The Drake Equation Revisited

[TheBigDog]

Originally Posted by Wiki

The Drake equation states that:



where:

N is the number of civilizations in our galaxy in which communication might be possible;

and

R* is the average rate of star formation per year in our galaxy
fp is the fraction of those stars that have planets
ne is the average number of planets that can potentially support life per star that has planets
fℓ is the fraction of the above that actually go on to develop life at some point
fi is the fraction of the above that actually go on to develop intelligent life
fc is the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
L is the length of time such civilizations release detectable signals into space.[2]

I was looking up the Drake Equation the other day and I wonder if it is complete. As I am doing my work on the Prophesy Chronicles, I have been doing research on the idea of interstellar travel and settlement. The equation seems to assume that civilizations don't expand beyond their initial planet. But it is already in our technical capability (if not politically or economically feasible) to begin interstellar flight now. In a century or two we might be settling on other planets. But that is not part of the Drake Equation. The typical finding of those who use the equation determine that there are between 10 and 20 civilizations such as ours at any given time in our galaxy. But what about settlement? What does the ability to explore and settle other planets do the the Drake Equation?

It seems to me that it needs at least one other factor, perhaps two or three. I have created this thread to discuss how the Drake Equation would need to be modified based upon the idea of interplanetary settlement. If that is a possibility, then what are the likely number of civilizations in our galaxy?

Bill

[Boerseun]

Well, the equation attempts to approximate "the number of civilizations in our galaxy in which communication might be possible", so I suppose if you really want to be anal about this, you should first define what you mean with "civilization".

For instance, let's say the Prophesy pans out in real life, and humanity settles its second planet. Will humanity then count as one or two civilizations?

I would venture to say that it would still be only one civilization.

Then, I guess, the only amendment necessary would be the definition of L. Because "L is the length of time such civilizations release detectable signals into space", it can be said that if a civilization is spread across more than one planet, any possible event that would prevent that civilization from releasing signals to space should only happen on one of the civilization's planets. If a planet-terminating asteroid impact happened, only one planet will be blown up. Of course, trans-planetary politics (the rise of the Galactic Amish Armed Forces, for instance) might shun technology on more than one planet simultaneously. So, in hindsight, I guess that the definition of "L" can stand as is, but it should be kept in mind that it can be much longer than thought once a civilization spreads.

[TheBigDog]

I think the formula is planet centric by design, in that a civilization belongs to only one planet. When the equation tells me that there may be 100 civilizations, how many places can I point my radio waves and communicate with someone? I would think the answer is 100, even though there may be a million inhabited worlds among those 100 civilizations. So I think it needs to reflect at a minimum the planetary count.

The whole purpose of spreading out to other planets is to prevent extinction. All the eggs in one basket and all that.

Bill

[Moontanman]

I think there is a very good chance that civilizations dispense with planets very early on. The number of planets with civilizations may not be an indicate of anything but the starting points of civilizations. Artificial habitats could be spread out with no regard what so ever for inhabitable planets. One inhabited planet might seed civilizations around every star in the galaxy, so the variable of life bearing planets could very well be meaningless.

[Donk]

Larry Niven usually tries to get his science right, if controversial at times. He writes:

For protoplasmic life forms, there are not many habitable planets in the galaxy. Nature makes an unreasonable number of conditions. To insure the right composition of atmosphere, the planet must be exactly the right distance from a G type sun, must be exactly the right size, and must have a freakishly oversized moon in its sky. The purpose of the moon is to strip away most of the planet's atmosphere, generally around 99 percent of it. Without its moon a habitable world becomes shockingly uninhabitable; its air acquires crushing weight, and its temperature becomes that of a "hot" oven. ~ World of Ptavvs

He repeated the same theme in several other places. If true, it would cast grave doubt on the accepted figure for the number of life-bearing planets. Anyone here know whether he was talking sense?

[Moontanman]

Originally Posted by Donk

Larry Niven usually tries to get his science right, if controversial at times. He writes:

He repeated the same theme in several other places. If true, it would cast grave doubt on the accepted figure for the number of life-bearing planets. Anyone here know whether he was talking sense?

It's now known as the Rare Earth Hypothesis, basically it's the idea that conditions on the Earth depend on so many variables that are connected and interdependent that the idea of complex life one another planet is all but impossible.

There are other schools of thought, one big if, the formation of the moon, is thought by some to not be all that unusual. Both Venus and Mercury are not thought to have been affected by huge impacts of the type that formed Earths moon and in those cases either no moon was formed (Mercury) or the moon formed orbited in retrograde fashion and impacted the planet (Venus). If this idea of the way terrestrial planets formed is true then large moons may not be all the rare. Until we actually see other planets it is difficult to really know.

Rare Earth hypothesis - Wikipedia, the free encyclopedia

Rare earth: why complex life is ... - Google Books

[Moontanman]

I think this is also relevant,

Hypothetical types of biochemistry - Wikipedia, the free encyclopedia

[Boerseun]

I don't think biochemistry would have any bearing on the Drake Equation.

It's fundamentally about calculating the odds for how many civilizations we can communicate with, in other words, how many civilizations have stumbled upon radio astronomy.

What their biological make-up would be to get to that point should be irrelevant, because the fundamentals of radio astronomy is universal.

I guess there could be vast numbers of civilizations that never get past our version of Roman times, where you have a big, well-structured and well-ordered civilization, which simply never gets around to inventing electricity or never go through a whole Industrial Revolution because the entrenchment of slavery simply does not make labor-saving a priority.

But that's not what the Drake Equation attempts to calculate, either.

I think what might make matters more complex, however, is that we have invented radio astronomy and we assume that its the way to go. What wonders still lie waiting for discovery as far as communication goes? We simply don't know. We assume that Pulsars are what they are, because it makes sense in the context of our current knowledge. For all we know, Pulsars can be stars that have been intentionally imploded by a super-advanced civilization to serve as galactic navigation beacons (okay - forget that they exist in the early years of the universe, far far away, but it illustrates my point). Assuming that radio astronomy is the ticket might as well be the same as a guy who invented writing and is casting bottles with notes into the ocean because that is the epitome of communication in his context, and everybody else will communicate with him in the same way. His entire life passes by without him receiving a single note. On his deathbed, he assumes that he was the only guy in the world. Yet, all around him, every second of every day, billions of radio signals criss-cross his island and fly over his lonely head. He dies, sad and alone, writing his final note. Maybe there's some other medium of communication just one step up from our current technological paradigm, and we're merely casting bottles into the ocean of space.

Consider for instance, that today, in the age of optical storage media where laser diodes are taken for granted, the only physical communications that we've ever cast into the void is phonograph records on Voyagers 1&2 - a mere few decades ago. That was the technological paradigm of the day. A needle scratching a platter.

So I guess if the Drake Equation is to be updated, current technological truths on Earth should be kept in mind, and we should remember that if we apply it as it is, we'll only find other civilizations who hold radio astronomy in the same esteem as we do.

Let's say a civilization stumbles on radio astronomy, and starts beaming its message to the universe - only to find out a mere ten or twenty years later that there's a much better system, which would achieve much better results for much less energy spent. On Earth, we would see their signal for twenty years and then silence. Would we assume that they've destroyed themselves? Who's to say that our technology would branch into the necessary direction to follow them to be able to listen to them using the new technology? There's still two civilizations, perfectly capable of communicating using radio astronomy, but the one branched into using nooglefetzers as the de facto universal communications medium, and the other branched off into using lobbleputzers. Nooglefetzers and lobbleputzers are incapable of communicating with each other, but both civilizations make excellent arguments as to why their particular technology would be the equipment of choice for other distant civilizations whom they wish to communicate with.

If there is a way to jump directly from the invention of electricity to the invention of nooglefetzers and bypass radio astronomy altogether, then we would never hear from that particular civilization at all. Which makes an excellent case that in employing the Drake Equation, we will only find civilizations very much like ourselves and we scrap all those that follow much different technological paths.

This whole argument rests very heavily on what nooglefetzers and lobbleputzers might be, and what limitations there might be on technology. But then again, the entire Drake Equation rests on guesswork in any case. It might be that radio astronomy is the end-all and be-all of galactic communication. But using the Drake method of employing your own numbers for the variables, it very well might be not, too. In which case there is a definite cause for an extra variable in the Drake Equation which might cater for this argument.

[Moontanman]

One of the fundamental factors in the Drake equation is "earth like planets" Alternate biochemistries expand that concept considerably.

[Larv]

This is my first exposure to the Drake equation. At first blush, it appears to me to be a logical extension of Isaac Asimov’s “Extraterrestrial Civilizations” (1979), in which he is makes one critically false assumption: biological life leads improbabilistically but nevertheless stochastically to intelligent life and civilization as if there were a natural driving force toward higher complexity. No such driving force exists in natural that I know of.

What I think is wrong with the Drake Equation is the absence of what I will call the “one-off factor.” The one-off factor would allow for the assumption that nature often produces just single events—ones arising from an infinitely rare set of circumstances—that produces a completely unpredictable emergent property. As such, the one-off factor would render the Drake Equation all but useless. So far as we know, abiogenesis was such an event. Add to that the improbably emergence of intelligence humans and eventually civilization on Earth, which seems to me to be much more one-off-ish than statistically predictable.

Like Asimov’s speculation, the Drake equation relies on large numbers of event opportunities that have no statistical basis for validity. They are simply saying that because there are so many planet-bearing star systems—“billions and billions and billions” (Carl Sagan)—that it is fair to expect that what happened on this planet will likely happen somewhere else.

Hasn’t the SETI experiments already proven one thing? If there were other civilized planets with our level of technology then we should be hearing from them by now. Where are the messages from space that beckon us to communicate with them? We seem to be awfully alone, don’t we?

Do all life-bearing planets eventually go through a transition from prokaryotes to eukaryotes? Do they eventually have their own versions of the Cambrian Explosion? Do they have the same kinds of environmental stresses and mass extinctions that we have had here on earth? And will they eventually adopt civilizations to cope with their vicissitudes?

Frankly, I don’t think we know nearly enough about the course of biological evolution from abiogenesis to civilization to make any judgments on the likelihood of extraterrestrial civilizations. I think the safest assumption is that we are uniquely intelligent and uniquely civilized, no matter how many “billions and billions and billions” of stars are out there.