Brainstorming Clever Ways To Detect Alien Civilizations 343
Phoghat writes "In what is starting to become a familiar theme, researchers have speculated on what types of observational data from distant planetary systems might indicate the presence of an alien civilization. Potential indicators of the presence of an alien civilization might include: atmospheric pollutants, like chlorofluorocarbons – which, unlike methane or molecular oxygen, are clearly manufactured rather than just biogenically produced; propulsion signatures – like how the Vulcans detected humanity in Star Trek: First Contact; evidence of stellar engineering – where a star's lifetime is artificially extended to maintain the habitable zone of its planetary system; or debris created from asteroid mining."
Re:clearly manufactured? (Score:4, Informative)
The actual suggestion, as originally proposed by James Lovelock and expanded-upon by others, is that you look for the following:
a) Dynamic equilibriums involving chemicals that are unstable in each other's presence and/or in the presence of the radiation from their sun
Unless the chemicals are replenished, such a system MUST reduce to a stable equilibrium, although this is insufficient to say HOW they are replenished.
b) Evidence that one or more of the chemicals cannot arise naturally (ie: there ISN'T a geological process, even an unknown one, that could ever create the compound)
Not all chemicals have a natural proginator. Doesn't matter how alien the world is, doesn't matter how strange or exotic, not everything can happen naturally. The reliance on a mysterous get-out-of-jail-free "unknown" simply doesn't cut it for some stuff. Chemistry is remarkably simple and the rules of what chemical reactions can and cannot happen are very well known. Those rules are as true in any solar system in Andromeda or on any planet that has no sun at all as they are here.
c) Evidence that the compounds resulting from the natural reaction of the compounds observed in the atmosphere are BELOW the levels that can possibly occur as a result of the reactions that must be taking place
We can observe every damn element in an atmosphere along with exactly what compounds those elements combine to form, their ratios and their temperatures. There are no hidden variables within the atmosphere itself. If the chemicals that should be there aren't, then the chemicals are being removed by a variable that is NOT a part of the atmosphere.
d) As environmental conditons change (such as distance from the sun, etc), the ratio of compounds in the atmosphere changes such as to oppose that environmental change
ie: There's one or more negative feedback loops - not just on the addition of compounds to the atmosphere but also on the removal. Geological processes don't work this way. This isn't through our limited knowledge. Volcanos don't select what gasses they spew according to the time of year. If the gravitational pull is enough, they may vary in frequency. What they cannot do is vary in composition.
In addition, the vast majority of chemical reactions have POSITIVE feedback loops, not negative ones. The only way to produce negative feedback loops in sufficient quantity to overwhelm the positive feedback loops is to have a living component.
Meet these four conditions and life is guaranteed present. It may be present at some level when not all four are met (the statement isn't reversible), but it can never be absent when all are true.
There is NO extension to these rules which will allow you to determine the presence of intelligent life.