"Borcis" wrote in message
...
Radi Khrapko wrote:
An answer to the Fermi's question, `Where are they?', is
presented.

Strictly speaking, it is answering a different question,
eg "why don't we observe them", implying the original one is rhetorical. I
don't agree that "Where are they?" is rhetorical. It's really not like
there
wasn't a lot of places where we could imagine "them" to be.

The answer is: we are alone because our Universe
is bad for a civilization. The combination of physical constants
does not need to be more fine tuned than is necessary to permit
one civilization and, since extreme fine tuning of the constants
is a very unlikely event, it is most likely that our Universe is
just good enough to permit development of only one
civilization.

Curiously enough, the assumption that we are alone would seem to
allow viewing as "significant fine-tuning" what we would otherwise
have to dismiss as probably irrelevant. Like the size of Moon, or its
apparent
diameter being the same as that of the Sun, say, or a lot of similar
coincidences that characterize our particular environment. I believe it
follows from your assumption that the more direct environment of the
unique
civilization that develops, must be regarded as very special.

The alternative anthropic principle can be
formulated as follows: `It is most likely to observe a universe
in which civilized life is an extremely rare phenomenon.'

Well, the last extremity of rarity is total absence... isn't it painful
that
the truth of your principle is discontinuous as frequency - 0 ?

How do you get at the notion that fine-tuning the universe for an unique
civilization should be less "extreme" than fine-tuning it for many
civilizations ? It seems you imply an appeal to an interestingly
pathological
version of the principle of parsimony.

Regards, Boris Borcic
--
L'anthropie met un terme aux dynamiques


My college astronomy textbook discusses this topic. They point out
that our civilization in a 1,000 years or less could send out seed ships
which would be able to launch another batch of seed ships within
10,000 years, leapfrogging across the galaxy. This process would
cover most of the Milky Way galaxy within a few million years.

Our system came into existence about 5 billion years ago. Using
an estimate of one civilization to every million stars that means
about 100,000 civilizations should have appeared in the preceeding
5 billion years of our galaxy before we came along. Each of these
100,000 civilizations had plenty of time (a few million years to
spread across the galaxy). But there is no evidence.

What could be the reason?

There is no evidence for such a prior civilization because for
some reason they all decide to stay at home. Or they all have
wars which end the civilization before they colonize. What
are the odds of all civilizations suffering this fate or choice?

There could be a civilization but it chooses not to reveal itself.

The reasons above seem pretty unlikely to me. That leaves
some unknown reason or, that civilizations are actually
extremely rare, far fewer than one in a million. Then the
most like cause for such scarcity is physical environment
and the unique series of events which created life on this planet.

"The Teleological Argument explains nothing and is fundamentally flawed
in its logic. In order for life to exist, the universe must have certain
necessary properties, but it does not follow that the universe has those
properties for the purpose of creating life. Likewise, since we exist, it
must be true that the universe has certain properties but it is incorrect to
say that since the universe has certain properties, we must exist."

Excluding creation by a deity, if we turned back the clock on this
planet to 5 billion years ago it would be very, very, very unlikely
that life would re-evolve. There is a huge string of random events
which would need to repeat to build life again and lead to civilization.

How do you get at the notion that fine-tuning the universe for an unique
civilization should be less "extreme" than fine-tuning it for many
civilizations ? It seems you imply an appeal to an interestingly
pathological
version of the principle of parsimony

There is no _purpose_ involved in what you call fine-tuning or evolution.
It is more accurate to call it a comparison of random events repeating
themselves in similar environments. Suppose there are only a trillion
random events which have to repeat identically to evolve life and lead
to a civilization. The odds of that sting of events repeating in this or
a billion universes like this one is vanishingly remote. There are a lot
of unknown variables in the Drake equation. You would have to
assume that only like 50 random events had to repeat in a suitable
environment in the universe to roughly duplicate our history.

Minsky ruled out computer simulations that might evolve life as
we know it for purposes of building consciousness precisely
because of the huge number of random variables involved in
the history of evolution--mind of mankind. I don't like the
term fine-tuning because it suggests an intentional manipulation
of an anthropic nature to a culminating event composed actually
of random happenings along the way which produced the
potential for an observing civilization of a pre-existing process.

Intractably,
Stephen

Interstellar travel is impossible since it would take centuries or
millennia to reach other stars. Aliens are not going to spend 1000
years traveling to our star, doing nothing but making a B line to our
star, when from their point of view, it's very unlikely that there is
life on a planet orbiting our star. Since you can't travel faster that
light no matter what your technology, the impossibility of
interstellar trave is independent of technology. This is the proof of
the nonexistence of UFOs. To claim otherwise is the same as believing
in UFOs. No matter what our technology, we'll never travel to other
stars except maybe nearby stars like Alpha Centauri which you could
reach in a few decades. Otherwise the distances are just too vast. You
just have no comprehension of interstellar distances. If you claim
that aliens can travel to other inhabited worlds, then why not say
that an alien space craft crashed in Roswell, New Mexico in 1947?

Absolutely no one in their right mind would suggest that Earth was the
only world with life in the entire Universe. It is unlikely but there
could even be other worlds with life within our own solar system, such
as on Mars, Ganymede, or Europa. I say "world" to encompass terrestial
planets, gas giants, moons, asteroids, comets, etc. There are about
100 billion stars in the Milky Way galaxy. If there was one planet or
moon with life for every 1000 stars, and one planet or moon with
intelligent life for every 1000 with life, that would be 100,000
worlds with intelligent life in the Milky Way, which is an average
sized galaxy out of 100 billion galaxies in the observable universe,
so you multiply 100,000 by 100 billion to get 10^16 worlds with
intelligent life in the observable universe. If you took a more
skeptical view that there was only one world with life for every
10,000 stars, and only one world with intelligent life for every
10,000 with life, that would still give us 1000 worlds with
intelligent life in the Milky Way galaxy, and 10^14 worlds with
intelligent life in the observable universe. No one would ever suggest
that Earth was the only world with life in the entire Universe.

Why not just take it a step farther and say that you are the only
organism in the Universe, and all others are figments of your
imagination? That's a small step from suggesting Earth was the only
world with life in the Universe. I mean if you are denying the
existence of life on other planets because you haven't seen it, how
many people have you personally seen? Have you seen all one billion
people in China? Have you seen all 300 million people in the United
States? Of course not, yet you accept their existence without
question.

Jeffery Winkler

http://www.geocities.com/jefferywinkler

Stephen Harris wrote:

There is no _purpose_ involved in what you call fine-tuning or evolution.

Okay, I tried to keep my fingers quiet, but this has just gotten to be
too much!

A "new" Anthropic principle goes as follows, and please note that the
primary entropic inclination of every object in a big bang induced
expanding universe says that you cannot make an unfounded faith-like
philosophical leap outside of this primary inclination of natu



1. The constants of the universe are finely tuned to require intelligent
life by the Principle of Least Action as a means for maximizing entropic
efficiency within the constraints of inherent asymmetries.

2. The weak argument simply states that the landscape is equally
important to this, and must be conducive to increasing entropy, e.g.,
the energy that we can expend in the direction of survival must be
readily expendable, so the cooperative environment enables entropy to
increase, and this means that the entropically preferred system can
raise the energy level enough to breach whatever relevant environmental
constraints in order that entropy may continue to increase.

3. In other words, the evolutionary process indicates that entropy
continues to increase to higher orders of entropic efficiency, (as it is
observably proven if humans "leaped" to evolve from apes to the fire
breathing monsters that they are today), and this is how asymmetries are
carried perpetually forth by the second law in the impossible effort
toward idealistically pure symmetry.

Nature express a primary inclination, and there's plenty of purpose
behind that. Technology is a huge player, so get off the random
roulette wheel of chance and adopt a real concept. How many systems in
nature can produce anti-particles?... puts us right up there with black
holes and super-novae in terms of entropic efficency on the high energy
end of things, and the fact that the human-system is possibly the ONLY
system that "attempts" to mix all levels of energy in nature is a strong
indication that we are linked to the universal like no other system in
nature is, but even the worst case scenario places us high on the list,
having a truly universal connection.

Like the man said... "god" doesn't throw dice', and they should have
listened the first time.

I've already show this group the physics of the entropic evolutionary
process by which the universe and humans commonly evolve, and yet they
continue as if nothing at all got said, even though I openly challenged
the group to "agree" that this is important... whatever... Whatever is
right!... Whatever happened to the good ole' days when John Baez, Matt,
Oz, Charles and others would be all over this for the neat and plausible
thing that it represents? I don't understand what's happend to this
place?

This argument, and some more radical conclusions, are in Chapter 9 of Barrow
and Tipler's "The Anthropic Cosmological Principle". In fact, it's now
called the Barrow-Tipler argument.

"Radi Khrapko" wrote in message
om...

An answer to the Fermi's question, `Where are they?', is
presented. The answer is: we are alone because our Universe
is bad for a civilization. The combination of physical constants
does not need to be more fine tuned than is necessary to permit
one civilization and, since extreme fine tuning of the constants
is a very unlikely event, it is most likely that our Universe is
just good enough to permit development of only one
civilization. The alternative anthropic principle can be
formulated as follows: `It is most likely to observe a universe
in which civilized life is an extremely rare phenomenon.'

Astronomical and Astrophysical Transactions 22 (2003) 847-850

Radi Khrapko

Radi Khrapko wrote:
An answer to the Fermi's question, `Where are they?', is
presented. The answer is: we are alone because our Universe
is bad for a civilization. The combination of physical constants
does not need to be more fine tuned than is necessary to permit
one civilization and, since extreme fine tuning of the constants
is a very unlikely event, it is most likely that our Universe is
just good enough to permit development of only one
civilization. The alternative anthropic principle can be
formulated as follows: `It is most likely to observe a universe
in which civilized life is an extremely rare phenomenon.'

Would you say that 1 on average, in each galaxy, fits the bill ?

What about 1.618 ?

Way too much ?

What about 1 in 40 galaxies ?

Happy Christmas,

(Radi Khrapko) wrote in
m:


This is an interesting idea, but the answer is far from obvious.
Assume that there are 100 universes where intelligent life is so
unlikely to occur that it only happens on one place and 1 universe
where it is a bit more likely so it exist on 900 planets. Then there
is 90% probability that we live in the last one, even if most of the
universes where life can occur are more hostile.

I cannot assume this. I can assume that there is 1 universe where it
is a bit more likely so intelligent life exists on 2 planets.

You can 'assume' anything you want, but if you want to convince others you
need some arguments too. Do you know anything about the distribution
function of the probability of life in different universes? That is what
you need to know to answer the question of how much life there is likely to
be in our universe using your method.

By observing how common life is we may then draw some conclusion
about exactly how sensitive the parameters are that control the
likelyhood of life in the universe, although obviously statistics
based on a single sample is chancy.

Life is common on the Earth only

We have no idea about whether or not that is true. We don't even know if
life exist on our closest neighbor, Mars, yet, even if we are working on
finding out.

"Borcis" wrote in message
...
Radi Khrapko wrote:

The answer is: we are alone because our Universe
is bad for a civilization. The combination of physical constants
does not need to be more fine tuned than is necessary to permit
one civilization and, since extreme fine tuning of the constants
is a very unlikely event, it is most likely that our Universe is
just good enough to permit development of only one
civilization.

Curiously enough, the assumption that we are alone would seem to
allow viewing as "significant fine-tuning" what we would otherwise
have to dismiss as probably irrelevant. Like the size of Moon, or its
apparent
diameter being the same as that of the Sun, say, or a lot of similar
coincidences that characterize our particular environment. I believe it
follows from your assumption that the more direct environment of the
unique
civilization that develops, must be regarded as very special.


There's no fine-tuning required to assume that in any significantly
large region of a galaxy that life evolves on one planet before it does on
others. It *is* possible that we're just the first in our neighborhood, if
not in our galaxy. [I think that the question of extra-galactic
civilizations is probably irrelevant from a practical perspective.]

Norm

In article ,
(Jeffery) writes:

Interstellar travel is impossible since it would take centuries or
millennia to reach other stars.

A multi-generational starship is certainly possible, as are robotic
probes without living beings aboard.

This is the proof of
the nonexistence of UFOs. To claim otherwise is the same as believing
in UFOs.

This is logically wrong. It sounds like George W. Bush saying "If
you're not with us, you're against us", overlooking the fact that there
are other possibilities. I certainly believe that interstellar travel
is possible (via multi-generational starships) but don't think there is
any evidence that Earth has been visited by aliens (thus I don't believe
in UFOs). To claim otherwise is NOT the same as believing in UFOs.

No matter what our technology, we'll never travel to other
stars except maybe nearby stars like Alpha Centauri which you could
reach in a few decades. Otherwise the distances are just too vast. You
just have no comprehension of interstellar distances. If you claim
that aliens can travel to other inhabited worlds, then why not say
that an alien space craft crashed in Roswell, New Mexico in 1947?

Again, logically wrong. There is no point in setting up your opponent
as a straw man then knocking him down.

Absolutely no one in their right mind would suggest that Earth was the
only world with life in the entire Universe. It is unlikely but there
could even be other worlds with life within our own solar system, such
as on Mars, Ganymede, or Europa. I say "world" to encompass terrestial
planets, gas giants, moons, asteroids, comets, etc. There are about
100 billion stars in the Milky Way galaxy. If there was one planet or
moon with life for every 1000 stars, and one planet or moon with
intelligent life for every 1000 with life, that would be 100,000
worlds with intelligent life in the Milky Way, which is an average
sized galaxy out of 100 billion galaxies in the observable universe,
so you multiply 100,000 by 100 billion to get 10^16 worlds with
intelligent life in the observable universe. If you took a more
skeptical view that there was only one world with life for every
10,000 stars, and only one world with intelligent life for every
10,000 with life, that would still give us 1000 worlds with
intelligent life in the Milky Way galaxy, and 10^14 worlds with
intelligent life in the observable universe. No one would ever suggest
that Earth was the only world with life in the entire Universe.

They key factor is the lifetime of a technological civilization.
However you define it, we have had one for a very short fraction of the
lifetime of the Earth. So multiply this fraction by your numbers above.
Of course, we are young and we MIGHT last much longer, but that is not
yet proven.

(Jeffery) wrote in
m:

Interstellar travel is impossible since it would take centuries or
millennia to reach other stars. Aliens are not going to spend 1000
years traveling to our star, doing nothing but making a B line to our
star, when from their point of view, it's very unlikely that there is
life on a planet orbiting our star.

If you are in suspended animation, who cares if it takes a long time to
travel? At least as long as you plan on one way colonization. Holiday
trips seems ruled out. It is likely to be expensive, yes, but far from
impossible. You could even hollow out an asteroid, build a city inside
and travel real slowly while living as ordinary.

Finding out that Earth harbors life isn't very difficult. We're planning
on sending up a telescope able to detect life on planets around nearby
stars within about a decade. You just need enough resolution to get a
spectrum of the atmosphere to see that Earth is not in equilibrium, and
as far as we understand chemistry life is the most plausible way of
generating an atmosphere with lots of oxygen. Any civilization with the
technology to attempt interstellar travel will have much better
equipment.

Since you can't travel faster that
light no matter what your technology, the impossibility of
interstellar trave is independent of technology. This is the proof of
the nonexistence of UFOs. To claim otherwise is the same as believing
in UFOs.

Certainly not. Just because interstellar travel is possible doesn't mean
anyone has been here. Would the non-existence of airplanes before 1903
have proved that heavier than air flight was impossible?

If you claim
that aliens can travel to other inhabited worlds, then why not say
that an alien space craft crashed in Roswell, New Mexico in 1947?

Because there is no evidence an alien space craft crashed in Roswell and
considerable evidence against it.

Jeffery wrote:

Interstellar travel is impossible since it would take centuries or
millennia to reach other stars. Aliens are not going to spend 1000
years traveling to our star, doing nothing but making a B line to our
star, when from their point of view,


Typically this assumes set answers to prior questions that failed to
have been asked, and admit other answers. Do aliens need to travel to
our star to become observable ? Suppose the contrary. What are the most
potent beacons of aliens existence we might imagine ? My entry is
"busting stars". Suppose that after a few centuries of detailed
observations of patterns of stars exploding in "nearby" galaxies, the
records shows that an ever-expanding proportion of explosions fits a
model of war fronts between intelligent races ?

I am sure this could make a nice DOE-subsidized paper ! "The Cosmic
Prisoner's Dilemma" could hypothesize an intergalactic arms race, s.t.
most of the intelligent races of the Universe end up learning a
compelling technology and survival strategy by observing their impact on
patterns of star explosions in other galaxies... after a millenum of
observations.

Absolutely no one in their right mind would suggest that Earth was the
only world with life in the entire Universe.

I don't agree with this. Under the premisses, our being alone *is* a
possibility that stands out both because it is (in some sense) the
simplest. What probably deserves scorn is the notion that we would ever
be able to *prove* that we are alone.

Regards, B.