Drake Equation: How can ne*fl*fi be large?

In the Drake Equation, why do so many people assign high values for
ne*fl*fi? In order for this to be true, intelligent life has to form
in most solar systems. I find this hard to believe.

I agree with the optimistic consensus that life forms on most
habitable planets. What encourages me the most is the fact that life
formed so early in the Earth's history. It may have taken a long time
on a geologic scale, but it happened quickly on a planetary time
scale.

I strongly disagree with the idea that planetary systems average 1 or
even 2 habitable planets. Even if there really is or has been life on
Mars and Europa, that doesn't mean habitable planets are commonplace.
Remember that Mars and Europa are in the same part of the Milky Way as
Earth. I recall reading in _Astronomy_ magazine once that the Milky
Way (like the Sun and other stars) also has a habitable zone. The
idea is that places too close to the Galactic Core are subject to too
many dangers of passing stars (like orbital disruptions, asteroid
impacts, nearby supernovas, etc.) while places too far from the
Galactic Core don't have enough metals, and any worlds that form are
gas giants or tiny asteroids. Then there's the theory that our solar
system is one of the few that rarely or never spend time in a spiral
arm (which poses many of the same dangers as the center of the
galaxy). Let's not also forget that some of the planets in the right
orbit around the sun might be the wrong size, have an eccentric orbit,
or might not even exist (like a system with gas giants in the wrong
places or a multiple-star system that lacks a stable orbit at the
right distance, etc.).

I think ne is small and possibly very, very small. I think a value
of .01 is optimistic. I think .1 is Pollyannish. I think expecting
this term to be 1 or greater makes Powerball ticket buyers look
realistic in comparison.

I strongly disagree with the idea that life is likely to evolve into
intelligent life. It took only a small percentage of Earth's history
for life to evolve from no life but billions of years for life to
evolve into intelligent life. Amd even then, we are the only
intelligent species. It seems to me that there are too many steps
needed for intelligent life to form. I think there are many planets
that can support simple life at least temporarily (like Mars and
Europa) but not complex life, which is much more fragile. Note that
during Earth's history, the larger, more complex creatures (like the
dinosaurs) have been the ones most likely to be wiped out while the
simpler organisms (like microbes and bugs) are the ones most likely to
survive. Even on planets where complex life forms, I think the chance
of intelligence is modest. There must be many planets where the most
intelligent creatures are comparable to dinosaurs, rats, ants, wolves,
etc.

I think fi is small and possibly very, very small. I think a value
of .01 is optimistic.

So we have (rounding to the nearest power of 10), R=1, fp=1, ne=.01,
fl=1, fi=.01, fc=1, and L=10^9. My wild guess of N is 100,000. If we
adopt my Pollyanna scenarios in which ne=.1 and fi=.1, we get
N=10,000,000. And yes, I think that many technological civilizations
really do live for billions of years. Just because we have hostile
tendencies doesn't mean that others would as well. I also think that
once a civilization colonizes space, it becomes effectively immortal.

On Tue, 10 Mar 2009 19:02:53 -0700 (PDT), Jason Hsu wrote:

In the Drake Equation, why do so many people assign high values for
ne*fl*fi? In order for this to be true, intelligent life has to form
in most solar systems. I find this hard to believe.

I agree with the optimistic consensus that life forms on most
habitable planets. What encourages me the most is the fact that life
formed so early in the Earth's history. It may have taken a long time
on a geologic scale, but it happened quickly on a planetary time
scale.

I strongly disagree with the idea that planetary systems average 1 or
even 2 habitable planets. Even if there really is or has been life on
Mars and Europa, that doesn't mean habitable planets are commonplace.
Remember that Mars and Europa are in the same part of the Milky Way as
Earth. I recall reading in _Astronomy_ magazine once that the Milky
Way (like the Sun and other stars) also has a habitable zone. The
idea is that places too close to the Galactic Core are subject to too
many dangers of passing stars (like orbital disruptions, asteroid
impacts, nearby supernovas, etc.) while places too far from the
Galactic Core don't have enough metals, and any worlds that form are
gas giants or tiny asteroids. Then there's the theory that our solar
system is one of the few that rarely or never spend time in a spiral
arm (which poses many of the same dangers as the center of the
galaxy). Let's not also forget that some of the planets in the right
orbit around the sun might be the wrong size, have an eccentric orbit,
or might not even exist (like a system with gas giants in the wrong
places or a multiple-star system that lacks a stable orbit at the
right distance, etc.).

One criticism I have of the Drake equations is that they deal in averages.
Many of the suns for varies reasons including these you outlined here are
not suitable.



I think ne is small and possibly very, very small. I think a value
of .01 is optimistic. I think .1 is Pollyannish. I think expecting
this term to be 1 or greater makes Powerball ticket buyers look
realistic in comparison.

Several people have made similar observations, one person put it at close
to zero.



I strongly disagree with the idea that life is likely to evolve into
intelligent life. It took only a small percentage of Earth's history
for life to evolve from no life but billions of years for life to
evolve into intelligent life. Amd even then, we are the only
intelligent species. It seems to me that there are too many steps
needed for intelligent life to form. I think there are many planets
that can support simple life at least temporarily (like Mars and
Europa) but not complex life, which is much more fragile. Note that
during Earth's history, the larger, more complex creatures (like the
dinosaurs) have been the ones most likely to be wiped out while the
simpler organisms (like microbes and bugs) are the ones most likely to
survive. Even on planets where complex life forms, I think the chance
of intelligence is modest. There must be many planets where the most
intelligent creatures are comparable to dinosaurs, rats, ants, wolves,
etc.

Our world it almost covered with water. One point I have never heard
mentioned is what if the world is covered with water. Intelligent life
could not have fire.


I think fi is small and possibly very, very small. I think a value
of .01 is optimistic.

So we have (rounding to the nearest power of 10), R=1, fp=1, ne=.01,
fl=1, fi=.01, fc=1, and L=10^9. My wild guess of N is 100,000. If we
adopt my Pollyanna scenarios in which ne=.1 and fi=.1, we get
N=10,000,000. And yes, I think that many technological civilizations
really do live for billions of years. Just because we have hostile
tendencies doesn't mean that others would as well. I also think that
once a civilization colonizes space, it becomes effectively immortal.


The problem is put one spacefaring colonizing ETI, give them speeds for .1C
and 100 million years which is nothing in geographical time. You now have
the Fermi paradox one of the greatest mysteries today.