
Galactic Settlement and the Fermi Paradox - CapitalistCartr
http://m.nautil.us/issue/80/aliens/galactic-settlement-and-the-fermi-paradox
======
coldtea
"A spacefaring species could easily settle the entire Milky Way given billions
of years"

That's somewhat of a wild assumption. What's a "spacefaring species"? Are we
one since we've built a few ships and went to the moon?

Have they solved problems that might be intractable, like being able to travel
anywhere remotely far in anything else than a "generation ship"?

Have they found the power to deploy those ships, and the materials (and
amounts required of them) to withstand the radiation of space, incoming
meteors and space debris over decades of flying, while still being able to
propel their spaceships out of their gravity?

And why would those settlements even be able to survive in space, going out on
some remote systems, and not knowing what they'll find there, and what exactly
their Earth-like planets will provide them?

> _William Newman and Carl Sagan later wrote a major rebuttal to Hart’s work,
> in which they argued that the timescales to populate the entire galaxy could
> be quite long. In particular, they noted that the colonization fronts Hart
> described through the Milky Way might move much more slowly than the speed
> of the colonization ships if their population growth rates were so low that
> they only needed to spread to nearby stars very rarely. They also argued
> that being a long-lived civilization is inconsistent with being a rapidly-
> expanding one, so any species bent on settling the galaxy would not last
> long enough to succeed. In other words, they reasoned that the galaxy could
> be filled with both short-lived rapidly expanding civilizations that don’t
> get very far and long-lived slowly expanding civilizations that haven’t
> gotten very far—either way, it’s not surprising that we have not been
> visited._

That sounds much more logical!

~~~
baja_blast
One thing I think often gets ignored is the fact advanced civilizations
require complex supply chains that would be extremely hard to bring to another
planet. If anything goes wrong everyone is wiped out. Also hopping from one
planet to the next would require the next planet to develop over a long period
before they could start the next generation ship.

~~~
Teever
There's no proof that an advanced civilization requires a complex supply
chain. In fact one of epochs of technological progression that occurs after an
industrial revolution could possibly be an industrial simplification where
supply chains and manufacturing processes reach a sort of apex in complexity
that leads to absolute simplification.

It may just be that such a developmental landmark is a prerequisite of a
civilization reaching interplanetary scale and it may even be a great filter.

------
saltyfamiliar
What if preoccupation with the material world is a primitive perspective that
civilizations simply grow out of eventually? There's an inescapable time limit
to the universe and it's all objectively pointless anyway. Why spend valuable
resources scouting the cold void of space when you can just turtle up on your
planet and live 100 lifetimes at .1x speed in VR?

------
irrational
I don't think we can start wondering about the Fermi Paradox until we actually
manage to get humans (or at least a von Neumann probe) to another star system.

We are the only intelligent more-or-less spacefaring species that we are aware
of and if we can't do it why would we think other hypothetical intelligent
spacefaring species can do it.

~~~
metalliqaz
Because we went from beating sticks together to manned spaceflight in less
than 1x10^4 years. Isn't it fair to extrapolate that to inter-stellar travel
in 1x10^6 years?

~~~
irrational
No, my gut feeling is that we will never reach another star with humans or a
self-replicating probe, so until we do I assume nobody else can/will either.

~~~
scrumper
Thing that's interesting to me is that we have a number of proposals for how
we might reach another star with essentially present-day technology. So even
us dumb humans think we could get a robot probe out there. A self-replicating
one is much further off of course.

Are you just questioning the Von Neumann machine aspect or the entire
feasibility of sending a basic dumb probe out to another star for a fly-by?

~~~
irrational
A fly-by doesn't count. Even the Voyager probes will someday fly-by some star.
Going to a star and setting up shop (whether a human colony or self-
replicating probes) is the only thing that counts in my book.

~~~
krapp
>Even the Voyager probes will someday fly-by some star.

Not necessarily. I think you underestimate how much of space is _space_ and
how little of it is anything else... and that most of that "anything else" is
dark matter. Only ~4% of the mass energy of the entire universe is matter.

It seems more likely than not to me that any arbitrary path through
interstellar space would never pass near anything larger than a grain of dust.

------
keiferski
Maybe I’m misunderstanding it, but the Fermi Paradox always seemed hopelessly
naive and myopic to me. We understand such a small percentage of reality, but
more importantly, everything we learn and observe is through our human
perspective.

It seems more logical to assume that the universe appears empty to us because
we are the only organisms _like ourselves_ , and that other life forms exist
in ways that are simply incomprehensible to us at the current level of
scientific understanding.

Edit: To use a metaphor I’ve just thought of (and think works): many people
assume that meeting extraterrestrial life will be akin to Europeans landing in
the New World. It’s more likely that it will be akin to the discovery of the
atom.

~~~
Voloskaya
That doesn't really change anything though.

Even if we assume that the vast majority of life forms are
undetectable/incomprehensible, there is still no good explanation for why
Earth would be the only place suitable for life forms similar to us.

Among the many steps necessary to evolve life as we know it, which one could
only happen here?

So the paradox is still there.

~~~
krapp
There are billions of stars in a galaxy, and billions of galaxies in the known
universe. There could be more worlds with life similar to ours than there are
grains of sand on Earth's beaches, and drops of water in its oceans, and we
could _still_ never even be aware of them simply because the universe is _that
vast._

~~~
Voloskaya
Precisely the opposite. There are so many possible world that match all the
criteria (that we know of) for life just within our galaxy, that we should
detect some of them. Our solar system is pretty young compared to the age of
the galaxy (4B years old vs 13B years old). Imagine a civilization identical
to ours, but that would have appeared a mere 1 billion years before us, not
only radio signals should be detectable (because the galaxy is just 100k light
years across), but a civilization similar to ours, with 1B more year to
develop technologically should have easily been able to send probes, at the
very least, all over the galaxy (see von neuman probes) so we should also see
that, and yet we don't.

And this just assuming a single civilization, while as you said: there could
be more worlds with life similar to ours that there are grains of sand on
Earth. So where is everyone?

~~~
harshalizee
Detect with what? We've had radio signals for about a century or so and our
signals have barely made out of the solar system at which point it's just
background noise. We just barely can detect planets and only in optimal
conditions. Our tech for all extra terrestrial purposes is laughably
primitive.

~~~
Voloskaya
You greatly overestimate the size of the solar system. Our solar system is a
mere ~20 light hours in radius. We even have two man made objects out of the
solar system (Voyager 1 and 2). In a century, our signals already made it past
~15 thousands star systems.

So now imagine a civilization similar to us but slightly older, not only would
this civilization's signals have reached all parts of our galaxy, but those
signals would likely be much stronger than we have produced in the last 100
years. It would also be possible for a civilization a few hundred millions
years older than us to send probes to every star of the galaxy by now.

------
axilmar
We really can't reach any actual conclusion at this point.

We may say today that interstellar travel is impossible, but tomorrow we may
find a solution.

We may say today that we are alone, only to be visited by intelligent aliens
somewhere in the next millennia.

We may never be visited by anyone or visit anyone, but the universe may be
full of intelligent life.

We simply cannot compute anything for such a problem, with so many unknowns.

------
seiferteric
Maybe we are the colonizers. Perhaps panspermia is the method in which distant
civilizations choose to spread through the galaxy.

~~~
ben_w
My gut feeling says panspermia is likely occurring regardless of whether Earth
life is descended from stuff from other worlds or vice-versa. I don’t expect
it to be a deliberate colonial mechanism, thought perhaps it might work as a
deliberate terraforming mechanism, as one step in a plan in the vein of Stuart
Armstrong’s talk on disassembling Mercury and using it to directly colonise
the entire supercluster essentially simultaneously?

~~~
seiferteric
Maybe our perspective is just wrong. If you consider that DNA itself is the
life on earth, and not "us" in particular and that maybe DNA is the only life
possible in this universe then this view makes more sense. Humans could be
viewed as just an appendage of DNA.

~~~
yesenadam
"We are survival machines – robot vehicles blindly programmed to preserve the
selfish molecules known as genes. This is a truth which still fills me with
astonishment"

\- Richard Dawkins, _The Selfish Gene_ , 1976

Dawkins talking about the first sentence, about 1980:

"...that was no metaphor. I believe it is the literal truth, provided certain
key words are defined in the particular ways favoured by biologists. Of course
it is a hard truth to swallow at first gulp. As Dr Christopher Evans has
remarked, "This horrendous concept - the total prostitution of all animal
life, including Man and all his airs and graces, to the blind purposiveness of
these minute virus-like substances - is so desperately at odds with almost
every other view that Man has of himself, that Dawkins’ book has received a
bleak reception in many quarters. Nevertheless his argument is virtually
irrefutable" ...

[http://www.politicsforum.org/forum/viewtopic.php?t=58430](http://www.politicsforum.org/forum/viewtopic.php?t=58430)

------
jjaredsimpson
I believe we are alone in Milky Way.

Self assembling replicators from some civilization should have colonized and
cataloged every star system over billion year time scales.

It's inconceivable that no intelligent space faring civilization would have
thought to do this.

~~~
semi-extrinsic
I've been mulling this over: given the constraints of information travelling
at lightspeed and physical objects travelling at a lot less, what if it simply
doesn't make financial sense for any actor in a market economy to colonize the
galaxy?

What if the ROI of space colonization even at multi-decade or multi-century
timescales is negative? Then why would anyone do it?

~~~
kochikame
There doesn't have to be an economic motive

What if they just feel like exploring, and gaining knowledge, and seeing
things no one else has ever seen?

~~~
semi-extrinsic
Well, they'd still have to be able to pay for everything they need to go off
on that voyage.

------
ncmncm
Either of the following suffices to account for the evidence:

1\. Expansionist civilizations that encounter one another reliably obliterate
one another. Non-expansionists don't spread out.

2\. Advanced civilizations have no need for goldielocks-zone planets. Where
mass is needed, Kuiper-belt objects are more convenient sources. The notion of
Dyson spheres seems especially silly: even extreme primitives would have
confined fusion power, and have no need to rely on primitive, diffuse stellar
radiation.

Both could be true, along with others not listed.

------
cm2012
The universe is just really, really big. If there's no way to exceed the speed
of light it makes perfect sense we haven't detected other life.

