Interesting Reads on ETs

On Jun 10, 8:07*pm, Fred M. McNeill wrote:



The age of the universe and its vast number of stars suggest that
unless the Earth is very atypical, extraterrestrial life should be
common. Earth is not special, but merely a typical planet, subject to
the same laws, effects, and likely outcomes as any other world. There
are an estimated 200–400 billion (2–4 ×10^11 ) stars in the Milky Way
and 70 sextillion (7×10^22 ) in the visible universe. Even if
intelligent life occurs on only a minuscule percentage of planets
around these stars, there might still be a great number of
civilizations that exist in the Milky Way galaxy alone.

Interesting articles :http://en.wikipedia.org/wiki/Extra-Terrestrial

http://en.wikipedia.org/wiki/Fermi_paradox

and others, from those.

Immortalist wrote:

On Jun 10, 8:07*pm, Fred M. McNeill wrote:

The age of the universe and its vast number of stars suggest that
unless the Earth is very atypical, extraterrestrial life should be
common. Earth is not special, but merely a typical planet, subject to
the same laws, effects, and likely outcomes as any other world. There
are an estimated 200–400 billion (2–4 ×10^11 ) stars in the Milky Way
and 70 sextillion (7×10^22 ) in the visible universe. Even if
intelligent life occurs on only a minuscule percentage of planets
around these stars, there might still be a great number of
civilizations that exist in the Milky Way galaxy alone.

Earth comes from the third generation of star production. The first
generation wouldn't have planets, and people have stated (I dunno how
authoritatively) that second generation planets would be too poor in
metals to host technology, or perhaps even a solid surface.

If you have to wait for the third round to get a useful planet, that
cuts the numbers down noticeably.

I started to discuss the Fermi paradox, but deleted that bit when I
got further down in the message and see you've already got that
covered.
--
I used to own a mind like a steel trap.
Perhaps if I'd specified a brass one, it
wouldn't have rusted like this.

On Jun 12, 11:53*am, Immortalist wrote:
The age of the universe and its vast number of stars suggest that
unless the Earth is very atypical, extraterrestrial life should be
common. Earth is not special, but merely a typical planet, subject to
the same laws, effects, and likely outcomes as any other world. There
are an estimated 200–400 billion (2–4 ×10^11 ) stars in the Milky Way
and 70 sextillion (7×10^22 ) in the visible universe. Even if
intelligent life occurs on only a minuscule percentage of planets
around these stars, there might still be a great number of
civilizations that exist in the Milky Way galaxy alone.

Or, if it's a *really* minuscule percentage, there might be one
civilization per galaxy. Or, it it's a really, really, really
minuscule percentage, just one in the whole cosmos.

Congratulations on spelling "minuscule" correctly.

On Jun 12, 10:54*am, Greg Goss wrote:
Immortalist wrote:
On Jun 10, 8:07 pm, Fred M. McNeill wrote:

The age of the universe and its vast number of stars suggest that
unless the Earth is very atypical, extraterrestrial life should be
common. Earth is not special, but merely a typical planet, subject to
the same laws, effects, and likely outcomes as any other world. There
are an estimated 200 400 billion (2 4 10^11 ) stars in the Milky Way
and 70 sextillion (7 10^22 ) in the visible universe. Even if
intelligent life occurs on only a minuscule percentage of planets
around these stars, there might still be a great number of
civilizations that exist in the Milky Way galaxy alone.

Earth comes from the third generation of star production. *The first
generation wouldn't have planets, and people have stated (I dunno how
authoritatively) that second generation planets would be too poor in
metals to host technology, or perhaps even a solid surface.

If you have to wait for the third round to get a useful planet, that
cuts the numbers down noticeably.


If the elements required for life came into existence during the
formation of third generation stars because these elements needed to
be fused and dispersed by super novas in the form of stardust, does
that mean that if there is large number of alien species that they are
only about as old as humans?

I started to discuss the Fermi paradox, but deleted that bit when I
got further down in the message and see you've already got that
covered.
--
I used to own a mind like a steel trap.
Perhaps if I'd specified a brass one, it
wouldn't have rusted like this.

On Jun 12, 12:18*pm, Butch Malahide wrote:
On Jun 12, 11:53*am, Immortalist wrote:

The age of the universe and its vast number of stars suggest that
unless the Earth is very atypical, extraterrestrial life should be
common. Earth is not special, but merely a typical planet, subject to
the same laws, effects, and likely outcomes as any other world. There
are an estimated 200–400 billion (2–4 ×10^11 ) stars in the Milky Way
and 70 sextillion (7×10^22 ) in the visible universe. Even if
intelligent life occurs on only a minuscule percentage of planets
around these stars, there might still be a great number of
civilizations that exist in the Milky Way galaxy alone.

Or, if it's a *really* minuscule percentage, there might be one
civilization per galaxy. Or, it it's a really, really, really
minuscule percentage, just one in the whole cosmos.


The Rare Earth hypothesis argues that the emergence of complex life
requires a host of fortuitous circumstances. A number of such
circumstances are set out below under the following headings: galactic
habitable zone, a central star and planetary system having the
requisite character, the circumstellar habitable zone, the size of the
planet, the advantage of a large satellite, conditions needed to
assure the planet has a magnetosphere and plate tectonics, the
chemistry of the lithosphere, atmosphere, and oceans, the role of
"evolutionary pumps" such as massive glaciation and rare bolide
impacts, and whatever led to the still mysterious Cambrian explosion
of animal phyla. The emergence of intelligent life may have required
yet other rare events. In order for a small rocky planet to support
complex life, Ward and Brownlee argue, the values of several variables
must fall within narrow ranges. The universe is so vast that it could
contain many Earth-like planets. But if such planets exist, they are
likely to be separated from each other by many thousands of light
years. Such distances may preclude communication among any intelligent
species evolving on such planets, which would solve the Fermi paradox.

http://en.wikipedia.org/wiki/Rare_Earth_hypothesis

But The mediocrity principle is the notion in philosophy of science
that there is nothing very unusual about the evolution of our solar
system, the Earth, any one nation, or humans. It is a heuristic in the
vein of the Copernican principle, and is sometimes used as a
philosophical statement about the place of humanity. The idea is to
assume mediocrity, rather than starting with the assumption that a
phenomenon is special or has somehow violated the laws of the
universe.

http://en.wikipedia.org/wiki/Mediocrity_principle

Congratulations on spelling "minuscule" correctly.

Immortalist wrote:

On Jun 12, 10:54*am, Greg Goss wrote:

If you have to wait for the third round to get a useful planet, that
cuts the numbers down noticeably.


If the elements required for life came into existence during the
formation of third generation stars because these elements needed to
be fused and dispersed by super novas in the form of stardust, does
that mean that if there is large number of alien species that they are
only about as old as humans?

Only really if you consider "about as old" as meaning "plus or minus a
billion or so years." Our planet is subject to periodic big thumps to
the gene pool, notably 250 million and 65 million years ago.
Depending on your theories, those disasters may have sped up our
evolution or delayed us by a quarter billion years.

It changes the math, but doesn't give us Star Trek or Known Space
where everyone has exactly the same tech level, advancing through the
series in near lockstep.

(In the known space version, you can imagine that the two billion year
old slaver with the mega-amplifier stepped out of a stasis field every
few dozen millenia and yelled "die" at the galaxy, eventually dying
himself a quarter million years ago or so. Or four million years ago
if you want to mesh it with Protector.)
--
I used to own a mind like a steel trap.
Perhaps if I'd specified a brass one, it
wouldn't have rusted like this.

Immortalist wrote:

and whatever led to the still mysterious Cambrian explosion
of animal phyla.

When was sex invented?
--
I used to own a mind like a steel trap.
Perhaps if I'd specified a brass one, it
wouldn't have rusted like this.

Greg Goss wrote:
Immortalist wrote:
and whatever led to the still mysterious Cambrian explosion
of animal phyla.

When was sex invented?

2007, according to your local teenagers. (Don't take my word for it, ask them.)

Dave
--
\/David DeLaney posting from "It's not the pot that grows the flower
It's not the clock that slows the hour The definition's plain for anyone to see
Love is all it takes to make a family" - R&P. VISUALIZE HAPPYNET VRbeableBLINK
http://www.vic.com/~dbd/ - net.legends FAQ & Magic / I WUV you in all CAPS! --K.

On Tue, 12 Jun 2012 18:40:08 -0400, (David
DeLaney) wrote:

Greg Goss wrote:
Immortalist wrote:
and whatever led to the still mysterious Cambrian explosion
of animal phyla.

When was sex invented?

2007, according to your local teenagers. (Don't take my word for it, ask them.)

So before that, did we reproduce by fission, or what?

--
Bill Snyder [This space unintentionally left blank]

On 6/12/2012 3:18 PM, Butch Malahide wrote:

Congratulations on spelling "minuscule" correctly.

"Miniscule" is a proper variant of "minuscule".
See any dictionary.