Fermi paradox, your own belief?

In message , Jim Burns
writes

I've taken a couple statistics courses, but this kind of thing
is not something I remember having to deal with. Does anyone have
a reference that explains how you get from probability
space to parameter space and what it means? I don't think a 90%
confidence interval means that you have a 90% chance of the
parameter lying within certain bounds. This problem here refutes
that, I think.

I have access to a pretty good university library and inter-
library loan, if needed.

If you are interested in this stuff there are several good Entropy and
Bayesian websites. Together with the collected works of Ed Jaynes online
- try a web search for Wolf's dice and his Brandeis lectures. I am not
sure if all of the material is all online these days - the book may be
published.

His previous collected works is in book form as E.T. Jaynes, "Papers on
probability, statistics and statistical physics".

It doesn't deal precisely with the life in the universe problem. But he
does successfully dissect and resolve some of the underlying arguments
about what it means to be truly random and how to determine the right
uninformative prior for a given problem.

Any mistakes here are mine and mine alone.
Do not blame the Bayesians for my errors.

Regards,
--
Martin Brown

In rec.arts.sf.science Paul F. Dietz wrote:
Geoff McCaughan wrote:

Not so. If "we are the only ones", this means there is some unique set of
circumstances which resulted in life in this one instance. A simpler
universe would be one where life was more mundane.

Why is this simpler?

It means the universe is more uniform.

--
Burn the land and boil the sea,
You can't take the sky from me.

In rec.arts.sf.science Paul F. Dietz wrote:
Geoff McCaughan wrote:

Not so. If "we are the only ones", this means there is some unique set of
circumstances which resulted in life in this one instance. A simpler
universe would be one where life was more mundane.

Why is this simpler?

It means the universe is more uniform.

--
Burn the land and boil the sea,
You can't take the sky from me.

In rec.arts.sf.science Paul F. Dietz wrote:
Martin Brown wrote:


We don't know what the underlying model is so there is no way to
estimate a single number for P(life) at present with such limited data.

But we apparently are allowed to express the prejudice that presence
of life is 'simpler' than its absence, in the absence of any data to
justify that prejudice.

A universe with no life would be simpler than a universe with life. However
we can't sensibly argue for a universe with no life.

A universe with one instance of life is less simple than a universe with
many instances of life.

--
Burn the land and boil the sea,
You can't take the sky from me.

In rec.arts.sf.science Paul F. Dietz wrote:
Martin Brown wrote:


We don't know what the underlying model is so there is no way to
estimate a single number for P(life) at present with such limited data.

But we apparently are allowed to express the prejudice that presence
of life is 'simpler' than its absence, in the absence of any data to
justify that prejudice.

A universe with no life would be simpler than a universe with life. However
we can't sensibly argue for a universe with no life.

A universe with one instance of life is less simple than a universe with
many instances of life.

--
Burn the land and boil the sea,
You can't take the sky from me.

Geoff McCaughan wrote:
Not so. If "we are the only ones", this means there is some unique set of
circumstances which resulted in life in this one instance. A simpler
universe would be one where life was more mundane.

Why is this simpler?

It means the universe is more uniform.

It means nothing of the kind.

Suppose that whether or not life arises in any given system (or whether
a technological civilization arises--it doesn't much matter which you
choose) is a Bernoulli trial, with probability p. Suppose that there
are N systems on which life (or techie civilization, respectively) could
arise.

If p 1/N, then the expected number of inhabited planets (or planets
with civilizations) is large. If, on the other hand, p 1/N, chances
are that there are no other planets with life (or civilizations). The
distribution is no more uniform in one case than in the other; the only
thing that has changed is the probability.

The fact that conditions are more or less uniform does not mean that
life *must* be evenly distributed to our eyes.

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

Geoff McCaughan wrote:
Not so. If "we are the only ones", this means there is some unique set of
circumstances which resulted in life in this one instance. A simpler
universe would be one where life was more mundane.

Why is this simpler?

It means the universe is more uniform.

It means nothing of the kind.

Suppose that whether or not life arises in any given system (or whether
a technological civilization arises--it doesn't much matter which you
choose) is a Bernoulli trial, with probability p. Suppose that there
are N systems on which life (or techie civilization, respectively) could
arise.

If p 1/N, then the expected number of inhabited planets (or planets
with civilizations) is large. If, on the other hand, p 1/N, chances
are that there are no other planets with life (or civilizations). The
distribution is no more uniform in one case than in the other; the only
thing that has changed is the probability.

The fact that conditions are more or less uniform does not mean that
life *must* be evenly distributed to our eyes.

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

Erik Max Francis wrote:

John Schilling wrote:

This is sufficient to reasonably say that either technological
civilization
is very, very, very rare, or that there is a very, very, very
effective
barrier preventing technological civilization from reaching Kardashev
II
status.

All it's sufficient to say is that Kardashev type II civilizations are
rare (or are very capable of hiding). The effective barrier may simply
be that the existence of type II civilizations is wishful thinking --
we're nowhere near being a type II civilization, and we have no strong
reason to believe we can or will get there in small, evolutionary steps.
We might, but we might not.

The concept of a type II civilization is an abstraction invented as a
way to delineate our thinking about what types of civilizations (if any)
might be out there. It's presumptive to take it as a concrete
prediction that we should expect to get to ourselves, and thus other
civilizations should also get to as well. It's part of an answer to the
question, "How powerful could civilizations really be?" not an answer to
the question, "How powerful should we expect civilizations to get?"

In other words, talking about a "barrier" to type II civilization
evolution may itself betray a deep-seated confidence in thinking that
type II civilizations are a concrete prediction of current technology
theory. That is not at all the case.

Even if there is only one Type-IV civilization in our universe it (they)
could change everything we know or assume about the evolution of life
and the universe. Imagine what a Type-IV could do or might be doing even
now. In that case, all bets are off about what is really going on.
Something to think about when you can't get to sleep some night. :-)


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Erik Max Francis wrote:

John Schilling wrote:

This is sufficient to reasonably say that either technological
civilization
is very, very, very rare, or that there is a very, very, very
effective
barrier preventing technological civilization from reaching Kardashev
II
status.

All it's sufficient to say is that Kardashev type II civilizations are
rare (or are very capable of hiding). The effective barrier may simply
be that the existence of type II civilizations is wishful thinking --
we're nowhere near being a type II civilization, and we have no strong
reason to believe we can or will get there in small, evolutionary steps.
We might, but we might not.

The concept of a type II civilization is an abstraction invented as a
way to delineate our thinking about what types of civilizations (if any)
might be out there. It's presumptive to take it as a concrete
prediction that we should expect to get to ourselves, and thus other
civilizations should also get to as well. It's part of an answer to the
question, "How powerful could civilizations really be?" not an answer to
the question, "How powerful should we expect civilizations to get?"

In other words, talking about a "barrier" to type II civilization
evolution may itself betray a deep-seated confidence in thinking that
type II civilizations are a concrete prediction of current technology
theory. That is not at all the case.

Even if there is only one Type-IV civilization in our universe it (they)
could change everything we know or assume about the evolution of life
and the universe. Imagine what a Type-IV could do or might be doing even
now. In that case, all bets are off about what is really going on.
Something to think about when you can't get to sleep some night. :-)


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Geoff McCaughan abagooba zoink larblortch
:

In rec.arts.sf.science Paul F. Dietz wrote:
Geoff McCaughan wrote:

Not so. If "we are the only ones", this means there is some unique
set of circumstances which resulted in life in this one instance. A
simpler universe would be one where life was more mundane.

Why is this simpler?

It means the universe is more uniform.


If there is only one planet with life on it in the entire universe, the
universe would still be perfectly uniform.