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Are we alone? The Drake equation

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johnson1010
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Are we alone? The Drake equation

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We are getting all kinds of interesting data these days about exo-planets. Below, io9 took some time to plug some numbers into the Drake equation to see what it might imply about life in our galaxy.


http://io9.com/how-do-new-astronomical- ... 1460293627

http://en.wikipedia.org/wiki/The_Drake_Equation


The Drake equation doesn't really tell us about life in our galaxy.

Almost none of the variables can be pinned down with any definitive value. Instead, why i think the Drake equation is valuable is that it tells us what we need to know before we can make some accurate predictions.

It is not an answer, but a way to frame the questions we might ask.
In the absence of God, I found Man.
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Are you pushing your own short comings on us and safely hating them from a distance?

Is this the virtue of faith? To never change your mind: especially when you should?

Young Earth Creationists take offense at the idea that we have a common heritage with other animals. Why is being the descendant of a mud golem any better?
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Re: Are we alone? The Drake equation

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How does the Drake Equation match up with experience?
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Chris OConnor

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Re: Are we alone? The Drake equation

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Ant, I don't understand the question. What experience?
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Re: Are we alone? The Drake equation

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In answer to Ant, since we have no experience, your question is unanswerable. Personally, I have always found Drake's equation to be an interesting thought experiment, but since it relies of so many assumptions, for all practical purposes, it is useless.

I am goind to take a moment here and post a little essay I wrote a few months ago. It is part of a series I call "Philosopher at Large."

Is Anybody Out There?

Ever since that moment, lost in the dim reaches of pre-history, when some individual looked up into the night sky and asked this rhetorical question, humanity has pondered the possibility of extra-terrestrial life, specifically intelligent life. A second question is, assuming the existence of such intelligent beings, have they visited the Earth?

There are various schools of thought on this subject. At one end of the spectrum you have those who believe that we are alone in the universe; that no where else does life exist - any life, not just intelligent life. This is usually based on a very simplistic idea, that the Bible (or other religious text) does not mention life on other worlds, so it must not exist. To me, this is the height of arrogance. It is also rather frightening, when you consider the size of the cosmos. Talk about lonely, or as the herione of the motion picture Contact aid in her closing line, "What a waste of space." Of course, if this should be the case, it answers the question of why we have never been contacted - there is no one at the other end of the line.

In opposition (far opposition) to this viewpoint, there are those who believe the universe is teeming with intelligence, and that Earth has been, and is being visited, by members of advanced civilizations. Here also, the 'evidence' for such visits is as best, questionable. I know, crop circles, Roswell, and many "eyewitness accounts" claim to prove the truth of such visits. I remain skeptical of such 'evidence.'

Presuming the existence of such extraterrestrial intelligence, why haven't we heard from them?

In his Theory of Relativity, Einstein postulated that the speed of light (approximately 186,000 miles per second) is the maximum velocity achievable in our universe. No matter how hard we try, we can go no faster. So the signals are on their way, it is just going to take a few million more years for them to get here.

In his novella, The Crystal Spheres (1984), science fiction writer David Brin has his narrator ask the question "Where the Hell is everybody?" In answer, he posits an intriguing alternate possibility as to why no one has visited us yet. Oh, they are out there, but they are still herders and farmers, living in thatch roofed cottages, and relying on animal power to augment their own muscle. Or maybe they are still in the hunter/gatherer stage. At any rate, they lack the technology to travel to us, or even to send a signal "We are here!" That we are the first to achieve space flight, to reach the level of technology that allows us to take those first tentative baby steps off the planet of our birth. That we are destined to become the Elder Race to which all others will look for guidance. Kind of a scary thought.
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Re: Are we alone? The Drake equation

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Nice job, Cattleman. :-)

So we're all somewhere on the spectrum ranging from total disbelief in extra-terrestrial life to belief that ET has been here to Earth possibly numerous times and in fact may still be here now.

David Brin's "intriguing alternate possibility as to why no one has visited us yet" is one of many that I can think of. Another couple are as follows...

1. There are billions of other worlds at various levels of development including many far more advanced than Earth. Maybe they have discovered intelligent life elsewhere in the cosmos but just aren't at the level to reach it or communicate with it yet. Maybe the technology to interact with other worlds is literally thousands of years more down the line for us humans and even for these other more advanced intelligent beings on other worlds. Afterall, the distances involved are just mind-blowing.

2. There are billions of other worlds at various levels of development and many are already interacting with each other. There could easily be entire networks of worlds interacting with each other in the cosmos. Just because they haven't found us or contacted us doesn't mean these worlds aren't in communication with some of their neighbors.

The revised Drake Equation shows the possibility of literally billions of other worlds in the Milky Way that could and might support life. It doesn't take much imagination to think that any of those worlds that have reached the ability to travel between the stars just aren't aimed at us. As Carl Sagan said we're but a mere pale blue dot. Perhaps they have other worlds in sight much closer and much more exciting than us. Even advanced beings would need to pick their target destination carefully.
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Re: Are we alone? The Drake equation

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How does the Drake Equation match up with experience?
Well, the drake equation is an attempt to find variables which should be considered when trying to estimate how many intelligent civilizations there may be in a given cluster of stars.

Our experience is that there is one confirmed civilization in one star system among a few dozen bodies which orbit that star. Though we haven't found any yet, there are a couple other bodies in the star system which may also harbor life, or may have harbored it in the past.

Mars may once have had life but we are nowhere near at a conclusive discovery there, meaning we haven't studied it enough to determine one way or another. Europa is perhaps the best other place beside earth to look for life in our star system as it is a stable object with standing oceans of liquid water, so conditions there may be right for life as well.

That too requires futher research.

So our experience tells us that at least one, and perhaps up to three objects in this one star system have or have had life on them.

The next question becomes how many other star systems out there are like ours in their star and orbital body arangement? And of those star systems how many objects are in the obvious "goldilocks zone" of that star.

This is the number which is beginning to have some traction with our recent avalanche of discovered exo-planets.

http://www.pnas.org/content/early/2013/10/31/1319909110

many of the other variables have no concrete values, but that doesn't mean the equation has nothing to say.

It doesn't tell us how many civilizations are out there. It tells us what we need to discover in order to find out how many civilizations are out there!

Besides that we can get an idea of the range of answers, or gives us a picture of just what kind of needle we may be looking for in this haystack. Hey, it's a dark needle, not silver! that changes things!

here it is, as broken down from the io9 article.
The Drake Equation goes like this: R * fp * ne * fl * fi * fc * L = N where:

R = the average rate of star formation in our galaxy
this is a number we can put numbers to.

fp = the fraction of those stars that have planets
Kepler is helping us put numbers to this variable as well.

ne = the average number of planets that can potentially support life per star that has planets
Again, kepler has input on this. There are still a wide variety of variables within this category. So we could say that this is telling us that we've got a truck load of apples, but we can't yet determine how many of those apples are spoiled.

fl = the fraction of planets that could support life that actually develop life at some point
here we can only work with our solar system. But we can make some reasonable extrapolations from our data set to look at a range of possibilities. Either that our planet and our star is special beyond all likelihood and we should put in a very low value here, or that life is a natural extension of chemistry and we should find it occuring pretty readily wherever the circumstances permit it.

We know that our star isn't special, and the resources that produced our planet are not special. And that the underlying activity of our bodies are not special. What we don't know is how often life gets rolling on a planet. If mars also had life, and europa does have life, then that tells us a bit more about how often life DOES develope where it looks like it COULD develope.

If earth is the only place in our star system that did develope life despite there being other places where it could have, then that will tell us that life is harder to start up than we might otherwise infer.


fi = the fraction of planets with life that actually go on to develop intelligent life (civilizations)
This is not a number we can estimate very well. It will be a long time before this gets pinned down with any accuracy, and if we never discover another instance of a civilization, then perhaps never. But this is the kind of info we need to get pinned down if we are going to try to estimate how often civilizations arise.

fc = the fraction of civilizations that develop a technology that releases detectable signs of their existence into space
The same as above

L = the length of time for which such civilizations release detectable signals into space

Same as above. So some of these variables can only be populated with speculation, and in no way do we get an answer which we could hold up to everyone and say, look what we found out is true! No. What we can say, is that here are the assumptions we are making. Based on those assumptions, and the facts we do know, or are beginning to be compiled by kepler and other sources, given THIS fact, and THESE speculations, here's a range of values that we could be looking for out there.

If we make conservative estimates on the items we are speculating about and still get astronomically high values for how many communicative civilizations there must be, yet we don't find any evidence of these civilizations, then it tells us we are mis-understanding the things we need to search for because we were way wrong! Being wrong tells us as much, if not more, than when we find out we were right!
In the absence of God, I found Man.
-Guillermo Del Torro

Are you pushing your own short comings on us and safely hating them from a distance?

Is this the virtue of faith? To never change your mind: especially when you should?

Young Earth Creationists take offense at the idea that we have a common heritage with other animals. Why is being the descendant of a mud golem any better?
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Re: Are we alone? The Drake equation

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Perhaps fermi's paradox is because it's so difficult to live sustainably on a planet, and that interstellar travel simply won't work out like it does in the sci-fi books. If we speculate that it would only take us a thousand or so years to develop interstellar technology, then the ready availability applies to every other sentient species. But we haven't seen a single clue. It makes me think the technology to do these things is a fantasy.
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Re: Are we alone? The Drake equation

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Another thing is having to wrestle with the time frames invovled.

There may have already been a thousand civilizations in our galaxy at least as technologically advanced as ours, but the last one died off and their last detectable signal went blazing past us a million years ago. Or when Davinci was alive, and we won't be able to find that signal now.

Maybe by the time our signals stop reaching other systems will be JUST the time when they will be able to detect us!

It may be that life and civilizations are a common occurence in galactic time frames, but that doesn't mean we are all part of the class of 2013 of civilizations! despite it being common, we might still be the only civlization in our galaxy at this point.

Many wide and weird possibilities, and like i said, the Drake equation doesn't answer which is right, but instead tells us how we might ask the right question.
In the absence of God, I found Man.
-Guillermo Del Torro

Are you pushing your own short comings on us and safely hating them from a distance?

Is this the virtue of faith? To never change your mind: especially when you should?

Young Earth Creationists take offense at the idea that we have a common heritage with other animals. Why is being the descendant of a mud golem any better?
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Re: Are we alone? The Drake equation

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It may be that life and civilizations are a common occurence in galactic time frames, but that doesn't mean we are all part of the class of 2013 of civilizations! despite it being common, we might still be the only civlization in our galaxy at this point.
What's scary is to think there might have been thousands of civilizations. Because the most obvious conclusion is that not a single one of them is still around. There is something about our universe that doesn't treat advanced civilizations kindly. Perhaps sustainability is a monstrously difficult feat. Look at us, we've only just become "advanced" in the last hundred years or less. And we're already looking at extinction scenarios. The threats we have to fight aren't only our own doing. What happens when a natural ice age starts up, or when a series of asteroids hurtles at us, or when the sun farts too loudly? We need to diversify our investment and get the hell off this rock.
In the beginning the Universe was created. This has made a lot of people very angry and has been widely regarded as a bad move.” - Douglas Adams
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Re: Are we alone? The Drake equation

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Chris OConnor wrote:Ant, I don't understand the question. What experience?
What I meant was this:

Science strictly practiced is an attempt to ultimatley bring theory and fact into agreement. That can only be achieved by testing and a search for confirmation or falsification.

Having said that, please tell me how the Drake E can be anything but abstract speculation at best.

Should we just "do the math" to prove it?
Thats would be circular reasoning would it not?

Thanks.
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