Limits on the Drake eq.

Write your own Drake equation in a spreadsheet so you can alter the
paramaters as you get new data and things look really good for the
density of civilizations in the galaxy until.........
You put in the age of a civilization before it either dies or somehow
becomes invisible to us or uninterested in us. Put in any reasonable
number of years for this ranging from 20,000 to 1 million years and
suddenly your density of civilizations at a given time goes
waaaaaaaaaaay down.
I assume any FTL ET will have almost no interest in us because the
volume of space available to them and hence the number of more
interesting places than earth becomes infinite then.
Consequently, the "Great Silence" should surprise nobody.

Write your own Drake equation in a spreadsheet so you can alter the
paramaters as you get new data and things look really good for the
density of civilizations in the galaxy until.........

It seems to me the Drake Equation came about in the time of the Nuclear Arms
Race. So all folks worried about how long a society could last until they
had the big war and destroyed themselves. No aliens - see guys the nuclear
war happened and wiped most out.

Today I believe we have a greatly more unfriendly universe. Massive comet
storms, colliding brown dwarfs, giant volcanoes, strange retro viruses,
colliding asteroids, nuclear war, roaming black holes, interstellar war,
screwed up governments, Governments that turn in on themselves (Ming and
Obama), climate change. -- the hostile list goes on. When you come upon a
civilization that exists - multiple it by a real small number to make it a
viable civilization that will accomplish space exploration.

Val
Kraut

On 15/02/2011 12:09 PM, Val Kraut wrote:
Write your own Drake equation in a spreadsheet so you can alter the
paramaters as you get new data and things look really good for the
density of civilizations in the galaxy until.........

It seems to me the Drake Equation came about in the time of the Nuclear Arms
Race. So all folks worried about how long a society could last until they
had the big war and destroyed themselves. No aliens - see guys the nuclear
war happened and wiped most out.

Today I believe we have a greatly more unfriendly universe. Massive comet
storms, colliding brown dwarfs, giant volcanoes, strange retro viruses,
colliding asteroids, nuclear war, roaming black holes, interstellar war,
screwed up governments, Governments that turn in on themselves (Ming and
Obama), climate change. -- the hostile list goes on. When you come upon a
civilization that exists - multiple it by a real small number to make it a
viable civilization that will accomplish space exploration.

Val
Kraut



Anyway, we still have absolutely no idea whatsoever how likely it is
that life will evolve if conditions are suitable, nor how likely it is
that intelligent life will evolve therefrom. We know only that it is
possible, since it clearly happened at least once.

So the rest of the equation doesn't matter.

Sylvia.

Here's what Frank Drake said to me at the 30th anniversary of project
Ozma at Greenbank Observatory.

Think of the Drake Equation as a way of figuring out the number of
light bulbs in a town. Let's say you've got a factory that makes 100
light bulbs a minute. That's 6,000 light bulbs an hour. Let's also
say that light bulbs last 2,000 hours. So, there's 12 million light
bulbs burning out there. Now, let's also say that 10% the light bulbs
made are red lights and 90% the light bulbs made are white lights.
So, we know that there are 1.2 million red lights and 8.8 million
white lights.

This light bulb equation has the same form as the Drake equation;

Number of bulbs = Rate of Bulb Production x Fraction of type x
Lifetime of Bulb
1,200,000 = 6,000 per hour x
0.10 x 2,000 hours


So, Drake equation;

Number of ETI = Rate of Star Formation x Fractions x Lifetime
of Civlization

The problem is we don't really know the fractions in detail, or the
lifetime. Though number of Stars in the Galaxy is 200 billion and
their life span is 10 billion years so the rate is about 2 per year.

It does give us a way to think about the problem.

Now, one thing we do know is the history of life on Earth. We know
for example that life formed as soon as conditions were right. This
was single celled life. This life lasted for half the history of life
on Earth. Then, evolution came up with photosynthesis. This created
a problem with oxygen. This caused life forms to react to the
increasing levels of oxygen - which caused them to create bodies to
shelter away from the oxygen. All this may be very unlikely to
happen. That is, its easy to create cells. Hard to create bodies.
We have no idea if the Earth were lucky or not.

Now, life went along for most of the rest of its history without
brains. Then, brains appeared. Once brains appeared it very quickly
happened that technology appeared. Now, it turns out that technology
is polluting and creates weapons of mass destruction and so far uses
up very hard to get resources - depleting them at a prodigious rate.
Whether technology and extreme intelligence is beneficial or not over
the long term isn't well known. Again, Earth may be lucky. It may be
very unlikely that intelligent species find a way to long term
survival.

So, here's one approach to the list of fractions that seems reasonable
given our history on Earth so far;

0.5 - stars that have carbon oxygen and nitrogen around (Group 1
stars)
0.1 - stars that have habitable planets
0.000001 - stars that have multi-cell life.
0.001 - stars that have life with brains
0.001 - stars that have life with stable long-lived technology

So, we multiply this together and get 5xe-14 - one in twenty trillion
stars.

This means that with 200 billion stars - only one galaxy in 100 has a
stable technology. And since we're not stable yet, its not clear
that we're going to make it yet.

Here's another way to think about it;

100 billion stars in the galaxy could have life
10 billion stars have single celled life
10,000 stars have multi-celled life
10 stars have brainy life - but short lived (remnants of
technical civilization)
1/100 galaxies have stable long lived technical species.

Carl Sagan was much more optimistic. He felt that if the conditions
were right life was certain. He also felt that life led inevitably to
intelligence and that led inevitably to technology and that led
inevitably to stability. So, he guessed there was a 10% chance at
each step;

0.5 stars have carbon nitrogen oxygen etc.
0.1 stars have planets
0.1 planets have life
0.1 living systems have brains
0.1 brains develop technology

This comes up to 5e-4 and with a rate of star formation of 2 stars per
year we have 1/1000th of all stars made having life at some point.
So, we'll have 200 million traces of technical civilizations in the
galaxy and if we have lifetimes of;

In our galaxy Sagan then predicts;

LIFETIME NUMBER

1,000 years - 1 star alive and 200 million dead
10,000 years - 10 stars alive - and 200 million dead
100,000 years - 100 stars alive - and 200 million dead
1,000,000 years - 1,000 stars alive - and 200 million dead
10,000,000 years - 10,000 stars alive - and 199.99 million dead.
100,000,000 years - 100,000 stars alive and 199.9 million dead.

Most species don't last more than 100 million years on Earth.

The science fiction writer Brin pointed out that this just shows where
life got started. He argued that once life was space faring it would
continue to be space faring even if the species changed. So, he
attempted to correct the Drake equation with this in mind. Brin
argued that ETI would spawn a space faring life system and that life
system would continue for billions perhaps trillions of years. This
means that the 200 million civilizations are all alive and have
vigorous species spinning off of them.

Still, Sagan felt that with 200 billion stars we'd see something like
200 million dead civilizations - 100,000 live stars.

This gives us 1 in 1,000 to find the remnants of a civilization
according to Sagan- or the home world of very much alive space faring
species according to Brin - and 1 in 2 million stars alive according
to Sagan - or emerging civilizations according to Brin.

So, the average separation of stars in this region of the galaxy is 1
every 65.4 cubic light years. So, a dead civilization, using Sagan's
number occurs every 25 light years or so across the galaxy. A living
civilization every 320 light years across the galaxy.

These are the most optimistic numbers.

I tend to agree with Brin about the longevity of space faring
species. But I tend to think the history of life on Earth suggests
life is rare on the scale of galaxies and common in the cosmos.

I also believe some of the studies done by NASA on star lifting back
in the 1980s and 90s show us that most intelligent species will spread
across their galaxy in time periods short relative to their evolution
and in the process turn off stars preserving their fuel and matter for
later industrial use. As a result we should see large dark voids -
filled with matter - but dark - should be centered on regions where
life originated. We do in fact see this today. We think these voids
are filled with exotic matter and that there are unexplained channels
of bright matter connecting clusters of galaxies.

Its much less mysterious and more direct to say the cosmos is filled
with galaxies and that most of them have been turned off by the tens
of thousands of space faring life forms who are organizing for long-
term survival in an expanding cosmos. We can tell that these life
forms originated between 300 million and 100 million years ago and
that they travel star to star between 1/10th and 1/3 light speed.
Which is consistent with Earth's history and with the observed void
volume sizes observed in the cosmos.

On Feb 14, 5:14*pm, Sylvia Else wrote:
On 15/02/2011 12:09 PM, Val Kraut wrote:



Write your own Drake equation in a spreadsheet so you can alter the
paramaters as you get new data and things look really good for the
density of civilizations in the galaxy until.........

It seems to me the Drake Equation came about in the time of the Nuclear Arms
Race. So all folks worried about how long a society could last until they
had the big war and destroyed themselves. No aliens - see guys the nuclear
war happened and wiped most out.

Today I believe we have a greatly more unfriendly universe. Massive comet
storms, colliding brown dwarfs, giant volcanoes, strange retro viruses,
colliding asteroids, nuclear war, roaming black holes, interstellar war,
screwed up governments, Governments that turn in on themselves (Ming and
Obama), climate change. -- the hostile list goes on. When you come upon a
civilization that exists - multiple it by a real small number to make it a
viable civilization that will accomplish space exploration.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *Val
Kraut

Anyway, we still have absolutely no idea whatsoever how likely it is
that life will evolve if conditions are suitable, nor how likely it is
that intelligent life will evolve therefrom. We know only that it is
possible, since it clearly happened at least once.

So the rest of the equation doesn't matter.

Sylvia.

Actually Earth has been a total failure in more ways than you and most
others care to admit. However, Eden/Earth has been a good prototype
of what not to do.

http://translate.google.com/#
Brad Guth, Brad_Guth, Brad.Guth, BradGuth, BG / “Guth Usenet”

On 2/14/2011 5:09 PM, Val Kraut wrote:
Governments that turn in on themselves (Ming and
Obama)

My government never "turned in on itself"; it's not my fault that
troublesome do-gooder Gordon didn't accept my offer to become dictator
of "Urth" or whatever in Daizan's name you call it. ;-)

Ming
Mingo City
Planet Mongo