A Space & astronomy forum. SpaceBanter.com

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » SpaceBanter.com forum » Astronomy and Astrophysics » Astronomy Misc
Site Map Home Authors List Search Today's Posts Mark Forums Read Web Partners

Missing sial, iron, and nickel explains Fermi paradox



 
 
Thread Tools Display Modes
  #1  
Old July 28th 07, 04:21 PM posted to sci.astro,sci.space.policy,sci.astro.seti
[email protected]
external usenet poster
 
Posts: 15
Default Missing sial, iron, and nickel explains Fermi paradox

The Earth's crust is made of two layers called sima
and sial. Sima is the lower and denser layer. It is
made mostly of basalt. Sima is 5 to 10 km thick and
covers the entire surface of the Earth. Sial is 20-70
km thick and covers only 30% of the Earth's surface;
this is the elevated part of the Earth's surface called
continents. The remaining 70% of the Earth's surface
is covered with oceans. Sial is sometimes called
granitic layer of the crust, because it is made mostly
of granite, which is made mostly of silica
(SiO2 content = 72%).

None of the existing theories explain how the sial
was selectively scooped up from 70% of the Earth's
surface and deposited on the Moon. A glancing collision
with a ball-shaped moon could not have scraped off sial
from 70% of the Earth's surface. Even a shovel-shaped
moon could not have scraped off so much sial.

The temperature of Earth increases about 36 degrees
Fahrenheit (20 degrees Celsius) for every kilometer
(about 0.62 miles) you go down. Near the center, its
thought to be at least 7,000 degrees Fahrenheit
(3,870 Celsius). This means that the sial is made of
hard and rather cool rock.

If a geological process removed the sial from 70% of
the Earth's surface, it must have taken place when
the sial was still hot and liquid because sial is not
a pile of rocks, but a solid, rather uniform layer
of bedrock. This hypothetical process had to lift
liquid sial up to 70 km against the force of gravity.
__________________________________________________ __

It is very difficult to imagine any geological or
astronomical event that could selectively scoop up
sial from 70% of the Earth's surface. I believe that
the most probable event was a sequence of three
collisions:

1. HYPOTHESIS: About 4.5 billion years ago the Kuiper
belt object that is now 2003EL61 collided obliquely with
another, unnamed, large Kuiper belt object. The oblique
impact caused 2003EL61 to spin rapidly and it transformed
its shape from a ball to american football. The
probability that the impact was oblique is low, on the
order of 0.01, because the 2003EL61 is the only large
object in the solar system that spins rapidly and has
american football shape.

2. FACT: The absence of planet in the place where
Ceres asteroid is now is the only exception of the
Titius-Bode Law. HYPOTHESIS: 4.5 billion years ago
there was a bigger asteroid in the place where Ceres
is now. Let us call it Theia and let us call the
unnamed large Kuiper belt object Orpheus. Ceres has
rocky core overlain with icy mantle. Theia had
the same composition as Ceres but it was larger.
Orpheus was made mostly of water ice. It was not
broken into small pieces by the impact with 2003EL61
because the impact was oblique. The impact hurled
Orpheus into a collision path with Theia. When Orpheus
hit Theia, the impact moved Theia toward Jupiter and
melted most of the water ice. The average distance
between 2003EL61 and Ceres is on the order of 5000 Gm
(35 AU). Diameter of Orpheus was probably on the order
of 1000 km. Diameter of Theia is unknown; let us assume
that it was 2000 km. The probability that Orpheus hit
Theia is on the order of 10^-13.

(/ 1.0 (expt (/ (* 5000.0 1000000000) 2000000) 2)) =
1.6e-013

3. HYPOTHESIS: The enormous gravity of Jupiter hurled
Theia toward the Earth. As Theia was moving toward
the Earth, its mantle of liquid water was vaporized by
the sunlight, creating watery atmosphere. Theia became
giant comet. Its rocky core collided with the Moon thus
creating a new, hot Moon. A few hours later Theia's
watery atmosphere collided with the Earth. It ablated
some of the Earth's sima and all sial except the back
30% of the Earth's surface. The original crust was made
of 20 km thick sial layer on top of 10 km thick sima
layer. Some of the original sial layer near the back
of the Earth was not ablated by the collision, but it
was pushed by the collision towards the back of the
Earth where it piled up and formed the very thick sial
layer that is now known as the continents. Dust
particles made from the sial, the Moon, and the rocky
core of Theia were suspended in the huge atmosphere
that enveloped the Earth and the new Moon. Some of
the atmosphere was captured by the new Moon. Very
large quantity of the dust fell on the Moon and the
Earth over a period of several thousand years. Soon
after the collision the Moon and the Earth were hot,
so the dust melted as soon as it fell. The Moon was
cooled quickly by the contact with the atmosphere, so
a few hundred years later it was so cool that the dust
falling on the Moon did not melt. When the collision
separated Theia's rocky core from its atmosphere, the
atmosphere quickly expanded due to the heat generated
by the collision and due to reduced gravity (no core).
The expansion reduced density of the atmosphere before
the collision with the Earth. Theia was quickly loosing
its volatile atmosphere after the collision with Orpheus
because much of its elliptic orbit was close to the sun.
If it was loosing its atmosphere at the rate of 0.1
meter per day, it had to collide with the Earth in about
10,000 years. The probability that the collision between
Earth and Theia took place within 10,000 years since the
collision between Theia and Orpheus is on the order of
10^-9.

(/ 1.0 (expt (/ (* 816620000 1000.0) 1000000) 2)) =
1.49955e-012

The probability that all these events occurred is
on the order of (0.01)*(10^-13)*(10^-9) = 10^-24.

One percent of stars in our galaxy, called Milky Way,
has Earth-like planets which have liquid water and
thus seem capable of supporting life. This means
that the probability that the Earth has oceans and
continents is on the order of 10^-26.

There are about 100 billion (10^11) stars in our
galaxy and about 7*10^22 stars in the entire visible
universe. The probability that another planet in
the entire visible universe has oceans and continents
is on the order of (10^-26)*(7*10^22) = 7*10^-4;
about one event in one thousand.
__________________________________________________ __

FACT: Moon is deficient in iron and nickel. Moon's
Fe/Si ratio is equal to 0.22 as a whole (crust +
mantle + core). This is the lowest known Fe/Si ratio
of any object in the solar system. Comet gas tails
contain high concentrations of ionized carbon monoxide
gas. Nickel carbonyl and iron pentacarbonyl form upon
treatment of the metals with carbon monoxide. Both
carbonyls are volatile liquids at room temperature.
Nickel carbonyl forms by the direct combination
of carbon monoxide and nickel metal at room
temperature. Nickel carbonyl decomposes back to Ni
and CO upon contact with hot surfaces.

HYPOTHESIS: When Theia became a comet, it produced
lots of carbon monoxide. When Theia's rocky core
collided with the Moon, a chemical reaction between
iron, nickel and carbon monoxide produced carbonyls.
The carbonyl vapors were suspended in the atmosphere
surrounding the Earth and the Moon until the
atmosphere condensed on the Earth.

FACT: A troilite-rich nickel-iron particle found on the
Moon has surface erosion that, according to the authors
of the following article, is due to passage through a
cloud of hot gas and particulate matter:
Science 5 February 1971: Vol.171. no.3970, pp.479-480
Lunar Metallic Particle ("Mini-Moon"): An
Interpretation. David S. McKay, James L. Carter,
and William R. Greenwood.
__________________________________________________ __

Australian astronomer, Nick Hoffman claims that the
Earth is a unique planet because it has continents
(http://www.spacedaily.com/news/life-01x1.html).
He has not explained why there are no continents
on other planets.

I believe that the missing Earth's sial provides the
explanation and I agree with Hoffman that life cannot
evolve into a technological civilization on a planet
that is devoid of continents.

In the absence of continents there would have been no
advanced forms of life on Earth because the entire
surface of the Earth would have been covered with
oceans and the only source of minerals for the marine
life would have been hydrothermal vents. The vents
cannot support great abundance and diversity of life,
which is necessary for speedy evolution of life.
Marine life of our planet is confined to places that
have abundance of iron, nitrates, phosphates and
silicates. Nearly all of these minerals are
transported from continents by rivers and winds.

If the planet has no continents, it has no land animals
that can make fire, smelt metals, and create
technological civilization. If the planet has no
continents, but it has an ocean, a giant asteroid impact
may create islands, but these islands are eroded by rain
and wind. There is no plate tectonics to counter the
erosion and it takes about one billion years of plant
evolution to produce roots that can prevent soil erosion.

The missing sial leaves empty space between tectonic
plates and thus makes plate tectonics possible on
the Earth. Venus is good example of an Earth-like
planet that does not have plate tectonics. Without
plate tectonics to dissipate heat from its mantle,
Venus undergoes a cyclical process in which mantle
temperatures rise for a few hundred million years
until they reach a critical level that weakens the
crust. Then, over a period of a few million years,
subduction occurs on enormous scale, completely
recycling the crust. The subduction would have killed
all higher forms of life if they had been present on
Venus.

We are lucky to have massive Moon. Earth's obliquity
(the angle between the Earth's equator and the plane
of its orbit) is 23.5 degrees. If the massive Moon
had not existed, the Earth's obliquity would have
varied wildly between 0 and 80 degrees. Such
variation would have caused extreme climatic changes.

We are lucky to have plenty of water. If we had had much
less water, all our flora and fauna would have perished
during a snowball period. Terrestrial life barely survived
during the snowball periods under two kilometers thick
layer of ice (http://en.wikipedia.org/wiki/Snowball_earth).
Evolutionary rates were incredibly slow then.

We are lucky to have plenty of heavy elements (called
metals). According to Wikipedia:
(http://en.wikipedia.org/wiki/Metallicity)
"These youngest stars, including the Sun, therefore have
the highest metal content, and are known as "Population I"
stars. Across the Milky Way, metallicity is higher in the
galactic centre and decreases as one moves outwards."

We are lucky to be far away from the galactic center
and its high concentration of dangerous, exploding stars.

We probably survived cataclysms and close calls that
left no evidence that we can study.

My estimates are not precise but they do not have to be
precise to convey important truth: we are the only
civilization in the visible universe, so SETI is a waste
of time. There is another proof that planets having
continents are extremely ra if they had been common,
extraterrestrial civilizations would have colonized our
galaxy and our planet billions of years ago.
__________________________________________________ ______

My explanation/understanding of plate tectonics of all
terrestrial planets of Earth size except the Earth:

Terrestrial (Earth-like) planets are made of high density
minerals covered with low density sial. The sial abounds in
silicates, so its physical properties are similar to the
properties of ceramics. Ceramics are brittle. Their thermal
conductivity and coefficient of thermal expansion are low.
The dense interior of the terrestrial planets abounds in metals,
so its physical properties are similar to the properties of
metals. Metals are ductile. Their thermal conductivity and
coefficient of thermal expansion are high.

When a terrestrial (Earth-like) planet is young and hot,
its sial surface is liquid. When the planet cools, its sial
solidifies. Sial does not conduct heat well, so it traps the
heat that is generated in the interior by the radioactive decay.
The entire planet warms up and it expands because all its
minerals have positive coefficient of thermal expansion.
The metallic interior expands more than the ceramic sial,
because its coefficient of thermal expansion is higher.
Great tension builds up in the ceramic sial until it shatters
like a glass pane. We call this event an earthquake. Liquid
magma and volcanic ash escape through the cracked sial into
the atmosphere. We call this event a volcanic eruption. When
the magma cools and solidifies, it seals the cracks in the sial
and the next cycle begins.

If the entire surface of a terrestrial planet is covered with
sial, enormous tension builds up in the sial over millions of
years. When the sial shatters, the earthquakes and volcanic
eruptions are enormous. Volcanic ash absorbs sunlight and thus
cools the atmosphere so much that all land animals freeze to
death.

Ads
  #2  
Old July 28th 07, 05:21 PM posted to sci.astro,sci.space.policy,sci.astro.seti
N:dlzc D:aol T:com \(dlzc\)
external usenet poster
 
Posts: 155
Default Missing sial, iron, and nickel explains Fermi paradox

Dear Andrew.Nowicki.00:

wrote in message
oups.com...
The Earth's crust is made of two layers called sima
and sial. Sima is the lower and denser layer. It is
made mostly of basalt. Sima is 5 to 10 km thick and
covers the entire surface of the Earth. Sial is 20-70
km thick and covers only 30% of the Earth's surface;
this is the elevated part of the Earth's surface called
continents. The remaining 70% of the Earth's surface
is covered with oceans. Sial is sometimes called
granitic layer of the crust, because it is made mostly
of granite, which is made mostly of silica
(SiO2 content = 72%).

....
It is very difficult to imagine any geological or
astronomical event that could selectively scoop up
sial from 70% of the Earth's surface.


I can imagine such a thing. Impact Earth "off-center" with a
massive object of composition similar to what we have now. The
differential rotation imparted to the combined object starts a
wave, that ends up being a single lobe. The lobe is elevated
above the "nominal" surface of the Earth, which will selectively
"sort" lighter materials from denser materials. As the lighter
materials are collected in the lobe, the amplitude gets higher,
until it ultimately it pinches off. The Moon is born.

David A. Smith


  #3  
Old July 28th 07, 06:11 PM posted to sci.astro,sci.space.policy,sci.astro.seti
Einar
external usenet poster
 
Posts: 1,219
Default Missing sial, iron, and nickel explains Fermi paradox


wrote:
snipsnipsnip

Imagine the Solar System when it is forming out of the primal nebula,
it formed out of. The cloud that formed the Sun has rotated,
flattended by that rotation into a disc, most of the mass has gathered
into the center forming a young Sun, already burning with fusion
flame. Within the rest of the material of that disc, our familiar
planets have begun to form.

However, the situation is not identical from today. The disc has not
yet dissipated, and it is excerting gentle but constant drag on
Jubiter, causing it to gradually loose orbital energy forcing it to
move closer to the Sun.

Inside it, the familiar rocky planets are forming, but in addition
there is a planet forming outside what is now the orbit of Mars. As
Jubiter moves closer itīs greater gravity ultimatelly perturps the
orbit of that protoplanet, which has achiewed roughly the size and
mass of Mars of today.

Eventually the orbit of that planet is disturbed to such a degree that
it leaves its orbit and is flung towards the Sun. In its path towards
the Sun it encounters the Earth and collites with it, in such a way
that enough material is thrown up from Earth into Earth orbit that the
Moon is eventually formed. The remains of the planet go on and impact
the Sun and are vapourized.

Some time later, a gigant nearby supernova clears away the dust-disc
and Jubiter stops drifting towards the Sun...end of scenario.

Cheers, Einar

  #4  
Old July 29th 07, 04:50 PM posted to sci.astro,sci.space.policy,sci.astro.seti
Ian Parker
external usenet poster
 
Posts: 2,554
Default Missing sial, iron, and nickel explains Fermi paradox

There have been several explanations advanced for the Fermi paradox
ranging from a short finite life of civilization - The view advanced
by Von Neumann amoung others, to us living in a simulation.

The most disconcerting possibility is a Fermi race. This assumes that
a small, if not just one, number of civilizations will send Von
Neumann probes to the stars and will occupy the galaxy. The galaxy
comes on a first come, first served basis.

There has been lots of speculation. Perhaps it would be a good idea if
we were to discuss how we could choose experimentallly between one
possibility and another. If we did have a 1km telescope we could find
out how many worlds there were with oxygen in their atmosphere and
hence photosynthesis. If there is any truth in the "race" hypothesis
the cost of a telescope might well be justified on security grounds.


- Ian Parker

  #5  
Old July 29th 07, 08:09 PM posted to sci.astro,sci.space.policy,sci.astro.seti
Einar
external usenet poster
 
Posts: 1,219
Default Missing sial, iron, and nickel explains Fermi paradox


wrote:
snipsnipsnip

On the lack of observed alien civilization, we need to remember that
the universe is still pretty young. Sure, 13 billion years sounds a
real lot, but remember if we subtract 3 billion years that leaves 10
billion. The point is, itīs taken life here about that time to evolve
intelligent life. While that might take shorter time ellsewhere, one
has to remember that evolution of life from bacteria is not simple and
unlikelly to take a short time. In addition, we need to consider the
age of stars, and evolution of matter inside the galaxy. The fact is
that heavyer elements than hydrogen have to be manufactured by stars.
Basigly, generations of stars have to live and dye for enough material
to be available for rocky planets of the sort we live on. Remember,
stars arenīt shortlived. Now, subtract another billion years and half,
and 8.5 billion is the time we have before the Solar System began to
form. That is the time that the Milky Way has for succeeding
generations of stars to live and dye, and to result in increasingly
higher concentrations of heavy materials. Apparently the Sun is a
third generation stars of its type, i.e. the universe has had enough
time to produce three generations of yellow stars of that particular
type. There is though one litle bit, Iīve heard somewhere that the Sun
is a billion years younger than is the average age of third generation
yellow stars.

So, if the third generation is the first generation with enough heavy
materials present for rocky planets to be likelly enough, and the Sun
is relativelly young among that groups of stars, that leaves perhaps a
chance that if life has evolved on theyr planets that it has had a
longer time to evolve. Even so, there are so many uncertainties about
evolution of life, that the age difference could easilly be eaten up
by that.

Cheers, Einar

  #6  
Old July 30th 07, 03:42 PM posted to sci.astro,sci.space.policy,sci.astro.seti
Joe Strout
external usenet poster
 
Posts: 972
Default Missing sial, iron, and nickel explains Fermi paradox

In article . com,
Einar wrote:

wrote:
snipsnipsnip

On the lack of observed alien civilization, we need to remember that
the universe is still pretty young. Sure, 13 billion years sounds a
real lot, but remember if we subtract 3 billion years that leaves 10
billion. The point is, it?s taken life here about that time to evolve
intelligent life. While that might take shorter time ellsewhere, one
has to remember that evolution of life from bacteria is not simple and
unlikelly to take a short time.


This is missing the point. The time from the beginning of the Universe,
to the formation of a technological civilization, should take the form
of a normal distribution (i.e. bell curve), as pretty much any other
natural process does, due to the central limit theorem. If our
civilization is average (i.e. by the Copernican principle), then the
mean of this distribution is somewhere around the present. That means
that about half of the civilizations that will ever arise, arose before
us; and half will arise after us.

Now, we don't know what the standard deviation of this distribution is,
but we can make some guesses by looking at our history. How tightly
constrained was the development of civilization just now, given our 4.5
GY history? The answer appears to be, not very. Some really pivotal
moments in evolution, like the CretaceousTertiary extinction event, were
the result of highly random processes (a major impact event in this
case) which could have just as easily happened much sooner or later. So
the standard deviation is probably hundreds of millions of years at
least.

But with a standard deviation that high, and given that there are over
200 billion stars in the galaxy, there would necessarily be some
outliers to the population who happened to evolve very much earlier than
the rest of the population -- even at 3 sigma (standard deviations) away
from the mean, you'll find 0.37% of the population, which would be 540
million civilizations, half of which evolved earlier than the mean by
three sigma. Even if most of those stars can never support life, the
numbers (of both stars and years) is so large that it's very hard to
avoid the conclusion that the first civilization must almost certainly
arise a billion years or more before the mean.

This, combined with the observation that it takes only a few hundred
million years (after the development of space colonization) to settle
the whole galaxy, presents Fermi's paradox.

There are darn few parameters you can tweak in this analysis that make
much difference. The only escape I see is to assume that planets where
civilization can arise are very, VERY rare, so that the total population
size is not in the billions but perhaps in the thousands. Of course,
even with N=1000, there should be at least one civilization that
develops at least three sigma before the mean. So we have to further
assume that we are NOT an average observer, but are one of the first
civilizations to arise, maybe even the very first. Otherwise, we would
have arisen in an already-settled galaxy, and this does not appear to be
the case.

But of course, that makes a philosopher of science uncomfortable as
well. The odds of us, as a civilization, happening to be the first are
quite low. Moreover, if there are eventually going to be many orders of
magnitude more people, spread throughout the galaxy and over millions or
billions of years, why do you and I happen to be born into this time,
when there are fewer than 10 billion of us, all cooped up on one planet,
and within a few hundred thousand years of the birth of civilization?
The odds against THAT boggle the mind.

The most logical explanation is that all civilizations, including ours,
destroy themselves (or are destroyed) before interstellar colonization
begins. But, despite the logic of it, I find I can't accept that. So,
I'm left befuddled, with no neat solution. I consider this one of the
great mysteries of our time, right up there with the nature of
consciousness.

Best,
- Joe

--
"Polywell" fusion -- an approach to nuclear fusion that might actually work.
Learn more and discuss via: http://www.strout.net/info/science/polywell/
  #7  
Old July 30th 07, 04:27 PM posted to sci.astro,sci.space.policy,sci.astro.seti
jizba
external usenet poster
 
Posts: 3
Default Missing sial, iron, and nickel explains Fermi paradox

Joe Strout wrote:
In article . com,
Einar wrote:

wrote:
snipsnipsnip

On the lack of observed alien civilization, we need to remember that
the universe is still pretty young. Sure, 13 billion years sounds a
real lot, but remember if we subtract 3 billion years that leaves 10
billion. The point is, it?s taken life here about that time to evolve
intelligent life. While that might take shorter time ellsewhere, one
has to remember that evolution of life from bacteria is not simple and
unlikelly to take a short time.


This is missing the point. The time from the beginning of the Universe,
to the formation of a technological civilization, should take the form
of a normal distribution (i.e. bell curve), as pretty much any other
natural process does, due to the central limit theorem. If our
civilization is average (i.e. by the Copernican principle), then the
mean of this distribution is somewhere around the present. That means
that about half of the civilizations that will ever arise, arose before
us; and half will arise after us.

Now, we don't know what the standard deviation of this distribution is,
but we can make some guesses by looking at our history. How tightly
constrained was the development of civilization just now, given our 4.5
GY history? The answer appears to be, not very. Some really pivotal
moments in evolution, like the CretaceousTertiary extinction event, were
the result of highly random processes (a major impact event in this
case) which could have just as easily happened much sooner or later. So
the standard deviation is probably hundreds of millions of years at
least.

But with a standard deviation that high, and given that there are over
200 billion stars in the galaxy, there would necessarily be some
outliers to the population who happened to evolve very much earlier than
the rest of the population -- even at 3 sigma (standard deviations) away
from the mean, you'll find 0.37% of the population, which would be 540
million civilizations, half of which evolved earlier than the mean by
three sigma. Even if most of those stars can never support life, the
numbers (of both stars and years) is so large that it's very hard to
avoid the conclusion that the first civilization must almost certainly
arise a billion years or more before the mean.

This, combined with the observation that it takes only a few hundred
million years (after the development of space colonization) to settle
the whole galaxy, presents Fermi's paradox.

There are darn few parameters you can tweak in this analysis that make
much difference. The only escape I see is to assume that planets where
civilization can arise are very, VERY rare, so that the total population
size is not in the billions but perhaps in the thousands. Of course,
even with N=1000, there should be at least one civilization that
develops at least three sigma before the mean. So we have to further
assume that we are NOT an average observer, but are one of the first
civilizations to arise, maybe even the very first. Otherwise, we would
have arisen in an already-settled galaxy, and this does not appear to be
the case.

But of course, that makes a philosopher of science uncomfortable as
well. The odds of us, as a civilization, happening to be the first are
quite low. Moreover, if there are eventually going to be many orders of
magnitude more people, spread throughout the galaxy and over millions or
billions of years, why do you and I happen to be born into this time,
when there are fewer than 10 billion of us, all cooped up on one planet,
and within a few hundred thousand years of the birth of civilization?
The odds against THAT boggle the mind.

The most logical explanation is that all civilizations, including ours,
destroy themselves (or are destroyed) before interstellar colonization
begins. But, despite the logic of it, I find I can't accept that. So,
I'm left befuddled, with no neat solution. I consider this one of the
great mysteries of our time, right up there with the nature of
consciousness.

Best,
- Joe

Following your line of thought, one might argue that on average
our solar system will be visited occasionally by one of the
early advanced civilizations. If by 'occasionally' one means every
500,000 years or so, the chances of such a visit during the last
10,000 years may be quite low. Because of the great distances
the effort to colonize a planet may not be worth while. On the
other hand, there may be places in our solar system where evidence
of such visits still exists. In the past I have suggested just
such evidence on the asteroid Eros (see IOD 5-3), and others have
found anomalies that do not appear to be made by natural processes
on Phobos (see "Phobos monolith") on Mars (see UFO crash on Mars) and
even on the moon (see the illustration on p. 33 of Ad Astra 2007 -or
ask the Ad Astra editor for a copy).
  #8  
Old July 30th 07, 05:08 PM posted to sci.astro,sci.space.policy,sci.astro.seti
Jochem Huhmann
external usenet poster
 
Posts: 606
Default Missing sial, iron, and nickel explains Fermi paradox

Joe Strout writes:

The most logical explanation is that all civilizations, including ours,
destroy themselves (or are destroyed) before interstellar colonization
begins. But, despite the logic of it, I find I can't accept that. So,
I'm left befuddled, with no neat solution. I consider this one of the
great mysteries of our time, right up there with the nature of
consciousness.


I think the most logical explanation is that "interstellar colonization"
has a pretty low priority for most or even all civilizations. It just
doesn't happen. They struggle to colonize their own planet, have a short
boom period, run out of natural resources and then either go extinct or
struggle on to organize long-term modest surviving and do away with
"colonization".


Jochem

--
"A designer knows he has arrived at perfection not when there is no
longer anything to add, but when there is no longer anything to take away."
- Antoine de Saint-Exupery
  #9  
Old July 30th 07, 05:15 PM posted to sci.astro,sci.space.policy,sci.astro.seti
Ian Parker
external usenet poster
 
Posts: 2,554
Default Missing sial, iron, and nickel explains Fermi paradox

On 30 Jul, 15:42, Joe Strout wrote:

On the lack of observed alien civilization, we need to remember that
the universe is still pretty young. Sure, 13 billion years sounds a
real lot, but remember if we subtract 3 billion years that leaves 10
billion. The point is, it?s taken life here about that time to evolve
intelligent life. While that might take shorter time ellsewhere, one
has to remember that evolution of life from bacteria is not simple and
unlikelly to take a short time.


This is missing the point. The time from the beginning of the Universe,
to the formation of a technological civilization, should take the form
of a normal distribution (i.e. bell curve), as pretty much any other
natural process does, due to the central limit theorem. If our
civilization is average (i.e. by the Copernican principle), then the
mean of this distribution is somewhere around the present. That means
that about half of the civilizations that will ever arise, arose before
us; and half will arise after us.

You are indeed correct, but how do you know the distribution is
Copernican. Why not a race? A race to me seems eminanly logical but so
far nobody has commented on it. If a race is indeed true there are
consequences in terms of how we should act.

1) We need to know how close to us other civilizations are. We are
running 42km and we need to look back and see where the other
competitors are. A 1km telescope - figure admittedly pluced out of the
air.

2) We do need to build interstellar VN probes. This to an extent
represents the tape.

Now, we don't know what the standard deviation of this distribution is,
but we can make some guesses by looking at our history. How tightly
constrained was the development of civilization just now, given our 4.5
GY history? The answer appears to be, not very. Some really pivotal
moments in evolution, like the CretaceousTertiary extinction event, were
the result of highly random processes (a major impact event in this
case) which could have just as easily happened much sooner or later. So
the standard deviation is probably hundreds of millions of years at
least.

This is to some extent of the nature of a BTW. Genetic markers on
mammalian species show that the main mammal types evolved in the early
to middle Cretaceous. Fossils BTW are quite rare because fossilization
is a rare process. Genetic markers are in fact better in showing when
Evolution took place.

Thus the Cretacious/Teriary extinction was less relevant than has been
supposed up to now.

But with a standard deviation that high, and given that there are over
200 billion stars in the galaxy, there would necessarily be some
outliers to the population who happened to evolve very much earlier than
the rest of the population -- even at 3 sigma (standard deviations) away
from the mean, you'll find 0.37% of the population, which would be 540
million civilizations, half of which evolved earlier than the mean by
three sigma. Even if most of those stars can never support life, the
numbers (of both stars and years) is so large that it's very hard to
avoid the conclusion that the first civilization must almost certainly
arise a billion years or more before the mean.

How many competitors are running? Are we winning? Will we send an
interstellar probe in the equivalent of 2hr 6min?

This, combined with the observation that it takes only a few hundred
million years (after the development of space colonization) to settle
the whole galaxy, presents Fermi's paradox.

We need to send an interstellar probe in 2hr 6 min. If we don't .....

There are darn few parameters you can tweak in this analysis that make
much difference. The only escape I see is to assume that planets where
civilization can arise are very, VERY rare, so that the total population
size is not in the billions but perhaps in the thousands. Of course,
even with N=1000, there should be at least one civilization that
develops at least three sigma before the mean. So we have to further
assume that we are NOT an average observer, but are one of the first
civilizations to arise, maybe even the very first. Otherwise, we would
have arisen in an already-settled galaxy, and this does not appear to be
the case.

But of course, that makes a philosopher of science uncomfortable as
well. The odds of us, as a civilization, happening to be the first are
quite low.


In a race situation the odds are high. If we were not the first we
would all be Centurians. Alpha Centurians would have terraformed the
solar system, and we would be in a park on Earth ... if that.

Moreover, if there are eventually going to be many orders of
magnitude more people, spread throughout the galaxy and over millions or
billions of years, why do you and I happen to be born into this time,
when there are fewer than 10 billion of us, all cooped up on one planet,
and within a few hundred thousand years of the birth of civilization?
The odds against THAT boggle the mind.

The most logical explanation is that all civilizations, including ours,
destroy themselves (or are destroyed) before interstellar colonization
begins. But, despite the logic of it, I find I can't accept that. So,
I'm left befuddled, with no neat solution. I consider this one of the
great mysteries of our time, right up there with the nature of
consciousness.

What reason have you got for assuming that? A race is equally logical.
Anyway if you really do believe we are going to destroy ourselves you
are duty bound to try to do something about it.

Von Neumann said half jokingly that supernova explosions, which we now
know to be supermassive stars, were civilizations detonating the
ultimate doomsday machine.

Von Neumann was wrong in his applicarions of games theory. The world
is not polulated by rational, intelligent Machiavellians, it is
populated by rather stupid people who often do not see where their
best interests lie. The Middle East situation to take an example is
really a "stag hunt" where both participants would do far better to
cooperate, if only they would realize it.


- Ian Parker

  #10  
Old July 30th 07, 06:42 PM posted to sci.astro,sci.space.policy,sci.astro.seti
Joe Strout
external usenet poster
 
Posts: 972
Default Missing sial, iron, and nickel explains Fermi paradox

In article . com,
Ian Parker wrote:

This is missing the point. The time from the beginning of the Universe,
to the formation of a technological civilization, should take the form
of a normal distribution (i.e. bell curve), as pretty much any other
natural process does, due to the central limit theorem. If our
civilization is average (i.e. by the Copernican principle), then the
mean of this distribution is somewhere around the present. That means
that about half of the civilizations that will ever arise, arose before
us; and half will arise after us.

You are indeed correct, but how do you know the distribution is
Copernican. Why not a race? A race to me seems eminanly logical but so
far nobody has commented on it.


It's implied in what I've written; somebody (or a very small number of
somebodies) is going to evolve a technological civilization first, and
by hundreds of millions, if not billions, of years before the average
civilization. They will then proceed to colonize the galaxy, with the
result that the vast majority of civilizations will arise to find
themselves in an already-settled galaxy. Call this a race if you like,
but it's an extremely unfair one, since most likely it will be over
before the #2 civilization even appears.

If a race is indeed true there are
consequences in terms of how we should act.


Like what? We're talking about things on the timescale of hundreds of
millions of years. What we do in the next century or two isn't going to
make any difference.

1) We need to know how close to us other civilizations are. We are
running 42km and we need to look back and see where the other
competitors are. A 1km telescope - figure admittedly pluced out of the
air.


This seems rather pointless. All indications are that there is NOBODY
else out there. So, either we're in some sort of nature preserve and
the ancients are intentionally hiding from us, or for some weird reason,
we happen to be the first, and the galaxy is ours.

2) We do need to build interstellar VN probes. This to an extent
represents the tape.


I'm no fan of VN probes. But we'll be out there ourselves soon enough,
if indeed the galaxy isn't settled already (as appears to be the case).

This is to some extent of the nature of a BTW. Genetic markers on
mammalian species show that the main mammal types evolved in the early
to middle Cretaceous. Fossils BTW are quite rare because fossilization
is a rare process. Genetic markers are in fact better in showing when
Evolution took place.

Thus the Cretacious/Teriary extinction was less relevant than has been
supposed up to now.


Still quite relevant, though. Whenever there is a mass extinction, it's
followed by an explosion of new species. All evidence I know of
supports the rough approximation that life in the Cretacious had gotten
stuck into a bit of a rut (a local maximum, in optimization terms), and
the impact event certainly knocked it out of that.

But of course, that makes a philosopher of science uncomfortable as
well. The odds of us, as a civilization, happening to be the first are
quite low.


In a race situation the odds are high. If we were not the first we
would all be Centurians. Alpha Centurians would have terraformed the
solar system, and we would be in a park on Earth ... if that.


Clearly, the park (if we're in one) extends beyond the Earth; we see no
signs of life anywhere in the solar system. Perhaps our whole local
cluster of stars is part of the park, or maybe it extends only to the
edge of our solar system.

However, I think the Copernican objection applies regardless. Why do we
happen to be humans, and not Centurians or whatever? If the galaxy has
been settled for hundreds of millions of years -- as would be the case
if we're not the first -- then any random observer would very likely be
one of that ancient race, not some simian on some backwater world that
still thinks digital watches are a pretty neat idea.

--
"Polywell" fusion -- an approach to nuclear fusion that might actually work.
Learn more and discuss via: http://www.strout.net/info/science/polywell/
 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Missing sial, iron, and nickel explains Fermi paradox [email protected] Policy 827 September 4th 07 06:26 PM
Missing Earth's sial explains Fermi paradox Andrew Nowicki SETI 44 May 1st 07 05:47 AM
Missing Earth's sial explains Fermi paradox Andrew Nowicki Policy 43 April 9th 07 09:48 PM
Why is 70% of Earth's sial missing? Andrew Nowicki Astronomy Misc 15 April 7th 07 08:10 PM
Fermi Paradox localhost SETI 0 August 10th 03 12:26 AM


All times are GMT +1. The time now is 10:29 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
Copyright Đ2004-2022 SpaceBanter.com.
The comments are property of their posters.