The Fermi Paradox and SETI Success

On Aug 14, 9:20 pm, (John Wilkins) wrote:
Paul J Gans wrote:



In talk.origins John Harshman wrote:
...
Yes, one solution would be for all civilizations to render themselves
undetectable very soon after becoming detectable. This assumes they
don't go in for travel or communication, and never make noticeable
changes to their habitat (like Dyson spheres and such). It seems to me
that this assumption would require humans to be a very unusual sort of
intelligence, because we're going to go in for communication and travel
as soon as we figure out how, if we don't collapse first.

Other civilizations might well be signalling us like mad using
techniques we've not yet invented.

Or techniques we have abandoned? Semaphores?

They keep chucking large rocks at us, but their aim isn't very good.

Matt

Paul J Gans wrote:
In talk.origins Friar Broccoli wrote:
On Aug 14, 1:06 am, John Harshman
wrote:
Friar Broccoli wrote:
On Aug 13, 8:38 pm, John Harshman
wrote:
K_h wrote:
Fermi's paradox suggests that there are little or no other intelligent
civilizations within the Milky Way galaxy. On the other hand, intelligent
life should exist on a substantial fraction of planets with life because
natural selection broadly increases intelligence with time.

.

Does it? News to me. What evidence do you have that this is the case?

.

There has been an increase in the intelligence of a broad range of
species on earth with time.

Has there? What broad range, exactly? And if natural selection
broadly increased intelligence with time, we would expect all
species to be undergoing this push, wouldn't we?

I don't see how this follows at all. I would expect different
species to adopt widely differing strategies depending on
circumstances. In plants, intelligence would be a complete
waste of resources. Others like Starfish and Jellyfish have
used other strategies to ensure they can navigate and persist in
their environments without needing intelligence.

The definition of evolutionary success is reproduction.

Not sufficient; the definition of evolutionary success is occupying and
dominating an ecological niche. A species can reproduce and yet become
extinct if it is preyed on by another species.

Those Galapagos finches Darwin studied were successful NOT because they
reproduced; that's the mechanism, not the goal. Their success was that
they *radiated* into all the available ecological niches on those islands.


Using
that paradigm I conclude that intelligence, however defined,
is totally useless for evolutionary success.

The value of intelligence is it gives the species the ability to quickly
occupy new ecological niches without needing to evolve genetically.
Humans became the top predator on Earth without taking millions more
years to evolve bigger fangs and larger size and faster legs than
saber-toothed cats and other existing predators. We did it by
outsmarting the saber-tooths and any other species vying for the top
predator niche.

What intelligence did for humans was NOT to produce more offspring than
beetles. It enabled humans to become farmers (herbivores); hunters
(carnivores); SCUBA divers (deep-sea swimmers); fliers; and most
recently, outer space explorers. We did all that without needing to
wait millions of years to evolve wings, gills, carapaces, etc. Thus
humans colonized the entire planet, including the oceans and the air and
soon outer space. All ecological niches. All by the same genetic humans.



--
Steven L.
Email:
Remove the NOSPAM before replying to me.

In article ,
says...


Chris.B wrote:
On Aug 15, 1:18 am, John Harshman mumbled:
That was Chris. B's second bizarre, stream-of-consciousness post in this
thread. What newsgroup does he/she usually live in, and is he/she always
like that?


Third. Can someone answer my question?

I could think of a descriptive phrase or two, but they wouldn't actually
answer your questions, merely describe the obvious.


-Tim

Max wrote:
On Aug 14, 12:41 pm, John Harshman
wrote:
Paul J Gans wrote:
In talk.origins John Harshman wrote:
K_h wrote:
Fermi's paradox suggests that there are little or no other intelligent
civilizations within the Milky Way galaxy. On the other hand, intelligent
life should exist on a substantial fraction of planets with life because
natural selection broadly increases intelligence with time.
Does it? News to me. What evidence do you have that this is the case?
There is also the problem that there could easily be more than one
kind of intelligence. Many living (and non-living) things respond
to stimuli. At what point does that become intelligence?
Does the definition of intelligence require that television be
invented?
I believe that the operational definition of intelligence as used in the
Drake equation does require this, or at least an intelligence capable of
inventing interstellar communication and/or travel.

That is, in the Drake equation, f_L should be far
smaller than most people think it is. Even on planets that are life
friendly the formation of life should be extremely rare for the below
reasons.
The Drake equation assumes that the ETs will be blasting out
electromagnetic waves at a furious rate. *We* started doing
that only in around 1920 or so and already we are doing less
and less of it. By 2120 we could easily be using wired or
directed sources and no indiscriminate electromagnetic radiation
at all.
Yes, one solution would be for all civilizations to render themselves
undetectable very soon after becoming detectable. This assumes they
don't go in for travel or communication, and never make noticeable
changes to their habitat (like Dyson spheres and such). It seems to me
that this assumption would require humans to be a very unusual sort of
intelligence, because we're going to go in for communication and travel
as soon as we figure out how, if we don't collapse first.

Will we? It seems without a strong stimulus the impetus is lacking.

I agree with you that it's unlikely that humans will utilize a
significant fraction of the power of the Sun just to send messages into
a Galaxy they believe is probably lifeless anyway.

For such a thing to occur, we're going to need to already detect another
extraterrestrial civilization beaming messages to us (proving that they
do exist). Or at least have made enough progress on the first 4 or 5
terms of the Drake Equation: That is, find some extrasolar planet where
there are *some* forms of life, even if not yet technologically advanced.

Right now, we don't even know if *life* is a fluke unique to the Earth,
let alone intelligence. So let's stop jumping the gun here. The first
order of business is to detect *life* in the Universe. That would be a
"strong stimulus" that intelligence might also exist out there.


--
Steven L.
Email:
Remove the NOSPAM before replying to me.

John Harshman wrote:
Kermit wrote:
On Aug 13, 5:12 pm, "K_h" wrote:
Fermi's paradox suggests that there are little or no other intelligent
civilizations within the Milky Way galaxy. On the other hand,
intelligent
life should exist on a substantial fraction of planets with life because
natural selection broadly increases intelligence with time. Here on the
Earth, for example, numerous mammals have a high degree of
intelligence and
many of them could reach human intelligence with a few more million
years of
evolution.

This contradiction can be resolved if the origin of life is far
harder than
commonly believed. That is, in the Drake equation, f_L should be far
smaller than most people think it is. Even on planets that are life
friendly the formation of life should be extremely rare for the below
reasons.

For life to start, a molecule must arise that can make approximate
copies of
itself. Once that happens then natural selection can work its
magic. But a
molecule that can make approximate copies of itself must be a fairly
sophisticated nano-machine being comprised of dozens, if not
hundreds, of
molecules and it must arise via inorganic and non-evolutionary
processes.

From the study of DNA and genes, it is known that all life on the
Earth has
a common origin (undoubtedly from a molecule of the aforementioned
kind).
Since Earth is a life friendly planet, why hasn't another molecule
(of the
aforementioned kind) arisen? If it had, then life on the Earth would
have
organisms with two different molecules for genetic codes: DNA and
something
else.

Since all Earthly life is based on DNA, this suggests that, over the
four
billion years of life on Earth, this has never happened again. That is,
over the last four billion years, no other molecule has arisen by
inorganic
and non-evolutionary processes that can make approximate copies of
itself.
And Earth is a life-friendly planet so chances are optimal that such a
molecule should arise.

This suggests that the formation of such a molecule is a very rare
event.
In other words, the reaction rate of inorganic chemistry per square
meter
times the surface area of the Earth, times the average depth such
reactions
take place, times four billion years is , much less, than the
number of
such reactions needed before an approximately self reproducing molecule
arises by chance.

If that first molecule had not arisen here on the Earth then the
Earth would
probably have been lifeless ever since. This same reasoning applies
if life
first started somewhere else in the solar system and then migrated to
Earth
(for example from Mars). If life rose independently on Mars once,
over the
past four billion years, then that suggests that the reaction rate of
inorganic chemistry per square meter, times the surface area of a
Mars sized
world, times the average depth such reactions take place, times four
billion
years is about the number needed so that an approximately self
reproducing
molecule arises by chance once, ~ 1.

It seems too much of a coincidence that the laws of chemistry work
out in
such a way that life arises, on average, once per terrestrial world per
several billion years. Rather, for such cases, it seems much more
likely
that life arises multiple times or almost never. The latter possibility
makes sense from a combinatorial perspective. A self reproducing
molecule
will be composed of dozens to hundreds of other molecules. But the
total
number of permutations for such a molecule's components will far
exceed the
total number of inorganic chemical interactions that take place per
terrestrial world per several billion years.

A simple combinatorial thought experiment explains why. The number
of ways
of stacking a deck of playing cards is so huge that if 67.8 billion
solar
masses were converted entirely into protons then each proton stands
for a
different way of stacking the deck. But there are 92 naturally
occurring
chemical elements and a self reproducing molecule will probably be
composed
of hundreds of atoms from the set of 92 different kinds (there only
52 cards
in a playing deck).

So, in the Drake equation, f_L could be something really small like
10^-90.
In this case the fact that life exists on the Earth simply shows that
the
universe is super huge and its true size far exceeds the visible
universe.

General relativity says that the universe sits on top of an infinite
amount
of gravitational potential energy. During both cosmic inflation and
dark
energy inflation the universe falls down its own gravity well converting
huge quantities of its gravitational potential energy into vacuum
energy and
expansion energy. This probably explains why the universe is so huge.

So the universe could contain 10^150 planets, for example. If f_L is
10^-90
then the total number of planets in the universe that have life is
around
10^60. So there are a lot of planets with life out there but none of
them
are close by. So this is one possible explanation for why there is
only one
example of life in the solar system. And this explanation is consistent
with Fermi's paradox. It also suggests that any other life in our solar
system got there via migration.

In light of all this, it cannot be concluded that water, oxygen, and
methane, for example, are indicators of extraterrestrial life. The
presence
of these simple gases in the atmospheres of other planets can easily be
explained by inorganic processes.

If Earth is the only planet in 10^150 with life then that suggests
that the
universe is fine tuned for Earthly life. If a substantial fraction
of the
10^150 planets have life then that suggests the whole universe is finely
tuned for life. If the universe if not fine-tuned for life then that
suggests the number of planets with life should be around the
logarithmic
middle of 10^150 or around 10^75.

In conclusion, it seems there are lots of planets with life out there
but
none of them will ever communicate with humans.

k

It seems like once multicelled life evolves, intelligence would be
almost inevitable given sufficient time.

Sure, with the important bit being "sufficient time".

It's not that NS has any
progressive trend, it's just that it's an attribute which would be a
possible path for a species, given the right variables. Just as larger
animals are inevitable, given that we started very small. Not that
larger is the trend so much as a common direction taken with a random
walk. Look at how many times camouflage, poison, flying, snaring
appendages, armor, and the like evolved. If a plague wiped out humans
this year, there would likely be intelligent tool makers within 20
million years: apes, otters, cephalopods, elephants, cetaceans,
monkeys, parrots all have species comparable to our recent ancestors
in intelligence. (To the degree that the term means *anything in such
disparate species).

I would be interested to know how you figured out that 20 million years
would be "sufficient time". That's where you lose me. It seems to me
that if that were the case, we would have seen additional intelligent
species by now, since cephalopods etc. have been around for quite a bit
longer than 20 million years.

No, humanity would have to go extinct first.

We're suppressing the competition, much as the dinosaurs suppressed the
mammals before they went extinct. With our intelligence and inner
drive, we won't abandon any ecological niche to another species. We've
got deep-sea submersibles and jetliners and ballistic missiles, we can
go anywhere. For the dolphin to evolve legs and take over, or for the
octopus to evolve strong legs and take over, humanity has to go extinct
first. Or abandon the planet.

On Earth, such mass extinctions occur relatively infrequently, maybe
every 30 or 40 million years on the average.

Forcing functions, like bolide impacts, radiation flux from nearby
supernovae, continental drift, etc., may be driving these mass
extinctions. Without any such forcing functions causing such mass
extinctions--say on a geologically dead planet far from any other
asteroids, meteorites or stars--life might never evolve beyond the
bacterial stage, if at all.

If a meteorite 10 kilometers wide had hit the Earth 10,000 years ago in
the Paleolithic period, there would have been a mass extinction wiping
out humanity, and then the dolphins or parrots or octopi might have a
shot, if we wait another 20-30 million years. They won't have to fight
off human predators any longer.

On a very active planet (like the moon Io with daily volcanoes, or one
inside a globular cluster with hundreds of nearby supernovae), evolution
has no time to adapt to new conditions and again life won't evolve
beyond the bacterial stage.

So maybe a rate of mass extinctions every 30 million years is the key.
It keeps the ecosystem pot simmering gently to drive major evolutionary
paradigm shifts, without totally wiping out the biosphere.



--
Steven L.
Email:
Remove the NOSPAM before replying to me.

The Enigmatic One wrote:
In article ,
says...

In conclusion? You have just denied the entire rest of your post. First
you claim that life is rare but intelligence is inevitable given life.
And to conclude you claim that life is common but intelligence is rare.
What exactly are you smoking?

Not true. He stated that there is lots of life, but that it is extremeky
rare, 1 in 10^75 planets puts an awful lot of space between worlds.

Note that I really don't mean to disagree with your well-reasoned
conclusions. The post you responded to really was a mess. I just wanted to
point out your own substantial error in understanding the post.

It would help me understand much better if you wouldn't snip the
statements we're talking about here. But looking back, I see that you
are right about this. He's talking about 1 in 10^90 stars supporting
life, which means there's very unlikely to be another instance in our
galaxy. Silly claim, but not the silly claim I was attacking there.

Kermit wrote:
On Aug 14, 12:26 pm, John Harshman
wrote:
Kermit wrote:
On Aug 13, 5:12 pm, "K_h" wrote:

snip

It seems like once multicelled life evolves, intelligence would be
almost inevitable given sufficient time.
Sure, with the important bit being "sufficient time".

This may turn out to be the limiting factor. I can easily imagine
planets where there aren'*t 4 billion years of stability to allow the
development of intelligence. We may turn out to be outliers in that
respect, which may be the mundane (and ultimately disappointing)
explanation for why we have seen so few visitors (i.e. none).

That would be a potential explanation if indeed there were some
predictable mean time to intelligence under conditions of stability. I
see no reason why that should be true.

We are on the edge of the galaxy.

About 2/3 of the way to the edge, actually.

Could it be that this is conducive
to fewer disruptive events than planets on stars with nearby
neighbors? Do they have higher rates of radiation - which would be a
problem I would think for complex molecules equivalent to DNA, or more
asteroid strikes?

Hardly more asteroid strikes, since they all come from within the
system. Perhaps more nearby supernovae, which might disrupt things. Or
might not.

It's not that NS has any
progressive trend, it's just that it's an attribute which would be a
possible path for a species, given the right variables. Just as larger
animals are inevitable, given that we started very small. Not that
larger is the trend so much as a common direction taken with a random
walk. Look at how many times camouflage, poison, flying, snaring
appendages, armor, and the like evolved. If a plague wiped out humans
this year, there would likely be intelligent tool makers within 20
million years: apes, otters, cephalopods, elephants, cetaceans,
monkeys, parrots all have species comparable to our recent ancestors
in intelligence. (To the degree that the term means *anything in such
disparate species).
I would be interested to know how you figured out that 20 million years
would be "sufficient time".

There are several species who seem to be at the level of intelligence
of our 20 MYA-ancestors (ignoring for the moment what this means for
mollusks and cetaceans), and plenty at the level of our ancestors 100
million years ago.

Yes, but most of these are also at the level of intelligence of *their*
20-mya ancestors, or 100-mya ancestors. Lineages are not, as a rule,
increasing in intelligence over time. Ours did, but ours is unusual.
Mere addition of time does not make an intelligent species. Most
descendants of our 20-mya ancestor are not any smarter than that
ancestor. Most descendants of our 100-mya ancestor are a bit smarter
than that ancestor, because there was an Oligocene arms race within
placental mammals. But after that, things mostly settled down. You are
extrapolating where extrapolation doesn't work.

It's not surprising, after all, that our "recent"
ancestors were considerably smarter than our more distant ancestors.
The common ancestor of us all were undoubtedly not very bright... our
line had to pass thru monkey intelligence to get to us. Surely, if
conditions favored it, another line of critters that is comparable to
those ancestors could achieve the same level as we are now, in the
same length of time?

Yes. If conditions favored it. It appears, based on the evolutionary
record, that conditions rarely favor it, and in fact have favored it
only once in all of earth history.

That's where you lose me. It seems to me
that if that were the case, we would have seen additional intelligent
species by now, since cephalopods etc. have been around for quite a bit
longer than 20 million years. That would suggest that "sufficient time"
is quite a bit longer too.

Why? We are simply the first to reach human levels of intelligence (as
far as the evidence shows). But there are many that are as smart as
Cetaceous mammals. I can argue that some cetaceans, apes, and the
elephants are as smart as our 20 MYA-ancestors. Maybe if we don't
interfere, there will be others as smart as we are now in 20 MY or
less.

Cetaceous mammals? Whales? Or was that "Cretaceous"? Why would you
expect that? We're smarter than our 20-mya ancestors, but cetaceans,
apes, and elephants are not smarter than their 20-mya ancestors. As you
said, human-level intelligence happens when conditions favor it, and
it's apparent that conditions rarely favor it. Almost never, in fact.
What you say could happen, but the evidence suggests it probably won't.

As many others have pointed out, the other
adaptations you mention have happened convergently many times (except
flight, which has only been achieved 4 times that we know of). Yet
there's only one intelligent species, a quite recent one, and the
absolute minimum necessary for anyone to be there to count.

At one point, there was a first flying species. The first tool-using,
high tech species may interfere, wittingly or unwittingly, with the
development of others - witness the environmental effect we are having
on the planet. I should point out that there was at least one other
intelligent species - neanderthal - who used tools and might have
flown spaceships by now, if we (or something) hadn't somehow wiped
them out.

I suspect not; they don't seem to have had it in them. But you raise the
point of incumbency, that our existence precludes the evolution of
another intelligent species. Perhaps, but the evidence suggests that
such an explanation is unnecessary. If we're all that's holding them
back, why are there no American intelligences before 15,000 years ago?
Why no Australian ones before 40,000 years ago? Why no Eurasian ones
before 50-80,000 years ago? It's only quite recently that this
incumbency objection even became possible.

I don't think you would consider unreasonable the suggestion that if
some virus wiped out bats and birds overnight, that in 20 million
years there might be numerous species of mammals with true flight.

Maybe, and here incumbency might be a real force preventing evolution in
that direction. But maybe not. Flight evolved only once in mammals, only
twice in archosaurs. On the scale of likelihood it's ahead of
intelligence, but way behind, for example, herbivory.

And it took
4 billion years to get that one. By contrast (though only, apparently,
by contrast), multicellularity is easy; it happened at least 5 times
(animals, plants, fungi, red algae, brown algae), more if you're generous.

Any potentially intelligent tools users out there wouldn't have to
start from scratch. Tsk. Sounds almost like something Pitman would
say; but I'm sure I'm just reading you wrong. It is not 4 billion
years from an otter brain to the equivalent of a human brain. Yeast
doesn't pick up rocks to open lunch with, nor use mud slides just to
have fun with.

Agreed. I was talking there about the probability, given only that life
has arisen. Obviously the probability is greater if you start with
fairly smart life. But then to answer the original question you have to
find the probability of fairly smart life and multiply them together.
Judging by the record (a poor judge, but all we have), the two biggest
bottlenecks are eukaryotic genomes (not sure what exactly about them,
perhaps complex gene regulation, but something that seems required for
multicellularity) and human-level intelligence itself. Both have
happened only once in history. Even things that happened four or five
times in history should be considered bottlenecks.

On Fri, 15 Aug 2008 12:32:41 -0700, John Harshman
wrote:

Hardly more asteroid strikes, since they all come from within the
system.

Asteroids and comets come from within the system, but their dynamics may
be influenced by what is outside the system. There is some evidence in
the case of the Solar System that our regular passage through the
galactic plane causes an increase in comets entering the inner system
due to perturbations in the Oort cloud. It is entirely possible that the
behavior of planetary systems in denser regions of galaxies is much more
chaotic.
_________________________________________________

Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

þus cwæð Ernest Major:
In message
,
Inez writes
On Aug 14, 11:42 pm, Tim Tyler wrote:
Timberwoof wrote:
I suspect that just as when one system of biochemistry establishes
the pattern of life, things that use it will eat anything else
that shows up, it is likely that when one highly intelligent
species shows up, it will limit the opportunities for anything
else to evolve into sentience.

Whales are not "highly intelligent", then?
--

No. They're all at or below sea level.

Cough. Cough. River dolphins.

Nearly all extinct, which shows you shouldn't go trying to rise above
your station.

þus cwæð Mike Dworetsky:
"Robert Carnegie" wrote in message
...
Paul J Gans wrote:
The Drake equation assumes that the ETs will be blasting out
electromagnetic waves at a furious rate. *We* started doing
that only in around 1920 or so and already we are doing less
and less of it. By 2120 we could easily be using wired or
directed sources and no indiscriminate electromagnetic radiation
at all.

I'd look for industrial emissions, such as signals from the cross-
country electric power grid. But maybe we will quickly improve our
efficiency and reduce energy losses, or switch to a 100% hydrogen
economy.

I'm told that the United Kingdom is unique in having power demand
surges in the evening at particular times each day. This is because
certain television programmes have large numbers of viewers, and when
the programme breaks or ends, tea is brewed, by using electric
kettles. With digital choices, catch-up, and services such as
YouTube, this may soon change. (And anyway, I recently heard about
it once more from the people who broadcast the television programmes
for which claims are made.)


Especially at the end of the soap "East Enders". Last week a
documentary about Britain included the National Grid controller who
keeps a TV on in the control room, so he knows when the program ends,
and he is able to bring up the various hydroelectric pumped storage
dynamos on time until the 50-Hz average frequency is stabilized again.

I thought it was the commercial break in /Coronation Street/ that was
the main offender?