[Knalus]

Originally Posted by troutman

Please, get started. Which variables cannot be determined? Which can be determined? What other variables should be included?

We cannot determine:
ne: The number of planets capable of supporting life.
We have dfficulty understanding what is the minimum requirements for life. What kind of chemistry would life use? Would Silicon based Life forms use the same chemistry? Can Silicon based life-forms even exist? Would we even identify such life as life if we even saw it? Astrobiologists (an absurd term if there ever was one) can help us to determine the limits of life that this planet has been able to produce, which may give us a minimum value - of course this is IF we can determine the average planet's variables from here, which is a big if. But it's possible that the "Astrobiologists" cannot determine the range of environments capable of initiating life. In my opinion even the variable is suspect, as it is not even named correctly.

fℓ: The fraction that would go on to develop life.
We would actually have to have data - and loads of it - in order to determine this variable. It's a statistical variable, and to do statistics, we need a greater number of data points than 1. If we did have this data, we would pretty well have our answer as to whether or not there is intelligent life in the universe, and we would come up with a better equation than this farce.

fi : The the fraction of the above that actually go on to develop intelligent life.
See the above argument. In addition, what constitutes "intelligent"? Would a Dolphin be considered intelligent? I would think this would result in an argument. This variable would mean different things to different researchers, and we couldn't even come to a consensus on this if we tried. It's like trying to place a variable to a philosophical question. Each philosopher will have a different answer. Some would have more than one. As a portion of the equation, it doesn't even need to be there - we can skip directly to the next variable, and exposes the silliness of the equation itself.

fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space. This variable could possibly be confirmed based on radio telescope work, however we may have to conclude that until positive ID has been done, this number is currently approaching zero if we were to go this route.

L = the length of time for which such civilizations release detectable signals into space.
This equation once again requires more data points than zero. We don't know how long our own civilization will do such a thing. Heck, we have difficulty knowing what constitutes "detectable", as we can't even see our own signals.


Besides this, there are a great many variables that are missing, that have as great or greater a part in figuring out the answer. One being our distance of detection and ability to detect. This at least has some form of answer, even if that answer is ultimately wrong.
But the thing that gets me the most is we are missing out on the greatest mystery on our planet regarding the history of life. As a geologist, it's front and center in my way of thinking, but for an astrophysicist it's something he doesn't spend much time considering. The Cambrian Explosion was the beginnings of true multi-cellular life on the planet, and we have no answers at this point as to why it occurred, what factors were necessary for it's occurrence, why it took so long to happen, and if it was a happenstance that is not necessary for other theoretical life forms to go through. Read Stephen Jay Gould's "A Wonderful Life" to get a better handle on the extraordinary events that occurred during that odd few million years that shaped every single biological event that has since happened. I will concede that life is possible on other planets - it could even be common. But multi-cellular life? Until we figure out the mysteries of the Cambrian, it is my opinion that we may be utterly alone.


End Rant.