
Type III Societies (Apparently) Do Not Exist - antognini
http://arxiv.org/abs/1604.07844
======
Semiapies
This really tells us extremely little about advanced civilizations, beyond
that we haven't seen them doing a few variations on a very specific
activity—harnessing all the stellar radiation in their galaxy.

There are huge number of assumptions based on that idea. A fundamental one is
that a civilization in a relativistic universe would grow to densely inhabit a
galaxy. Another is that they would _need_ that much energy. Another is that
even if they _did_ have need for that much energy, they'd bother collecting EM
radiation from stars.

That third is an interesting one to me. Now, you could muck up the night sky
for the entire Milky Way, or you could, with Sufficiently Advanced Technology
(tm), annihilate a total of 10 Jupiter-masses a year across the whole galaxy.
For your average star system, that's extracting energy from 1.1 billion kg of
mass a year, or roughly what NYC's garbage collection services dispose of
every two weeks.

Pondering that, I suspect it's the wrong idea to imagine that a very advanced
civilization, something we can only understand in the dimmest sense, would be
constrained by something as specific as stellar energy emissions.

~~~
zamalek
> Another is that they would need that much energy.

Even _if_ they needed that much energy, the best way to do that [that we know
of] is to build a Dyson sphere. With every star shrouded by a Dyson sphere you
no longer need to shroud the galaxy.

A more critical assumption is that a type III civilization even _cares_ about
masking its presence. If they were even worried about being attacked, the
speed of light would mask their progress for a great deal of time and, because
of the distances involved, even seeing them once the light reaches you would
be a massive accomplishment - most likely you'd have to search for individual
stars in _another_ galaxy which are disappearing in unusual ways.

A type II civilization could possibly build a telescope with a large enough
aperture but I assume that type II civilizations would be long past their
ignorant warring ways.

~~~
Retric
Dyson's spheres have low long term fuel efficiency. They are better off
destroying the stars and burning their fuel in fusion reactors. At least with
our current understanding of physics.

Also, a civilization could have dimantled Andromida Galaxy 2 million years ago
and can't tell yet. For more distant objects the gap gets rather wide.

~~~
DennisP
Stars use different fuel than reactors. To fuse simple hydrogen, four nuclei
have to collide at once. This is so unlikely that it requires a very large
mass of fuel to sustain a reaction: at least the size of the Earth, according
to one article I saw.

It's entirely possible to burn deuterium in small reactors but there's only
about 1/2500 as much deuterium as hydrogen.

(Perhaps some unthinkably advanced civilization could figure out how to get
energy from hydrogen fusion in a small reactor, but you did specify "our
current understanding of physics.")

~~~
Retric
That's not accurate, stars have several fuel cycles for pure hydrogen. At 1.3
solar masses you sun mostly get:
[https://en.wikipedia.org/wiki/CNO_cycle](https://en.wikipedia.org/wiki/CNO_cycle)

As to size, on galactic scales all our current fusion designs are tiny. Scale
it up to even just 20 miles on a side and proton proton fusion is doable. For
a type III civilization capable of destroying starts that's also tiny.
Remember your suggesting dysons spheres as the 'reasonable' option.

PS: The proton proton chain also produces deuterium as an intermediary.
[https://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain_re...](https://en.wikipedia.org/wiki/Proton%E2%80%93proton_chain_reaction)

------
coldtea
They call economics a "dismal science", but I find such attempts at
'astrophysics' (or whatever this and stuff like the Drake equation are called)
even more dismal...

Tons of unknown variables filled-in with vigorous hand waving, ad-hoc and
unproven assumptions left and right, etc, and some high school math thrown in
for good measure...

~~~
ep103
I think you're taking a wrong look at this paper. This paper isn't actually
about whether or not type 3 societies exist. This paper is about the fact that
there appear to be no galactic clusters that show a particularly abnormal,
greater, amount of electromagnetic emission than the known standard. Which,
actually, I'm pretty dang surprised hasn't been searched for already. Then, in
order to be a little whimsical and make sure the paper gets read, (s)he
explains where they came up with the idea for this experiment.

Seems to me like a completely rationale thing to measure about the universe.
Imagine if the result had come back true?

~~~
kbenson
> This paper isn't actually about whether or not type 3 societies exist.

Ah, I see. It's a play on words. "Apparently" is meant as "is visible", not in
the sense of "this is true". Astronomer humor.

------
nostrademons
Plot twist: the "dark matter" in the universe actually consists of Type III
societies harnessing the electromagnetic radiation of their galaxies by a
means as-yet unknown to us.

~~~
vox_mollis
Unfortunately, this idea has been explored and discarded. Thermodynamics
requires the emission of detectable EM energy from such shells, just at longer
wavelengths. We'd expect to see dark matter emitting in microwave or IR, but
we don't.

~~~
CamperBob2
It doesn't require that a Dyson Sphere be an isotropic radiator, though. It
could be emitting its heat in a different direction.

~~~
breischl
Well, if you emitted it all in a beam away from the plane of your galaxy, that
might make you very stealthy. That would impart thrust on the sphere... which
if it wasn't perfectly balanced might cause it to wobble, and then start
rotating...

... and now we have a sci-fi reason for quasars. :)

~~~
Semiapies
You could direct the waste in two beams perpendicular to the plane of the
galaxy, in order to balance net thrust.

I question how stealthy that would really make you, though. If someone was
bothering to look for stealthy civilizations, they'd just have to scatter some
observatories around their region of the galaxy, then watch. Eventually, your
structure would occult a star from the POV of one of those observatories, or
they'd pick up your beam scattering in interstellar gasses or dust clouds.

~~~
breischl
Of course you'd need two beams. If you used a single beam it would be a
stellar rocket... which might be fun in different ways. Certainly gives the
phrase "interstellar warfare" a different meaning.

I realize this is all space opera, not hard SF. It's still fun.

~~~
Mtinie
"But Sir, these are the correct stellar coordinates for the Zorgoph home
world! They should be right here!"

"There's nothing here, Captain. Nothing at all. So you're saying that they
moved an entire star system? In the last solar cycle?"

Good times, good times.

------
drKarl
If we expect to see the "brightness of the blackbox caused by the radiation of
a Type III Kardashev Civilization", and we inspect galaxies that are maybe
millions of light-years away from us, would we not be looking at how did those
galaxies look millions of years ago?

That is, maybe there are Type III Kardashev Civilizations and their usage of
the energy of their galaxy in fact radiates energy that would be visible to
us... except that they've evolved to that point much later that the light
we're receiving since it takes millions of years for that light to reach us.

In those millions of years they could very well have reached that
technological level, but it will take some more millions of years for that to
reach us... by that time mabye that Civilization doesn't exist anymore...
Maybe our civilization doesn't exist anymore...

In this case we extract information from the radiation that comes from those
galaxies, and the information is too slow to travel such vast distances, since
it can't go faster than the speed of light.

In summary, we're looking for ANCIENT Type III civilizations.

~~~
blincoln
> In summary, we're looking for ANCIENT Type III civilizations.

Yes. This is because of the low probability that intelligent life develops
somewhere else at even close to the same time as it did on Earth.

Our best understanding is that life has existed on Earth for something like 4
billion years, and complex life has existed for about 500 million. However,
complex life capable of building spacecraft (or even radios) has only existed
for a few hundred thousand (that is being extremely generous, of course), and
only developed that technology in the last ~100 years.

If intelligent life has or will evolve somewhere else in the universe, and
progresses anything like it did here, then the odds seem overwhelmingly in
favour of one of two scenarios:

\- It evolved millions of years ago, and if it has not wiped itself out, is
virtually god-like by our standards due to its head start on technological
development.

\- It has not yet evolved, or at best is the equivalent of primates or the
proto-humans of several hundred thousand years ago.

------
sgt101
I wonder what ants think of airports? Or what mice believe about tube trains
as they scuttle under the platform.

We are separated from mice (or at least somewhat similar animals) by
approximately 40m years of evolution, I think that the separation to a Galaxy
altering level entity would be much more profound, and frankly we wouldn't
understand what it was if it came and tickled us.

~~~
xemoka
We are in no way separated by 40m years of evolution. Our common ancestor
'is'. That mouse you see today has been evolving just as long as you have, but
with different priorities.

~~~
gohrt
Our common ancestor 'is' what?

We are separated from mice by 80million years of evolution -- 40million from
the common ancestor, and 40million to the other modern species.

Or simply 40million years of divergent evolution.

------
kabdib
Harnessing stellar output might not be that interesting. Power density inside
stars kind of sucks (about that of a reptile) and stars have bad failure
modes.

You're probably better off disassembling the suckers and storing their matter
in a sensible way, rather than have it sit there, burning. Stars are kind of
like trash fires; maybe we should be looking for _less_ energy in a type III
civ, not shielding.

~~~
heavenlyhash
Just to play devil's advocate -- density isn't everything either.

Plants on Earth play an incredible optimization game. Water is necessary not
just for chemical metabolism, but because _throwing it away_ is an essential
part of the internal material transport systems of a plant. Evaporation in the
leaves creates a relatively lower osmotic pressure in the higher levels of the
plant. Between capillary action and the slight but insistent pull to replace
evaporated water in the leaves, plants have a pumping mechanism with
essentially nil energy input: minerals and nutrients gathered in the roots
just ride on up with the tide.

Stars may be a similar story for efficient fusion. Sure, with sufficiently
advanced technology, I can make inordinately denser energy sources with less
boil-off. But do I want to? Maybe letting the brute physics of a gravity well
do the job simply has unbeatable efficiency -- just like evaporation as one
end of a pump for plants on Earth is clearly no comparison to any motorized
pump for volume, but for cost-effect, nothing else comes close.

~~~
kabdib
A Type III civ is probably going to take the long view. The _really_ long
view. And in the long run, efficiency is everything.

Stars are just so wasteful; all that energy going into convection currents,
and you have to build this big damned sphere to capture all the energy. Better
to lift the damned thing and, at the very least, make a dwarf star out of the
larger ones. Now you're talking trillions of years of burning (it's still a
trash fire, but at least it's manageable).

------
maxander
Could be great news- it rules out (within some limitations) most of the
_really bad_ paperclip-maximizer scenarios.

At least if society is doomed we'll only doom ourselves, and not the entire
Milky Way! One takes what cheer one can get when pondering this sort of
subject.

~~~
xiphias
It means it won't take long after we are doomed. Singularity which can bring
doom and eternal life comes at almost the same time. I would pick longevity
over Singularity any time.

------
api
My speculation has for a long time been what I call the uniform cooling
hypothesis. There are no type III civilizations because such things haven't
happened yet.

If the universe is all the same age and if the emergence and evolution of life
is tied to the overall thermodynamic evolution of the universe, then
everything might be approximately of the same scale and complexity within a
certain standard deviation.

If this is true then when we go out there we will meet all the others who have
also just developed to that level.

~~~
stcredzero
Yes, but if someone is off by just one percentage point, then they're 13
million years ahead. There needs to be something so unlikely about sentient
life, that it only arises approximately one at a time in each galaxy, or the
Fermi paradox would apply.

~~~
api
This hypothesis works best if we propose an extremely narrow developmental
range.

Of course since we have basically no data, we can't actually argue either way
beyond vague hand-wavey speculation. You can't calculate standard deviation
from a sample size of one.

~~~
stcredzero
In general, sub percentage point uniformity is taken as evidence of a very
strong synchronization mechanism. The extreme uniformity of the cosmic ray
background was taken as evidence of inflation, which is quite an extreme
position, if you look at the numbers.

That such a synchronization mechanism should work with such precision over the
entire universe seems very unlikely. Filtering would not require
synchronization, so that seems much more likely.

~~~
api
The only way I can imagine it being that synchronized is if evolution itself
is somehow tightly coupled to cosmic inflation.

Here's the speculation in more detail:

Evolution can be viewed as an information transfer mechanism that learns about
the universe and transfers that information into the genome. (This is one
interpretation found in evolutionary information theory.) As the universe
inflates there is more total information in it, and therefore more information
for evolution to learn. At certain points, a kind of information density
"critical mass" is reached and phase transitions occur: the emergence of life,
complex life, cooperative/multicellular life, higher order intelligence,
industrialization and complex society, etc. Since the total amount of
information in the universe is (we're speculating) tied directly to the arrow
of time, this occurs simultaneously everywhere at approximately the same time.

Again this is hypothesis bordering on speculation since we do not know of any
mechanism that directly couples information content to cosmic inflation like
this, or even how we would go about measuring such a thing objectively. For
instance it's not possible to differentiate between random and encrypted data
using Shannon information measures, so what statistic would you use?

~~~
stcredzero
Then I'll invoke Occam's Razor. A simple filter explains the situation more
cleanly, and doesn't need the addition of a wild-sounding mechanism that
affects evolution that's attached to inflation.

Furthermore, if it has such a powerful and pervasive effect on evolution, why
haven't we already discovered it in our studies of evolution to date? We live
on a planet chock full of evolving life.

------
pjdorrell
He estimates f_l, the probability of life arising in a habitable planet, as
0.1.

Abiogenesis has never been observed to occur independently of its presumed
occurrence when life started on Earth.

Given the current state of scientific knowledge on this topic, the only
certain lower bound on this number is the probability of molecules in a
suitable "organic soup" arranging themselves into a self-contained bacterium.
And that probability is a _very_ small number.

If f_l is _very_ small, then there is no need to be pessimistic about our own
long-term survival. We see no advanced alien civilisations, because there is
no other life out there of any kind - the rest of the observable universe is
sterile.

~~~
gerbal
Even if abiogenesis is common, the transition from simple to complex cells is
incredibly uncommon. As far as we can tell it only happened on earth once in 4
billion years.

f_l may be 0.1 but f_i is almost certainly multiple orders of magnitude
smaller.

------
stcredzero
I don't think societies/civilizations are a viable organization scheme on
cosmic time scales. What if very advanced civilizations all reorganize
themselves into symbiotic aggregations of less-than-wholly-individual
entities? Communications between these entities inhabiting virtual reality is
so fast that the aggregate seems like a hyper-intelligent hive mind to human-
like sentience?

If we take mind upload as a given, then it should also be possible to create
"clones" of our minds with ease. This level of technology will have a profound
effect on the value society places on individuality.

~~~
jobigoud
> What if [...] all

"all" is usually the key issue with solutions to the Fermi paradox. We can
certainly find reasons for any given civilization to go the other way, but
it's more difficult to argue that _all_ of them do.

~~~
stcredzero
There are very strong reasons to believe that all civilizations (multitudes of
independent, individualistic semi-cooperating sentient creatures) are
inherently chaotic and therefore unstable. There are loads of arguments as to
why they are doomed to fail, or to try to expand exponentially. If we take a
cold and realistic eye to technological civilizations, they do seem doomed to
self-destruct or "sublime" into something incomprehensible. There aren't many
examples in nature of things that are the confluence of two or more super-
exponential processes that are long-term stable. (In our case, those would be
population, energy use, and technological change.) In fact, I think there are
basically none.

~~~
tremon
I think you take a particularly narrow view of what constitutes a "society".
Arguably, current human society is the product of over 10,000 years of
continuous development. Yes, there have been numerous changes in structure and
power, but our fundamental "human" identity hasn't really changed in that
time.

I would also argue that life itself has proven remarkably long-term stable on
our planet. Granted, it has not been stable enough to produce a type-III
society, but if we remove homo sapiens from the planet for a thought
experiment, there exist other species that are developing communication or
tool-use skills and might succeed us even on the technological path.

So my view is that, unless we continue to fail spectacularly, life will still
continue without us. Even if we do not reach type-III, that does not
necessarily preclude Earth from producing a type-III society in the future.

~~~
stcredzero
_I think you take a particularly narrow view of what constitutes a "society".
Arguably, current human society is the product of over 10,000 years of
continuous development. Yes, there have been numerous changes in structure and
power, but our fundamental "human" identity hasn't really changed in that
time._

Sounds like you are the one who has a narrow view of "society," rather. In the
abstract, it only need be something like "a multitude of cooperating but
competing, independent self-preserving, self-advocating sentient interests."
That's fairly abstract while still being a sure recipe for highly non-linear
and chaotic effects.

 _Even if we do not reach type-III, that does not necessarily preclude Earth
from producing a type-III society in the future._

But then you're setting up a situation where a series of chaotic and unstable
arrangements snuff themselves out or flare-out in a puff of singularity-
colored smoke, ending with the appearance of the first stable meta-societal
form.

------
weberc2
> Whether technological societies remain small and planet-bound like our own,
> or ultimately span across galaxies is an open question in the Search for
> Extraterrestrial Intelligence.

What questions in this field are _not_ open?

------
tomswartz07
Somewhat tangentially related: a non-scientific discussion on what Type I, II,
and III Societies are, and why they might not quite make it.

[https://www.youtube.com/watch?v=XhkwT466ykc](https://www.youtube.com/watch?v=XhkwT466ykc)

------
amelius
Why would technologically advanced species explore the (mostly empty)
universe, when they can sit inside their holodecks and have much more fun?

~~~
eridius
4 reasons come to mind:

1\. Advanced societies have probably solved the aging problem, leading to
either extremely long lives or effective immortality. As long as these
societies keep reproducing (and they will, unless they deliberately engineer
out the urge to procreate, which I consider to be unlikely), they'll need
space to spread out. Sure, they could probably pack themselves like sardines
into a single solar system, but that only works if they'll be spending 100% of
their time in virtual reality, and that would be begging the question.

2\. A need for resources. Type III societies can capture 100% of the output of
a star, but even this amount of energy might not suffice once society grows
large enough. And even at that level it's still probably easier to manipulate
matter than it is to convert energy into matter, so it'll be more efficient to
harvest planets and asteroids and whatnot for raw building materials, which
means leaving the solar system.

3\. Even assuming they manage to create virtual reality that is 100%
indistinguishable from reality, it's likely that there will still be a lot of
beings that will reject the idea of living 100% in virtual reality simply
because it's virtual. Even if it's indistinguishable from reality, they'll
still know it's not real. So they may visit VR, but will want to actually live
in the real world. Or in other words, humans have shown a tendency towards the
perverse, and it's not unreasonable to assume aliens will too.

4\. Any kind of scientific research still being done at that level will likely
require the use of reality instead of VR. VR is a simulation, and even if it's
indistinguishable from reality to your senses, it's still presumably not
actually simulating reality down to the planck level (because it's part of the
universe, it cannot simulate the entire universe at the same fidelity that the
universe itself operates at, as that would presumably require more information
than the universe contains), and so there's probably a fair amount of research
at that level that simply can't work in simulation and requires testing
against actual reality.

~~~
stcredzero
_1\. Advanced societies have probably solved the aging problem, leading to
either extremely long lives or effective immortality. As long as these
societies keep reproducing (and they will, unless they deliberately engineer
out the urge to procreate, which I consider to be unlikely), they 'll need
space to spread out._

If they had as little agency around the issue of population control as you
suggest, this makes me question their status as "advanced."

~~~
eridius
I did not suggest that they have little agency around population control. What
I suggested was that aliens will continue to _want_ to have children, and so
space will be needed for those children given that the parents won't be dying
any time soon.

Beyond that, if you have effectively infinite space and resources, there's no
need at all to have even the slightest bit of population control. Population
control is only necessary to ensure adequate resources (including space to
live) for everybody. But when there's no constraint on resources, there's no
reason why anybody shouldn't have as many children as they desire.

~~~
stcredzero
_I did not suggest that they have little agency around population control.
What I suggested was that aliens will continue to want to have children_

So you suggested that their civilization as a whole had little agency around
population control.

 _Beyond that, if you have effectively infinite space and resources, there 's
no need at all to have even the slightest bit of population control._

You're forgetting simple geometry. Space empires can only expand proportional
to n^3, while their population could potentially expand proportional to k^n.
Also, in a situation where there are multiple star-faring "species," a
hegemonic, exponentially expanding entity might well be viewed by others as
worse than obnoxious.

~~~
eridius
You're ignoring constant factors. Space empires will likely expand much faster
than dictated by population needs, to the degree that, as it spreads out, it
will presumably experience a reduction in population density. Sure, with
multiple star-faring empires, there may be a limit to how far in space a given
empire can expand, but a Type III society is capable of building all sorts of
gigastructures, including ringworlds and dyson spheres, so even a moderate
expansion out of a single solar system will provide plenty of room for
population expansion. It's also likely that immortal or long-lived species
will end up having a relatively low number of children (given effective
immortality and complete control over reproductive capability, it seems likely
that aliens will choose to have a low number of children over their lifetime
and will likely wait much longer before having their first child, which means
even a simple doubling in population will take place over a relatively long
time).

Given these reasonable assumptions, it seems likely to me that most space-
faring civilizations of this level of technology will never experience any
kind of pressure on living space. If you've ever read the Culture series (by
Iain M. Banks) then you might reasonably expect such a civilization to
"Sublime" before running out of space. Or to eventually alter themselves so as
to remove the desire to procreate in a deliberate move to "retire" from the
galactic stage.

I said "most" because there is of course the possibility that some species
comes along that has the urge not just to procreate but to have as many
children as possible as fast as possible, and manages to achieve this level of
technology without ever altering this behavior. Such a species that is driven
to expand its population as fast as possible may then experience restrictions
on living space, but such a species would eventually have to enact population
control, which could take the form of altering themselves to remove this urge
to procreate as fast as possible and therefore will become just like "most
space-faring civilizations".

~~~
stcredzero
I am a big fan of _The Culture_. Also, it sounds like you just posited that
advanced civilizations would effectively exercise population control,
otherwise avoid shortages and avoid the necessity of rapid spatial expansion
though technological means.

~~~
eridius
My belief is that advanced civilizations would naturally end up with what is
effectively population control, without any actual active work towards that
goal. As birth control becomes easy and prevalent, unwanted pregnancies stop
happening. And it seems reasonable to me that, given greatly extended life
span / effective immortality, people will naturally choose to wait longer
before having children (if they have any at all) and will have relatively few
children and/or will have a long duration between children. So this does
pretty much amount to population control, without having any actual
restriction on any given individual's ability to have children.

~~~
stcredzero
_So this does pretty much amount to population control_

From the POV of an outsider or a different species, would any entity care
about the difference between "effectively/pretty much" and what you deem to be
"actual" population control?

I doubt it.

So basically, you haven't been disagreeing with me, just splitting hairs on
what the words "population control" means. I'm using a more generic criteria:
Is the population controlled?

~~~
eridius
I think I'm drawing the distinction between "active population control" and
"passive population control". I define "active population control" as anything
where the goal is to control population and active steps are taken in that
direction, typically with the effect of reducing freedom of individuals (e.g.
a simple control would be "no more than 2 children per couple", which means an
individual cannot decide to have 3 children). Whereas "passive population
control" is basically where population growth ends up controlled as a side-
effect of other changes, generally without any limits on the freedoms of
individuals (for example, eliminating unwanted pregnancies would be a form of
passive population control; the goal isn't to control the population but
rather to eliminate an undesired situation, and no individual's freedom is
curtailed, but the overall effect would be fewer children across the entire
population).

------
epicureanideal
Or, the blackboxes might not emit the radiation we expect because of some
technology or physics that we don't know about yet.

~~~
cwmma
Like maybe there is a very good reason NOT to be emitting radiation at that
obvious wavelength, because we might not be the only ones looking...

~~~
venomsnake
We are very secure trough obscurity.

~~~
coldtea
Security through obscurity give huge success at minimal effort.

It might not be 100% secure but it's not meant to be, either. Just more secure
than nothing.

------
state_less
Why should an advanced civilization necessarily create the artifact mentioned
in the article. The conclusion because we don't see this artifact, so type III
societies don't exists seems too strong. Maybe they don't create giant veils
around galaxies and instead have virtualized themselves, or can simply convert
matter to energy at will. What use would there be in wrapping a giant ball of
dust around a galaxy when you can convert matter directly to some other
energy/form? Probably I think "they" are formless and more information based
than physical. We aren't even sure if this reality is real or a simulation
anyway, so why limit our thinking to advanced civilizations in the world as we
know it?

~~~
largote
The problem with the Kardashev scale is that it ties the advancement of a
civilization with its energy consumption.

In order to qualify as a Type III civilization, you pretty much need to
harvest ALL of the energy in a galaxy.

------
TheOtherHobbes
I'm unconvinced by the Kardashev assumption that energy is the limiting factor
for civilisation.

It's more likely that beyond a certain point you have all the energy you can
use, and the limiting factor becomes collective intelligence.

I'd guess that in the same way that processors keep getting more efficient, so
do civilisations. At the highest levels the energy signature of a civilisation
is virtually indistinguishable from the cosmic microwave background - if it's
observable at all.

~~~
duaneb
> It's more likely that beyond a certain point you have all the energy you can
> use, and the limiting factor becomes collective intelligence.

Why is this more likely?

~~~
tremon
My off-the-cuff response is that energy could be harvested locally in many
places, but society as a whole will be bounded by the speed of communication
(which might not exceed c). It's possible that too long communication lines
will fracture society into separate "islands".

------
repn001
After reading The Dark Forest, my bet is that an advanced society would never
advertise themselves in such an obvious fashion.

------
basicplus2
well.. if we don't get off this planet within the next (approx) 4 Billion
years.. our species will snuff it as the sun grows to a red giant.

so assuming all life across the universe starts from similar beginnings as us,
then this tells us something about what an advanced civilisation needs to be
capable of to survive.

