
Dissolving the Fermi Paradox - monort
https://arxiv.org/abs/1806.02404
======
poppingtonic
The conclusion of this paper is, paraphrasing, "We should stop using point
estimates for what should be distributions. When we do that, we get much lower
bounds and have a better chance at being more precise, whether or not we are
alone." It opens up avenues for more questions, which is the correct stance
given how little we know.

------
PaulHoule
Ecosystems are limited by the availability of water, not sunlight. Also there
are more "habitable" places in the universe which are underground oceans (the
default condition outside the frost line) as opposed to a tiny fraction of
rock worlds which have to parametrically fine tuned to have water -- ex. there
are 10-20 worlds that have underground oceans in our own solar system.

Why would a spacefaring civilization care about dry worlds inside the frost
line? The most absurd thing about "Battle: Los Angeles" is not that aliens
would come to Los Angeles (as opposed to Detroit) to steal water, but that
they would come to a planet which has a thin layer on the surface as opposed
to being just a run-of-the-mill dwarf planet or asteroid or comet or whatever
you call it that is closer to 50% water.

If civilizations of the dark had deuterium fusion they might see very little
reason to mess around with the puny resources to be found close to a star.
It's entirely plausible that a generation "starship" could live off the land
and hop from comet to comet to the next star in 10,000 years but probably the
crew would lose interest long before the first millenium.

~~~
TeMPOraL
> _The most absurd thing about "Battle: Los Angeles" is not that aliens would
> come to Los Angeles (as opposed to Detroit) to steal water,_

Hey, they landed near all major coastal cities; the movie was just following
one group of soldiers fighting off one part of the invasion force.

> _but that they would come to a planet which has a thin layer on the surface
> as opposed to being just a run-of-the-mill dwarf planet or asteroid or comet
> or whatever you call it that is closer to 50% water._

Fair enough.

Disclaimer: I really liked the movie and wish there was a sequel made.

EDIT: My guess would be that the alien military tech was running off water
(probably hydrogen/oxygen), so they started the invasion on the coasts to have
essentially unlimited supply of water, but the actual purpose for the invasion
was something else entirely. The "aliens need our water" hypothesis was AFAIR
proposed by some talking head in the movie, not stated as in-universe fact.

~~~
squirrelicus
H2O isn't exactly rare in the universe, it's the third most common molecule
after H2 and CO. Getting water into orbit is absurdly expensive compared to
getting it from the other rocks with lower gravity and atmo, like Ceres.

Weird premise for a movie

~~~
PaulHoule
Exactly, H2O is rare on rocky planets. It makes more sense to mine it from
Pluto.

~~~
onychomys
Or to just go to the rings of Saturn, which are mostly water ice, and which
give you the added advantage of having something pretty to look at while you
refuel.

~~~
PaulHoule
Exactly, go outside the frostline and you are swimming in it. If you want to
get away from it (or move it around) you can use some of it to make fuel or
use it directly as reaction mass.

Beyond the frost line the scale is so much bigger. A population of 1 trillion
beings in the Oort cloud is not going to be in a position of taking over the
Earth and moving population there because it doesn't move the needle. They
could create more "living space" by cutting up a Kuiper Belt Object and
turning it into small ringworlds. I am not joking when I talk about Pluto as a
better space colonization target than dry Mars.

Space technology from outside the frost line would have to be reconfigured to
work inside the front line, why bother?

------
Sniffnoy
I'm going to repost the same comment I made on Reddit:

This is quite interesting. It certainly sounds like this does dissolve the
Fermi paradox, as they say. However, I think the key idea in this paper is
actually not what the authors say it is. They say the key idea is taking
account of all our uncertainty rather than using point estimates. I think the
key idea is actually realizing that the Drake equation and the Fermi
observation don't conflict because they're answering different questions.

That is to say: Where does this use of point estimates come from? Well, the
Drake equation gives (under the assumption that certain things are
uncorrelated) the expected number of civilizations we should expect to detect.
Here's the thing -- if we grant the uncorrelatedness assumption (as the
authors do), the use of point estimates is entirely valid for that purpose;
summarizing one's uncertainty into point estimates will not alter the result.

The thing is that the authors here have realized, it seems to me, that the
expected value is fundamentally the wrong calculation for purposes of
considering the Fermi observation. Sure, maybe the expected value is high --
but why would that conflict with our seeing nothing? The right question to
ask, in terms of the Fermi observation, is not, what is the expected number of
civilizations we would see, but rather, what is the probability we would see
any number more than zero?

They then note that -- taking into account all our uncertainty, as they say --
while the expected number may be high, this probability is actually quite low,
and therefore does not conflict with the Fermi observation. But to my mind the
key idea here isn't taking into account all our uncertainty, but asking about
P(N>0) rather than E(N) in the first place, realizing that it's really P(N>0)
and not E(N) that's the relevant question. It's only that switch from E(N) to
P(N>0) that necessitates the taking into account of all our uncertainty, after
all!

[Note afterward: Over on Reddit, hxka points out that that should be P(N>1),
not P(N>0). Or really it should be P(N>1|N>0)...]

------
btilly
I have trouble calling it a paradox, because there is nothing that needs
explaining in my view. Just throw in the fact that known fudge factors are
important, and throw in the fact that there are more fudge factors that we
don't know.

For example the traditional Drake equation doesn't include as a major factor
"large moon that stabilizes the axial tilt over evolutionary time". And yet
that seems to be needed and at least somewhat rare.

The traditional Drake equation doesn't include as a major factor "life not
wiped out by a supernova over evolutionary time". And yet per
[http://earthsky.org/astronomy-essentials/supernove-
distance](http://earthsky.org/astronomy-essentials/supernove-distance) there
are estimates that this might happen on average once per 15 million years.
From the Cambrian explosion to the present is around 540 million years. The
odds of that forbearance is on the order of 7 billion to 1 against. How much
does THAT change the Drake equation?

~~~
jobigoud
It doesn't have to include these specifics. They are just sub-factors
contributing to higher level factors.

Your first is covered by "fl, the fraction of those planets that actually
develop life", and your second is covered by "fi, the fraction of planets
bearing life on which intelligent, civilized life, has developed".

What you are saying seems to be the same as OP. It's not a paradox because the
chances are insignificant, so we are indeed alone.

------
light_hue_1
It's "papers" like this by people that are either clueless or malicious that
make everyone pine for the pre-arxiv days.

Everyone considered this option. From the very first day the paradox was
posed. We don't know the parameters well, it's within our margin of error that
no one else is out there, so it's an option. This is such an absurd claim to
take as your own that it's literally on the wikipedia page!

It's also extremely shortsighted in order to get media attention. This
resolves nothing about the paradox. What about the universe prevents other
intelligent species from existing nearby? Sure, it's within our margin of
error, but where is this coming from? Too few planets, too little abiogenesis,
etc? Many factors or a single one? Is our existence simply a consequence of
the fact that we're here therefore the dice must have landed well for us? Or
is there something fairly unique about our solar system / planet / species /
etc.

That's the real scientific question that keeps people up at night.

~~~
titzer
I dunno, I kind of doubt that Eric Drexler is clueless or malicious. Maybe if
you read the paper and understood their approach you'd have less of a knee-
jerk reaction. They are arguing (as pointed out in comments elsewhere) that
the math on probabilities should be using distributions, and this is what they
do, and they go on to show that the resulting probabilities are far, far lower
than the simplistic Drake equation would suggest.

~~~
jessriedel
> the math on probabilities should be using distributions

Do you really think that this is novel in any way whatsoever? There is some
yearly chance of nuclear war, and I don't know about geopolitics so I have a
prior distribution over that yearly chance. Should I cite this paper?

I actually really like the authors, and for all I know the paper may have some
new insights or perform a calculation that hasn't been done before, but let's
not pretend that prior distributions over probabilities is a new idea.

~~~
true_religion
What does novelty have to do with dissolving the Fermi Paradox?

Is Fermi is some well established science, with repeated experimental proof,
upon which numerous other conjectures have been built on?

Does it really require a _novel_ approach to attack its basis?

~~~
jessriedel
The top-level commenter wrote

> Everyone considered this option. From the very first day the paradox was
> posed. We don't know the parameters well, it's within our margin of error
> that no one else is out there, so it's an option.

And the person I replied to was rebutting this point (that the approach is
obvious and considered long ago).

It's fine to write review articles, or clean up old arguments and repackage
them, but it shouldn't be presented as a new idea, and in particular it should
point to the prior work.

~~~
titzer
I don't think they are claiming to have invented math on probability
distributions and I didn't mean to suggest that that is what is novel about
this paper. They used a different, more powerful technique to look at the math
of the Fermi Paradox and came to a conclusion different than that following
from the normal treatment of the Drake equation. That's a reasonable
contribution, IMO.

~~~
jessriedel
But if you just _formalize_ an approach that was considered by everyone right
from the start, this isn't coming to a different conclusion.
([https://news.ycombinator.com/item?id=17304389](https://news.ycombinator.com/item?id=17304389))

------
not_a_moth
How can we be expected to take seriously a probability estimate of life being
"out there"? Only 10 years ago we discovered how many Earth-like planets are
likely in our galaxy (I didn't see this aspect mentioned in the paper...), and
they are also calculating a probability of abiogenesis (emergence of life),
which, while I'm not an expert, seems highly speculative.

~~~
Anderkent
Why can't you estimate probability of something speculative? Of course it must
be speculative if you're talking probabilities; otherwise you'd just know if
the life is out there or not.

If the assumptions are very speculative, you just end up with very wide
probability distributions, which is exactly what the paper argues for.

------
gmuslera
The reasoning seem to be "as we don't have enough data, lets conclude whatever
I want".

The Fermi paradox assumes that if there are aliens more advanced than us
somewhere for a long time, they should be here by now. Maybe more advanced
technology enables interstellar travel (maybe not, maybe is not practical at
all), maybe they may not have all our motivations (expansion, technological
advancement in our own focus, exponential growth, etc), maybe they don't want
to expand or announce themselves because they went cyber or try to pass
unnoticed in the dark forest, or things that we can't even imagine yet, as we
are not advanced enough.

We just don't have enough data to give a meaningful answer. And maybe never
will. The only way to decide if we are alone in the universe or not is
actually finding someone else. But with so much outside our physical or
practical line of sight we can't just say that there is no one else because we
didn't see anything.

~~~
jobigoud
When talking about the Fermi Paradox it's not about what this or that extra-
terrestrial civilization might do. It's about what _none of them_ is doing.

When you say "maybe they don't want to expand", if you want this to explain
the paradox, you actually mean "none of them want to expand". Because if just
one did, we would see it.

~~~
gmuslera
Is not "none of them" but "all the ones that reached certain knowledge level",
after you know something, you avoid expanding or showing yourself.

The dark forest idea comes from Liu Cixin Three Body Problem trilogy, if you
show yourself you risk being destroyed by even more powerful civilizations
that are hidden in the dark. And they are hidden because are afraid that the
same happens to them, with a third one or with the one they destroyed after
they advanced enough.

It is not the only possible reason, just one of the possible things that we
don't know (or even don't know that we don't know) that can disprove or at
least atenuate enough the paradox hypothesis.

Can be like explaining a caveman why you can't make a building high enough to
reach the moon, so far he knows would be doable and even desirable for us, so
why we didn't built one yet?

------
carry_bit
Related slides: [http://www.jodrellbank.manchester.ac.uk/media/eps/jodrell-
ba...](http://www.jodrellbank.manchester.ac.uk/media/eps/jodrell-bank-centre-
for-astrophysics/news-and-events/2017/uksrn-slides/Anders-Sandberg---
Dissolving-Fermi-Paradox-UKSRN.pdf)

------
jl2718
I would rephrase the question as: What are reasonable bounds on the number of
intelligent civilizations, given that we have observed exactly one in the
archeological record of our own planet, and no others elsewhere with current
technology?

So, tiny sliver of time over billions of years, and communications technology
that only reaches to a few nearby stars.

Trying to use probability of certain chemistry is, I think, highly subject to
errors and failure to consider some alternative possibilities.

Life itself, however, is a totally different equation because it’s nearly as
old as the earth. This might suggest that there is a lot of it out there.

------
sbensu
Related recommendation: this podcast episode[1] was very good, covered many
solutions to the Fermi Paradox, and discussed the OP's article.

[1] [http://rationallyspeakingpodcast.org/show/rs-203-stephen-
web...](http://rationallyspeakingpodcast.org/show/rs-203-stephen-webb-on-
where-is-everybody-solutions-to-the-f.html)

------
chmike
In my opinion, takling the ET existence using the drake equation is not
efficient because it boils down to estimate or guessing values.

I favor the following reasonning. For simplification, let consider the
universe as homogene. Now, let _p_ be the probability that life emerges in one
unit of time and space. (1- _p_ ) is the probability that life does not emerge
in the unit of volume and space.

If _v_ is the number of volume units in the universe and _t_ the age of the
universe in unit of time, then the probability that life never emerges in the
universe is (1- _p_ )^( _v_ * _t_ ). If _p_ is bigger than zero, this
probability will tend to 0 with a growing _v_ and _t_ , regardless of the
magnitude of _p_. This always converges to 0. Soon or later, life will emerge
in the universe as long as it can emerge spontaneously.

What is the probaility that our solar system is the only place in the universe
where life emerged. Let _s_ be the volume of our solar system. That
probability is (1- _p_ )^(( _v_ - _s_ ) * _t_ ). Since _s_ is very small
relative to _v_ , that probability is very close to the above probability. And
with growing _v_ and _t_ this probability tend to zero. In other words the
probability that life emerges elsewere in the universe after removing the
volume of our solar system is not much affected. It still tends toward 1.

This should give you the idea. The only unknown variable is _p_. But even if
we don't know it's value, we can draw two important conclusions from this. 1)
it doesn't matter how small _p_ is, soon or later life will emerge. 2) the
probability that we are alone in the universe is tending toward 0 with
increasing _t_ and _v_.

Could we be the most advanced ? Why discarding the ufological data ? It's time
this non-sense and ostrich attitude stops.

------
ISL
If the argument stated above is correct, there is an awful waste of space.
(Thanks, Carl!)

There is nothing in physical law to suggest that here is substantially
different from anywhere else in the universe. To believe that here is
manifestly different from _every other place_ in the universe is a really
surprising claim.

~~~
mdpopescu
First, we know with absolute certainty that here is substantially different
from anywhere else: we know there's life here, we haven't found life anywhere
else. (And the null hypothesis is that we haven't found it because it doesn't
exist.)

Second, it's a waste of space only if 1) it was created on purpose and 2) the
purpose wasn't "to allow us space to expand". If either of those is false, I
don't see how it can be called "a waste of space".

~~~
ISL
_First, we know with absolute certainty that here is substantially different
from anywhere else: we know there 's life here, we haven't found life anywhere
else._

I'll take the other side of that bet. What odds are on offer (10^15:1?
10^80:1?)?

~~~
Anderkent
Wait, are you saying you'll take a bet where you pay 10^15 to 1 if we do not
find life out there? I'll take you up on that for $0.01 on my side.

------
8bitsrule
_expectation that the universe should be teeming with >intelligent life<._

It's only a paradox if you're capable of entertaining such an expectation.
Based on my life experience, I'd estimate the probability is about the same as
finding a bottle of my favorite drink sitting on the doorstep.

------
jackconnor
I feel like if aliens come they might keep themselves hidden, rather than
announce their presence. If so, it could be Fermi was right, we just haven't
seen the evidence of it yet, since the Fermi Paradox presupposes that their
should be intelligent life and the we actually can point to evidence of it.

------
carapace
We're in quarantine.

To other life forms humans look like H.R. Giger's xenomorph aliens from the
movies.

We're obviously intelligent, yet we absolutely refuse to communicate with
other life forms. we're not even interested in the possibility.

We consume other organisms with rapacious abandon, converting them into more
of ourselves as fast as we can. We are strip-mining the oceans of protein, our
chattel livestock out-mass all other land animals by several times, and still
we consume. We clearcut forests leaving patterns visible from space.

We cover everything with asphalt and concrete to create huge sprawling nests
that are inimical to life other than our own (and a few species that can live
with us.) Again, this is clearly visible from space.

From orbit we look just like a disease.

There's a place in Washington (state), a lake, where the UFOs take off and
land (underwater) and the cheeky fuckers will _wave back_ at you from windows
in the ships.

We're not alone. We just suck.

~~~
taylorswift_
where is this lake in WA state? have you been there? are you reptilian?

~~~
carapace
> where is this lake in WA state?

I' don't know. Even if I knew I wouldn't say in a public forum like this, it
would be irresponsible.

> have you been there?

No. If I wanted to talk to aliens I wouldn't go rubbernecking at them like a
yokel.

> are you reptilian?

We're all reptilian. ;-)
[https://en.wikipedia.org/wiki/Triune_brain](https://en.wikipedia.org/wiki/Triune_brain)
[https://en.wikipedia.org/wiki/Recapitulation_theory](https://en.wikipedia.org/wiki/Recapitulation_theory)

The "reptilian" thing is a human psychological issue, there are no reptile
aliens secretly ruling Earth.

~~~
taylorswift_
but how do you know it exists if you've never been there? who told you?

> there are no reptile aliens secretly ruling Earth.

perhaps not ruling it...

~~~
carapace
Look, my basic point is that we're not alone, rather nobody wants to talk to
us because we're terrifying ravenous monsters.

> but how do you know it exists if you've never been there? who told you?

I can't tell you that in a public forum. And again, even if I could I
wouldn't. Either you don't believe me in which case what's the point? Or,
worse, you _do_ believe me and want to go there.

I'm not interested in helping anyone talk to aliens, it's just frustrating to
me personally whenever the subject of the Fermi Paradox comes up because it's
such a foolish question.

The critical issue people are dealing with whether it's UFOs, reptilians, crop
circles, bigfoot, pyramid power, crystals, etc... it's all one thing: where is
the edge of consensus reality?

To me, the important thing is this: if we don't learn to live in harmony with
Nature, and damn quickly, we're going to crash our world civilization.

We don't need aliens to fix our shit. We have the technology and the
understanding, it's really down to our fundamental nature: do we wake up and
course-correct fast enough or will the oceans rise and wipe us out, leaving a
world-wide desert and tropical regions at the poles?

~~~
taylorswift_
Oh I'd love to go to that lake...

I agree it's foolish conjecture and I believe we are certainly not "alone". I
had an experience when I was 10 that infused fear and curiosity in me.

I'd like to say I am hopeful about our future but we are just evolved
organisms from a long chain of creatures designed to compete for survival...
it's in our own nature to self-destruct.

~~~
carapace
Ah well, time will tell, I imagine. :-)

If you want weird, edge-of-reality stuff that's fun and mostly safe I
recommend the book "The Secret Life of Plants" ("Life" not "Lives", that's a
different book):
[https://en.wikipedia.org/wiki/The_Secret_Life_of_Plants](https://en.wikipedia.org/wiki/The_Secret_Life_of_Plants)

------
mchahn
Can some tell me what the "{\em ex ante}" I see in several places means?

------
tachkotic
The time span of human civilization is too small to witness the emergence and
extinction of intelligent civilization elsewhere. Universe is really very vast
in terms of distance and time.

------
jpm_sd
TL;DR - It's not a paradox, because we're probably alone. Kind of a letdown!

~~~
jandrese
The Drake equation is the epitome of garbage in garbage out. Trying to draw a
line using a single data point.

There was recent news from NASA about the discovery of organic molecules on
Mars and the possibility of life there at some point in the past. Discovery
that life once existed on Mars would blow up the assumptions in the Drake
equation.

As for the Fermi paradox I'm still of the opinion that its solution is simple
but depressing: Interstellar travel is so difficult that by the time you're
capable of it you don't need it anymore, and even when you're capable of it
you still don't get very far outside of your stellar neighborhood. Unlimited
power systems, reactionless drives, and FTL travel (or even high-c travel) are
depressingly impossible. And then the cold hand of entropy and the aggregate
chance of disaster make it extremely dangerous to even attempt. Basically
without Sci-Fi propulsion/power you end up traveling at an interstellar
snail's pace, and the longer the trip the more likely it is that a random
meteorite smashes through your vessel, or you simply run out of spare parts
and materials to make them, and the amount of fuel you need to just keep the
lights on becomes enormous.

If you can build a starship that can travel between solar systems with our
current understanding of physics, then you can build orbital colonies for
basically unlimited living space much much easier. For one, they can be
powered by solar cells instead of needing to carry fuel. It's not like we are
going to run out of raw materials either. Even restricting yourself to the
belt the amount of material available would last basically indefinitely. Worst
case you can start breaking up moons.

So even in a universe full of life everybody is alone. Especially if you think
about how genetic algorithms tend to get hung up on local maxima, so lots of
planets waste millions of years with dumb dinosaurs with no space program or
radio telescopes.

~~~
TeMPOraL
Also, VR. I already fear the future of humanity is not exploring strange new
worlds, but creating virtual ones, and converting the solar system into more
computronium.

(And the weird thing about that is that I feel it's a _bad thing_ for some
reason, but I can't articulate a coherent argument against it.)

~~~
greglindahl
There are a bunch of scifi novels that explore the issue, and most of them
feature bad things that result.

~~~
jandrese
To be fair, if it turned out all hunky dory then the novel wouldn't be very
exciting. Sometimes the downsides are rather contrived.

------
psychometry
Does anyone else find this question totally uninteresting? There's no
discussion to be had about this paradox that doesn't devolve into an N=1
predictive model.

~~~
goatlover
I find it interesting because if N=1, then we're an incredibly statistical
fluke, and yet there's no reason to suppose that our solar system or planet is
that much of an anomaly.

~~~
vertexFarm
I feel like this is about the same as wandering out into the antarctic pole of
inaccessibility, whispering "is anyone out there" one time in 1974, waiting a
couple minutes, and then pondering on how it's such an incredible statistical
fluke that nobody has responded.

------
FreekNortier
They are here just not in a way most people would think. When you are ready to
know you will know.

------
shawn
It has always seemed arrogant to think that aliens exist anywhere within our
galaxy. Look at how many galaxies are out there. Now realize that the universe
extends far beyond our Hubble sphere.

We can’t hope to colonize even a fraction of 1% of our galaxy, even with
wildly futuristic technology.

There is one option, though: Become our own aliens. If we set up colonies
separated by time and distance, we will culturally diverge within a century,
and genetically within a few millennia-ish.

~~~
adrianN
Von Neumann probes could probably colonize a good chunk of the Milky Way given
a few hundred thousand years.

~~~
ghaff
That in turn makes assumptions about the practicality of interstellar travel
etc. But, yes. The counterpoint to space is big is that so are timescales.

~~~
adrianN
Interstellar travel is definitely possible. The only question is how long the
trips take. You can build nuclear pulse propulsion vessels fairly easily that
can reach a few percent of the speed of light. Those things can cross the
Milky Way in less than ten million years.

~~~
ghaff
I wouldn't use the term "definitely." But it looks like "just" a (very hard)
engineering problem [i.e. no known fundamental reasons why it's impossible].
And humans are pretty good at solving engineering problems over relatively
short periods of time.

ADDED: There are also questions of resources, motivations, and e.g. whether
we'd even want to build self-replicating probes.

~~~
adrianN
No, speed is the hard engineering problem. The Voyager probes for example have
reached escape velocity from our solar system. That's fairly primitive rocket
technology.

------
transfire
"Space is big. Really big. You just won't believe how vastly, hugely, mind-
bogglingly big it is. I mean, you may think it's a long way down the road to
the chemist, but that's just peanuts to space."

There is no way we are alone.

~~~
Buttons840
Every once in a while we see a headline that says something like "There are
more planets than we previously thought", or "There are more galaxies than we
previously thought". When people see these they often conclude that the odds
that life exists elsewhere are greater than previously thought, but it's also
perfectly logical to see those headlines and concludes that the odds of life
forming are lower than previously thought, because (per Fermi) "Well then
where is everyone?"

Look at the math:

odds of life existing elsewhere = (10^n planets) / (10^(-m) odds of life
forming on a planet)

We don't know what `n` and `m` are. It may be that `m` is much larger than
than `n`. Yes, the number of planets is very large, but the odds of life
forming is apparently very small. It may be that there is a very large number
of planets, but a very very very very small chance that life would form on a
planet.

~~~
bena
We're still working out how to get to Mars. Currently it will take close to a
year. The longest time someone has spent in space has been just over a year.

It is not easy. It is not quick.

Even if we travel at the fastest possible speed, it takes 4 years to get to
the next star. So, where are they? Too far away to reach.

The assumption that these problems are possible to overcome is a big one.

