear war won’t do this, and indeed it is possible even today to create a large bunker run on a nuclear power supply able to be sealed air tight and be self-sufficient for centuries or more.
That’s a very long time for a world to recover or solve the problem of some super-plague.
It is, nonetheless, a valid objection to the Dyson Dilemma.
We can conceive weapons that might kill all intelligent life and extrapolate that civilizations with the technology to counteract so weapons probably have even more dreadful weapons on hand too.
The problem is it gets very hard to accidentally kill everyone as they get spread out through a solar system let alone several thousand solar systems and the Fermi Paradox always deals with Non-Exclusivity.
Which is to say, it doesn’t matter if 9 out of 10 civilizations kill themselves off completely, because it only takes 1 that doesn’t.
We have survived and thrived under the threat of nuclear war for seventy years, so the idea that technology inevitably dooms civilization is not as strong as it was when the Fermi proposed this paradox in 1950, five years after Hiroshima and Nagasaki and 9 years after Enrico Fermi proposed the idea of a thermonuclear device, and H-bomb, to his friend and fellow Manhattan project colleague Edward Teller.
The H-bomb being first deployed in 1952.
At that time, almost two decades before the moon landings made off-world colonization a very tangible thing the idea of blowing up your own world and going extinct seemed a lot more probable.
That takes us to #4.
That it is practical to build a Dyson Swarm.
This is a short one because it’s basically a definite yes.
In an era of thousands of satellites orbiting Earth and irritating slow but steady progress on robotic construction and improved launch methods it seems a safe bet that we could build rotating habitats around Earth, mining facilities on the Moon, and slowly but surely construct more and more as those places become industrially significant and we don’t have to pay the gas bill every time we want to build something on Earth and launch it into space.
If you have off-world industry you break the bottleneck from Earth’s gravity well and building a Dyson Swarm just becomes a long, slow, protracted process.
You just keep adding more and more orbital constructs, first around Earth then in orbits around the sun near Earth, and so on.
It may take thousands of years, but it would be an accelerating process, and a thousand years is nothing on astronomical timelines.
More technology just makes it easier and lets you do it more luxuriously.
0 comments:
Post a Comment