Frank Drake’s famous equation, first outlined at the Green Bank Conference in 1961, tries to estimate the number of civilizations in our galaxy with which communications might be possible. Such attempts are obviously speculative, but Drake concentrated on factors like the number of habitable planets, the fraction of those that contain life, and the fraction of those on which civilizations eventually appear. The equation in its entirety looks like this:
Here, N is the number of civilizations with communications potential in the galaxy, with R* the rate of star formation, fp the fraction of stars with planets, ne the number of planets that can support life per system, fl the fraction of planets that develop life, fi the fraction that develop intelligent life, fc the fraction that go on to communicate and L the life time of a technological civilization.
Zsolt Hetesi and Zsolt Regály (Eötvös University, Budapest) discuss the kind of civilizations that may emerge in a recent paper. As far as SETI goes, the real number of interest will always be the number of extraterrestrial civilizations with which we can actually make contact.
Curiously, the authors leave the existing fc variable out of their version of the equation, but they do go on to discuss the need for it, painting three types of extraterrestrial cultures: utterly silent civilizations, ‘talker’ societies (those that start communication in the middle age of their total lifetimes) and ‘colonizer’ civilizations (those for whom the communication phase is short because they later choose not to be observed). Clarifying such factors plays a major role in the equation’s outcome, but as with many of its variables, we lack the information to plug in correct values.
Nor is our understanding of the conditions under which life can form anything but fragmentary. We may learn that a Jupiter-class planet in the outer system is needed to reduce the number of objects striking the inner system. Similarly, the Moon’s effect on our planet may have been key to life’s formation, affecting not only the tides but Earth’s crust, since it is now believed that the Moon came from an ancient collision that broke it away from the Earth. The resulting thinner crust resulted in a system of plate tectonics that allowed internal heat to dissipate slowly rather than through catastrophic events (think Venus, whose thick crust seems to undergo periodic crustal melting).
Moreover, the authors believe the equation needs to take into account the kind of communications possible between civilizations. For SETI work, electromagnetic waves are usually assumed to be the method, but their speed limits the distance within which we can reasonably hope to establish contact with another civilization. Thus the Drake equation needs a factor that acknowledges the volume of the sphere of radio signaling useful for SETI. This and a better of understanding of galactic habitable zones could reduce the Drake results by a much steeper factor.
Indeed, Hetesi and Regály find huge problems with the very notion of SETI. From the paper:
If evolution is the correct theory for the emergence of life on Earth, then SETI will be one of the weakest and most dangerous enterprises of mankind. It is weak because the line of evolution is so circuitous that the expectations for the existence of other intelligent beings in our Galaxy are not well founded. It is dangerous because natural selection augurs nothing good for us in an encounter if intelligent (but evolution-made) ETIs exist. Evolution results in species that are conditioned for survival at the expense of others.
Last but not least we should mention that those who are committed to SETI ought to think through the problem of communication. It is a known fact from the philosophy of epistemology that our species cannot communicate with other species intelligently and we do not understand the process of communication well or the process of thinking. The assumption that we shall communicate with an extraterrestrial species is only a dream.
The paper is Hetesi and Regály, “A New Interpretation of Drake-Equation,” Journal of the British Interplanetary Society Vol. 59 (2006), pp. 11-14. It’s a gloomy assessment, but one that might be read as a balance to Frank Drake’s own recent thoughts. Looking at the new interest in M-class red dwarfs as possible homes to life, Drake says this: “We used to think N was about 10,000. Now I think it could be a great deal larger. To find out, we must point our radio telescopes at new targets. We have to look between stars – there could be friendly rogues calling from the gossamer swath of the Milky Way. There might be planets nestled near cold, tiny stars, where intelligent creatures would have no concept of day or night. And I wonder, do these Camelotians ever sleep?” That’s from a Wired Magazine article Drake wrote in 2004, reminding us that the range of intelligent opinions on the value of N is nowhere near settling down.
This current anti-SETI trend is certainly getting “interesting”.
Not only are all sorts of people questioning whether we have
any celestial neighbors these days because they aren’t calling
us and/or waving big signs in our direction, but the primitive
fear of danger from potential external threats seems to be on
the rise again. A sign of the sociopolitical times in general,
rather than being based on any real scientific evidence, I
would say.
So according to Hetesi and Regály, not only won’t we be able
to talk to any aliens, the mere act of searching for them (not
communicating, mind you), could spell doom for humanity.
I agree with them that the ultimate instinct of all living things
is survival, but that does not necessarily mean that to survive
as a galactic culture one must conquer and destroy any
potential competitors. It would make a heck of a lot more
sense to cooperate or at least leave each other be, since in
the Milky Way alone there should be more than enough
resources and room for everybody.
For some of the scientific evidence behind why it makes
more sense for intelligent social beings to work together
rather than fight each other, see Frans de Waal’s new
book, Primates and Philosophers: How Morality Evolved
here:
http://www.pupress.princeton.edu/titles/8240.html
As for this attitude of let’s not do SETI because not only
won’t it do any good, we could get hurt in the process –
hoy, where is that grand sense of optimism and adventure
and discovery I grew up with? Let’s not go outside, folks –
we might get hurt or, gasp, learn something new that
could contradict our preconceived notions of existence!
You know what will really doom us as a species and
civilization? Sitting on our butts doing nothing and
going nowhere. That is the road to stagnation and
extinction. To survive as a civilization, we need to
expand and explore.
Of course we could just get rid of all our technological
trappings, conduct some serious population control,
and go back to living like hunter-gatherers. The air
will be cleaner at least. And life will probably be just
dandy – until that unmonitored NEO decides to connect
with Earth one day and we go the way of the dinosaurs.
Hmmm… maybe NEOs are nature’s way of clearing a
planet of species that don’t get off the planet soon enough
to make way for one that will some day.
Loads of speculation presented here.
Let’s suppose …. with generation ships or other yet-undeveloped-but-conceivable technology, we might expect to colonize say a planet or two of e Eridani in a few centuries. eE is maybe 300-500 Million years old, which is probably much too young for the evolution of intelligent species. We might hope to colonize planets of Sirius and Procyon — both slagged by supernovas in their youth — rough on developing life — and both likely too massive and hot to survive beyond a billion years themselves, which also argues against the appearance of a local intelligent species….
And so on. The points are (a) successful interstellar colonization invalidates the reasoning behind the Drake Equation, (b) successful interstellar colonization programs conducted by ourselves or other species would very probably lead to a densely populated galaxy.
A densely populated galaxy, assuming its inhabitants use technology of the sort we might expect to develop for ourselves in the relatively near future, ought to be readily apparent to us, particularly with our present and future space telescopes. Since we don’t see this — or don’t understand that we are viewing such a thing — I’m inclined to thing that spacefaring intelligent species are, at best, rare and distant.
Happy Columbus Day!
There’s probably uncountable numbers of planets in this galaxy with life. The question of course is how often does not only intelligence but tech using intelligence arise. If tech users were prevalent “we would know them by their works.” There might be ancient races striding throughout space and time. If such races arose during earlier galactic epochs, when the galaxy was more lethal than current, then there should be additional races closer to our own developement level. Okay where are they? Either tech users are extroardinarily rare or they’re ducking and covering. Why?
SETI itself is a usefull, worthwhile endeavor. I would be cautiouse in trying active advertising till we know more and have more mature technology. No use in sticking your hand into the beaver hole instead of at least waiting for the flashlight to check it first.
Caution in becoming advertisers is warranted because all we currently can do is assume and I point to the cruder interpretation of the word assume. I firmly believe we need to move outward. I agree with ljk in some respects on this issue. I did see reference to an M class star that’s suppose to move close by within about one million years. If we’re living in some pastoral splendor at that time our decendents will have a spectacular view of their extinction when the massive amounts of cometary material stirred up come into the inner solar system.
I do not feel comfortable with the concept of early advertising though. It may be harmless. It may be beneficial. We may have, if I may mangle Kipling, some neighbor of ours try to assume “Purple Man’s Burden.” If we go out and meet them the outcomes may again run the spectrum of possibilities. At least by then we should have the option of running away.
First off, just because the world is currently going through a bit of sociopolitical turmoil doesn’t mean that we shouldn’t take the possibility of aliens being dangerous seriously. Just because we’re all security focussed doesn’t make the issue go away.
If you want to swallow a whole load of transcendence arguments and really want to advertise our presence to aliens, would you settle for some kind of compromise like putting the beacon several parsecs away from our planet?
I worry about an alien invasion about as much as I do
an earthquake: It isn’t very likely to happen where I
live, but if it does happen there is very little I can do
to stop it.
An invading ETI would have a number of relatively
low-tech ways to get rid of us and we would be
essentially powerless to stop them at our present
stage of so-called security. Controlled NEOs aimed
at Earth or a manufactured plague are just two
possibilities that come to mind.
But do you really think we have more to lose than
gain by exploring the wider galaxy? I’m not necessarily
saying we should be blaring trumpets everywhere we
go. Indeed, we might accidentally “disrupt” a somewhat
lower-level society by our uncautious explorations. But
I just cannot accept our being terrified into societal
paralysis by the presumed “monsters” out there.
If they don’t exist, no problem. If they are powerful
enough to travel between stars and for some reason
want Earth over all the other billions of star systems
and their worlds in the Milky Way, then tell me what
we could do to stop them? We don’t have a “Space
Force” and the number of nuclear missiles are rapidly
dwindling. We also don’t have a NEO deflection
strategy in place aside from various white papers.
For those of you who have children, you know that
as much as you want to protect them and do whatever
you can to keep them safe, locking them away in a
room is not the answer if you want them to grow up
into mature, functioning adults. The same goes for
human society. We now know there are plenty of
“rooms” in our reality, so staying locked in the one
called Earth while trying to maintain our present
civilization just is not reasonable. And we are not
going back to the Stone Age, at least not on a
major voluntary basis. So it’s either up or nowhere,
and let’s try to make ourselves ready for the new
neighbors.
Hi Larry
I agree about the colouring of attitudes by the socio-political environment we’re in. Certainly none of the risks nor issues have changed as far as ETIs in our galaxy go – invasion, colonisation and simple indifferent carelessness have always been risks that SF writers and thinkers have explored for decades. That a few more nervous Nellies have joined the chorus is neither here nor there – we still have no SpaceGuard and no decent in-space capabilities, but neither have we been invaded in all of our species history.
So what remains as possibilities?
(1) No ETIs capable of starflight. Possible as intelligent, technological lifeforms might be such a rare combination of accidents they almost never happen.
(2) We’re in a preserve/zoo. ETIs might have FTL and effectively police home systems of primitive worlds. We’ve no way of knowing if there are automated Wardens patrolling Sol Space, so it’s a possibility.
(3) We’re protected. A slightly more aggressive version of (2) in that we’re the product of Someone’s experiments and They’re fiercely guarding their interests.
(4) We’ve been ignored. Maybe Sun-like stars really are such an unlikely habitat for intelligence – so much UV and so little ozone, the oxic biosphere only lasts a billion years and vital methane is photochemically degraded within a century – that the Red Dwarf Federation couldn’t be bothered developing our kind of system.
(5) They’re saving us for after the main course.
Adam
Damon Knight would have loved Adam’s option 5!
I just had a thought. Its not relevant to this discussion of the Drake equation, but it is relevant to the concept of intersteller migration, if something like the Heim hyperdrive turns out to be possible. Its rather homorous as well, so hear me out.
As you know, the U.S. has many social conservatives, many people of the religious right. As you also are aware of, these people place a great deal of emphasis on the decay of society with regards to what they refer to as “unnatural’ sex acts. Now, any zoologist will tell you that when you take high-order animals (mammals such as primates and the like) and place them in unnaturally crowded conditions, they tend to engage in sexual activity much more often than in the wild and that much of the activity is unnatural (same sex sex, females humping males, etc.). given this line of thought, perhaps the reason for the purported increase in unnatural sex and sexuality in general is due to the continual increase in the global population, coupled with the fact that there is no longer a physical frontier to expand to (on Earth).
However, if there was a new frontier where we all could leave here and go somewhere new, is it not likely that population density and, hence, wonton sexuality might therefor decrease? This is where ideas such ad Heim theory and the heim drive come in.
If Heim theory is correct AND if the hyperdrive is possible (admittedly these are some Shaq O’neill sized IFs), the development of such would certainly help create alot of new frontier for people to go to.
In which case, would it not be the moral duty of every conservative christian in America to help fund the neccessary experiments to confirm (or disprove) Heim theory and, if shown to be real, help us develop the hyper drive? Afterall, reduction of “unnatural” sexuality seems to be one of their primary priorities.
Any comments?
Me again. My last comment is a little off the wall (but relevent to U.S. politics). Anyways, I have read “Rare Earth” and find its arguments compelling. Particularly the part about the necessity of having the large moon as well as plate tectonics. Especially plate tectonics. Then, I thought of Venus, which lead to a particularly depressing chain of thoughts. It actually took me several hours to get over it.
There is a theory that venus (and Mars) has no plate tectonics because it lacks a large moon. That is, the large moon generates the tidal stresses that result in plate tectonics.
There is also a theory that the “youngness” of Venus’s crust is due to the fact that there is a planet-wide crustal “over turning” where the crust turns inside out ever few hundred million years. This explains not only why the planet looks “young” but also why the planet rediates more heat energy than it absorbs from the sun. Venus is slowly radiating all of the internal heat that came out as a result of the last “over-turn” event.
The reason for this crustal over turning is that, since there is no plate tectonics, there is no incremental release of the internal energy that would occur from plate tectonics. So, the energy and pressure builds up until it releases itself in a planet-wide crustal over turn, which creates the Venus-like conditions.
Couple this with the most accepted theory on the origin of Earth’s moon (great impact), you quickly come to the conclusion that there are not a whole lot of “Earths” in our galaxy. Because any “Earth” that lacks a moon is going to be a “Venus”. Also, it may also be a result of this giant impact that gave Earth its plate tectonics, without which, we would be a Venus rather than an Earth (and we would not be here).
I’m not an astrophysicist or anything like that, but does anyone think there is validity to my thoughts with this? Particularly about Venus?
If this line of reasoning is correct, it may be that Habitable planets (planets that you can live on without a space suit – just like in Star Trek) may be as rare as blue moons, probably more rare. In which case, there really is not anywhere to go and, therefor, no reason to bother with intersteller travel. Because we are stuck with either O’neill space colonies or post-human uploading where we end up running around as “software” in somebody’s giant quantum computer, both options being just as available in this solar system as in any other. Neither of these options turn me on.
Kurt
Possibly correct. But still there should be a few or some borderline enough to be modified (i.e. more distantly orbiting habitable moons of gas giants should have a lively crust). So the effort is still worthwhile.
This point you made does bring to mind something that bothers me. In reference to Venus has anyone ever adequately explained it’s rotation?
As far as the lack of h2o to lubricate plate techtonics I’ve also seen theories that negate this to a degree. The gases formed naturally within the deep crust of a planet could fill in as lubrication for plate action. Not as well but could possibly suffice.
Adam
You’re point 4 is interesting. What would be the crustal condition of a planet orbiting within the habitable zone of a dwarf and rotationally locked? I’ve seen the theory Kurt addresses and if true would a red dwarf planet be viable?
We really do need to “get out there.” If nothing else there are galactic catastrophies that only can be survived by being far away. As a species we’re vulnerable as long as we stay not only on this planet but within this solar system. Being cautiouse is not playing ostrich. When you approach an action that can have permanent and unsavory consequences you should display some caution. Unless some plateau of science allows nearly effortless travel domination/extermination of life on other worlds would be impractical at best. However throw in some type of racial imperative be it hardwired drives, philosophical or religeous dogma and things can get interesting. Neither paranoia nor disrequard of potential bad outcomes should decide this issue.
I wonder if some of the most habitable environments might not turn out to be on the gravitiationally ‘flexed’ moons of gas giants. Well, okay, not flexed as much as Io is, but you get my drift.
Phil
Okay, this is how silly this isolationism sounds to me.
Humanity is an aggressive species. So aggressive that we’ve driven numerous other species to extinction. So aggressive that we commonly attack each other.
Let’s say that in a couple of hundred years we develop a miraculous method of travel that lets us instantly move large amounts of mass anywhere we want in the universe. Let’s further conjecture that we suddenly discover a beamed signal from space, from a place no human has ever visited. The signal seemingly indicates that it comes from a society that has only recently developed technologically, because they obviously haven’t developed our ability for instant travel and instant communication.
So as aggressive as we historically are, who here thinks that humanity’s immediate response will be to mount a large scale invasion/eradication force? Anyone?
From the article “Evolution results in species that are conditioned for survival at the expense of others.”
That’s wrong. That’s the old misunderstanding of evolution of “the strong killing off the weak”.
Evolution is about reproduction and filling an available niche. Species that reproduce go on, those that don’t leave.
Also, interstellar travel requires the mastery of energy and technology to a level that nothing we have would interest them.
The old fear that aliens will invade, take over, take all our stuff and have sex with our women is just projecting our fantasies.
Any interstellar civilization would be advanced enough so that the Prime directive would apply. And backing that up would be, as I said before, by their lights, we would have nothing worth bothering with.
SETI is safe.
JD
I am not convinced by the “Rare Earth” argument on the Moon/tectonics score and think it’s much more likely a matter of oceans on oceanic crust and water in the mantle. As for Venusian crustal overturn, there’s growing evidence that model is overly simplistic and that current Venus is the end state of a long process, perhaps involving dessication of a formerly wet planet.
However there is something to the idea that moons are important, or at least regular tides, at least as life got started. But since life kicked off on Earth pretty quickly, before most time estimates of tide-locking around red dwarfs, I can’t see later tide-locking having much influence on life’s future development.
Eric, there’s nothing stopping aliens from doing the same to us first if such a technology was possible. Perhaps lost peoples and communities are victims of alien snatchings – as Stephen Baxter and Arthur Clarke’s “Times Eye” posits. Maybe. Perhaps They are like the “Star Trek” Preservers who snatched and replanted “samples” of Earth culture throughout the Galaxy. I had some compelling dreams along those lines, but have never managed to turn them into a story plot. Maybe it’s a trope that’s been done to death?
All things are possible when there’s no data or the data is ignored. As far as we can tell there has been no large scale modification of the solar system or the Galaxy. There are no nearby Dyson Clouds and no Galactic beacons shining a radio beam or laser light at us. Thus while I doubt some of the specifics of “Rare Earth” its conclusions seem more supported by the evidence than the contrary.
SETI might be safe because there’s no one home.
Adam
Since astrobiologists have had great success in discovering life in extreme environments here on Earth, and have used them to extrapolate as to what kind of life may exist on Mars, Europa, and other vistas in our Solar System and beyond, I decided to see is there are any online analogs to a successful SETI/METI contact in my hometown newspaper.
Luckily, I struck paydirt right on the front page of the local metro section:
http://www.jacksonville.com/tu-online/stories/101006/met_5518139.shtml
No one who is urging a cautious, go-slow approach to SETI/METI is espousing an “Isolationist” viewpoint – what is being urged is a common sense approach that takes into account aliens will have a full range of emotions and characteristics in common with Humans. The notion that all aliens are good could see Adam’s Option #5 becoming a reality at some point in the future.
I at least am not advocating that every ETI with a starship
is necessarily a “good” being – and we could debate what
is good and evil in the larger context on its own thread.
While I am also not advocating that we should just fly to
and colonize every planet in the galaxy, I think it is a bit
premature to worry about finding alien “monsters” on
other worlds. We have just 5 robot space probes heading
out to the stars. Two we no longer communicate with,
2 more will be silent by 2025, and the most recent one
hasn’t even flown by Jupiter yet.
None of them are designed to explore even the nearest
star system, which would take them 77,000 years to reach
as it is. The only ETI who will ever find them are ones
with a very sophisticated interstellar culture and a lot of
serendipity.
As for sending actual starships to other places in the
galaxy, I don’t forsee even the first real robot probe
heading to Alpha Centauri until the end of this century
or maybe early in the 22nd – but please, prove me
wrong on this one! We won’t even have humans on
Mars until the 2040s at the estimated earliest, so I
have trouble seeing us get a star probe out any
sooner. But again, prove me wrong here.
The point is, we don’t have to worry about our starships
infiltrating the galaxy for a long, long time. Most of the
deliberate METI will take decades to reach their targets
(with decades for a return response, if any), the longest
being the Arecibo Message to Messier 13, which will take
25,000 years just to get to that globular star cluster.
My theory is that really advanced ETI may know about
our presence through remote means – see Robert Bradbury’s
work on Matroishka Brains at:
http://www.aeiveos.com:8080/~bradbury/MatrioshkaBrains/index.html
But that to such beings we aren’t worth the effort to meet
or contact; we’re just a record in their vast databases.
If we survive and grow up enough to encounter them
on their own turf – fine. If not, the Universe will carry
on as before. After all, outside of a few astronomers,
who else on Earth notices a supernova and does little
more than wonder if any civilizations around or near
the exploded star got fried into oblivion?
Maybe the real issue here about everyone’s alternating
rejection of alien life and fear of what it might do to us
comes from the fact that they – which also means the
Universe as a whole – IGNORES US. Worse than any
alien invasion (at least it would mean that somebody
wants us for something, albeit negative) is the thought
that we humans aren’t even important enough to warrant
a hello by other beings.
Is this the last of the Great Demotions? Have we gone
from thinking we’re the Focus of Everything, Even God,
to we’re just a tiny blip on the galactic radar and the
rest of the Cosmos has better things to do?
Or is it that, like children growing into adolesence, we
are finally starting to realize that there are bigger things
than Mommy and Daddy (Earth, human society) and the
idea of an unknown Universe with all its potential dangers
and possibilities frightens and thrills us at once?
The “Rare Earth” guys believe that having the large moon is necessary for plate tectonics because the tidal stresses generate mantle “currents” necessary to break up the crust into plates and to keep it broken up. This may not be the case, but it does make sense to me. The point is that we have only three data points to work with: Earth, Venus, and Mars. Earth’s got plate tectonics, the other two don’t. Since Mars is small, it might not count as a data point, which leaves Venus. Why Venus rotates as it does is also a mystery yet to be explained.
Given the large numbers of “hot and warm jupiters” that we are finding, a planet orbiting a warm jupiter (i.e. the jupiter being in the goldilocks orbit)will certainly get enough tidal stresses to have plate tectonics. Maybe most habitable planets in the galaxies do indeed orbit warm jupiters. The problem with this is the current theory postulates that the jupiters migrate inward over time (because they have to form outside the “snow line”), which suggests that cold jupiters become warm jupiters and later hot jupiters before the death spiral into the parent star. This suggests a “short” biological time period for such a habitable planet.
On the other hand, if the common pattern is for the jupiters to spiral inward over time, why haven’t our Jupiter and Saturn done the same?
There is alot we don’t know. It seems to me that only two comments can be said at this time. One, there are a lot of hot jupiters out there. Two, the presence of detected extra solar planets does correlate with the metallicity of the parent star. The correlation with steller metallicity does suggests that at least some of our theories of steller and planet formation are correct.
On the issue of ETI, it is actually the opinion of almost every evolutionary biologists that the evolution of intelligence is so unlikely of occurance that it is unlikely to have been repeated in the rest of the galaxy, even if there are zillions of habitable planets.
I have a different “Drake’s equation”, based loosely on “Rare Earth”. It goes like this:
1) How many G and K stars are there?
2) How many G and K stars are there in the galactic habitable zone?
3) Of the stars that pass these first two filters, how many of them have the right metallicity? Current survey suggests about 10-20% in our steller neighborhood.
4) Those that pass this filter, how many have an Earth-sized planet in the goldilocks zone AND the Jupiter in the right place (current thought is the jupiter screens out all of the debris that tend to whack planets)?
5) After all of this, then you get to the “Rare Earth” criteria like having the large moon, plate tectonics, tides, and everything else they rant about.
6) After all of these filters, you then have a one in 400,000 chance of getting a technolgical civilization. I figure this because out of the 4 billion year it took to make us, we’ve had civilization for 10,000 year. Hence, the 1:400,000 chance assumption.
I really do think we’re alone. At least in the Milky Way.
Look at the bright side. We get FTL, think of all that real estate and resources out there, all of it just for us!
Somebody better tell the Mexicans not to stir
up any hypothetical trouble for us in the galaxy,
because they are planning to conducting their
own METI:
Time capsule to be beamed from Mexican pyramid
Reuters Oct. 10, 2006
*************************
Mexico’s Teotihuacan, once the
center of a sprawling pre-Hispanic
empire, is set to become the launch
pad for an attempt to communicate
with extraterrestrial life.
Starting on Tuesday, enthusiasts from
around the world will have a chance to
submit text, images, video and sounds
that reflect human nature to be included
in the message. Those…
http://www.kurzweilai.net/email/newsRedirect.html?newsID=5975&m=25748
I don’t entirely buy the concept of it being a requirement to have a massive moon capable of stabilising the axis or to drive tectonic plates. Surely somewhere between the too-small tidal effects we get from our local star and the tides in the red dwarf habitable zone which synchronise the planet’s rotation, there are stars around which a habitable planet would receive solar tides comparable to our lunar tides. A quick calculation I did suggests 55 Cancri might be in the right range for this kind of thing.
Presumably interplanetary smashes are common even if moon-forming ones are rare, so maybe we’re just orbiting an unusually massive star and receiving unusually small solar tides for a habitable world.
In order to account for the true prevalence of communicative civilizations (that is, those that engage in METI), I suggest we introduce a METI factor fm into the classical Drake Equation:
http://www.cplire.ru/html/ra&sr/irm/Drake_equation.html
A blog declares the Drake Equation is obsolete:
http://sentientdevelopments.blogspot.com/2007/05/drake-equation-is-obsolete.html
To quote:
Although possibly outside the auspices of this discussion, the Drake Equation does not account for the presence of post-radio capable civilizations, particularly post-Singularity machine intelligences. This is a problem because of what these types of civilizations might be capable of.
The equation is used to determine the number of radio capable civilizations as they conduct their business on their home planet. Again, this is a vary narrow view of ETI’s and the space of all possible advanced civilizational types. Moreover, it does not account for any migratory tendency that advanced civs may have.
The Drake Equation does not tell us about exponential civilizational growth on account of Von Neumann probe disbursement. It does not tell us where advanced ETI’s may be dwelling or what they’re up to (e.g. Are they outside the Galaxy? Do they live inside Jupiter Brains? Do they phase shift outside of what we regard as habitable space? etc.). This is a serious shortcoming because the answers to these questions should help us determine not just where we should be looking, but they can also provide us with insight as to the makeup of advanced intelligence life and our own potential trajectory.
In other words, post-Singularity ETI’s may represent the most common mode of existence for late-stage civilizations. And that’s who we should be looking for rather than radio transmitting civs.
The Man To Contact When Calling Home From Across The Galaxy
by Leslie Mullen for Astrobiology Magazine
Moffett Field CA (SPX) Aug 28, 2007
In the field of astrobiology, few people have had a bigger influence than Frank Drake. In 1960, he conducted the first radio Search for Extraterrestrial Intelligence (SETI). He formulated the “Drake Equation,” which set the standard for the search for alien life in our galaxy, providing scientific rigor to a field of inquiry that previously had been derided as pure science fiction.
Drake, along with Carl Sagan, designed plaques that were carried on the Pioneer 10 and Pioneer 11 spacecraft. The Pioneer plaques depicted symbolic messages for any aliens the spacecraft might encounter as they travel outside our solar system. Drake also worked with Sagan on the Voyager Golden Record. Containing sounds and images of life on Earth, the record was sent on both the Voyager 1 and Voyager 2 spacecraft.
Full article here:
http://www.spacedaily.com/reports/The_Man_To_Contact_When_Calling_Home_From_Across_The_Galaxy_999.html
To quote:
AM: Have you ever felt the need to make any changes to the Drake Equation over the past 47 years?
FD: No. I do get letters all the time suggesting we should add more factors, like the role of politicians. But all of that is a part of the already existing factors, so there’s been no need to change it. It’s held up well. The numbers may change, but not the equation itself. One rapidly changing factor in the equation is the typical number of planets in the habitable zone. Well, that number is changing all over the place, but that just reflects a healthy march of science towards the real truth.
Hi Larry
Just a thought, but I think the Drake Equation is a “business-as-usual” baseline – it’s what we’d expect if there’s no radical departure from our current approx. Type I status. Imagine a civilisation in near stasis after conquering its animal urges and the damage wrought by industrialisation. Uses most of the sunlight its planet receives, has built an orbital ring, but isn’t into astro-engineering, feels no compelling need to expand. Exploits rare minerals off-world to maintain technology at home, but isn’t really off-world. “Robots can do it, so we don’t have to.”
I can imagine endless reasons why that situation might obtain – it’s one of the three possible outcomes for a civilisation that Landis assumes in his Percolation Paper on the Fermi Paradox. Imagine most of the populace is whiling away near-immortality living in endless “World of War-craft” virtual realities. Perhaps they’ve all Uploaded and “VirtualLife” is better than fiddling with recalcitrant matter. They’re rich enough to maintain a SETI program as a hobbyist activity, but 99.9% of the “Real Action” is focussed inwards.
Interstellar travel is a “disruptive technology” which has planet wrecking potential – as Zebrowski and Peregrino’s book reminds us – and it may be a genie that many put back in the bottle, or never let out.