Fermi paradox, your own belief?

I think the heart of the problem of Fermi's paradox is sophistry, i.e. the
premise itself is flawed by it's wording and unspoken implications....
That being" that an alien civilization might be advanced enough to travel
the galaxy, but they cannot be advanced enough to be here and observe us
without our knowledge."
Orion

"gswork" wrote in message
om...
ON the off chance you don't know, Fermi's paradox is basically - if
even conservative estimates suggest that adanced life in the galaxy is
abundant then even more conservative estimates show that the entire
galaxy should be explored already, so why aren't the aliens here?

various reasons are given as to why they're not : advaned life is
rarer than we thought, space travel is more difficult than we think,
they are here(!), they've put us in quarantine until we grow up,
civilisation destroy themselves at some crucial point etc etc.

This is old hat for many, but it may interest or stimulate you. I'm
really just looking for opinions, your opinions on why we don't
encounter aliens regularly.

The one i tend to believe is that whilst life may not be so
overwhelmingly rare, advanced technological space faring life is -
very very rare indeed. So rare it may even be that we are alone in
this galaxy, or maybe sharing with a handful of others dotted around
the milky way, with one each in the magallenic clouds!

I think this because, based on what i've read, Earth has been around
for nearly 5 billion years, microscopic life for perhaps 3 billion,
and more complex life for only 700 million or so. Not only that but
left to it's own devices the Earth would have only another few hundred
million years before the Sun's ever increasing heat output starts to
tip the delicate balance of the eco system and potentially make it too
hostile to complex life, driving life back into the seas, back into
more primitive forms.

A couple of billion years hence, maybe more, the earth tips over into
runaway greenhouse and becomes a milder, but equally deadly version of
Venus, utterly devoid of life. Later still the sun exits the main
sequence, becomes a red giant, and that's pretty much it for the inner
3 planets.

So Earth can support complex life for something like 1.5 billion years
start to finish. It took half that to to get to Humans, and were not
100% sure that we are really a space faring race (in interstellar
terms) or will last long enough to become one. If the dinosaur killer
event didn't happen then there'd be no reason for humans to exist.
Indeed it would only take a series of subtle variations and humans
would not have evolved at all. The evolution of technological
advanced intelligent animals seems really very precarious.

Life itself may be rarer than we think, and space faring life may be
so exceptional that it's more likely we *won't* encounter aliens.

An interesting book on this is Isaac Asimov's 'Extraterrestrial
Civilisations'. It's a 1979 book (IIRC) so the science is
occasionally missing a later discovery or theory, but mostly it makes
sense today and is well written and interesting. (perhaps you have
book recommendations in this area too?)


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Brian Tung wrote:



See Sagan's "Cosmos." He has a neat sentence in there that introduces
the entire sequence: "There will be one final, perfect day, then..."



Sagan's picture of solar evolution misses the gentle warming that
precedes its ascent up the red giant branch. The problem is that the
warming is only gentle from the perspective of the Sun. From the
perspective of the Earth and life on it, the warming will be rather
steep. So although he places that perfect day just before the RGB
ascent, so that such perfect days end abruptly, the reality (at least
as better understood today) is that they will peter out as the Sun
becomes warmer and warmer over "just" the next billion years or so.


There's actually a bigger problem for multicellular life--over the long
term, carbon dioxide in the atmosphere has been consistently declining
over earth's history due to the increased output of the sun (which
allows silicate rocks to remove more from the air), and in less than a
billion years it's predicted to reach a level where plants will no
longer be able to perform photosynthesis. It would be even less than
that if it wasn't for the recently-evolved monocot plants--grasses, palm
trees, bamboo and such--that use a form of photosynthesis that requires
much less carbon dioxide than other plants (10 parts per million as
opposed to 150 parts per million for most other plants, such as trees).
So, in a few hundred million years these types of plants will probably
replace all other forms as carbon dioxide drops to levels where only
they can survive, and then eventually they too will die out. One recent
model suggests this will happen within 500 million years or so. Some
articles on this:

http://www.recyclingpoint.com.sg/Art...thisdoomed.htm
http://www.xs4all.nl/~carlkop/toast.html
http://news.bbc.co.uk/1/hi/sci/tech/...000/649913.stm

and here's a page with a chart showing the long-term decrease in CO2
over the last few hundred million years:

http://calspace.ucsd.edu/virtualmuse...ge2/07_1.shtml

I also recommend the book "The Life and Death of Planet Earth" by Peter
Ward and Donald Browlee (at
http://www.amazon.com/exec/obidos/tg...983419-4001517
) for a pretty detailed look at what scientists predict about the long
term future of the earth and the biosphere, including the issue of
decreasing carbon dioxide. The same authors also wrote "Rare Earth" (at
http://www.amazon.com/exec/obidos/AS...983419-4001517 )
which is very relevant to the Fermi Paradox since their argument is that
while single-celled life may be common throughout the universe, there
may be quite a lot of unlikely conditions required for multicellular
life to have the chance to evolve. There's a debate about the "rare
earth hypothesis" he

http://www.space.com/scienceastronom..._1_020715.html

--
Jesse Mazer
http://www.jessemazer.com

Brian Tung wrote:



See Sagan's "Cosmos." He has a neat sentence in there that introduces
the entire sequence: "There will be one final, perfect day, then..."



Sagan's picture of solar evolution misses the gentle warming that
precedes its ascent up the red giant branch. The problem is that the
warming is only gentle from the perspective of the Sun. From the
perspective of the Earth and life on it, the warming will be rather
steep. So although he places that perfect day just before the RGB
ascent, so that such perfect days end abruptly, the reality (at least
as better understood today) is that they will peter out as the Sun
becomes warmer and warmer over "just" the next billion years or so.


There's actually a bigger problem for multicellular life--over the long
term, carbon dioxide in the atmosphere has been consistently declining
over earth's history due to the increased output of the sun (which
allows silicate rocks to remove more from the air), and in less than a
billion years it's predicted to reach a level where plants will no
longer be able to perform photosynthesis. It would be even less than
that if it wasn't for the recently-evolved monocot plants--grasses, palm
trees, bamboo and such--that use a form of photosynthesis that requires
much less carbon dioxide than other plants (10 parts per million as
opposed to 150 parts per million for most other plants, such as trees).
So, in a few hundred million years these types of plants will probably
replace all other forms as carbon dioxide drops to levels where only
they can survive, and then eventually they too will die out. One recent
model suggests this will happen within 500 million years or so. Some
articles on this:

http://www.recyclingpoint.com.sg/Art...thisdoomed.htm
http://www.xs4all.nl/~carlkop/toast.html
http://news.bbc.co.uk/1/hi/sci/tech/...000/649913.stm

and here's a page with a chart showing the long-term decrease in CO2
over the last few hundred million years:

http://calspace.ucsd.edu/virtualmuse...ge2/07_1.shtml

I also recommend the book "The Life and Death of Planet Earth" by Peter
Ward and Donald Browlee (at
http://www.amazon.com/exec/obidos/tg...983419-4001517
) for a pretty detailed look at what scientists predict about the long
term future of the earth and the biosphere, including the issue of
decreasing carbon dioxide. The same authors also wrote "Rare Earth" (at
http://www.amazon.com/exec/obidos/AS...983419-4001517 )
which is very relevant to the Fermi Paradox since their argument is that
while single-celled life may be common throughout the universe, there
may be quite a lot of unlikely conditions required for multicellular
life to have the chance to evolve. There's a debate about the "rare
earth hypothesis" he

http://www.space.com/scienceastronom..._1_020715.html

--
Jesse Mazer
http://www.jessemazer.com

"Orion" abagooba zoink larblortch
:

I think the heart of the problem of Fermi's paradox is sophistry, i.e.
the premise itself is flawed by it's wording and unspoken
implications.... That being" that an alien civilization might be
advanced enough to travel the galaxy, but they cannot be advanced
enough to be here and observe us without our knowledge."

There's a more fundamental sophistry:

N=1 is a valid sample wherefrom to derive a probability of any sort of life
in the universe as a whole.

Perhaps that probability actually turns out to be so low that we're all
that is. Show me specific evidence to the contrary, or is it actually a
matter of religion and not science?

"Orion" abagooba zoink larblortch
:

I think the heart of the problem of Fermi's paradox is sophistry, i.e.
the premise itself is flawed by it's wording and unspoken
implications.... That being" that an alien civilization might be
advanced enough to travel the galaxy, but they cannot be advanced
enough to be here and observe us without our knowledge."

There's a more fundamental sophistry:

N=1 is a valid sample wherefrom to derive a probability of any sort of life
in the universe as a whole.

Perhaps that probability actually turns out to be so low that we're all
that is. Show me specific evidence to the contrary, or is it actually a
matter of religion and not science?

Jesse Mazer abagooba zoink larblortch
:

There's actually a bigger problem for multicellular life--over the
long term, carbon dioxide in the atmosphere has been consistently
declining over earth's history due to the increased output of the sun
(which allows silicate rocks to remove more from the air), and in less
than a billion years it's predicted to reach a level where plants will
no longer be able to perform photosynthesis. It would be even less
than that if it wasn't for the recently-evolved monocot

D00d! So we have to drive around the block a few more times. BURN those
fossil fuels, baby! It's GOOD for the ecosystem.

Jesse Mazer abagooba zoink larblortch
:

There's actually a bigger problem for multicellular life--over the
long term, carbon dioxide in the atmosphere has been consistently
declining over earth's history due to the increased output of the sun
(which allows silicate rocks to remove more from the air), and in less
than a billion years it's predicted to reach a level where plants will
no longer be able to perform photosynthesis. It would be even less
than that if it wasn't for the recently-evolved monocot

D00d! So we have to drive around the block a few more times. BURN those
fossil fuels, baby! It's GOOD for the ecosystem.

Bryan J. Maloney wrote:
There's a more fundamental sophistry:

N=1 is a valid sample wherefrom to derive a probability of any sort of life
in the universe as a whole.

Perhaps that probability actually turns out to be so low that we're all
that is. Show me specific evidence to the contrary, or is it actually a
matter of religion and not science?

That doesn't contradict Fermi's Paradox (or perhaps it's better to say
Conundrum?), which says, *if* intelligent life is common, how come we
haven't seen any? It doesn't presuppose that intelligent life is in fact
common throughout the galaxy or universe.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

Bryan J. Maloney wrote:
There's a more fundamental sophistry:

N=1 is a valid sample wherefrom to derive a probability of any sort of life
in the universe as a whole.

Perhaps that probability actually turns out to be so low that we're all
that is. Show me specific evidence to the contrary, or is it actually a
matter of religion and not science?

That doesn't contradict Fermi's Paradox (or perhaps it's better to say
Conundrum?), which says, *if* intelligent life is common, how come we
haven't seen any? It doesn't presuppose that intelligent life is in fact
common throughout the galaxy or universe.

Brian Tung
The Astronomy Corner at http://astro.isi.edu/
Unofficial C5+ Home Page at http://astro.isi.edu/c5plus/
The PleiadAtlas Home Page at http://astro.isi.edu/pleiadatlas/
My Own Personal FAQ (SAA) at http://astro.isi.edu/reference/faq.txt

(Brian Tung) abagooba zoink larblortch
:

Bryan J. Maloney wrote:
There's a more fundamental sophistry:

N=1 is a valid sample wherefrom to derive a probability of any sort
of life in the universe as a whole.

Perhaps that probability actually turns out to be so low that we're
all that is. Show me specific evidence to the contrary, or is it
actually a matter of religion and not science?

That doesn't contradict Fermi's Paradox (or perhaps it's better to say
Conundrum?), which says, *if* intelligent life is common, how come we
haven't seen any? It doesn't presuppose that intelligent life is in
fact common throughout the galaxy or universe.

So it's as much as a "paradox" as "If leprechauns are common, how come we
haven't seen any?" Does this question occupy any time among those who
consider themselves to be "rational" or "skeptical" people?