
Alone in a Crowded Milky Way - BerislavLopac
https://www.scientificamerican.com/article/alone-in-a-crowded-milky-way/
======
ohazi
I don't buy this argument. Let's pretend for a moment that there are currently
5-20 intelligent species in our galaxy, and everyone except us developed deep
space ships and successfully colonized thousands of other planets (make up
almost any numbers you want here; the results still hold).

What would our telescopes see? It seems like we would most likely see exactly
what we see today.

The probability that one of those ships happened to fly anywhere close to our
solar system, while we were looking, is still vanishingly small.
Omnidirectional radio transmissions spread so quickly that they fall below the
noise floor almost instantly over interstellar distances.

Space is really really really _really_ big. We can see stars. We can just
_barely_ see some planets in a few _very_ specific configurations. We can
sometimes make coarse estimates of the chemical composition of those planets.
And that's about it. We don't really know how to detect life on extrasolar
planets. The ones we've already found could be teeming with life and we
wouldn't know it.

~~~
pfdietz
Why would they stop at thousands of colonies? What is it preventing the
colonies from themselves creating colonies? Also, realize that a colony in the
system of another star will move away from the originating system. In our neck
of the galactic woods the rate of separation is typically about 10^-4 c, so in
a million years they'd separate by 100 light years.

~~~
Retric
The problem with endless expansion is it requires stability over very long
time scales. Sending a probe to another solar system is hardly enough. If you
can send a ship say 100 light years from your home planet that’s 2,000+
repetitions of terraforming and colonizing a planet, building up an industrial
base, then sending ships to every planet in reach. Under ideal conditions that
might take 10,000 years assuming everything went well so you need 20 million
years to colonize our galaxy. But, assuming everything goes well for 20
million years and colonization continues to be a priority seems unlikely.

It’s very possible to reach a wall where zero teraformable planets are within
reach of your ships. For large civilizations that’s unlikely to totally block
expansion, but it might make the path very convoluted thus increasing total
time by a rather extreme factor.

~~~
TheOtherHobbes
Culture rot will kill you quicker than density of colonisable planets.

The transport layer is the easy part. Content integrity is a much harder
problem.

All of your probes and colony ships have to reproduce the source culture - or
some viable subservient spin-off - with 100% accuracy.

This explicitly means 100% reproductive success of all features, especially
the politics and economics, with no errors.

For a successful colony, stability and conformity have to be maintained for
long periods - centuries at a minimum, perhaps even millions of years.

And of course this assumes the source culture is stable in the first place.

Otherwise you're just seeding the galaxy with potential competitors, and/or
setting up some kind of galactic Battle Royale.

I'm bemused by the suggestion the first option is actually possible. The
second seems more likely, but might not be considered a success in the sense
of creating a stable galaxy-spanning civ capable of common strategic goals.

~~~
andrewflnr
> All of your probes and colony ships have to reproduce the source culture -
> or some viable subservient spin-off - with 100% accuracy.

The only thing that needs to be preserved is the desire to build more
colonies. I'll grant even that's a stretch, but demanding 100% cultural
fidelity is silly for discussing the Fermi paradox.

~~~
brlewis
> The only thing that needs to be preserved is the desire to build more
> colonies

That's hard. I'd say harder than solving the physical problems of interstellar
travel. Once a generation has learned to live with the limited resources of a
starship, living with the limited resources of a planet is going to be a very
attractive option. What's their incentive to colonize more from there?

~~~
dwaltrip
It's always going to be a small percentage that desires to venture further out
to new areas. On a newly settled planet, most will not want to leave. But some
will.

~~~
brlewis
But you have to wait for that society to forget that living on a starship
means spending your whole life never venturing out, while a planet lets you
spend your life exploring.

~~~
Faark
Or, you know, some just want to get away from the other individuals.

That is, if we are talking about something comparable to current humans.
Immortal super AIs might don't care about idling in the void for a few million
years, just for the opportunity to re-sync those gained experiences to their
decentralized knowledge a few million years down the line. I really like the
single omnipotent AI scenario, since being immortal and not depending on
others changes quite drastically what strategies can be successful - it won't
be anything like human kings who need to keep their subjects at bay and
working for them to support their power and limited life. But we shouldn't
restrict our imagination, if we are talking about possibilities and galactic
time-spans.

The important part is, as mentioned by GP, the desire to expand, since this is
a dominant strategy. In comparison, not every living being on earth has the
drive to participate in evolution by e.g. creating offspring. Those usually
just drop out of the "game" and likely won't matter in the long term, at worst
making it a bit harder for the others initially till their disappearance. What
matters are those who have persistent impact... e.g. by colonizing/making
offspring.

------
rm445
Discussions of the Fermi paradox get swamped with people's individual
hypotheses. It's nice to see an article that tries to develop a whole
different _kind_ of answer. The known possibilities seem to be:

1\. We're alone (or very nearly so) due to an early filter. i.e. it was
vanishingly unlikely for life to develop as far as it has here.

2\. We're alone (or very nearly so) due to a late filter. i.e. life develops
in lots of places but, terrifyingly, it becomes overwhelmingly likely to wipe
itself out rather than spread.

3\. Life develops frequently but there's some sort of interstellar ecology
that makes species stay hidden or be wiped out.

4\. Life develops frequently but is overwhelmingly likely to develop some
other interest (becoming inward-looking, or exploring other dimensions) rather
than colonising all of space.

This article's suggestion that Earth may be in a backwater wouldn't be
sufficient by itself, so it is coupled with the idea, derived from
observations on human colonisation of Micronesia, that expansion happens in
waves and life on Earth happens to be in between waves. The problem is,
advanced technological civilisations expanding across the galaxy isn't the
same thing as Polynesian explorers eventually being followed by Europeans. Why
would the waves die away? This is a late filter with extra steps.

~~~
8bitsrule
5\. No Aladdin's lamp. There's no FLT, no wormholes, no solution to the huge
distances. And/or interstellar space is so full of toxins or plasmas no
lifeform can survive it. And/or all EM data transmissions are
reduced/scrambled/swallowed/encrypted by the void. All the experiments are
naturally locked in separate containers.

6\. _Klaatu barada nichto._ We are indefinitely locked in solitary,
incommunicado, for creating and using nuclear weapons. On ourselves.
Immediately.

~~~
lainga
I find (6.) somewhat anthropocentric in that it assumes nuclear weapons are
the _nec plus ultra_ of destructive power. You might as well have said in 1917
that we were incommunicado for inventing chlorine gas, or shotguns (whose use
the Germans did object to as a war crime!)

~~~
yborg
They aren't. We almost have the capability to do much worse ourselves already.
If you want big-bang type weapons, you can modify an asteroid orbit to drop a
K-T event on the planet. It's not very target-able, but if you want to try and
wipe out civilization, it would be pretty effective.

------
roca
I find most Fermi-paradox arguments drift towards being too biology-centric
even if they acknowledge the possibility or probability of a transition to
machine-based life.

For example this paper assumes that you need classic "habitable worlds" to
colonize a solar system, but it's unclear why machines would need more than
relatively small rocks or comets.

The paper also assumes that each colony needs to operate as a continuous
entity and can therefore collapse or experience massive cultural shift. But if
it's all machines, then you can put some powered-off seed ships in long orbits
for cheap self-recolonization (seems strictly easier than crossing
interstellar space in the first place).

I'd like to see more studies on the feasibility of those ultra-long-lifetime
interstellar ships (assuming plausible tech like general AI). Maybe there are
thermodynamic or other reasons why that can't be done.

(Personally I'm in the camp of "abiogenesis is actually really hard so we're
the first civilization in our light-cone; the doomsday argument holds, and
will be a theistic eschaton".)

~~~
ajnin
Machines need to be maintained. Machines of useful complexity include such
parts as microprocessors. To create new or replacement parts, nothing less
than the full Earth industrial complex is required. It's not clear how to
package all that in a ship, including enough reserves to bootstrap an industry
up to the point it is possible to build microprocessors. I doubt that "machine
life" could subsist on a small barren rock with more success than biological
life.

~~~
roca
It's very interesting to consider what would be required for a minimal
industrial complex that supports microprocessors. My intuition is that it
would be much smaller than "the full Earth industrial complex". Seems like a
question that is actually answerable with research, and potentially important
too as a hedge against our current industrial complex collapsing.

~~~
robbiep
Here’s an article on that: [http://caseyexaustralia.blogspot.com/2018/09/how-
to-industri...](http://caseyexaustralia.blogspot.com/2018/09/how-to-
industrialize-mars.html?m=1)

~~~
roca
Excellent link, thanks! That's exactly the sort of analysis required, though a
lot more is needed.

I didn't follow why mining has to be (or should be) so human-labor-intensive.

------
yibg
The problem with these types of arguments is they are assumptions built on top
of other assumptions.

We don’t know how to colonize other star systems, so we don’t really know the
factors at play. How easy is it to travel to another planet and start a
colony? We don’t know. How likely is it that that colony will colonize other
planets? We don’t know. We are taking numbers we guessed and multiplying with
other numbers we guessed to get to an answer. If any of them are much off the
answer doesn’t make sense?

What if the amount of resources to successfully travel to and colonize a
planet in another solar system is so high that the vast majority of attempts
fail and only a few attempts can be made? We can have n (pick some random
large number) intelligent civilizations in our galaxy and not know a thing
about them.

~~~
DubiousPusher
My thoughts exactly. I've always found it funny how people imply there's some
major issue with cosmology because the Drake equation shows there should be
intelligent life all over. Even though some of the terms in that equation are
very not known and it would only take a few being an order of magnitude or two
smaller than expected to result in a paucity of intelligent life rather than
an abundance.

~~~
yibg
Right. The Drake equation was never supposed to "show" anything. I think the
original intent was to lay out the factors at play and stimulate conversation,
not to provide a probability. I think over time, the imagination of the public
have taken over though and put more confidence behind things than we should.

------
cletus
So this article started as a good intro and overview of the Fermi Paradox
(which is somewhat of a misnomer because as far as Fermi was concerned it
wasn't a paradox at all) but it faltered at the end when it talked about
habitable worlds.

This is a topic Isaac Arthur [1] has gone into great depth about. If you
haven't found his YouTube channel yet prepare to lose several days of your
life. I find his arguments here compelling.

Basically planets only matter as a source of raw materials. Planets are highly
inefficient ways of creating living area. The most likely outcome for a
spacefaring civilization is actually a Dyson Swsrm. 1% of Mercury's mass used
this way could create orbiting habitats that support a quadrillion people and
fully utilize the sun's power output (a so called Kardashev-2 or K2 [2]
civilization).

And these are simply O'Neil Cylinders [3], which don't require any materials
that don't already exist.

The beauty of this is it doesn't require much more technology than we already
have. Better yet, it doesn't even require commercial nuclear fusion
(personally I'm not yet convinced this is even viable).

Take this further and a K2 civilization is not subtle and is highly
detectable. For it not to be violates thermodynamics. We've seen no evidence
of any K2 civilizations within millions of light years, which suggests their
existence is highly unlikely (within the cone of spacetime we can observe).

Given this seems to be such a natural evolution you can extrapolate and say
that we are pretty much alone.

Remember it's not about what most civilizations do because it only takes one
to go this road. The argument that no civilizations become K2 civilizations
use much harder to swallow than a few do. This notion gets more absurd the
more civilizations there are.

[1]:
[https://www.youtube.com/channel/UCZFipeZtQM5CKUjx6grh54g](https://www.youtube.com/channel/UCZFipeZtQM5CKUjx6grh54g)

[2]:
[https://en.wikipedia.org/wiki/Kardashev_scale](https://en.wikipedia.org/wiki/Kardashev_scale)

[3]:
[https://en.wikipedia.org/wiki/O%27Neill_cylinder](https://en.wikipedia.org/wiki/O%27Neill_cylinder)

~~~
Balgair
These are all under our current understanding of physics, which does a good
job, but we know it's not the full picture. Matter, the stuff you and I are
made of, is ~5% of the universe's mass-energy. We understand the physics of
this stuff fairly well.

Dark Matter is, as far as we can tell, is entirely made of stuff that falls
down and does nothing else. Dark Matter is ~25% of the universe. We have a
fair few theories of what Dark Matter is, if/how we can use it, how to make
it, move it, etc, but it's still very active research. We have a toehold on
Dark Matter.

Dark Energy, which makes things fall _up_ , is ~70% of the universe. We are
almost completely stumped as to what it is and how it works beyond making the
universe roomier. We're just totally knackered on Dark Energy.

Any civ that is thinking that seriously thinking about (let alone putting
down-payments on) discombobulating planets in order to make more lawns to mow
and gardens to weed is _very_ likely to have more than a toehold on Dark
Matter and is likely trying to make Dark Energy levitate tequila shots.

And that's just the physics that we know we're missing. K2 civs are probably
far more aware of yet more dragons in the mists.

So, concluding (correctly) that since we don't see the IR heat of K2 planet
demolitions, that we're alone, is not the best conclusion. We've not a clue as
to what the rules of the universe are yet. We can talk about strategy once we
learn how the knights and bishops move about the board.

------
mouzogu
My theory is that any advanced civilisation reaches a point at which a vast
amount of destructive power becomes accessible to individuals. At this point
it becomes only matter of time until that civilisation is destroyed.

The analogy I use is to imagine that every adult human on Earth woke up
tomorrow morning with a button on their wrist that could destroy the Earth.
How long do you think we would last?

We haven't reached a stage where an individual can create a nuclear bomb, a
new kind of super-virus or some other doomsday weapon but I imagine its not an
implausible scenario in the future. I think this is kind of a wall that all
advanced civilisation may hit at some point.

~~~
merpnderp
It’s not hard to imagine in the near future that having a PhD in biology and
access to a moderately equipped lab would grant a person the ability to create
super plagues capable of killing most humans.

Couple that with the wide spread nihilism that wants to destroy the world
because they can’t stand the injustice of life, and it’s a pretty good bet our
time as a species is limited here.

If I were king for a day I’d do everything I could to get the message out that
things are getting better, injustice is shrinking every year, and there is
hope.

~~~
ColanR
> It’s not hard to imagine in the near future that having a PhD in biology and
> access to a moderately equipped lab would grant a person the ability to
> create super plagues capable of killing most humans.

Pretty sure that's already the case.

------
bmdavi3
Does a lion born in a zoo understand it's being held captive by (in
comparison) super intelligent humans? When it's tranquilized, does it know
this isn't a normal thing for a lion? When the caretaker throws food out or
pets it, does the lion have the capacity to think about it in any other way
than what it means right now for the lion - food, feels nice, etc?

If there's a correspondingly more intelligent alien species hanging out on our
planet with us, would / could we even hope to know?

~~~
lordnacho
But Lions don't appear to have any abstraction ability, or reflective thought.
By that I mean you as a human can imagine yourself thinking about some
hypothetical situation, as well as consider what kind of evidence would
support a given hypothesis.

I think this might have actually happened (apocryphal?), but just imagine if
you took humans from another country and put them in a zoo. They would surely
figure it out, based on the evidence at hand.

~~~
bmdavi3
Definitely agree.

Just like how a lion or a chimpanzee wouldn't make a convincing zoo for
another lion or chimp, a human could figure out they're in a zoo made by
another human.

But when you make a zoo for an animal that isn't on your level, you can figure
out what's needed to satisfy it (even if it's really crappy compared to their
normal environment).

So if something smarter than us by an order of magnitude or more made a zoo
for us, it would be a much more elaborate and convincing zoo, and I'm not sure
we'd figure it out.

~~~
hnick
If we are talking super-advanced, it wouldn't even need to be a physical zoo.
Just mess with enough of our brains enough to make us not want to do certain
things and we'll stay on this rock forever.

------
ryanSrich
The article does a good job of explaining some of the numbers, but it’s
important to remember just how large they are.

To a spacefaring civilization a million years might be the human equivalent of
a decade.

The sad truth is that intelligent humans (enough to think and act on thoughts
of space travel) have barely existed on the cosmic timeline, and likely won’t
live long enough to know the answer to whether or not we’re alone. Not because
of some romanticized fermi gate paradoxical reasoning, but simply because we
ran out of time.

~~~
lonelappde
What do you mean? How is running out of time different from a Fermi gate?
Without a gate, why would time run out? The only natural limits are the time
limit to colonize another planet, then another solar system, before our earth
and sun lose their ability to sustain life.

------
BerislavLopac
I personally subscribe to the school of thought that interstellar travel is
impossible, except through some form of suspended animation or generation
ships (which both have its own problems). So no warp/hyperdrives, no
wormholes, no shortcuts to travel between the stars. This article dismisses
that notion before it even begins, but this is the only theory that fits the
currently observed laws of the universe.

~~~
m4rtink
Even with no FTL, you can still do interstellar travel just fine if you make
people live longer, which is being worked on for other reasons already.

~~~
jcranmer
It's not individual lifespans that are the issue, it's the lifespan of your
equipment. If your rocket breaks down in the interstellar void, you have no
resources with which to fix it.

And then you need to be able to bootstrap the entire industrial base to build
a new rocket at your destination without any help whatsoever aside from what
you brought with you. Given the history of interoceanic colonization efforts
on Earth, this suggests that the difficulty ranges from "insane" to
"impossible."

~~~
m4rtink
I think thats stil managable, even simply by redundancy and sending fleets of
ships. Also 3D printing of replacement parts seems pretty promissing and is
already being looked into (there is a basic 3D printer or the ISS).

~~~
tptacek
There is, but it doesn't really do anything, right? They printed some plastic
toys with it; it's not operations-critical.

------
papito
I think it's time we stop looking for life near other stars and start saving
our own. This planet is completely neglected. You want to live on Mars? That
should be fun, without a magnetic core. Living underground, like rats.

If you want to know what frontier living feels like, take a week off and stay
in one of the Inupiat villages on the edges of Alaska. You'll be climbing up
walls in 3 days. And _that_ is a luxurious vacation compared to frontier
living on a barely habitable planet. Netflix? Nah, bro. They still have
Blockbuster.

------
rainworld
More likely we really are alone:
[http://aleph.se/andart2/space/seti/dissolving-the-fermi-
para...](http://aleph.se/andart2/space/seti/dissolving-the-fermi-paradox/)

~~~
bagacrap
That paper only claims that it is _plausible_ we're alone, meaning the Fermi
paradox is only a question, not a conundrum.

------
bena
Fermi paradox. I never liked it.

It presumes too much.

It presumes that technology will advance to the degree that we overcome the
speed of light. Not directly, but that's where it has to wind up.

Because no matter how you slice it, it's still four years to Alpha Centauri at
the fastest possible speed we know. That means it will be at a minimum 8 years
before we know if anything was successful.

And yes, for the travelers, _they_ experience time dilation, but we here on
Earth would not. That time does matter. Even with self-replicating Von Neumann
probes, they still have to send that information back. That's still going to
take time.

How many resources can you dedicate to a bet that's going to take at least a
decade to show a return? How many of those bets can you make before you've
depleted your resources to the degree that you simply cannot do it anymore?

I think we may find ourselves up against the uncomfortable truth that our
cosmic range is rather limited.

~~~
m4rtink
IIRC Fermi paradox does not expect FTL - a locust style colonization effort
should be able to settle the whole milky way quite quickly (couple hundred
thousand years) even with not very fas sub light travel.

~~~
bena
Like I said, not directly, it doesn't, but once you start digging down, you're
going to need that.

A couple hundred thousand years is quick on a cosmic scale, but we, as a
species, have never undertaken any project on that scale ever. No species has
that we have evidence of.

Any sublight travel is a one way trip with almost no hope of ever knowing it
was a success by the people back home. No one funds that. And I don't blame
them. There is no return in any fashion for the people who remain. And little
to no return for anyone who starts the journey. The only thing you can
possibly satisfy is some minor curiosity.

Travel to Proxima Centauri at the current highest speed we've sent probes into
space would take over 80,000 years. If you double that speed. It will still
take over 40,000 years.

So, cosmically, the time scale is short. And compared to light, the speed
needed is slow.

But we're not light, are we? We don't exist on cosmic scales. I'm not
concerned with the theoretical limits of physics. I'm more concerned with the
practical limits of us.

~~~
antepodius
Don't be; 'we' won't be doing it. These are evolutionary/revolutionary
timescales; how many millenia away do you think general artificial
intelligence is?

~~~
bena
First, I think what we're searching for isn't intelligence so much as
consciousness. So I'm going to treat general AI and consciousness as pretty
much the same thing.

Considering we don't exactly know what consciousness is or what it means to
"be intelligent", I have absolutely no clue how long it will take. But unless
there is something I'm unaware of, I do think that we're approaching the
problem from a wrong direction.

Think about it like this, we know that intelligence/consciousness is an
emergent property of a lot of life on this planet. Including some life that we
previously didn't consider aware in the traditional sense. Plant life may have
some sort of intelligence/awareness.

When an artificial intelligence can express a genuine desire to avoid
termination, we'll know we've gotten it.

Then again, do we even express genuine desires? Or are we simply inefficient
meat computers responding in predictable ways to external stimuli?

So the question is whether or not general AI is even possible for us to make.

And then the assumption is that this general AI will be able to plan on the
cosmic scale. But why? First, what's the life span for most electronics at
this point? That factors into desire. What happens beyond our death is only of
academic concern to us. To assume it won't factor into their decision making
process is just speculation.

And if you presume we'd have programmed this general AI with the desire, well,
it's not really a general AI, is it? We've robbed it of a decision. We've
taken an entire forest of decision trees from it. It can't not choose to
colonize the stars.

Then you're also making the assumption that general AI won't come to the
conclusion that colonizing the stars is an inefficient use of resources.
General AI doesn't really change the problems with the Fermi paradox, it only
seems to add new problems.

~~~
antepodius
>First, I think what we're searching for isn't intelligence so much as
consciousness. So I'm going to treat general AI and consciousness as pretty
much the same thing.

That's not how I think about it at all. I think you're underestimating how
alien AI could be to us, in general. I.e., I think you're anthropomorphising
it unnecessarily.

There's an idea called the orthogonality thesis, which says: The intelligence
of an arbitrary agent can vary independently of its goals.

Here, I'm using intelligence to mean just the ability of an agent to
generate/evaluate/execute plans to further its goals. A modern chess AI on
modern hardware is more intelligent than one from the 1980s. In principle, you
could have any arbitrary utility function attached to any level of
intelligence.

This idea was brought up because often, when people heard about the paperclip
maximiser (an agent that tries to maximize the number of paperclips- and thus
wants to take apart everything in its lightcone and turn it into paperclips),
they said: "But why would something so clever do something so stupid and
pointless? A superintelligence would surely realize it was being stupid and
decide to do something smarter."

But there's no reason to think this! When you take away the agent's goal of
maximising paperclips, there's no perfect platonic ghost of consciousness
left! The paperclip maximiser, as defined is _just_ an algorithm that predicts
the future, looking for actions that maximise paperclips, and executes them.
Given unbounded compute power, it can just look through arbitrarily many
counterfactual simulations of the future given different plans, pick the plan
that maximises the number of paperclip-like structures in the universe, and
execute it. The rest is implementation details, given we don't have unbounded
computing power, but the point is such a system doesn't need to be conscious
to be powerful.

If you have an AI without a utility function, you don't have an AI. 'General
intelligence' just means the AI's computing/reasoning/versatility power, in a
vague sense. It has nothing to do with whatever particular utility function an
agent might be trying to maximize.

The paperclip machine doesn't 'want' to colonize the stars; it's just a system
that will do that if it can, because tautologically, it's a system that tries
to turn as much as it can into paperclips.

I don't really think there is a Fermi 'paradox'. We don't have solid priors on
how often agents arise in the universe. The fact there aren't any visible
aliens should either just lower our estimates of how likely life is, or maybe
there's some sort of anthropic principle argument to be made here where we
probably wouldn't observe a universe where aliens come to visit, because in
nearly all possible universes where intelligent life survives and goes from
star to star it just eats all the stars very quickly on astronomical
timescales or something, such that the chances of intelligent agents like us
arising while there's visible evidence of other agents is incredibly slim.

~~~
bena
Like I said, we don't even _know_ what consciousness _is_.

To say there is a platonic consciousness is kind of saying you know what that
looks like. And to say that you could grant something an intelligence capable
of solving the problem of colonizing the stars while also denying it the
ability to choose its own goals is an assumption I'm not willing to grant.

In other words, there _is_ "a reason to think this!" We are that reason. Other
life on this planet is reason to think this.

------
dade_
I find it strange that the author thinks that Dark Forest theory is
implausible. It strikes me as the simplest of explanations.

Granted Cixin Liu stretches physics into all sorts of implausible places, but
it does make a strong argument for the theory.

[https://www.goodreads.com/book/show/48838110-three-body-
prob...](https://www.goodreads.com/book/show/48838110-three-body-problem-
boxed-set?ac=1&from_search=true&qid=cqWNAtigNA&rank=1)

~~~
jmull
I loved those books, but the dark forest theory doesn’t make sense. Given a
dangerous universe it would make sense for a civilization to try to
communicate with other civilizations to create alliances for mutual safety.

The civilizations that are able to forge alliances will tend to out-compete
lone wolves.

Liu assumes that it is somehow a lot easier to wipe out a civilization than
communicate with it, and that for some reason your civilization has to decide
to wipe out another civilization without communicating with it.

~~~
ceejayoz
> Liu assumes that it is somehow a lot easier to wipe out a civilization than
> communicate with it...

This may be true, though. We struggle to effectively communicate with
creatures on our own planet available in real-time, like dolphins and
elephants, who appear to think and have language of sorts.

Launching some relativistic sand at another planet may well be a lot easier.

~~~
jmull
We seem to communicate pretty well with dolphins, elephants, and other
animals. Consider trainers who work with these animals on a daily basis and
have rich and productive relationships with them.

~~~
ceejayoz
We can explain "go press that button" or "lift your leg" fairly well. We
can't, as yet, put a dolphin through something like an elementary school level
education.

------
smallstepforman
Well, even if we're not alone, we must acknowledge that someone had to be
first to develop the ability to travel through the cosmos. It may actually be
us.

~~~
BerislavLopac
We already have that ability. It's just that this travel is insanely slow and
requires the energy levels that we can't easily produce in those timescales.
It is quite possible (I would even say likely) that any faster travel is not
very viable, and it might never be possible to make any kind of FTL engine.

~~~
alecco
We don’t have yet the communication technology for anything far from our
system.

------
radford-neal
The simulations in this article are compatible with the more abstract analysis
in my paper at
[http://www.cs.utoronto.ca/~radford/anth.abstract.html](http://www.cs.utoronto.ca/~radford/anth.abstract.html)
(see Section 7).

The brief summary is that we observe two things: (1) we exist, with the full
set of memories we have, (2) these memories don't include any evidence of
other intelligences (I'll assume - readers who think they've ridden on UFOs
can draw other conclusions).

The existence of our particular civilization (in all its detail) is more
probable if intelligent life is more probable in general (assuming one
dismisses arguments about infinite universes containing all possibilities, so
you can never conclude anything from anything).

But if intelligent life is generally more probable, it's more probable that we
have seen other intelligent life, contrary to observation.

So the most likely situation given what we observe is a compromise -
intelligent life is fairly likely (explaining our existence), but not really
likely, or at least not really likely to explore other stars (explaining why
we haven't seen any aliens).

One unfortunate possibility is that intelligent life reaching our
technological level is common, but getting to the level of colonizing the
galaxy is uncommon. But that needn't be highly likely. It's also possible that
there's other intelligent life out there not far away, in which case it may
well be within our ability to detect it with a bit more effort. That's what
one would conclude from this article as well.

------
zw123456
I have a somewhat nihilistic theory around the Fermi paradox. What if all
intelligent life annihilates itself before reaching high enough technical
proficiency to achieve widespread inter-planetary travel (or time travel). The
idea is that intelligent life emerges from the process of evolution (natural
selection) where the stronger survive. But that leaves you with people who
have the tendency to kill each other and themselves off. As the technological
ability to completely annihilate ourselves increases the probability that it
will eventually happen goes up over time. As technological prowess increases
and population increases, intelligent species eventually destroy themselves by
using up all their resources or ruin the planet with climate destruction
before achieving inter-planetary capability. Similar to how yeast will
reproduce until they all kill themselves off in their own waste product
(alcohol). It is possible that this is a universal axiom, hence intelligent
life does not spread across the galaxy. I know this is a depressing thought
but it's an idea that has haunted me once it occurred to me.

~~~
hesdeadjim
The models attempt to encapsulate this issue through the variable of how long
a civilization lasts. As easy as it is to imagine civilizations similar to us,
it’s equally easy to imagine others where other variables prevent the intense
egoism we evolved as a species. Or worlds where competition is less fierce
perhaps. Etc..

Either way I find it fascinating that we could be living in what is
essentially the rural area of the galaxy.

~~~
lonelappde
With a sample size of 1, there is no way to estimate the possibility of a
species fundamentally unlike us becoming spacefaring.

We can count stars pretty well, but we can only barely estimate the
probability of an earth-like planet existing around a star and forming
cellular life.

------
mnemonicsloth
It bothers me that the authors' assumptions are so controversial and that they
hide them in the middle of the article.

In the simulations the authors are using, civilizations have lifetimes,
meaning that all of them end after a while. And that simply isn't supported by
events. Technological civilization has never vanished even from our little
one-planet civilization. Polities do decline, but there is usually someone
there to pick up the pieces. In an interstellar civilization there would be
more recovery opportunities: interstellar visitors who arrive to see why a
collapsed planet went offline.

The authors of this piece are asking us not just to assume that simultaneous
disaster is possible on ten, a hundred, or a thousand planets. They are asking
us to assume that it happens to every single time a civilization has achieved
interstellar travel, and that it has been happening for the last ten billion
years.

Simultaneous catastrophes on thousands of worlds affecting millions of species
for billions of years? Life arising only once could easily be the more
plausible option.

~~~
adabsurdo
> Life arising only once could very well be the more plausible option

Indeed I feel like coming to this conclusion is something that the authors -
and most of us rationalist types - do not _want_ to come to.

Because if you accept that hypothesis, then it follows as a consequence that
an alternative view of the world makes a lot more sense: what if, rather than
living in an emergent, random universe where life sprouts up everywhere,
hundreds of billions of times, but somehow _always_ disappears before we can
ever observe it outside Earth, we are instead living at the center of a
universe where we are the sole intelligent species that ever existed? In that
system of the world, the universe is being directed by beings existing outside
its bounds - gods. A simulation created and managed by uncaring observers - as
hypothesized by the likes of Elon Musk? Or a benevolent God in the
Judeo/Christiano/Islamic tradition?

The truth is that this alternative is being rejected a priori, indeed not even
acknowledged, by the authors of the article or most people in this thread,
because it is an affront to their core beliefs, not through pure logical
reasoning.

~~~
danans
> The truth is that this alternative is being rejected a priori, indeed not
> even acknowledged, by the authors of the article or most people in this
> thread, because it is an affront to their core beliefs, not through pure
> logical reasoning.

I think it isn't acknowledged because it is inconsistent with literally
everything we have learned about physics and the universe, and even if it were
true, as you said, they are outside this reality and don't care. They set the
simulation parameters, and then walked away, so they are irrelevant.

If however, you point to something like miracles occuring in our reality to
back up the "gods" view, then you aren't really having the same discussion as
the authors.

------
chmike
I don't understand why ufological data is systematically ignored. This leads
to biased reasoning.

~~~
plutonorm
I agree. To talk about the possibility is to commit scientific suicide. Even
cautiously talking about the topic immediately outs you to others as a
crackpot. I think it's undeserved. Especially when we are now seeing just how
many habitable world's are out there. It seems plausible that we have been
visited by curious extra terrestrial civilisations. The bizare patents coming
out of the US navy suggest to me that no one knows where these things are
coming from, if they are real.

~~~
anthonypasq
> It seems plausible that we have been visited by curious extra terrestrial
> civilisations.

no it doesnt. It seems increasingly implausible

~~~
chmike
How do you justify this claim ?

------
ncmncm
I see two alternatives, each sufficient:

1\. Expansionist civilizations eventually encounter another one, and reliably
obliterate one another. (Note, this is not "Dark Forest": it requires no long-
lasting structure of any kind, just the occasional chance encounter that turns
out badly.)

2\. Expansionist civilizations find goldielocks planets both unnecessary and
limiting, and just leave them the hell alone. They probably mostly use
Neptune-like planets, when they have a use for a planet at all. Maybe they are
at "our" Neptune right now, and have not contacted us, because why bother?
We're "made out of meat".
<[https://www.mit.edu/people/dpolicar/writing/prose/text/think...](https://www.mit.edu/people/dpolicar/writing/prose/text/thinkingMeat.html>)

------
snake117
This brings to mind Dr. Greer and the Sirius Disclosure project [0]. The first
documentary, Sirius, is available on YouTube [1] and the second documentary,
Unacknowledged, can be viewed on Netflix.

To be clear, I'm not sure if I entirely believe in all of this myself.
However, I don't regret watching any of it. At the very least I got some
inspiration for short stories/screenplays.

[0] - [https://siriusdisclosure.com/](https://siriusdisclosure.com/) and
[https://www.youtube.com/channel/UCC6B4Y0oFACv9QBlf0ebBcg](https://www.youtube.com/channel/UCC6B4Y0oFACv9QBlf0ebBcg)

[1] - [https://www.youtube.com/watch?v=5C_-
HLD21hA](https://www.youtube.com/watch?v=5C_-HLD21hA)

------
ws66
One thing I fail to see mentioned here and in such articles is the complexity
of colonization. We are falling in the trap of "idea == profit". A lot needs
to be done, and can go wrong, between both.

Some examples I am thinking of, and I am certain people will have more... All
are compounded by the LY distances between colonies and whatever home is:

\- Terraforming - It would be the exception that new planets are 100%
hospitable to a specific species. How long to properly terraform, and then how
long before the can get to a point where they can launch a new sub-colony?
Need proper population, technology and resources.

\- Culture drift - how long can the colony and home share the same culture,
with same values and objectives?

\- Political drift - Imagine you are part of a colony, with "home" some 4 LY
away. How long before you will want to have full autonomy, specially given the
distance?

\- Cultural and political factions - Is it possible that individuals in the
colony have different objectives, resulting with political infighting or open
war? What would then be the impact on the colony?

\- Protection - Depending on technological advancement, how can a colony
protect itself from external rogue elements (big warship gone rogue, pirating
the colonies for resources?)

For sure, many of these things depend on the type of species colonizing its
region, how much sentience and free will they have. I also assume they haven't
solved FTL travel!

------
rosybox
This is article went off the rails when it talked about evidence for past
civilizations on Earth being undetectable:

> The only real evidence after a million or more years would boil down to
> isotopic or chemical stratigraphic anomalies—odd features such as synthetic
> molecules, plastics or radioactive fallout.

Civilization on the scale such as ours creates huge waves of extinctions in
the planet's species leaving lots of evidence easily available for us to see
that it happened.

In addition we've affected the Earth's atmosphere with our carbon emissions
and that's going to leave evidence behind as well that will last a very long
time.

Also, all that easily accessible oil that we've been using to power our
engines would not exist, because nobody is going to be leaving such an
abundant and easy to use source of fuel around. The oil and gas we use took
tens and hundreds of millions of years to form.

Finally, and not least of all, the quoted paragraph mentions radioactive fall
out, but any radioactivity would be blatantly obvious unless this civilization
used none of it. There would be a very clear indicator in our dating methods
of any radioactive activity in the past.

I think it's safe to presume that instead of some past civilization that
didn't use the most abundant natural source of energy around, didn't make use
of nuclear energy and somehow managed to leave the species record clean it
simply didn't exist. I don't feel like it takes more than a few moments to
just realize how unlikely that take is and shouldn't have been included in the
article.

~~~
s1artibartfast
You might find the the paper [1] and HN submission interesting. I believe it
addresses every concern you raised, and comes to the opposite conclusion.

[1] [https://fermatslibrary.com/s/the-silurian-hypothesis-
would-i...](https://fermatslibrary.com/s/the-silurian-hypothesis-would-it-be-
possible-to-detect-an-industrial-civilization-in-the-geological-record) [2]
[https://news.ycombinator.com/item?id=21840320](https://news.ycombinator.com/item?id=21840320)

------
CuriousReader13
What’s the point of settling on planets if you can sustainably develop
anywhere in space, which I think is within the reach of any typical space-
faring civilization?

~~~
m4rtink
I guess, you can do both. Well unless you want to use the mass of the planet
for a more efficint purpose, eq. habitat swarm.

------
jnurmine
On Earth, there have been previous life-forms which have died out, there have
been more or less intelligent life-forms which have died out (various
dinosaurs and exhausted branches of hominids etc.), there have been previous
civilizations with varying scientifical/technological achievements; but there
has never been a species on Earth which has created a civilization as advanced
as humans have.

So, we are the first ones to reach this point on the Earth. Not the first ones
ever, but first ones to get this far.

If we assume the patterns of evolution observed on the Earth are nothing
specific to Earth and they repeat throughout the Universe, there are/have most
likely been life-forms (simple and complex) of varying degrees of
intelligence, as well as civilizations of varying degrees of technological
advancement.

However, since we apparently see absolutely no trace of anyone else, either
they failed to successfully bootstrap their colonies outside of their home
planet/moon, or we got here first. It's unlikely, and absence of evidence is
not evidence of absence, but someone has to be the first. Maybe it's us, from
our little blue planet.

~~~
zizee
> but there has never been a species on Earth which has created a civilization
> as advanced as humans have.

It's an interesting to think about what traces an industrial civilization like
ours would leave behind if we were to be wiped out tomorrow. Most evidence
would be gone in a few thousand years. Wait a million and it would be almost
like we were never here.

[https://www.theatlantic.com/science/archive/2018/04/are-
we-e...](https://www.theatlantic.com/science/archive/2018/04/are-we-earths-
only-civilization/557180/)

[https://news.ycombinator.com/item?id=19707426](https://news.ycombinator.com/item?id=19707426)

Never say never :-)

------
stevev
I am intrigued by the simulation theory. That we as a species has reached a
certain level of advancement to simulate a reality and experience it; or we
may just be npcs or temporary programs for another intelligent race in this
simulation.

We could also be a zoo/prison planet far into enemy territory. Currently being
experimented and observed. Hybridization in order to infiltrate our actual
civilization that’s located elsewhere.

------
Magi604
Perhaps slightly off topic, but the title reminded me of this picture I took a
few years back.

[https://www.flickr.com/photos/earlvontapia/16211171391](https://www.flickr.com/photos/earlvontapia/16211171391)

I really wanted more of the Milky Way to pop out, but was hard given the
sensor and the lens I was using.

------
graycat
(1) Biological life colonizing other planets? The individual beings would not
live long enough to make the journey. So, would have to have reproduction of
generations during the trip, and that means one heck of a big spaceship. Then
for any of the motivations, I would be easier just to stay home.

(2) Sending self-reproducing robots? Why? What's the motivation? E.g., why
should I consent to spending big tax bucks to send robots out that would need
millions of years to have any effect back on earth? I won't.

Okay, there is the scenario that a planet is ready to die, and the beings want
to move to a new land. Again, for anyone alive, what is their motivation? That
is, either stay home and wait for, say, the star to nova or just die on a long
space trip? Just stay home; as bad as a star nova would be, just stay home.

One more scenario is that fast space travel is possible but uses physics we
don't understand and, thus, can't detect.

------
rubyn00bie
I guess the primary argument to this is the number of stars, and the amount of
time the universe has been around... but like the universe is _very young_.
Our universe currently has an expected lifespan of like a trillion years. That
is to say, if it's lifespan is 100 years, it's currently a ~13 month old
infant.

There is a supremely _good_ chance we, humans, are and will be the creepy ol'
species we write movies about that has colonized stars and existed "since the
beginning."

Should we ever successfully make it off this rock that and to another star
that is...

It's fun to think about too, how will our species handle billions of years of
separation at distant ends of the universe? Will we use gene therapy to ensure
our "look" and aesthetic, or will culture and evolution be unpreventable
yielding humanoids nearly unrecognizable to our current form?

------
lifeisstillgood
I would be especially careful of arguments that end up like "it's a great
opportunity for humankind as no-one else is there to compete for the next
million years"

It might be true. But the most likely thing we will find on the nearest
habitable planet is a legal writ and summons.

------
pjdorrell
The boring answer is that the initial origin of life depends on a sequence of
extremely improbable chemical reactions (even given the prior existence of the
most favourable possible “organic soup”), and there is no other life of any
kind in the observable universe.

~~~
baja_blast
life arose on Earth immediately after it cooled down and Earth then was
nothing like what it is today. The organic chemical reactions are extremely
probable not improbable.

------
archeantus
It seems to me that the millions of events that happened in order to get to
where we are now (alive on a rocky, water and oxygen-filled planet, in the
Goldilocks zone of a healthy star) were sequential in nature and they took a
finite amount of time to occur.

Assuming that there was A Beginning, where everything started at the same
time, wouldn’t the steps to get to where we are in this process take about the
same time for everyone else? Meaning that if there are other civilizations out
there, that they’d more or less be as advanced as we are? Which is pretty
sophisticated in certain areas at home, but not yet super capable in the long-
distance human space travel department.

Not a scientist, just thinking out loud the thought I had reading the article.

~~~
IAmGraydon
Perhaps, but even tiny variances could cause shifts in the timeline of
thousands or millions of years, which would be a blink compared to the age of
the universe. Look how far we’ve come in the last 200 years. Imagine a
civilization that is only 10,000 years ahead of us.

~~~
archeantus
I’d love to see what the iPhone 10,000 ends up looking like

------
m3kw9
I think big filter is plausible where as we advance in tech, the probability
of us accident using to kill off everything increases. It starts with nuclear
weapons and then maybe later mini black holes, etc.

------
lenkite
_(First wears tin-foil hat)_. It may be more likely that we are under
_observation_ and a mature inter-stellar space faring alien civilisation has
_commandments_ not to interact or interfere with the _primitive natives_. They
occasionally mess up and then the _UFO 's_ are seen. But their propaganda
department clears the mess up.

------
nkrisc
From our perspective, even if another species had colonized millions of stars,
it would still be like looking for dust on a mountain.

------
j_m_b
The theory of this article is that we are not just in a gulf of space but also
a gulf of time. We are after all on the relative outskirts of our galaxy,
vastly isolated from other civilizations. Perhaps one day we'll be the ones
knocking on our neighbor's door to say hello!

------
jajag
Previous discussion on the possibility (mentioned in the article) that an
advanced industrial civilization existed on Earth:
[https://news.ycombinator.com/item?id=21840320](https://news.ycombinator.com/item?id=21840320)

------
hindsightbias
Afaik, nobody has debunked the Borra paper, so we already found them.

Discovery of peculiar periodic spectral modulations in a small fraction of
solar type stars

[https://arxiv.org/abs/1610.03031](https://arxiv.org/abs/1610.03031)

~~~
tokai
This study fails to replicate Borra's results.

[https://iopscience.iop.org/article/10.1088/1538-3873/aaeae0/...](https://iopscience.iop.org/article/10.1088/1538-3873/aaeae0/meta)

~~~
hindsightbias
Drat! Thanks

------
johnwheeler
I think if you look at patterns in nature this has to be possible. Surely
there are some remote ant colonies that don’t have interaction with anything
outside the natural resources that sustain them.

------
mirimir
There are arguably too many unknowns to do much more than speculate.

But let's say there's some other planet with comparable technology. At what
distance could we detect its routine radio emissions?

~~~
fernly
No more than 1000LY, per this article:

[http://www.setileague.org/askdr/howfar.htm](http://www.setileague.org/askdr/howfar.htm)

i.e. 1% the diameter of the Milky Way:

[https://www.universetoday.com/21998/the-diameter-of-the-
milk...](https://www.universetoday.com/21998/the-diameter-of-the-milky-way/)

~~~
mirimir
Thanks.

I wonder what percentage of the sky those larger SETI telescopes have looked
at so far. I tried searching the SETI site, but had no luck.

But anyway, that's a small enough volume that it could plausibly be
temporarily dead or quiet, as TFA argues.

------
carapace
Fascinating theory, but we aren't Pitcairn Island.

> Why, then, have we found no irrefutable evidence of aliens visiting Earth?

We have evidence, it just gets "refuted" for psychological reasons. The Fermi
Paradox is a Rorschach test, and has nothing to do with reality.

In reality, humans in every culture have recorded incidents of communications
with non-human intelligences.[0]

In reality, the Brazilian Military has gotten much less coy about UFO
phenomenon in recent years and has started declassifying documents. Their
overall conclusion is that, whatever they are, UFOs are real, pose no national
security threat, and should be researched and discussed by society at large,
with some urgency.

Here's a fascinating lecture by a Brazilian UFO researcher about the overall
situation in Brazil and he describes three encounters that are known to have
government involvement (so the researchers know what to ask about, in these
cases.)

"Operation Saucer - UFO military encounters in the Brazilian jungle"
[https://www.youtube.com/watch?v=ThkmRsEBOY0](https://www.youtube.com/watch?v=ThkmRsEBOY0)

> In 1977, numerous UFOs were seen in the Brazilian city of Colares, Pará. The
> UFOs fired light beams at people, causing injuries and sucking blood from
> 400 witnesses. After a rise in local concern, the mayor of the city
> requested help from the Air Force. Operation Saucer started, during which
> numerous photos were taken and testimonies collected. Operation Saucer is
> just one of the compelling cases which A. J. Gevaerd, editor of Brazilian
> UFO magazine, talked about in his latest lecture in Copenhagen, paving the
> way for complete Disclosure in his country. Kudos to Exopolitics Denmark for
> setting up their excellent annual conference at the Danish National Museum
> on September 26 in Copenhagen!

The first case involves thousands of people, living on an island in the
Amazon, who were attacked by UFOs over a period of several years (1975-1977
IIRC). Flying cans with visible pilots were shooting people with bending
"light" beams and sucking up their blood. It got so bad that thousands of
people evacuated and the Brazilian Army sent in a unit to find out what was
going on and try to make contact. I won't spoil the rest of the story here.

To me, the strangest thing I can see is the question: Why would people (aliens
or humans) who have evidently advanced technology go around attacking poor
villagers to _suck their blood_!? WTF?

[0] (I myself once attended a event at an airport hotel at which some purple
telepathic space dolphins were guest lecturers. FWIW, their basic TL;DR: was
"Be nice to each other." Aliens were attending underground raves in Seattle in
the 90's.)

~~~
ceejayoz
> pose no national security threat

> sucking blood from 400 witnesses

Pick one.

~~~
carapace
Sucking blood from 400 people posed no _national_ security threat.

Don't get me wrong, I'm not trying to trivialize what these folks went
through. I'm pointing out that the threat was in a small, localized area.

