So, in this video I’m going to try to be optimistic about humanity’s future (out
of character I know BUT I kind of have to, to setup this video).
Okay, I’m going to presume that atomic warfare doesn’t happen, overpopulation doesn’t
happen, killer meteor that destroys everything doesn’t happen, we go to Mars, setup a colony
or hundred, become a fully-fledged space-faring civilisation with bases of operations in different
star systems, everything’s happy, utopian future, hurray.
…But, I don’t even need to go around naming achievements to justify how good a civilisation
is.
There’s actually a scientific scale to measure how advanced a civilisation is, believe it
or not.
It’s called the Kardashev scale (named after a Soviet astronomer Nikolai Kardashev) and
it measures a civilisation on its total energy consumption, basically how much energy is
needed to keep the society going.
We are here and need to be here for the thing I’m explaining to start to be realised,
but you don’t know what any of this means so I’m going to have to spend the next half
an hour explaining it.
It’s actually quite simple.
As a civilisation advances in technology, it is safe to say the total energy consumption
will too, so we will progress up the scale, pretty easy to understand.
There are milestones on this scale, which define the scale of our civilisation.
Type One, here, marks a civilisation that can ‘use and store most energy that reaches
the host planet’, Type Two ‘can use and store nearly all energy output from a host
star’ and Type Three is like Type Two BUT FOR AN ENTIRE GALAXY.
This scale is logarithmic, the further you reach, the more energy needed to progress.
We can use decimals to define civilisations in between the milestones.
Just for scale, Type One needs 10,000 Terra Watts.
Type Two needs 10 billion times more than that, and Type Three needs 100 ExaWatts of
energy, which is a staggeringly huge amount.
To measure a civilisation, we can use this equation, formulated by the one and only Carl
Sagan back in whenever he did this.
You replace P with the wattage and K becomes the scale of civilisation.
As of 2012, the total for humanity is 17.54 terawatts, which if we plug that in to the
formula, this means that human civilisation is a Type 0.724 civilisation.
Decent.
Right, so here’s the bit I need to be optimistic about.
We’re going to assume that our civilisation will keep growing and growing eventually become
a Type One and then Two civilisation, at which point we will need an entire sun’s worth
of energy to keep us going.
But how the hell are you going to generate an entire sun’s worth of energy?
Use a sun of course.
Makes sense.
And finally, after too long a time, we get to the Dyson Sphere, you know, the one in
the title.
A Dyson Sphere is a hypothetical structure a civilisation can build around a sun that
will transfer (virtually) the entire output of that star into usable energy.
If we are going to keep progressing as a civilisation, we are going to have to build something like
this in the next few thousand years, well, according to Michio Kaku at least, but he
seems like a trustworthy guy.
Now, these structure come in a variety of different flavours, to suit any civilisations
needs.
You can have a plain old Dyson Sphere, or instead try a Dyson Belt, Dyson Ring, Dyson
Swarm, Dyson Hoover or Dyson Shell or some combination of these.
These are all a little bit different, but I’ll explain that later.
First, HISTORY.
The concept of a Dyson sphere dates back to an exciting period in history known as...
the 1930s?
Urrgh, that’s not very exciting.
Anyway, and to a book by this British bloke about sci-fi space travel, where we see our
first glimpse of a star-encompassing structure.
And, like all good inventions, it’s named after somebody else.
I guess Stapleton Sphere was just too boring.
Skip forward to the 1960’s (don’t worry, nothing really important happened in between
then anyway) and to physicist and mathematician Freeman Dyson.
He proposed the same thing that we’ve just discussed, that civilisations will need stars
to power their societies eventually.
He then proposed one massive structure could (in theory) surround a star and ‘collect’
it’s energy – calling it a shell.
He published a paper about it in 1960 and so the Dyson Shell was born, which is exactly
the same as a Dyson Sphere, just less catchy.
However, in his paper he didn’t talk about how (in theory) you could build such a sphere,
and as a result I know what you are imagining.
A hollow ball enclosing a star.
Well, good luck with that.
I’m not even going to talk about how hard that would be to design but instead try to
illustrate how hard it is to build, I’m just going to talk about how impossible it
is to collect those materials needed to build one.
So, let’s make some assumptions.
You are going to build one around a star exactly like the sun, with a radius of nearly 700,000
kilometres.
The shell itself will have a radius of 0.25 AU (37 1/2 million kilometres) and will be
1 cm thick.
We are going to ignore which impossible material you might construct it with and use steel
as an example, which won’t even be the photovoltaic cells but the frame they sit on, keep that
in mind.
A sphere’s area is 4 pi r^2.
Plugging in 37,399,467,500m gives us 1.76×1022square meters, the surface area of the sphere.
We can fold this out into a flat shape, in theory because there is no perfect representation
of a sphere in 2 dimensions, but we’ve assumed a lot of things so far so let’s not worry.
Multiplying by 0.01 metres (1cm), this gives us 1.76×1020cubic meters of material needed,
which is a number that I’m not going to pronounce because this video might last until
the next Olympic Games if I do.
Go Tokyo, woo!
Provided the steel has a 1% carbon content and therefore 99% percent iron content (1.7424e+20),
and presuming 80% of the Earth’s core is iron, we would need 23 Earth’s cores to
supply the iron to make just the frame for it.
Nearly two-dozen massive planets mined hollow.
This is ridiculous, what am I doing with my life.
We are going to have to completely obliterate entire solar systems, presuming they have
as massive a planetary system as we do, AND THEN transport all of it, every atom, light
years, which will cost unimaginable amounts of fuel and time and industry.
AND THEN we have to build the bloody thing, which will take hundreds and thousands of
years AND THEN, it has to be economically worth all the effort of designing, resource
collecting, transport, manufacture, engineering, construction and maintenance.
*breathe* Assuming ALL OF THAT, you can finally stand
back on what’s left of the planet you’ve gutted, along with many others, and watch
as thousands of years and an entire species work collapses and destroys itself in the
star because there is no physical material anywhere near strong enough to support that
kind of a structure.
OH WELL, BACK TO THE DRAWING BOARD.
UUUHHH.
*pause* This is why Freeman Dyson in 2013 stated he
wished it hadn’t been named after him, probably because most people’s interpretations were,
quote ‘physically impossible’.
But...
...there is another way.
Remember those variants from earlier...?
Unlike a complete shell, these work by having an orbiting network of structures, like a
ring or a disc or a belt composed of smaller energy gathering satellites.
This is the more realistic of the two, still very hypothetical concepts.
After all, this design has the ability to be added to incrementally and we are starting
to actually develop the tech for this now.
But what about this area?
That’s wasted energy right there...
right?
Well, we could try to build more rings there, but we have an underlying problem.
This area, where the orbits cross, is incredibly dangerous.
Incredibly incredibly dangerous.
I’ll explain.
A lot of people have this misconception about orbits, perhaps led by simplistic diagrams
like the one onscreen.
With the way gravity works, everything is attracted to everything else.
There is no outer limit on the pull of gravity.
This means a star 500 million light years away is pulling on you, just by a tiny amount.
On a bigger scale, the Moon and Sun pull on satellites in orbit, drifting them out of
sync with each other.
You still have tiny tiny molecules of gas up that high, which drag against the spacecraft
and slow it down towards Earth, hell, this is why the ISS needs to reboost so often.
Orbits naturally change, and to calculate how this would happen would be physically
impossible.
Sure, you can allow for the massive pull of planets, but as soon as the first spec of
debris gets anywhere near them, they will desynchronise.
And if they desynchronise, they might hit each other.
And the millions of shards of debris will hit more satellites, which will hit more until
you have a Kessler Syndrome shell of shrapnel travelling many kilometres a second obliterating
everything near that orbit, and rendering that altitude physically unusable for centuries.
According to this video, a destruction on that scale would actually cause a recession,
the biggest economic recession in the universe.
Oh yeah, and your civilisation has no electricity.
No power.
It’s basically an apocalypse.
So that’s fun.
*Sigh * However impossible I’ve made it sound, scientists around the world are working
right now to make it a reality.
We as a species have done the impossible before, so why let it phase us?
I mean, if another civilisation had a couple million year head start, I have no doubt they
would be trying to put in place some sort of stellar structure...right..now.
Wait...what?
Holy shit.
HOLY SH*T. HOLY SH*T.
Yes, because in 2015 star KIC 8462852 was found by the Kepler Space Observatory to have
strange light fluctuations, as far as we know, unique light fluctuations.
Fluctuations that would indicate some sort of swarm of spread out orbiting matter.
A swarm that we’ve never seen before.
It is wholly possible that this is our first glimpse of intelligent extra-terrestrial life,
or at least of their shadows from 1,480 years ago.
They may be constructing a Dyson Swarm, one of the more reasonable constructions when
trying to power a civilization.
But ultimately, we will never know for sure.
But it’s pretty cool, right..?
So that’s the Dyson Sphere.
It’s uses, origin, practicality, configurations and maybe even realisation.
I hope you enjoyed this video.
Thanks for watching.