Drake equation - 2005 edition

Where are they? Because I happen to believe that the number of extraterrestrial civilizations that can communicate with us is not too large, let me update the famous formula due to Drake.

The expectation value of the number of extraterrestrial TV programs that we will watch by the year 3000 is again a product of many comparably unknown quantities n_i. They count various necessary assumptions for such a TV program to be aired. Most of them are various probabilities and you can imagine that they are close to one or smaller than one by several or many orders of magnitude. By choosing the numbers according to your beliefs, you may obtain estimates that may imply that we should be watching aliens' TV programs every day - which seems ruled out - or, on the contrary, that we are almost certainly the only technologically advanced humans in the visible Universe; and in the most "pessimistic" case, even the only ones in the Landscape (where it becomes more difficult to count the number of galaxies per background). ;-)

The number of TV shows is approximately a product of

• the number of galaxies in the visible Universe
• the number of stars or, more speculatively, their equivalents per galaxy
• the percentage of stars that have planets
• the percentage of planets that have an acceptable temperature
• the percentage of planets that have an acceptable concentration of carbon
• the percentage of planets that have an acceptable concentration of oxygen (if you believe that life can be based on a completely different chemistry, sum over all possibilities)
• the percentage of planets that have an acceptable value of their spin
  
  
  
  
  
• the percentage of planets with rocky enough terrain to admit life
• the percentage of such planets with a good enough value of the gravitational field
• the percentage of planets that have viable enough system of plane tectonics that may be needed
• the percentage of planets that have a Jupiter in their solar system if it is necessary; otherwise substitute one
• the percentage of planets that have a good enough Moon if it is necessary; otherwise substitute one
• the probability of all collisions and other interactions that may be needed to create a viable Earth at the beginning
• the probability of all other physical and chemical assumptions that may be needed for early life but are not listed here or are not even known
• the probability that some critical amino acids are produced after the planet is created - which probably requires some thunderstorms and other events
• the probability that the first protein-like or RNA-like molecule - a molecule able to self-replicate and carry information - is created in a short enough time
• the probability that this RNA won't be the final stage of development of life
• the probability that a DNA-like molecule appears
• the probability that the non-trivial transition from prokaryotes to eukaryotes occurs successfully (these things may occur pretty quickly and likely if the environment is good enough - as shown by the fact that these things happened pretty quickly, relatively to the lifetime of the solar system, on Earth)
• the probability that one of the equivalents of evolution from the primitive multi-cellular organisms to the equivalent of mammals occurs successfully
• the probability that the equivalents of primates are created
• the probability that their monkeys actually start to control their environment in a slightly intelligent way
• the probability that they invent agriculture and/or organized hunting to have enough food so that they don't have to spend the whole days by looking for food
• the probability that they have big and powerful enough brains to start to develop some actual tools
• the probability that they actually start to do it and start to dominate the environment because of their intelligence as opposed to brute force
• the probability that their brute force is big enough so that the intelligence won't be defeated by brute force of other animals; sum the probabilities over all animals that are candidates for creating an advanced civilization
• the probability that their brute force is small enough so that they are actually forced to think instead of just eating the other animals forever; note that there is a marginal tension of this item with the previous item which may require a lot of fine-tuning
• the probability that their environment is challenging enough so that they must try to get better and smarter, instead of just eating bananas all the time
• the probability that their environment makes their life sufficiently easy - including pleasant enough climate - so that they can do everything necessary for their survival and other things, too
• the probability that they invent a language as a tool for communication - one that has the potential to be improved
• the probability that they successfully, compassionately, but resolutely kill a sufficient percentage of the primordial environmentalists 8,000 years before Christ who argued that it was immoral to cut the trees
• the probability that some of them become fascinated by the patterns in nature and start to develop the first ancient forms of science, arts, astronomy, and religion
• the probability that they establish big enough empires in which culture and science may be produced in a systematic fashion
• the probability that they invent trade and other things that are necessary for the accumulation of capital
• the probability that a sufficiently powerful religion that is able to force many people to memorize things and to focus on the big questions takes over, even if the actual answers at the beginning are wrong
• the probability that their Catholic Church won't convince everyone forever that the Holy Scripture contains the ultimate answers to everything that humans need to know
• the probability that they systematically develop the scientific method as a way to separate correct conjectures from the wrong ones regardless of the initial beliefs and independently of short-term interests
• the probability that they start to realize the ideas of enlightenment and the creative power of freedom; it includes the assumption that they will appreciate that the truth as they learned it does not have to be the final answer to everything
• the probability that the fate of their heretics will be difficult enough so that they're forced by the brute force of their Catholic Church to be good enough, but sufficiently simple so that some of these heretics survive for the critical time that is needed to make a real progress (note the analogy with the animals above; a similar theme occurs many times in this history)
• the probability that they actually develop a necessary set of scientific and technological discoveries
• the probability that they invent a social and political system analogous to democracy in which the leaders that become counter-productive may be replaced by the statistically more promising ones without involving a civil war and losses in each case
• the probability that their Great October Revolution won't swallow the whole world and that the communists (and similar groups) won't convince nearly everyone that they know what the ultimate model of the society should look like forever
• the probability that their civilization won't kill or otherwise neutralize a too significant part of their good and wise people because of some racial or political prejudices
• the probability that they won't exterminate themselves within a few years after they develop their weapons of mass destruction

We are obviously getting to the future, but we may continue...

• the probability that they will escape from various tempting ideas of socialism, communism, political correctness, NGOism, environmentalism, and new "atheist" religions - all of which have the power to stop or even revert the social, economic, scientific, and technological progress
• because of the importance of this assumption, let me add another related factor - the probability that the creatures will be rational enough not to be scared by various alarmist scenarios like the judgement day according to Jehovah's Witnesses or the Global Warming alarmists
• the probability that they will identify the effects of their civilization that actually have the power to cause significant problems or even instant destruction, and that they will be able to avoid the bad influence
• the probability that they will defeat all other dangerous anti-civilizational tendencies such as their counterpart of islamic fundamentalism that intends to return their worlds by millenia into the past
• the probability that a significant percentage of these beings will actually work on material and meaningful intellectual problems (such as industry, real science, and technology) relevant for making their life and civilization better, as opposed to huge social engineering programs, postmodern pseudoscience, and speculating with "higher order derivatives" and funds of hedge funds - i.e. the probability that the work of the people and the commodities sold on the market will keep its essence and won't become just a silly game with money and pseudoscientific ideas
• the probability that the life of the people who generate some kind of progress will be enough fun so that they won't start to disappear
• the probability that they will find a satisfactory source of energy that allows them to think about the ambitious goals and transcending the boundaries of their planets (and solar systems), including the probability that they will be able to defend this source of energy politically
• the probability that after all this difficult history, they will be still willing to communicate at all
• the probability that they realize and we realize that communication has two sides, and it is not enough just to listen, and it is not enough just to broadcast
• the probability that there will still be enough concentration of the capital, power, and curiosity so that they will be thinking about big scientific programs such as the GUT scale accelerators or intergalactic journeys
• the probability that the powerful ones will still be interested in these big scientific goals, as opposed to continued life with no new progress
• the probability that they will have powerful enough signal to broadcast intergalactically because the number of lines above make it likely (together with our direct observation of our Galaxy) that two such civilizations probably won't appear in the same galaxy
• for dimensional analysis, I must include the total number of TV programs that they will broadcast to the direction of Earth as a factor
• the probability that we have a good enough sensitivity to detect these signals
• the probability that we are using a compatible method of coding - and mathematics and information in general - so that we will distinguish their programs from noise
• the probability that we will actually decode their particular TV programs
• the probability that we're not the first civilization that has a chance to realize all the ambitions above
• the probability that we will realize that they are aliens even though we used to call them Albanians, for example
• the probability that we realize our relation to the aliens if there are any relations to be learned
• the probability that we will be here and care about science around the year 2500
• the probability that they will still think it's an interesting project to try to communicate with other civilizations even if the Alien's Reference Frame convinces them that the success is unlikely
• the probability that there exists no principle in science that makes the Earth physically special, equivalently to the Bible, after all ;-)

You see that there are many concerns. Even if the geometric average of the probabilities above is as large as exp(-1), you still obtain a product of order exp(-60)=10^(-26) and a very small number of candidates - probably less than one hopeful star per visible Universe.

There are simply many points at which the progress could have stopped - and the rest of the history could have been dictated by RNA dominance, prokaryotes, Catholic dogmas, environmentalism, communism, and other things whose very basic essence is to stop any further progress beyond their final vision of the planet; this includes ideologies labeled with the funny adjective "progressive".

Most of the steps in which the life on Earth was developing occured quickly; but it does not mean that they were guaranteed. Events can be fast once they occur, but they can still be unlikely. There were also many steps that required some kind of fine-tuning - the humans could have been neither too strong nor too weak, otherwise they could never develop the advanced civilization. And the same theme repeated itself many times...

You can also say that all these percentages and probabilities are really almost one - the events were nearly inevitable - and we should be seeing a lot of aliens around. With the current knowledge, I am afraid that this uncertainty can't be settled scientifically. The experimental state-of-the-art is that we don't seem to see any aliens, which makes the theory that we are unique more justified than the theory that the aliens are generic.