It’s possible that in a few centuries Humans may be able to capture all the energy on Earth,
in a few thousand years we might be able to capture all the energy from the Sun, and we
might be able to harvest all the energy from every star in our galaxy in 100,000 to one
million years.
Today I’d like to discuss the Kardashev scale and later on in the episode we shall
discuss Dyson spheres.
Let’s begin with the basics.
Right up until 1964 there wasn’t really a good way of measuring how advanced a civilization
was.
That’s why, in 1964, Soviet astronomer Nikolai Kardashev created the Kardashev scale.
The Kardashev scale is a method or one approach of measuring how technologically advanced
a civilization is, based on the amount of energy available to them.
When he created this, Kardashev originally only had three different categories.
A Type I civilization, able to harvest the energy output of a planet, a Type II civilization,
which is able to harvest the energy output of a star, and a Type III civilization, a
civilization able to harvest the energy output of a galaxy.
Kardashev originally only conceived of Type I, II, and III civilizations but subsequently
some folks have created additional extensions to the scale (Type IV and V civilizations),
and we’ll discuss these later on in the episode as well.
The scale is measured depending on a civilisation’s total energy output.
For Type I civilizations, this is 10^16 watts.
For Type II civilizations, this is 10^26 watts, and for Type III civilizations, this is 10^36
watts.
Again, this scale classifies civilizations by how much power is available to them.
So if your civilization has 10^16 watts available to them, it is a Type I civilization.
Also, it’s important to note that the Kardashev scale isn’t a uniform scale, because it
goes from planetary, solar to galactic.
If Type I were a grain of sand, Type II would be an entire beach, and Type III would be
all the beaches on Earth.
The scale isn’t so handy if you want to classify a civilization anything less than
a grain of sand.
If Kardashev knew that his scale would be used commonly, then I’m sure he would’ve
included Mankind and scaled it better.
First of, a Type I civilization, or a planetary civilization, can harness the total amount
of energy from their home planet.
It was said by Carl Sagan that here on Earth we currently are a Type 0.7 civilization,
almost a Type I civilization.
Mankind doesn't even make it onto the Kardashev scale.
Now while it’s said that to be a Type I civilization, you need to harness all the
energy on your home planet, you don’t necessarily have to get every single last bit of energy,
because that’s virtually impossible.
Your civilization would be there forever, trying to collect every last gust of wind,
creating as many generators as possible to convert every wave and tide to electricity,
and every single photon of sunlight that is directed at Earth.
No, your civilization just needs to reach 10^16 watts in order to be a Type I civilization.
Storing every bit of energy available on your planet, in order to be a Type I civilization,
is not strictly true.
And don’t be confined to only using the common methods to get energy.
You can always use fusion power.
In order to be a Type I civilization we would need to convert about 2 kilograms of matter
to energy per second.
Theoretically, we could do this by fusing about 280 kilograms of hydrogen into helium
every second, giving us a rate of about 8.9x10^9 kilograms per year.
But I’d say solar power is one of the most effective and is fairly easy to do, but we
shall discuss this when we come onto Dyson spheres.
Next on the scale, a Type II civilization, or a stellar civilization, captures the total
energy output of their home star.
This is where the use of megastructures such as a Dyson sphere is necessary.
A Dyson sphere is a hypothetical megastructure that completely surrounds a star, capturing
most or all of the available energy from it.
It was proposed in 1960 by Freeman Dyson.
Dyson originally imagined the Dyson sphere as hundreds or thousands of solar collectors
orbiting a star, not a complete sphere.
It’s understandable because of the name but whenever I’m discussing Dyson spheres
I’ll always be referring to thousands of solar collectors orbiting the Sun and not
the sphere variant.
A complete sphere, although has more space and is more effective at collecting sunlight,
is virtually impossible.
The main reason is because no known material could withstand the exceptional stresses on
a structure of such size.
Furthermore, it’s incredibly unstable.
A slight nudge on one side would cause it to fall straight into the Sun.
It’s going to have nudges every two seconds, because of all the comets and asteroids going
around the Sun in their highly elliptical orbits.
It’s a better idea to construct hundreds, if not thousands, of solar collectors and
space habitats orbiting the Sun.
This is called a Dyson swarm but, as I said, the Dyson swarm is what I’m talking about
when I’m discussing Dyson spheres.
A problem with having thousands of collectors orbiting the Sun, is that you could be missing
out on a lot of sunlight.
However, with enough collectors orbiting the Sun, you’ve got this opaque cloud of collectors
that captures every bit of sunlight and beaming it back to Earth for us to use or keeping
it for the collectors and space habitats.
While the system seems opaque, the collectors are in no danger whatsoever of crashing into
each other.
One because they aren’t that close to each other, and two because it’s not difficult
to make sure that each probe knows where every other probe is, knows the trajectory of each
probe years ahead and predict collisions years in advance and making sure they don’t happen.
Another problem with having this opaque system is that, chances are, the probes are going
to be occasionally blocking sunlight that would have hit Earth.
All you need to do is make sure that none of the collectors' orbiting paths intervene
with the sunlight that hits Earth.
A kind of patch “no-zone” that the probes never enter.
Or the probes could just orbit beyond Earth.
Of course, this wouldn’t be a problem if you only have a few hundred solar collectors
in a simple formation such a Dyson ring.
A Dyson ring is fairly self-explanatory, it’s simply where all the constructs share the
same orbit.
But as you get more advanced, you’re inevitably going to have formations more complicated
with collectors overlapping each other occasionally.
This type of system raises the question, how do you get all the material to build these
constructs orbiting the Sun?
The solar collectors aren’t your average Earth solar collector either, these collectors
will be at minimum a few kilometres across.
What’s good about having the collectors instead of a sphere, is that you don’t need
to do build it all in one go, you just constantly build more and more collectors and rotating
habitats, over the course of centuries, until you can’t fit anymore in.
You could start off by mass producing them here on Earth but developing several kilometre
wide solar collectors is it not an easy thing, at least for us right now.
Perhaps by the time we do such a thing we would be able to do it without a problem,
and just mass produce them here on Earth.
However, perhaps an easier method would be to disassemble an entire planet for the raw
materials.
Mercury seems like a pretty good candidate.
You could use self replicating probes, von Neumann probes, to build an army of probes
that could cannibalize Mercury, and use the matter to make kilometre long solar collectors
and set them in orbit around the Sun.
See the von Neumann probes episode, that we covered last week, for a more detailed explanation
and discussion on self replicating machines.
While the probes are at it, they might as well make a few hundred rotating habitats,
in preparation for Humans to use as living space in the future.
Constructing an entire sphere that completely encompasses the Sun is a completely different
story.
If you build it too far out, there’s not enough material in the entire solar system
to build it, even if it was only a few centimetres thick.
Build it too close and it gets too hot for life, electronics and perhaps the structure
itself.
As well as the Dyson sphere, there are many other variants.
There is the Dyson bubble, a system made up of many independent structures called statites,
satellites that stay at the same distance from the sun, using huge, thin light sails
to stay suspended in space.
These constructs would have a perfect balance between the push of radiation and the pull
of the Sun’s gravity.
It completely removes the possibly of two crashing into each other since they’re stationary.
And it doesn’t matter at what distance you put your statites.
You could have the statites at varying distances because the relationship between the radiation
pressure and the force of gravity from a star is constant regardless of the distance, so
long as there is nothing in the way of the star.
And like the cloud of solar collectors, you could pretty much cover all the sunlight from
the Sun, with enough statites.
Megastructures aren’t the only way to achieve a Type II status.
For instance you could do star lifting, removing matter from a star to use it for other purposes.
Star lifting is often thought as useless and over the top but actually it’s got many
benefits.
You might want to star lift to get some elements, especially hydrogen, to increase a star’s
lifetime, to create new stars, to decrease a star’s brightness, or even to prevent
a star from exploding.
In the far future humans might even use star lifting on the sun, in order to stop it from
expanding as a red giant.
That is, if we haven’t colonized a different solar system by then or gone extinct.
A more exotic method is to capture energy from a black hole.
One way of doing this would be to feed a black hole stellar mass, or mass from a star, into
a black hole, in order to collect the photons that would be emitted by the accretion disc.
Another method would be to just capture the photons already escaping the accretion disk.
This reduces angular momentum of the black hole, and is known as the Penrose process.
Other methods could include somehow collecting the energy of gamma-ray bursts or even the
emissions from quasars could possibly be a power source, that is if they’re collectable.
Last on Kardashev’s original scale is a Type III civilization, or a galactic civilization.
A Type III civilization is able to capture all the energy of a galaxy.
The methods to achieve Type III are just the same as Type II but on a larger scale.
One way of achieving a Type III status would be to put a Dyson sphere or Dyson bubble around
every star in your galaxy.
Or perhaps, you could attain energy from white holes, assuming they exist.
See the white holes episode for a more detailed explanation and discussion on white holes.
So as mentioned, Type I civilizations would harvest all of their energy from their planet,
which is about 10^16 Watts.
A Type II status is 10^26 Watts, which is pretty close to our Sun’s output, and a
Type III civilization is 10^36 Watts, just under the Milky Way’s output.
Famous astronomer, Michio Kaku, suggested that Humans may be a Type I civilization in
100 to 200 years, a Type II in a few thousand years, and Humans might be able to harvest
all the energy from every star in our galaxy in 100,000 thousand to one million years.
I’d say I agree with his predictions for a Type I and II civilization, but I can’t
see Humans having travelled to each star in the galaxy in less than a million years.
In the von Neumann probes video, we discussed that it would take von Neumann probes a few
million years to 10 million years to colonize every planet in the galaxy.
And that’s not including the time it would take to build each Dyson sphere.
Like a lot of topics we discuss on this channel you can apply them to the Fermi paradox.
We could tell if an alien civilization was using a Dyson sphere for example because it
would produce lots of heat, mostly in the infrared part of the spectrum, and astronomers
are trying to detect unusual, high amounts of infrared, but with no avail, meaning that
they are either really rare or don’t exist.
The best evidence of a Dyson sphere comes from Tabby’s star.
In short, the Kepler Space Observatory has been studying about 150,000 stars in a certain
region of the Milky Way and one star in particular showed some very strange dips in it’s brightness,
that cannot be explained.
There has been additional types suggested to the Kardashev scale, such as a Type IV
civilization: harnessing all the energy from an entire universe, and a Type V civilization:
harnessing all the energy from several universes, but at that point, it’s just astronomers
getting imaginative.
If we were to take it seriously though, we probably wouldn’t recognize a Type IV or
V civilization because we’ve got nothing to compare it to.
They would seem like gods to us.
Now while we would seem like ants to them as ants are to Humans, that doesn’t immediately
imply that they wouldn’t be interested in us.
I get this a lot in comment sections, that more advanced civilizations wouldn’t be
interested in us.
I think they would.
Using that analogy, if you had never seen an ant before, but knew that there was a possibility
that they exist although unlikely, and you came across one, you'd be pretty interested
in them.
It would be as exciting as discovering an extinct species.
With that being said, I do agree that we would be like ants to them.
The Kardashev scale categorizes civilizations going up the way but physicist John D. Barrow
suggested a scale going down the way.
This scale categorizes civilizations by how small matter they can control.
A Type I civilization would be able to control just normal, regular matter, a Type II civilization
would be able to control genes, Type III would be able to control molecules, Type IV would
be able to control atoms, Type V would be able to control protons, Type VI would be
able to control quarks and Type VII would be able to control spacetime.
Comment down below your thoughts on the Kardashev scale.
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on the Fermi paradox.
Thank you so much for watching, have a nice day.