The Fermi Paradox and SETI Success

On Wed, 13 Aug 2008 18:50:06 -0700, Timberwoof wrote:

This suggests that the formation of such a molecule is a very rare
event.

No, it suggests that once a particular chemical basis of life gets
established, another one won't.

That is the conclusion, if I recall correctly, of a recent Scientific
American article about this subject. There is an effort afoot to try to
find some evidence of a different form of organic material still on Earth.

On 14 Ago, 13:41, "'Rev Dr' Lenny Flank" wrote:
On Aug 13, 8:12 pm, "K_h" wrote:

On the other hand, intelligent
life should exist on a substantial fraction of planets with life because
natural selection broadly increases intelligence with time.

I quite disagree witht his part. Indeed, I think "intelligence",
particularly in the form of the "technological intelligence" required
for SETI, is an abject evolutionary failure. In our short tenure as a
species, and even in our microscopic-timed tenure as a technological
species, we've managed to produce the largest mass extinction since
the Cretaceous, and have put not only our own survival as a species at
risk, but the very existence of nearly the entire biosphere within
which we live.

It seems pretty logical to me that there should be NO other
technological intelligent species in the universe at the current time,
because they all kill themselves off (probably taking much of their
planet's life with them) before anyone else even knows they are there.
"Intelligence" is an evolutionary path to quick suicide. A dead end.
Literally.

It depends. Human-level intelligence allowed our species to
proliferate and spread in the world at expense of the biosphere. In
this aspect we have been like a cancer which reproduces at the expense
of the organism and eventually dies with it.

Maybe we are doomed, maybe we will be intelligent enough to find a
social organization that will allow our descendants to live until the
sun turns into a red giant, maybe we will develop interstellar travel
and spread in the Galaxy exploiting alien ecosystems like a pest.

Both solutions would require high intelligence anyway, thus even if we
were intelligent and wise enough to avoid self-destruction, it could
be unlikely that any other intelligent species will be too.

Tim Tyler wrote:
Eric wrote:
K_h wrote:

Fermi's paradox suggests that there are little or no other intelligent
civilizations within the Milky Way galaxy.

Not to me it doesnt. To me, it simply says either they havent found this
area interesting to explore, or (more likely) its too far to travel.
Even if ET can travel at faster than light, it will take a very very long
time to explore even a small part of the galaxy.

Galaxy is 100,000 light years in diameter. Age of universe is
13,730,000,000 years. Aliens who could travel at the speed of
light could zip back and forth across the galaxy some 68,650
times in that time.

Let's try those numbers again. Life requires at least a third generation
supernova to have formed enough of the heavy atoms to have some building blocks.
So that age needs to get trimmed by 2/3. Now as for that speed, why do people
always assume they can travel at C?, something more credible like .05C. Then
you have to realize they have to send a probe out to that star they are headed
to so they know they have a home with they get there. Of course it can report
back with radio at speed C. Then they likely need a sample return mission
before they commit to going off. When you finally add up all the time you
realize the factor that is the limit is: how long can your civilization remain
space flight capable? Is it in the billion year class? Our planet as an
example doesn't have much of a track record on that.

So: the galaxy is pretty small, cosmically speaking - and so the
original interpretation of the Fermi paradox is probably not far
off: if there are intelligent aliens in our galaxy, odds are
they are would be everywhere - so probably there are no aliens
in our galaxy - and SETI is mostly barking up the wrong tree.

On Aug 14, 12:05 am, Chris L Peterson wrote:
On Wed, 13 Aug 2008 21:41:58 -0700 (PDT), Friar Broccoli

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

That is not obvious. We have almost no idea at all about the
intelligence of animals over most of the period they have existed.
Except for humans, and possibly a handful of other species, it isn't
clear that a "broad range of species" is any more intelligent now than
several hundred million years ago.
_________________________________________________

Chris L Peterson
Cloudbait Observatoryhttp://www.cloudbait.com

You can lose the "except for humans"; we don't actually know that
some of those fossil animals weren't more intelligent than we are,
after all. They just didn't leave any signs of civilization, a hundred
million years later.

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?

[snip]

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.

--
--- Paul J. Gans

In talk.origins Timberwoof wrote:
In article ,
William Hamblen wrote:

On Wed, 13 Aug 2008 19:01:27 -0700, Timberwoof
wrote:

In article ,
John Harshman wrote:

Who says water is an indicator of life? It's only claimed to be
necessary for life. Methane, as far as I know, is never mentioned.
Oxygen is the indicator of life, and if you want to suggest an inorganic
process that can make a lot of free oxygen in an atmosphere, feel free.

Only oxygen?

Yeah... it's common and it does some handy chemical reactions. But
similar arguments can be made for water.

Oxygen is reactive enough that oxygen in the atmosphere would be
depleted unless restored from some source. The only likely source is
photosynthesis. Where you have atmospheric oxygen you have living
plants.

Yes, that makes sense. I had it in my head that other chemical bases for
live were being discussed, and perhaps some other element or compound
could fulfill a similar role.

But I agree: If oxygen is present in an atmosphere, that would be a
really really probable sign of life. :-)

But its absence would not be a sign that there is no life...

--
--- Paul J. Gans

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.

On Aug 13, 6:12 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.


Such arguments are based on using life on earth as a model, but
are also loaded with incorrect notions. First of all, there is no
"doctrine of progress" in evolution. Who says that intelligence is
sellected for? The most successful organisms on the earth are
the dumbest---bacteria---at least "dumbest by our standards".
Of all the human societies that have existed over the past 10,000
years, only one became oriented in the direction of intersteller
communication. We are new on the scene. There is no guarantee
that our culture will retain its high tech ways.

Take, for example, the Olduvai Theory:
http://dieoff.org/page125.htm

which basically is Richard Dunkin's theory
stating that over the long haul, our
high-population, high-resource demanding culture will
collapse leaving a low population, low resource demanding
stone age culture.

This notion follows other biological growth scenarios that are
governed by the logistic equation. So, it may be that there
are some flash-in-the-pan high tech worlds out there, that last
a time measured in decades or centuries, and quickly drop
back to that more efficient totally renewable low tech stone age
culture that they sprang from. The Universe could be jam-packed
with human scale intelligent life forms, that are happly chipping
flint into arrowheads and burning wood fires.

Or, it could be worse. The universe could be filled with ecologically
spent "Easter Islands", where there are only ruins, and not even
wood to burn.


k

-John

On Thu, 14 Aug 2008 09:01:04 -0700 (PDT), Ben Standeven
wrote:

You can lose the "except for humans"; we don't actually know that
some of those fossil animals weren't more intelligent than we are,
after all. They just didn't leave any signs of civilization, a hundred
million years later.

In a sense that is true. Defining "intelligence" seems extraordinarily
difficult. But in the context of this discussion, I think it can be
taken as the ability to create sophisticated technology (a likely
requirement for traveling between the stars). I think that if a
technological species had inhabited the Earth at some earlier time, we'd
probably have evidence of it.
_________________________________________________

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

If Earth is the only planet in 10^150 with life then that suggests that the
universe is fine tuned for Earthly life.

I don't see that conclusion at all. To me it suggests that Earthly
life is finely tuned for Earth, and that the universe as a whole is
scarily life-averse.

*If a substantial fraction of the
10^150 planets have life then that suggests the whole universe is finely
tuned for life.

What about it would suggest fine tuning? Maybe the universe is
untuned, and life adapts to the universe.

*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.

Why does it suggest that?

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

k