Brainstorming Clever Ways To Detect Alien Civilizations

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."

Comments

clearly manufactured?

[Culture20]

Potential indicators of the presence of an alien civilization might include: atmospheric pollutants, like chlorofluorocarbons â" which, unlike methane or molecular oxygen, are clearly manufactured rather than just biogenically produced

Clearly? Maybe here on earth. Who knows what natural processes exist elsewhere.

Re:clearly manufactured?

[interkin3tic]

Clearly? Maybe here on earth. Who knows what natural processes exist elsewhere.

If we make unmanned probes and send them out, and one of our probes turns up CFCs in an atmosphere like our own, and we go there and find no life, then you'll have the right to say "I told you so."

Re:clearly manufactured?

[jd]

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.

Dyson Spheres

[mbone]

Dyson spheres (or swarms) would probably be the best way to detect an advanced civilization, especially a Kardashev Type II or Type III civilization.

In a Dyson sphere (or swarm) a civilization surrounds an entire star to capture most or all of its luminosity; severely cutting down on its optical luminosity but accentuating the IR luminosity. (The physics of a rigid sphere surrounding a star are pretty challenging, and some sort of swarm or cloud seems more likely, at least to our limited technological understanding.) So, to hunt for a Dyson sphere, you look for objects with an unusual excess of IR, and a lack of optical light. The IRAS IR satellite was used to search for Dyson spheres within ~ 1000 light years of the Earth (producing a handful of so-so candidates). Carrigan calls these sorts of searches "Interstellar Archaeology." They have one great advantage in that they don't require any cooperation from the other end (i.e., no beacons or other signals).

As it happens, I have recently speculated that "Object X" in M33 (the Triangulum Galaxy) could represent the signature of a Dyson sphere / swarm from 3 million light years away. If this (unlikely) possibility were to be true, it would represent the signature of a Kardashev Type III or near Type III civilization. Interstellar Archaeology is the only possible form of SETI across such vast distances.

Re:Dyson Spheres

[wierd_w]

The linked PDF you provided speculates that "object X" might be a self-obscured star, obscured by its own ejecta.

If we assume that this is indeed a dyson swarm, then the purpose might not be exclusively for collecting energy.

A category II or III civilization would be doing asto-architecture, and would need tremendous amounts of raw materials. Heavy atoms are only produced naturally in one kind of environment: in the hearts of stars. If this star is regularly expelling large quantities of cosmic dust, as the linked article postulates, then it would make an excellent "Factory". Energy would be in copious abundance, and the star itself would be churning out millions of tons of heavy atoms every minute. Even with a short (compared to other stars) lifespan, it would make an excellent factory site for other large astro-engineering projects.

It would be far more economical than mechanically processing already aggregated matter clumps (planets, asteroids, etc)-- especially with a dyson sphere/swarm infrastructure. The emitted gas and dust would be strongly ionized, and a simple network of magnetic traps could passively funnel the more desirable metal and halide ions from the lighter non-metals, with very minimal post processing. It would go a long way toward eliminating material scarcity issues that would otherwise plague a category II or III civilization.

Spectrographic analysis of the dust cloud to see if it has an uneven distribution of heavy and light elements would be quite revealing if this is the case-- Heavy ions would be in greater concentrations nearer the solar mass than away from it-- contrary to what you would expect if it was merely a gravitationally bound stellar dust cloud. (the latter would have a fairly uniform distribution of dust and gas)

Sadly, since it is in another galaxy such spectrographic studies are not very easy to do in sufficient resolutions to make such distinctions. It would need to transit some other more luminous celestial object in order for us to get such a reading, so that the invisible gas envelope surrounding the object could be studied, but again, it being in a distant galaxy coupled with the slow rate of orbital rotation of stars around a galactic center mass makes this a wait that could be billions of years long for such an event.

I agree that it is a very interesting object though.

Alien Life Test

[NicknamesAreStupid]

1) Rotation wobbles more on Friday nights
2) Neon light from dark side
3) Traces of THC in the upper atmosphere
4) SETI calls go into voicemail

How to discover aliens in one almost easy step

[tftp]

This step is simple: invent an FTL method of communication.

The reasoning is also simple. If we can have FTL then it is a given that all developed civilizations are using it. Radio is simply too slow. We don't use pigeons anymore to send messages, do we? So why do we expect an alien civilization to spend terawatts of energy and thousands of years to blast radio signals into space?

But if we can't have FTL then pretty much we are prisoners of our star system. Perhaps generation ships can export our genes to other stars, but that is unlikely, and we will never [in practical terms] know how they fared. Ping times of thousands of years are simply out of our time scale, until we all become cyborgs or beings of pure energy.

So that's why FTL is the only possible solution. Anything less is just a waste of money and effort. This effort should be invested into science, in every way possible. Even if FTL is absolutely impossible in our Universe, perhaps we will find a neighboring Universe with physical laws that are more to our liking.

Simple: anything out of the ordinary

[Arlet]

Just look for anything out of the ordinary, and once you find it, try to come up with an explanation. This way you'll not only find life (if it exist) but also other interesting phenomena.