The Drake Equation revisited?

[irizarry]

The Drake equation has had an interesting evolution over time. Briefly resubmitted below.

Drake Equation (classical form):
N = R* • fp • ne • fl • fi • fc • L
Where,
N = The number of civilizations in our Galaxy
R* =The rate of star formation
fp = The fraction of those stars with planetary systems.
ne = The number of planets in each solar system that are suitable for life.
fl = The fraction of suitable planets on which life actually exists
fi = The fraction of planets where intelligent life exists
fc = The fraction of civilizations that develop a technology that emit signals.
L = The length of time these civilizations last with qualifying technology.


Many of these terms are open to opinion and motivated by a political sense left over from the cold war days. However I am interested in the least politically motivated variable (in my opinion-here we go again) in that of the term “ne”. Lets consider the recent extra solar planet discoveries, especially the gas giants that possibly exist in habitable zones in their respective solar systems. Gas giants in our solar system come with many moons. Of the large number of moons several are possible candidates for life. Has anyone heard of a modification for this “ne” term and multi-mooned gas giants that exist in habitable zones? You could just say this is by definition “The number of planets in each solar system that are suitable for life” and leave it at that. I am looking for slightly more detail.
That is, if it has been given any consideration. Other than the Drake Equation what other predictors has anyone heard of?
Is this the only show in town?

Irizarry
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[K6-III]

Another interesting variable is the presence of an asteroid belt, a necessary element to have sufficient extinction to drive evolution rapidly enought, but to not have too much extinction...

[irizarry]

“Excellent suggestion K6-III!” I forgot all about the evolutionary thing! I guess we can include both near earth asteroids and asteroids in the asteroid belt. And now that you mentioned the extinction thing the presence of an Oort cloud to generate comets when asteroids fail to do the job. Since the statistics are multiplicative I could add these guesses anywhere but to stay formal they should be combined in the fl or fi term or a new term altogether (what do you think is appropriate?). So much for the classical Drake Equation. Thanks

Irizarry
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P.S. This "new equation" to be is begging for a spreadsheet.

[PhysBrain]

I'd like to see a modification to the Drake equation which would indicate a probability of life of any kind being found in any one given solar system, or a given type of star. The terms in this formula would involve most of the terms in the original Drake equation, but leave out the bits about advanced lifeforms.

One of the things that always bothered me about the Drake equation is the obvious bias toward planetary bodies. While I will admit, that the presence of a habitable planet with a suitable atmosphere greatly improves the probablility of finding life as we know it, I don't think that one could rule out the formation of life in other extreme types of environments. As we have seen on our own planet with lifeforms living in the artic ice, or at the bottom of the ocean near volcanic vents, life will take hold whereever there is a sufficient source of energy and the necessary chemical compounds. I would suggest that life could develop on, say, a large cometary body in a stable orbit in the habitable zone around a star.

Anyway, just food for thought.

[irizarry]

It would be nice to have a statistical formula for predicting life “solar system by solar system.” Life could pop up anywhere! Freeman Dyson suggests that the first life we will find will be in the asteroids. This is of course if the case for ALH84001 turns out to be a false positive. This is the whole problem-there is no known recipe for life. No way of assigning a statistic because we have no external gage. Disappointing to say the least! I wonder does the Drake equation assume Gaussian or binomial distributions for each variable (or some other). It poses this question -do people think life is a binary state-life either exist or does not? Is there some in between states like Quantum has? Would a Schrodinger’s half-alive/half-dead cat show up in Drake’s Equation? And what would be the meaning of half-alive-“well along in the evolutionary process but yet not able to reproduce”. I'm grasping at straws here!

Irizarry

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[K6-III]

I remember reading that if one takes into account into the Drake Equation the necessity for an asteroid belt and a proportionately large moon, it is indeed possible and likely that we are alone.