
Fermi Paradox: If the Universe Is Teeming with Aliens, Where Is Everybody? - obblekk
http://books.google.com/books?hl=en&lr=&id=-vZ0BVSHix4C&oi=fnd&pg=PR9&dq=fermi+paradox&ots=s4bVK3fA4E&sig=iimM4koFjlfKUQMgbmNbPjtiVd8#v=onepage&q&f=false
======
exratione
To preempt some of the usual thought on this topic: no solution to the Fermi
Paradox can rely on every civilization taking a certain direction. It doesn't
matter how strong the incentives are for any particular course of action, the
numbers (of stars, planets, etc) even in just our galaxy are so very large
that even under rare life assumptions there are still going to be an enormous
number of civilizations at any given time, never mind over all history.

Some of those will have (or will have had) subcultures that generate self-
replicating colonies, probes, or whatever. Those visit every stellar system in
the galaxy in a very short time frame.

Possibly viable solutions include:

\- We are simulated.

\- Stochastic colonization leaves long-lasting uncolonized voids at all
scales.

\- Wolves. (Ecological wolves intent on making everything look natural, but
since they get to be unitary, they can be as odd as they want to be).

But non-wolf Great Filter arguments have the same issues as arguing that all
civilizations sublime, or leave, or whatever. There is always going to be
someone who doesn't.

~~~
MrScruff
_the numbers (of stars, planets, etc) even in just our galaxy are so very
large that even under rare life assumptions there are still going to be an
enormous number of civilizations at any given time, never mind over all
history._

The problem is we have no way of estimating the probability of life emerging
given favourable conditions. It could be 1x10^-100 for all we know.

~~~
jjoonathan
Life emerged very early in the geological history of Earth. The probability of
this happening is greater under the "P(life|conditions)≈1" model than under
the "P(life|conditions)≈0" model. Our historical observations give the
"P(life|conditions)≈1" model greater likelihood. It's not exactly proof, but
it's enough to convince me.

~~~
derekp7
So that brings up the question, if life happens so readily given the right
conditions, how come it only happened once on earth? And I don't buy the
explanation that one form out-competed all other forms -- given the diversity
that we have now, there can be millions of forms of life all existing at the
same place/time. But all instances we have now originated from one single
biogenesis event.

So, how do we know that there was only one biogenesis, and not multiple ones
that happen to resemble each other (i.e., that DNA-based life is the only
thing that ends up working, and it occurred multiple times)? From what I
gather, there are many markers in biological molecules, such as the direction
certain molecules form (left vs. right, etc), and that multiple biogenesis
events would have gotten these in random positions (i.e., your heart on the
right side instead of the left side of the body).

~~~
jjoonathan
> given the diversity that we have now, there can be millions of forms of life
> all existing at the same place/time.

Sure, each niche favors a different specialist, but why do you think that
whichever process led to the emergence of life will be any good at producing
competing specialists? I'd think that evolution of existing organisms would be
infinitely better at this task, as existing organisms have both a numerical
advantage and the strategic advantage of DNA (a "playbook" of previous
successful strategies to draw inspiration from).

Very few niches are available for the _emergence_ of life, even though there
are clearly many available for the _evolution_ of existing life. The available
niches require a level of sophistication that spontaneous process cannot
achieve but that evolution can achieve (e.g. photosynthesis).

~~~
waps
Actually, given that our star is a third-generation star, you could even ask
the question : why wasn't there life in our very own solar system before earth
even existed ? Before sol started burning or even coalesce ?

The first generation stars wouldn't have had anything but hydrogen clouds
surrounding them, but second generation stars would have had similar amounts
of other elements to what we have today floating around them.

Given that "our" biogenesis event happened only the second time it could
happen (here and in billions of other solar systems in our galaxy), where the
hell are the second generation societies ? Didn't they survive the supernovas
? (possible, I suppose, but not exactly hopeful for our own chances of
spreading across the stars). Was there some kind of large scale disaster ? But
the question is worse than that, because they should have been spacefaring ...
if they had anything like our numbers of satellites, we should have been able
to find something, somewhere, right ?

------
memracom
Why does everyone assume that if life has existed on another planet for a
billion or two years, it must necessarily be similar to life on our planet and
be intelligent with some sort of civilization? Why could it not be a planet
filled with brainless jellyfish and green algae?

People forget that our planet has been through several catastrophic events
that happened at certain times in our planetary evolution, and on other
planets those events did not happen, or happened at different points in their
evolution, or those events had a more severe impact. Things like the snowball
earth phase, and the comet that triggered the die off of most dinosaurs. Maybe
most planets are inhabited by symbiotic colonies of advanced trilobites 20
meters long crawling the ocean floor eating the abundant sponges. Have a look
at the wierd and wonderful pre-cambrian life forms that somehow combined to
create the kind of animalia that we know today. What triggered that? And
earlier, what triggered the abundant bacterial mats to start forming mobile
colonies?

Sure, life is everywhere in the universe but the trajectory that life took on
earth will be exceedingly rare and we may never encounter another such planet
even if we develop advanced star travel.

~~~
hcarvalhoalves
> Why could it not be a planet filled with brainless jellyfish and green
> algae?

It could be even worse. Maybe we're not finding "life" because the only thing
we have to compare to is life on Earth. Maybe there is life at different
physical / time scales that we completely miss. Maybe what we call life, and
specially _intelligent_ life, is nothing special at all.

I find amusing that the general expectation is to find slightly different
humans, with civilizations and communication and interstellar ships.

------
whatshisface
What if it's easier to build a utopia than a starship?

We already have way more money going into entertainment than into space
exploration, it's not that hard to imagine that all sentient species
eventually learn how to hack themselves into permanent happiness, and then
conclude they have no reason to risk death on the final frontier.

~~~
sanoli
A lot of human, throught humanity's history, had the material means to live a
pretty pleasant, labor-free life, and yet chose a different path, away from
hedonism. I suppose this will still be true many centuries from now.

~~~
burke
Pretty much any organism that manages to develop the intelligence to build a
starship will have a long history of evolution. Their mindset will presumably
be guided by ancient evolutionary pressures. For us humans, we're partially
motivated by a desire to explore and understand our surroundings. I think it's
realistic to assume that at least some subset of aliens should be motivated by
the same exploration drive.

------
belluchan
Enjoying the virtual reality world they made, which is probably better than
the real world. If you are smart enough to create a virtual world in which you
can do almost anything you wanted, why would you give two shits about the real
world.

Modern day gaming is the beginning of something much more significant in my
opinion.

~~~
akiselev
That may be true for some (many? most?) people, I could think of a couple of
reasons:

a) Desire to explore nature's imagination instead of that of another human or
AI. Perhaps we never hit a limit of computation, but there is an entire
expanding, constantly growing in complexity universe out there to understand!

b) Even with artificial penalties, I doubt any virtual world could carry the
same perceived risk as going out into the real world and risking getting eaten
by a black hole or burned by an exploding supernova (assuming of course, you
knew of/could tell the difference).

~~~
belluchan
In the future, I think that even when we end up interacting with the real
world we'll have a virtual one mapped over it, ala alternate reality stuff.
Check out Rainbows End for what I mean there.

We can't stop interacting with the real world, but I imagine in the future
most people wont. Current boredom is a reflection of our current technology
and creative state in virtual worlds, not indicative of what the future will
hold, it's only going to get better and while nature is amazing is so many
ways human imagination trumps it. Whenever we do see something new we take it
and add to it.

~~~
akiselev
Human imagination cannot "trump" billions of years of random interaction of an
untold amount of matter and the pressures of natural selection on self
replicating organisms. The natural world may not have such high a density of
activity as any created virtual world, and so it is different, but the
universe makes up for its relative homogeneity by being big. Very, very big.
So big that we can do no more than helplessly invent the exponent to help us
cope with the size of it all.

Until we have the computational ability to simulate all possible permutations
of the universe there will always be much to explore because no matter what
technology you create, its own creativity is bound by the culture which gave
birth to it. If intelligent life and advanced civilizations are even remotely
likely, there will be many different forms of imaginations and virtual worlds
created around the universe, each born of a distinctly different culture or
artificial intelligence shaped by a distinctly different history (unless there
is a global optimum towards which all greater intelligences converge on,
essentially a global optimum for natural selection).

If you were born on earth and learned an earth language as your first, how do
you come up with a language that is entirely uninfluenced by the culture you
grew up in, a brand new protolanguage? How do you even confirm that anything
you created is so new that it stands entirely outside of your culture's
previous ingrained assumptions and interpretation of reality? If your
imagination (and thus the collective imagination of the civilization) is
bounded, as it is by language, your education, etc., how do you know it can
ever "trump" everything this big, big universe has to offer?

------
3pt14159
[https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd...](https://www.google.ca/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CEEQFjAB&url=http%3A%2F%2Fwww.astro.ufl.edu%2F~lebo%2FAST2037%2FFermi's%2520Paradox%2520-%2520Stephen%2520Webb.docx&ei=kMrRUqzyDsX32QW2lIFQ&usg=AFQjCNHKQDX6K8mCoXHHuGCWhE_WHRh3yw&sig2=6okCviy35CLcGaJQAAfOQg)

Edit:

I'll add one to the above: it might be that there are enough hostile forces,
or at least the possibility of enough hostile forces, to make every
technologically capable civilization conclude to travel near the speed of
light to protect themselves from relativistic bombs. (Objects going very close
to the speed of light. Impossible to detect in time to deflect, a form of
advanced weaponry.)

Each alien civilization sees that there are no observable civilizations and
decides that the ones that have existed either died or fled into near-the-
speed-of-light vehicles. They rationally conclude to do the same, at least
while they advance their technology and search for life. The unfortunate part
is that time goes by _much_ faster for us than it does for them, (which
negates the advantage that many early civilizations would have had).

------
coenhyde
I would say the highest probability is that we're in a zoo. We'd be pretty
interesting to watch as a blossoming civilization.

~~~
api
Given that there are many stars that are far older than the Sun with Earth-
like planets, this is not _that_ far-fetched. We have already started setting
aside regions of our own planet as nature preserves, so it's not hard to
imagine someone incredibly more advanced than us reaching similar
philosophical conclusions and doing so on a solar system or star cluster
scale.

This might also involve an element of self-interest on their part. Perhaps
intervention has been shown to produce dangerous results.

------
dspillett
_> Where Is Everybody?_

That might not be the right question, or at least is isn't the only pertinent
question. Other quesitons: "why can't we see the ones that are around now"
and/or "what happened to the ones that aren't around now".

If we are detecting civilisations feom the RF output, then consider how quicly
we went from no RF output to nearly blowing ourselves to bits. Many
civilisations could have committed suicide in a short space of time too. Many
millions of them could have shone breifly and vanished millions of years
before we even started looking. That is a tad fatalistic: we haven't managed
to wipe ourselves out even though we threatened it to an extent. But there is
another good reason why an older civilisation would be difficult to detect:
efficiency. As a civilisation's technology improves, unless they find an
effectively unlimited energy source, it is likely that they will leak less and
less out: communicating point-to-point methods most of the time rather than by
broadcast, containing and reusing what would otherwise be waste products of
enery production/use. Of course they would never be 100% efficient, but they
only need to be efficient enough that by the time the side-effects of their
activity reach us they are not descernable amongst the background noise from
the stars, black holes and other parts of the cosmos.

Evidence of other life could be passing us by right now and our attmepts to
detect it are simply insufficient, in fact the more civilisations there are
out there the harder the problem could become: the signals from each would
interfere making the attempt to spot any one signal amongst the background
noise (in part natural noise and in part that from the other signals) that but
harder.

It is all moot at the moment of course: unless they are on our doorstep, to
the point where we couldn't miss them, meaningful communication in our
lifetimes is very very unlikely.

Of course there are other equally possible explanations, such as us being in a
simulation of sorts.

------
patrickmay
I find the argument that we're in a simulation rather compelling:
[http://io9.com/5799396/youre-living-in-a-computer-
simulation...](http://io9.com/5799396/youre-living-in-a-computer-simulation-
and-math-proves-it)

~~~
saidur
I think you would enjoy Thomas Campbell's work :)
[https://www.youtube.com/watch?v=fT8LaMrn_MM](https://www.youtube.com/watch?v=fT8LaMrn_MM)

~~~
tcgv
I really liked his definition of consciousness:

 _" Consciousness is the only thing that is fundamental. Everything else is
derived from consciousness, including this physical reality."_

------
increment_i
Wow, really enjoyed reading the great thoughts on this thread.

Similar to what others have said, I think the spectrum of 'intelligence' might
be exponentially larger than anything the human mind can comprehend at this
point in our development.

Since we're at the top of our planet's bio-hierarchy I think we tend to marvel
at our own cleverness, yet wonder 'Where are the others like us?"

If other lifeforms are around us, they don't necessarily have to attempt to
contact us or make themselves known to us in a way we could understand. There
are millions of microorganisms around you right now, but they could never
'contact' you or even observe you in any meaningful way.

~~~
tcgv
_" Now my own suspicion is that the Universe is not only queerer than we
suppose, but queerer than we can suppose."_ [1]

[1]J. B. S. Haldane. Possible Worlds and Other Papers (1927), p. 286

------
soneca
Not long ago I read a fiction piece (linked here in HN)that would imagine the
world (and universe) in 10^1, 10^2, 10^3, 10^4, 10^5, 10^6... years.

In this tale, Earth would have several species achieving intelligence, all of
them failing on interestelar colonization, and the last one, the wisest,
figured out from the basic physics knowledge they develop, that this kind of
travel would be impossible.

This basic assumption is very strong for me. Even if one civilization can
travel at light speed, the multiple civilizations on our universe right now
could be at millions of years of distance one of other.

~~~
akkartik
Yeah, that's a good one:
[https://news.ycombinator.com/item?id=6860839](https://news.ycombinator.com/item?id=6860839)

------
krisgee
Personally I think civilizations tend to undergo a singularity or destroy
themselves eventually and the exceptions to those two cases are rare enough
that communication becomes exceptionally rare.

~~~
obblekk
By singularity, you mean the creation of artificial intelligence?

If so, then shouldn't we be encountering these AIs?

~~~
sitkack
No, they would become addicted to pleasure stimulus, their version of digital
heroin and become "unproductive"

------
brianmcconnell
Another possibility is that intelligent life is relatively common, but highly
technological civilizations are rare. How would human civilization have panned
out if we had not been lucky enough to discover huge, easily accessible
reserves of petrochemicals? We might have continued to enjoy a population and
standard of living comparable to the 1700s, but not progressed to become the
energy intensive civilization we are today. One could argue that would not
necessarily be a bad thing in the long run.

It's also worth remembering that for 99.9% of our existence as a species, we
lived on a much smaller energy budget. So maybe that's the norm, and planets
where Saudi Arabia scale reserves of free energy are just sitting there for
the taking are quite rare. Then, of those that do, what percentage
successfully make the transition to become long-term spacefaring
civilizations?

For a good read on the Fermi paradox, be sure to check out David Brin's The
Great Silence.

------
FellowTraveler
Any sufficiently advanced civilization will have encrypted communications, and
thus their broadcasts will appear to be noise.

------
sanoli
I posted this comment on an older thread about the same topic: "If radio
signals is the best way for us to detect alien intelligent life, and vice-
versa, aren't we doomed to keep quiet then? I mean, how long until we phase
strong radio signals almost completely? I mean, has there been any growth in
the quantity and power of radio signals since, say, the 80's? It's an honest
question, since I don't know, but I see radio declining everywhere, except
for, I guess, airplane and naval communication. What else am I missing here?
Probably a whole lot, maybe someone could fill me/us in?"

------
twocommas
A good overview of the "Great Filter" in the context of the Fermi Paradox:
[http://en.wikipedia.org/wiki/Great_Filter](http://en.wikipedia.org/wiki/Great_Filter)

~~~
kordless
My personal theory is that dark matter is the great filter. We can't see them
because they've taken it to a whole another level.

------
leejw00t354
I think the mostly likely reason we don't see evidence for intelligent life in
the universe is simply because we don't realize how unlikely it is to evolve
intelligence.

Maybe there are a lot more evolutionary paths life can take on a world than
just something similar to what happened here on Earth. Maybe typically it's
unlikely for life to evolve to become much more than plant-like life forms.

I'm sure there are species in the universe which have evolved intelligence but
I think they're much rarer than we would assume here on our perfect example
world, Earth.

------
shurcooL
"Now, everything we know about terrestrial life tells us that life has a
natural tendency to expand into all available space."

At the same time, it makes sense that more advanced life will try to be more
efficient with its use of resources. This is a lot easier to do when you're
smaller. Perhaps, they would try to minimize their size, allowing them
_expand_ into _smaller_ space.

I'm sure this thought has been considered (e.g., see Men in Black 1), but I
felt like sharing it anyway.

------
saidur
There isn't a paradox. The universe is teeming with life.

I've always believed that there was no evidence for ETs and life out there. I
thought it was fiction. Then I spent all of last year trying to find
legitimate proof of their existence. I just kept my mind open yet skeptical
and looked at all the evidence I could find and simply analyzed the data. I
was shocked that my conclusion was that ETs exist, they have been visiting us
for quite some time, and they are generally benevolent.

You don't have to believe anything I say, in fact I wouldn't want you to. All
I can ask is that you also spend some legitimate effort doing your research.
Here's something to start your path down the rabbit hole:
[https://www.youtube.com/watch?v=7vyVe-6YdUk](https://www.youtube.com/watch?v=7vyVe-6YdUk)

------
sigzero
I believe we are it. That said, if there is alien life it could be at the same
stage of industrial development that we are and it will be a long long long
time before we meet.

------
thret
"Page xx is not part of this book preview"

Sigh, I hate crippleware.

I do love this paradox though, it makes for enjoyable conversation over a
bottle of wine with just about anyone.

------
LogicalBorg
The universe is teeming with intelligent mimes. They can't wait for us to
gesture silently to them through the cosmic void. Oh, the horror.

------
gtt
Thank you, everyone! This is probably the best thread I've read on hacker news
in years!

------
coldcode
Reading their equivalent to HN.

------
api
I'll toss another one in:

What if net-positive-EROEI controlled fusion is impossible?

We have only succeeded in producing nuclear fusion in two ways: atomic bomb
primers and net- _negative_ -EROEI reactors. Atomic bombs are technically
usable as space propulsion (Google Project Orion), but the max velocities
reachable are only on the order of 4-8% the speed of light. At that rate,
interstellar travel is severely curtailed to only the closest groups of stars.
We're talking over a hundred years to Alpha Centauri if you leave time (and
reserve extra mass) for acceleration and deceleration.

Net-positive-EROEI controllable fusion is the only power source I know of that
could allow anything near practical interstellar flight, so if it's not
possible for fundamental physical reasons I'd conclude that interstellar
flight is either impossible or nearly so.

If net-positive-EROEI fusion is impossible you could get very large, very
complex, and very long lived intelligences but they'd be confined to their own
solar systems.

\--

For completeness I'll throw in two more, though they're ones I often see
discussed:

(1) They're here, and that's what (some) UFO sightings are. They choose not to
make explicit contact for some reason that we are not aware of, and that all
visitors have _so far_ shared. This could include an altruistic prime
directive (intervention may harm us) or a selfish prime directive
(intervention has been shown in the past to produce dangerous results, like
post-singularity medieval warrior kingdoms or Nazis). A second reason for lack
of explicit contact might be extreme alien-ness. Perhaps they are making
contact but are doing so in ways that are _so goddamn bizarre_ that we do not
recognize it or culturally process it as such. The UFO literature is full of
really wacked-out tales. Maybe some of them are true?

[http://www.ufoevidence.org/cases/case708.htm](http://www.ufoevidence.org/cases/case708.htm)

Sounds like a joke, right? Or the guy was insane? But imagine a "post-
singularity" (for lack of a better term) intelligence that is utterly alien
trying to comprehend our TV transmissions and then trying to make contact.
Might the attempt not look something like that? Like some kind of weird dada-
ist staged imitation of scenes from "I Love Lucy" and "Father Knows Best" with
a dash of "The Outer Limits"?

Might you not also choose an isolated subject for safety reasons? Like a
farmer in a field?

Sometimes I wonder if the weirdest most "dada" UFO cases are the most
compelling. I would _not_ expect alien contact to look as rational and
methodical as meetings between human cultures. We're talking about an
intelligence from another biosphere here, or a machine intelligence built by
intelligences from another biosphere. Their thoughts might not even be
_translatable_ into English outside of the most objective domains like
mathematical physics. Consequently unless they staged an undeniably dramatic
contact event, we might be likely to dismiss their attempts to communicate as
episodes of madness on the part of witnesses.

(2) The theists are right. We are the special creations of (or evolution was
guided by) a supreme being and are unique. This is actually a variation on the
"we are living in a simulation" hypothesis when you think about it.

~~~
sanoli
I'm pretty ignorant of these details, so: why do atomic bombs only take us to
8% of the speed of light? What happens if we're at 8% and explode a couple of
more bombs?

~~~
api
Freeman Dyson did the math, and I am not a physicist. I am assuming some sort
of mass/energy trade-off.

[http://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsi...](http://en.wikipedia.org/wiki/Project_Orion_\(nuclear_propulsion\)#Interstellar_missions)

He figured 133 years to Alpha Centauri but without carrying extra mass to slow
down. I assume you'd have to double that at least if you carried bombs to
decelerate.

