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Joseph Lazio · Guest

[quote]"r" == randyj <rjewett@ufl.edu> writes:
[/quote]
r> "Dennis Taylor" <noemail@nospam.org> wrote in message
r> news:F_VRa.454323$3C2.12374723@news3.calgary.shaw.ca...
[quote]I>m just throwing this out for the sake of argument, but here goes:
[...]
So, given this, what if one of the primary requirements for life,
for a long
enough period to allow evolution of intelligence, is the presence
of a satellite big enough or close enough to maintain a molten core
and ongoing tectonics? That would certainly reduce the probability
of life in the universe, without requiring a mystical explanation.
[/quote]
r> Doesn>t the moon also keep the earth>s axis from wobbling around
r> any more than it does, such that if we didn>t have the moon, there
r> would be way more climate variation than we now have?

I had to track this claim down recently for a proposal. As far as I
can tell, Laskar & Robutel (1993, "The Chaotic Obliquity of the
Planets," Nature, 361, 608) were among the first, if not the first, to
make this claim.

While it is true that the Moon stabilizes the Earth>s rotational axis,
I>m not sure that we can draw any grand conclusions from this fact.
Would life have arisen anyway? If life arose at the bottom of the
ocean, near a ocean-floor vent, I have difficulty understanding why
the climate on the surface would have affected what was happening 5 km
below the ocean>s surface.

Once it arose, would life have survived had the Moon not existed? I
think we know the answer to this question. There have been serious
suggestions of a "snowball Earth," in which much, if not all, of the
Earth>s surface was frozen. Thus, the Moon>s effect in stablizing the
climate could not have been that important, at least for single-celled
life.

Would multi-cellular or terrestrial life have arisen without the Moon?
Again, I don>t think we can answer this question.

--
Lt. Lazio, HTML police | e-mail: jlazio@patriot.net
No means no, stop rape. | http://patriot.net/%7Ejlazio/
sci.astro FAQ at http://sciastro.astronomy.net/sci.astro.html

Alfred A. Aburto Jr. · Guest

[quote]"Dennis Taylor" <noemail@nospam.org> wrote in message
news:F_VRa.454323$3C2.12374723@news3.calgary.shaw.ca...
I>m just throwing this out for the sake of argument, but here goes: 1)
It>s
generally accepted that Venus and Mars have no plate tectonics, while
Earth[/quote]

Actually Venus shows evidence of plate tetonics because of the volcanic
activity observed ...

[quote]does. You can maybe excuse Mars because of its size, but not Venus. 2) Any
number of books have made reference to the importance of plate tectonics
in
the creation and maintenance of the Earth>s biosphere, because of
outgassing, recycling of deposited carbon materials, etc. 3) The biggest
difference betwen Earth and the other two is the presence of the moon,
which
also is probably a major reason for the continued existance of an active
and
molten core, due to heating from tidal action.

So, given this, what if one of the primary requirements for life, for a
long
enough period to allow evolution of intelligence, is the presence of a
satellite big enough or close enough to maintain a molten core and ongoing
tectonics? That would certainly reduce the probability of life in the
universe, without requiring a mystical explanation.
[/quote]
Your>re not correct about the Moon being responsible for Earths molten core
(Joseph Lazio commented on this too)--- it does cause tides but Earth>s
molten core is due to radioactivity. Venus also has a molten core by the
way, volcanic activity, and plenty of outgasing too ...

Now think of Jupiters satellites, Io, Europa, Callisto, & Ganymede ... Io is
the most volcanic place in the Solar System (due to tidal flexing from
Jupiter and the other satellites (primarily)) --- lots of mixing and
outgassing going on there --- Europa too, a frozen surface, but perhaps with
a warm liquid water interior ... same for Callisto and Ganymede ...

I don>t think you>re arguments can be generalized as making a case for a
requirement for life ... too many factors at play ... on Earth though the
right factors came together ... how rare is that? ... no one really knows
for sure now ... but I "estimate" :) we>ll find plenty of Earth like planets
in the future ... with life too no doubt ...
Al

[quote]
This argument is covered in "Where Is Everybody" by Stephen Webb, and I
find
it particularly convincing. It>s certainly something that would get around
the principle of Mediocrity.

"Steve" <steve@nospam4me.org> wrote in message
news:0MVRa.5684$9f7.675328@news02.tsnz.net...
John Leonard allegedly said:

If this interpretation is correct then given the age of the
Universe
and
the variation about an average (say, our Earth>s age) that would be
expected (this is essentially a guess), what possibilities might exist
regarding life in our Universe? In other words if we were to assume
that
we are not unique what might be the actual age of life? Is it
reasonable
to guess, merely on the basis of our (supposed) averageness that it
could
be much greater than our own?

John Leonard

There could be races out there several billion years ahead of us.

They probably exist as pure energy and pass right through us at the
speed
of
light on their way to wherever......and we don>t even know it...and we
appear to them as dull, stupid beasts barely out of the slime.

Read your newspaper.

It>s obvious there is no intelligent life on Earth.

We flatter ourselves - vain monkies that we are.

--
Steve

[/quote]

Dennis Taylor · Guest

"Joseph Lazio" <jlazio@adams.patriot.net> wrote in message
news:llsmp09lk7.fsf@adams.patriot.net...
[quote]"DT" == Dennis Taylor <noemail@nospam.org> writes:

Well, no. A huge difference between Earth and Venus, in addition to
the presence of a moon, is the thickness of their atmospheres. I>ve
certainly never heard of the Moon>s tides as being responsible for
keeping the Earth>s interior molten. That is ascribed to the presence
of radionuclides in its interior. Venus is different, not only
because it has lost its oceans, but because its atmosphere keeps the
surface so hot.

[/quote]
Well, there>s a slight but significant difference between a molten core and
plate tectonics. I don>t think anyone>s actually ever claimed that Venus is
solid to the core, just that it has no plate movement. And given that the
moon *does* demonstratably cause a significant amount of "flex" in the
Earth>s crust due to tides, I don>t think it>s unreasonable that A) the
energy transfer would contribute to the internal heat, and B) it would help
to keep the plates distinct. Kind of like stirring a pond that>s trying to
freeze over.

As to the atmosphere, this *could* be a case of mixing cause and effect. It
may be that the atmosphere wouldn>t be as thick with a large satellite to
strip it off. It may also be, as suggested in a book called "Oxygen - The
molecule that made the world" by Nick Lane, that the presence of life on
Earth prevented a Venus-like atmosphere from developing here (this sounds
like a bit of a chicken-and-egg argument, but I>m not really qualified to
rebut).

Dennis Taylor · Guest

"Alfred A. Aburto Jr." <aaburto@pacbell.net> wrote in message
news:j0TSa.2720$e23.85286069@newssvr21.news.prodigy.com...
[quote]
Your>re not correct about the Moon being responsible for Earths molten
core
(Joseph Lazio commented on this too)--- it does cause tides but Earth>s
molten core is due to radioactivity. Venus also has a molten core by the
way, volcanic activity, and plenty of outgasing too ...
[/quote]
Books that talk about the relationship between tectonics and the presence of
life mention not just volcanic activity and outgassing, but also recycling
of carbon materials due to plate subduction (is that the right word? I>m
doing this pre-coffee, so coherence is not guaranteed). Venus may have
volcanoes, but the references I>ve seen say that there do not appear to be
any actual crustal plates (and therefore no movement, no recycling of the
surface).

And BTW, you are claiming by inference (even if you don>t realize it) that
Earth has plenty of internal radioactives, but not Venus or Mars. Why would
this be? Sounds like a violation of Mediocrity again. More on this below.

[quote]
I don>t think you>re arguments can be generalized as making a case for a
requirement for life ... too many factors at play ... on Earth though the
right factors came together ... how rare is that? ... no one really knows
for sure now ... but I "estimate" :) we>ll find plenty of Earth like
planets
in the future ... with life too no doubt ...
[/quote]

True, but it may not be a case of yes/no requirements. It might be that life
can develop anywhere, but that in order to thrive and evolve, or even
survive long-term, certain factors will improve the odds. If a molten core,
tectonics, a large satellite, a distance from the sun suitable for liquid
water, are all factors that affect the chances of life, then the Earth may
be rare in that it has enough of these factors going for it.

The current most accepted theory for the existance of the moon is a
platenary impact that shredded off part of the early Earth. Maybe that>s
where the radioactives came from (but if so, why was the impactor so
blessed? This just moves the question back one step). In this case, maybe
the moon is not a cause, but a result of the same event that made life on
Earth possible.

There are other factors that might come into play as well. A recent
Scientific American issue had an article that suggested that terrestrial
planets may only be able to develop in a doughnut-shaped subsection of the
galaxy (with our system in it, of course).

In other words, the Fermi equation may not have enough of the important
factors built in. It may be that the chances of intelligent life are
actually much lower than most people have calculated. If you get the
probability down low enough, then things like planet-busting comets and
nearby novas become significant in wiping things out.

Let>s face it - we haven>t detected other civilizations, and if they>re out
there, we should have. So the possible explanations are:

1) God really did create the universe just for us
2) Life is very rare, and / or intelligent life is even more rare
3) We just happen to be in a part of the galaxy where there are no other
civilizations.

There are other possibilities but they generally have problems.

I won>t even bother discussing the problems with #1. Leave that to
sci.skeptic. #3 just exchanges one unlikely event for another, without
really explaning anything. #2 Seems to me to be the most likely, and the
only remaining question is: what factors make the Earth so unusual that
intelligent (?) life evolved here?

Jonathan Silverlight · Guest

In message <llsmp09lk7.fsf@adams.patriot.net>, Joseph Lazio
<jlazio@adams.patriot.net> writes
[quote]
Well, no. A huge difference between Earth and Venus, in addition to
the presence of a moon, is the thickness of their atmospheres. I>ve
certainly never heard of the Moon>s tides as being responsible for
keeping the Earth>s interior molten. That is ascribed to the presence
of radionuclides in its interior. Venus is different, not only
because it has lost its oceans, but because its atmosphere keeps the
surface so hot.

[/quote]
In his story "Wrong Way Street" Larry Niven wrote that the Moon helped
there, by stripping off most of the Earth>s atmosphere. Was that ever a
serious theory? I>d guess it>s been discarded in favour of the idea that
Venus has a thick atmosphere because it>s closer to the Sun and hence
hotter.
And would the Earth still have a thick atmosphere if it hadn>t been
blown off by the collision that formed the Moon?
--
"Roads in space for rockets to travel....four-dimensional roads, curving with
relativity"
Mail to jsilverlight AT merseia.fsnet.co.uk is welcome.
Or visit Jonathan>s Space Site http://www.merseia.fsnet.co.uk

Robert Casey · Guest

Jonathan Silverlight wrote:

[quote]
In his story "Wrong Way Street" Larry Niven wrote that the Moon helped
there, by stripping off most of the Earth>s atmosphere. Was that ever
a serious theory? I>d guess it>s been discarded in favour of the idea
that Venus has a thick atmosphere because it>s closer to the Sun and
hence hotter.
And would the Earth still have a thick atmosphere if it hadn>t been
blown off by the collision that formed the Moon?
[/quote]
I had heard that the difference is that the Earth has oceans of water
that ate most of the
carbon dioxide out of the atmosphere. Making limestone out of it.
Venus either never had,
or lost most of its water, thus this didn>t happen there.

It may be that the Moon wasn>t that essential for multicullar life on
Earth. The Sun also
makes tides, though smaller. Idea being that tides help the evolution
of seashore life
that doesn>t mind a few hours being high and dry. If so, than the
odds of finding
ET should improve some, though in my previous ramblings in this thread the
odds still seem pretty long. SETI hasn>t found anything, and there>s no
credable
evidence of UFOs and such. It>s not like the european explorers of old
finding
people living on every sizable land location (except Antartica) on
Earth. All those
people had a common ancester from hundreds of thousands of years ago. They
had Kon Tiki style rafts and such to get to new locations. But man has
never
gotten outside Earth>s gravity field yet (the Moon is still inside that,
and there>s no
Moon camps right now).

Oh, there>s likely ET out there somewhere, but it>s likely that we have
to go to
another galaxy to find them. Man may well have spread thru the Milky Way
Galaxy in a hundred thousand years, and that>s a pretty short time in the
history of the universe. If ET is elsewhere in the Milky Way, he should
have shown up here by now.....

Gary Thomas · Guest

The earth has a thiner atmosphere because of all the carbonates that are
tied up in earth>s chrust through precipitation and subduction. Venus
is so hot that carbonates are not stable hence the CO2 blanket. As for
plate techtonics, the latest radar scans of the Venus surface seem to
indicate not to distant plate activity.

Gary

Jonathan Silverlight wrote:
[quote]In message <llsmp09lk7.fsf@adams.patriot.net>, Joseph Lazio
jlazio@adams.patriot.net> writes

Well, no. A huge difference between Earth and Venus, in addition to
the presence of a moon, is the thickness of their atmospheres. I>ve
certainly never heard of the Moon>s tides as being responsible for
keeping the Earth>s interior molten. That is ascribed to the presence
of radionuclides in its interior. Venus is different, not only
because it has lost its oceans, but because its atmosphere keeps the
surface so hot.

In his story "Wrong Way Street" Larry Niven wrote that the Moon helped
there, by stripping off most of the Earth>s atmosphere. Was that ever a
serious theory? I>d guess it>s been discarded in favour of the idea that
Venus has a thick atmosphere because it>s closer to the Sun and hence
hotter.
And would the Earth still have a thick atmosphere if it hadn>t been
blown off by the collision that formed the Moon?[/quote]

Matthew F Funke · Guest

Jonathan Silverlight <jsilver@merseia.fsnet.co.uk> wrote:
[quote]
I>d guess it>s been discarded in favour of the idea that
Venus has a thick atmosphere because it>s closer to the Sun and hence
hotter.
[/quote]
Actually, "hotter" -- under identical conditions -- would yield a
*thinner* atmosphere. As others have noted, Earth lost lots of its
atmosphere through chemical interactions with the crust.
A hotter atmosphere, though, would mean that more gas molecules can
achieve escape velocity (since the mean kinetic energy of the molecules
increases with temperature) -- and leave the planet forever.
--
-- With Best Regards,
Matthew Funke (mff@hopper.unh.edu)

Jonathan Silverlight · Guest

In message <3F1C81FE.8090909@ix.netcom.com>, Robert Casey
<wa2ise@ix.netcom.com> writes
[quote]Jonathan Silverlight wrote:

In his story "Wrong Way Street" Larry Niven wrote that the Moon
helped there, by stripping off most of the Earth>s atmosphere. Was
that ever a serious theory? I>d guess it>s been discarded in favour
of the idea that Venus has a thick atmosphere because it>s closer to
the Sun and hence hotter.
And would the Earth still have a thick atmosphere if it hadn>t been
blown off by the collision that formed the Moon?

I had heard that the difference is that the Earth has oceans of water
that ate most of the
carbon dioxide out of the atmosphere. Making limestone out of it.
Venus either never had,
or lost most of its water, thus this didn>t happen there.
[/quote]
The sad thing is that Venus probably had oceans in the beginning, but it
was too hot to keep them. Perhaps even life - extremophiles are quite
happy living in boiling water, but when it>s all gone so are they.
--
"Roads in space for rockets to travel....four-dimensional roads, curving with
relativity"
Mail to jsilverlight AT merseia.fsnet.co.uk is welcome.
Or visit Jonathan>s Space Site http://www.merseia.fsnet.co.uk

Vector · Guest

On Tue, 15 Jul 2003 09:58:19 -0500, "Robi"
<r_buecheler@remove.yahoo.com> wrote:

[quote]Ask yourself a few questions.
1. Did Bush really say that?
2. Did God really tell him?
3. Would God really do something like that?
[/quote]
You are right, of course. And my comment is really contrary to my
usual way of thinking. I must plead legal intoxication. At least I
don>t drink and drive (ever). My apology.

m · Guest

Considering the thermal and baric conditions on Venus, does it seem
practical to assume that the sort of long chain molecules required for the
functional/informational requirements of even a primitive life form there
could be based on Carbon? Silicon, I suppose is a potential alternative.
That is, of course, assuming that life there is based on similar precepts to
that here (as we know it)............

Dr M.

"Dennis Taylor" <noemail@nospam.org> wrote in message
news:G1USa.479150$ro6.11472818@news2.calgary.shaw.ca...
[quote]"Alfred A. Aburto Jr." <aaburto@pacbell.net> wrote in message
news:j0TSa.2720$e23.85286069@newssvr21.news.prodigy.com...

Your>re not correct about the Moon being responsible for Earths molten
core
(Joseph Lazio commented on this too)--- it does cause tides but Earth>s
molten core is due to radioactivity. Venus also has a molten core by the
way, volcanic activity, and plenty of outgasing too ...

Books that talk about the relationship between tectonics and the presence
of
life mention not just volcanic activity and outgassing, but also recycling
of carbon materials due to plate subduction (is that the right word? I>m
doing this pre-coffee, so coherence is not guaranteed). Venus may have
volcanoes, but the references I>ve seen say that there do not appear to be
any actual crustal plates (and therefore no movement, no recycling of the
surface).

And BTW, you are claiming by inference (even if you don>t realize it) that
Earth has plenty of internal radioactives, but not Venus or Mars. Why
would
this be? Sounds like a violation of Mediocrity again. More on this below.

I don>t think you>re arguments can be generalized as making a case for a
requirement for life ... too many factors at play ... on Earth though
the
right factors came together ... how rare is that? ... no one really
knows
for sure now ... but I "estimate" :) we>ll find plenty of Earth like
planets
in the future ... with life too no doubt ...

True, but it may not be a case of yes/no requirements. It might be that
life
can develop anywhere, but that in order to thrive and evolve, or even
survive long-term, certain factors will improve the odds. If a molten
core,
tectonics, a large satellite, a distance from the sun suitable for liquid
water, are all factors that affect the chances of life, then the Earth may
be rare in that it has enough of these factors going for it.

The current most accepted theory for the existance of the moon is a
platenary impact that shredded off part of the early Earth. Maybe that>s
where the radioactives came from (but if so, why was the impactor so
blessed? This just moves the question back one step). In this case, maybe
the moon is not a cause, but a result of the same event that made life on
Earth possible.

There are other factors that might come into play as well. A recent
Scientific American issue had an article that suggested that terrestrial
planets may only be able to develop in a doughnut-shaped subsection of the
galaxy (with our system in it, of course).

In other words, the Fermi equation may not have enough of the important
factors built in. It may be that the chances of intelligent life are
actually much lower than most people have calculated. If you get the
probability down low enough, then things like planet-busting comets and
nearby novas become significant in wiping things out.

Let>s face it - we haven>t detected other civilizations, and if they>re
out
there, we should have. So the possible explanations are:

1) God really did create the universe just for us
2) Life is very rare, and / or intelligent life is even more rare
3) We just happen to be in a part of the galaxy where there are no other
civilizations.

There are other possibilities but they generally have problems.

I won>t even bother discussing the problems with #1. Leave that to
sci.skeptic. #3 just exchanges one unlikely event for another, without
really explaning anything. #2 Seems to me to be the most likely, and the
only remaining question is: what factors make the Earth so unusual that
intelligent (?) life evolved here?

[/quote]


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