Carl Sagan, Billions and Billions, Or, maybe not?

[amicus]

Carl Sagan, Billions and Billions, Or, maybe not?


“More Stars in the Universe than all the grains of sand on all the beaches and deserts on Earth…” It is said.

Well, I can’t prove that, and it does seem an outrageous number of Stars (Suns) populating the Universe. But, I accept that there are ‘billions and billions’ of Suns of all sizes.

That being said, Astronomers tell us also that a certain percentage of those, ‘suns’ will have planets rotating around them, some perhaps like our own Solar System.

Thus, there are said to be, ‘billions and billions’ of planets. The logical progression of thought and mathematics is to predict, thus, that there are ‘billions and billions’ of those planets that have life on them.

It is also rational to predict, that of those billions and billions, some should possess sentient life as developed as we are. Quite a few, in fact; also, billions and billions; if you crunch the numbers.

Bear with me, I’m building a case.

Carl Sagan wrote the book, ‘Contact’ which became a movie. SETI, Search for Extra Terrestrial Intelligence, I think, is a real program that has been in existence for about forty years.

The purpose of the SETI program, is to search for evidence of life in the universe.

The search involves the use of radio telescopes and other devices to listen to radio waves coming from space.

Mankind has been using radio waves for about 150 years. Radio waves are basically generated by applying electricity to a circuit composed of a capacitor, (a device that stores electricity) and a induction coil, (a device that creates a magnetic field), to create an alternating electric current in a given circuit.

That alternating current can be created at one cycle per second up into the mega billions of cycles per second. A cycle, is just the turning on and off of electric current; as it rises from zero to maximum. This determines the ‘frequency’ of the alternating current or ‘radio wave.’

It was discovered that these radio waves didn’t need a wire to travel on, but actually could be transmitted from one point to another almost instantaneously.

Soon mankind was sending messages over great distances by the use of radio devices. Ain’t science wunnerful?

The different ‘radio frequencies’ in the spectrum, show different characteristics. However they all share a similar characteristic: they travel at near the speed of light.

Well, mankind learned to measure the speed of light and lots of really neat ideas bubbled forth. We could shoot a radio wave at an object and measure the time it took to get there and back and determine the ‘distance’ to that object. Amazing stuff!

Anyway, that’s kind of the way it works. Mankind learned that it takes about eight minutes for radio waves and light to travel from our sun to planet earth.

Eight minutes. How far does light travel in a year? Well, a long way, so we identify that as a ‘light year’, the distance light travels in a solar year.

The nearest star is 26 light years away. How we know that, is more complicated that I can explain, but suffice it to say we did not shoot a radio beam at that star and wait for it to return in order to know the distance. Has to do with spectrum shift and Doppler effect I think.

The point of all this so far is just to lay a very basic foundation of how mankind might detect other life in the Universe.

Keep in mind the ‘billions and billions’ that I have been bombarding you with.

Mankind has been searching the stars with the SETI program and others means for about forty years. Not a long period of time in astronomical times, but still, a goodly period of research.

In those 40 years, mankind has not detected a single intelligent radio signal from outer space.

Again, the ‘billions and billions’ concept; if there are in fact, billions of intelligent life forms in the Universe, a proportionate number ‘should’ be as advanced as human kind. That is to say, ‘billions’, of species broadcasting radio waves into space for perhaps a few billions of years.

We have not detected even one.

If you have ever tuned a short wave radio set at any time of the day or night, you will hear thousands of radio signals bouncing around here on planet Earth.

Could mankind really be alone in the Universe?

I have been reading science fiction since I was very young and always wondered what the effect would be, what people on earth would think, when we did finally discover another life form.

Now I wonder what the true effect would be if we finally realized that there may be no other intelligent life forms in the Universe.

Wish I could have presented this more clearly. Assuming the probability factors almost dictate that there are many other intelligent life forms: assuming the apparent ability we have to detect radio communications from space, there should be thousands of signals coming from all points of space.

Yet there is none.

Why?


Amicus…

 

[neonlyte]

Maybe for the same reason we can't hear a dog whistle.

 

[amicus]

Nope. Nice try Neolyte but the equipment has the ability to 'hear' the entire spectrum. Further, in the past decade, the process has become automated and computerized so that millions of possible frequency channel are being simultaneously scanned continuously.

amicus...

 

[lil_elvis]

Static.

Considering the amount and energy level of radio-type waves generated by the billions and billions of stars, quasars, nebulae and the like, how could the pitance generated by man, or some other senitient being, compete?

 

[amicus]

http://hyperphysics.phy-astr.gsu.edu/hbase/starlog/strclos.html

The closest star to the sun is Proxima Centauri, but its brighter neighbor Alpha Centauri, a double star, is so nearly the same distance that data about it are usually given. It is about 4 light years distance, or about 3.8x1016 m.

My apologies...I had the movie Contact in mind, the 26 light year distance was to the signal source in that film. Thanks for the correction.

 

[mismused]

delete

 

[amicus]

Static.

Considering the amount and energy level of radio-type waves generated by the billions and billions of stars, quasars, nebulae and the like, how could the pitance generated by man, or some other senitient being, compete?

Interesting point lil_elvis....I do not have the technical ability to answer your question with certainty, but, I do know that we have maintained communication with several space probes within the solar system, Voyager one, among them, using very small amounts of radio energy generated on board the probe.

Further, the SETI scientists who are searching for signals would not do so, I think, if the background radio clutter in the Universe was thought to drown out all other signals.

Perhaps someone with a greater background than mine could answer that.

Happy Turkey Day....

 

[NoJo]

Be patient. They probably have a ton of emails to deal with. They'll get round to us eventually.

 

[Guest]

Be patient. They probably have a ton of emails to deal with. They'll get round to us eventually.

 

[amicus]

===================================================

ami cus,

If you accept the big bang at approximately 14 billion years ago (to get a nice, workable round number), and you figure that it took us 100 years (nice round number) to get to our present state from when we first had telegraph, etc., and divide that into the fourteen billion, you get the possibility of 28,000,000 civilizations.

If they were as successful as we have been. Some may not have been (assuming there were some), some may not have been, but assume they all were. As we have, also assume they had "the bomb," and "the ignorance" we have, then there may have been 28 million civilizations already blown to bits as we willl probably be by some fanatic nation (or civilized as we are).

Assume (to equalize things out) that half of those have already occurred, and disappeared, then the other half may follow us after our demise. Now, figure up where we, Earth, are on the universal development scale, and you can adjust your figures before and after.

Please note that there may be many out there that have yet to realize Morse's state, so it is possible that they're there but can't hear us.

Please note that not all of those are as dumb as you and I, and may therefore be smart enough to ignore us, thus we don't know about them.

That's it, I'm gone. Have a good time with your problem.

m

Thanks...m...in listening to Sagan on his television series 'Cosmos' and reading both Sagan and Stephen Hawkings and others on this subject...even if you discount all the things you mentioned and more...they say there still should be many, many millions of civilizations with radio capabilities at any one given time, to detect or be detected.

Have a wonderful holiday

 

[neonlyte]

Nope. Nice try Neolyte but the equipment has the ability to 'hear' the entire spectrum. Further, in the past decade, the process has become automated and computerized so that millions of possible frequency channel are being simultaneously scanned continuously.

amicus...

'We' try to measure what we perceive to be the entire spectrum. It is likely, from what I manage to understand from String Theory, there are many other Universes operating with spectrum out of phase with our own, and whilst the billions and billions arguement holds within a single range of spectrum, it does not hold (in String Theory) where there are billions and billions of Universes.

String Theory is an extraordinarily difficult concept to grasp, which is why the dog whistle arguement holds good. No human has ever heard a dog whistle, yet we know it is there outside of the spectrum we hear, similarly no human has ever seen a radio wave, (or heard the wrath of a grape - but that's another story), it is similarly conceivable we cannot 'record' the sounds emitted by another life form because we don't know what to look for.

String Theory explains why a researcher in Switzerland was able to make an atom disappear from his laboratory and instantly appear in a laboratory in USA - don't ask me to explain - the theory says the atom effectively disappears from one universe and reappears in another, the fact that we seem to be inhabiting both universes is covered by the billions and billions arguement. Of course the guy in Switerland never actually saw 'his' atom reappear in the US, but then I've never heard a dog whistle.

 

[mack_the_knife]

Be patient. They probably have a ton of emails to deal with. They'll get round to us eventually.

Likely our first contact will be extraterrestrial spam.

 

[Guest]

from Center for SETI Research

http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=179073

Drake Equation

"What do we need to know about to discover life in space?"
How can we estimate the number of technological civilizations that might exist among the stars? While working as a radio astronomer at the National Radio Astronomy Observatory in Green Bank, West Virginia, Dr. Frank Drake (now Chairman of the Board of the SETI Institute) conceived an approach to bound the terms involved in estimating the number of technological civilizations that may exist in our galaxy. The Drake Equation, as it has become known, was first presented by Drake in 1961 and identifies specific factors thought to play a role in the development of such civilizations. Although there is no unique solution to this equation, it is a generally accepted tool used by the scientific community to examine these factors.
--Frank Drake, 1961
The equation is usually written:

N = R* • fp • ne • fl • fi • fc • L

Where,

N = The number of civilizations in The Milky Way Galaxy whose electromagnetic emissions are detectable.

R* =The rate of formation of stars suitable for the development of intelligent life.

fp = The fraction of those stars with planetary systems.

ne = The number of planets, per solar system, with an environment suitable for life.

fl = The fraction of suitable planets on which life actually appears.

fi = The fraction of life bearing planets on which intelligent life emerges. For more information, please visit Dr. William Calvin's "The Drake Equation's fi"

fc = The fraction of civilizations that develop a technology that releases detectable signs of their existence into space.

L = The length of time such civilizations release detectable signals into space.

Within the limits of our existing technology, any practical search for distant intelligent life must necessarily be a search for some manifestation of a distant technology. In each of its last four decadal reviews, the National Research Council has emphasized the relevance and importance of searching for evidence of the electromagnetic signature of distant civilizations.

Besides illuminating the factors involved in such a search, the Drake Equation is a simple, effective tool for stimulating intellectual curiosity about the universe around us, for helping us to understand that life as we know it is the end product of a natural, cosmic evolution, and for making us realize how much we are a part of that universe. A key goal of the SETI Institute is to further high quality research that will yield additional information related to any of the factors of this fascinating equation.

 

[Guest]

Detecting New Planets

Detecting Other Worlds: The Photometric Transit or 'Wink' Method
Its fortunate for exobiologists and those who study circumstellar habitable zones that most stars do not much vary in their brightness. One particular brightness variationa sort of "wink" of the starprovides the only present means for detecting and studying Earth-sized extrasolar planets. This is known as the photometric transit method, and it relies upon a planet orbiting across the disc of its parent star in our line of sight.

Detecting Other Worlds: The Wobble Method
Almost all of them have been discovered using what can be colloquially called the "wobble method." This is an indirect method, which means the presence of a planet is inferred -- in this case, by a planet's effect on the star it orbits.

Kepler Mission: Detecting Earth-sized planets
The Kepler Mission has a simple objective: find small planets around other stars - worlds like Earth that could possibly spawn life. It promises to be one of the most exciting astronomy projects of the coming decade.

Symphony of New Planets
One of the fundamental premises of all SETI science is that inhabitable worlds are not rare. This assumption has garnered plenty of indirect support during the last five years as astronomers have finally succeeded in finding planets that orbit ordinary (and nearby) stars.

 

[lil_elvis]

Interesting point lil_elvis....I do not have the technical ability to answer your question with certainty, but, I do know that we have maintained communication with several space probes within the solar system, Voyager one, among them, using very small amounts of radio energy generated on board the probe.

Further, the SETI scientists who are searching for signals would not do so, I think, if the background radio clutter in the Universe was thought to drown out all other signals.

Perhaps someone with a greater background than mine could answer that.

Happy Turkey Day....

Currently, we only know of other solar systems by the effect of the collective gravity of the planets on the behvior of their suns. We can only see the light and other radio emissions of the stars, not the planets, and the emissions of the more distant stars must be greatly amplified in order to be heard.

Do the math, you're pretty good with numbers. We can only communicate with our own satellites to the edges of the solar system. Other systems are millions of times farther away. At present, our equipment has neither the sensitivity nor sophistication to filter out the natural chatter of the stars from the signal of some V'ger launched by Barin Gariius 7.

Rather humbling (even for a kool aide swilling republican).

But don't give up. I'm sure the Chinese can solve the problem for us for a lot less than it would cost NASA.

 

[Guest]

http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=179077

These discussions are excellent - see the site to read further.

Rare Earth Index

Is Our Planet So Special?
Could we be alone in our part of the galaxy, or more dramatic still, could we be the only technological society in the universe? Rare Earth, a book by Peter Ward and Donald Brownlee (University of Washington) point out the many ways in which our solar system may be optimized for our existence.

Fermi Paradox Part 1:
Our Galaxy Should Be Teeming With Civilizations, But Where Are They?
Is there obvious proof that we could be alone in the Galaxy? Enrico Fermi thought so -- and he was a pretty smart guy. Might he have been right?

Fermi Paradox Part 2:
What's Blocking Galactic Civilization?
Could galactic empires exist? In a previous article, we noted that there has been plenty of time for aliens keen on colonizing the Milky Way to pull it off. Why does the cosmos look so untouched and unconquered? What is keeping advanced extraterrestrials from claiming every star system in sight?

Fermi Paradox Part 3:
Zookeepers, Alien Visitors, Or Simple Life; How Can We Explain Our Isolation?
Its possible that the aliens have done cost-benefit analyses that show interstellar travel to be too costly or too dangerous to warrant ambitious colonization efforts. An alternative suggestion that would explain our apparent solitude is that the Galaxy is urbanized, and were in a dullsville suburb.

 

[amicus]

'We' try to measure what we perceive to be the entire spectrum. It is likely, from what I manage to understand from String Theory, there are many other Universes operating with spectrum out of phase with our own, and whilst the billions and billions arguement holds within a single range of spectrum, it does not hold (in String Theory) where there are billions and billions of Universes.

String Theory is an extraordinarily difficult concept to grasp, which is why the dog whistle arguement holds good. No human has ever heard a dog whistle, yet we know it is there outside of the spectrum we hear, similarly no human has ever seen a radio wave, (or heard the wrath of a grape - but that's another story), it is similarly conceivable we cannot 'record' the sounds emitted by another life form because we don't know what to look for.

String Theory explains why a researcher in Switzerland was able to make an atom disappear from his laboratory and instantly appear in a laboratory in USA - don't ask me to explain - the theory says the atom effectively disappears from one universe and reappears in another, the fact that we seem to be inhabiting both universes is covered by the billions and billions arguement. Of course the guy in Switerland never actually saw 'his' atom reappear in the US, but then I've never heard a dog whistle.

Saw a science channel thing on 'string theory' and researched a few articles on line just out of curiosity.

There are some areas of research and thought that I just don't get, fully. Alternative universes, quirks in time and others...there may be some validity to these things and then again, there may not be.

I almost dismiss them as 'angels on the head of a pin' sort of dialectic and metaphysical theories that question the 'known' universe just because it is known.

I am more a 'meat and potato' kinda guy....the many billions of possible civilizations all evolving along a line within the laws of physics and the universe, gravity and the K constant of light I find interesting.

To simply say that we 'may' not be able to communicate, is to dismiss the numerical probability that life occurs elsewhere in the universe quite as it did here.

I still cannot accept the conclusion that 'we' are the only form of life in the universe, however, with the numbers and the probability factor involved, it appears to me we should be able to detect millions of other civilizations.

Thus I am left with the question. They should be out there, we should be able to detect them, we cannot. Why?

Thanks....

amicus...

 

[neonlyte]

I forgot to say String Theory has either 10 or 11 dimensions as opposed to the four we currently accept, the other dimensions are complimentary but described as too small to be discernable but at any instant in time there are 4xpower10 potential variations of the single universe 'we' experience, some 4million odd, for each sentient body.

 

[amicus]

http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=179077

These discussions are excellent - see the site to read further.

Rare Earth Index

Is Our Planet So Special?
Could we be alone in our part of the galaxy, or more dramatic still, could we be the only technological society in the universe? Rare Earth, a book by Peter Ward and Donald Brownlee (University of Washington) point out the many ways in which our solar system may be optimized for our existence.

Fermi Paradox Part 1:
Our Galaxy Should Be Teeming With Civilizations, But Where Are They?
Is there obvious proof that we could be alone in the Galaxy? Enrico Fermi thought so -- and he was a pretty smart guy. Might he have been right?

Fermi Paradox Part 2:
What's Blocking Galactic Civilization?
Could galactic empires exist? In a previous article, we noted that there has been plenty of time for aliens keen on colonizing the Milky Way to pull it off. Why does the cosmos look so untouched and unconquered? What is keeping advanced extraterrestrials from claiming every star system in sight?

Fermi Paradox Part 3:
Zookeepers, Alien Visitors, Or Simple Life; How Can We Explain Our Isolation?
Its possible that the aliens have done cost-benefit analyses that show interstellar travel to be too costly or too dangerous to warrant ambitious colonization efforts. An alternative suggestion that would explain our apparent solitude is that the Galaxy is urbanized, and were in a dullsville suburb.

Thanks, Sweets....very interesting...

http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=179288

Would the detection of another intelligent society disrupt our own? Would it provoke hope, or fear?

If Project Phoenix succeeds, the public would be confronted with a monumental discovery. Would there be apprehension or defensiveness? Could we expect a harmonizing effect on our own society? How would religions deal with the confirmed existence of non-human intelligence light-years away?

In the past two decades, considerable thought has been given to both the near-term and long-term effects of a signal detection. Both historical analogs and contemporary social science have been used to infer how humankind might react.

Regarding the immediate consequences of success, it's worth pointing out that there will be no hiding of the discovery. If any signal is unambiguously verified as being extraterrestrial, it will be openly announced.

There have been frequent predictions that this announcement would be the most spectacular news story of all time. Polls suggest that the majority of Americans already believe in the existence of extraterrestrial beings. However, conditioned by the media's emphasis on UFO's, the public might expect a "message". This expectation might not be immediately fulfilled. The primary goal of Project Phoenix is to find the signal; to uncover and possibly decipher a message could require the development of additional telescope and receiving equipment.

Sociological studies suggest that announcement of a signal would lead to confusion and excitement, with a desire by individuals to "know more", but little panic or hysteria. While some religious groups are expected to reject the idea that we are not alone, most would not, and some would embrace the discovery as reinforcing their own beliefs.

The long-term effects are difficult to predict. Analogy is often made to Copernicus' dramatic new cosmology, which deposed Earth from its throne at the center of the universe. Another oft-cited historical analog is Charles Darwin's celebrated hypothesis on biological evolution. To the extent that such analogies are applicable, they suggest more of a gradual change in world view than a dramatic upset in the day-to-day conduct of society.


amicus...

 

[dr_mabeuse]

The big problem with SETI right now is data analysis. There are tons and tons of radiotelescope scans that have to be gone through and all the cosmic noise filtered out. It's very much like looking for a needle in a planet-sized haystack.

Aside from that, while radio signals do travel forever theoretically, (and *at* the speed of light, not "near" it. Radio waves and light are both electromagnetic radiatoin and differ only in wavelength), the strength of the signal weakens until it's virtually indetectable. So while we should be able to get most signals from within our own galaxy, we wouldn't be able to detetct extra-galactic signals, which is where most of your billions & billions or stars are. (The Milky Way contains about 400 billions stars)

And there's something else in the Drake equation, and that's the amount of time a technological civilization uses broadcast radio, which is quite inefficient. On earth, it's been about 150 years,and even now it's being phased out in favor of cable radio. Those "I Love Lucy" shows the aliens have been watching are about to be cut off.

What broadcast radio we use is also switching to digital, and if aliens have done the same and encrypted those digital signals, it might not be able to differentiate between them and random noise.

Stars, dust, anything that carries an electrical charge and moves generates EM radiation. The universe is a screaming cacaphony of radio noise. Finding some little signal in that racket is no mean feat.

 

[Alex756]

Did anyone already mention the limited lifespan of the planet's production of radio waves?

Now we have been doing it for a while now, but who is to say it won't stop. That there is a better technology out there we have yet to discover and as soon as that happens, and everyone upgrades *rolls eyes* I have a mother in law who refused to pay for touch tone and still has a pulse dial line...

but anyways, the limited time a civilization produces all this radio noise also has to be taken into contact.

It's inconceiveable that we are alone The fact we could be the babies babling to ourselves to hear ourselves say our latest word though, thats a possibility

~Alex

 

[Alex756]

And there's something else in the Drake equation, and that's the amount of time a technological civilization uses broadcast radio, which is quite inefficient. On earth, it's been about 150 years,and even now it's being phased out in favor of cable radio. Those "I Love Lucy" shows the aliens have been watching are about to be cut off.

What broadcast radio we use is also switching to digital, and if aliens have done the same and encrypted those digital signals, it might not be able to differentiate between them and random noise.

See someone was typing it much better than I was

so -yeah that-

~Alex

 

[Wildcard Ky]

http://www.seti.org/site/pp.asp?c=ktJ2J9MMIsE&b=179077

These discussions are excellent - see the site to read further.

Rare Earth Index

Is Our Planet So Special?
Could we be alone in our part of the galaxy, or more dramatic still, could we be the only technological society in the universe? Rare Earth, a book by Peter Ward and Donald Brownlee (University of Washington) point out the many ways in which our solar system may be optimized for our existence.

Fermi Paradox Part 1:
Our Galaxy Should Be Teeming With Civilizations, But Where Are They?
Is there obvious proof that we could be alone in the Galaxy? Enrico Fermi thought so -- and he was a pretty smart guy. Might he have been right?

Fermi Paradox Part 2:
What's Blocking Galactic Civilization?
Could galactic empires exist? In a previous article, we noted that there has been plenty of time for aliens keen on colonizing the Milky Way to pull it off. Why does the cosmos look so untouched and unconquered? What is keeping advanced extraterrestrials from claiming every star system in sight?

Fermi Paradox Part 3:
Zookeepers, Alien Visitors, Or Simple Life; How Can We Explain Our Isolation?
Its possible that the aliens have done cost-benefit analyses that show interstellar travel to be too costly or too dangerous to warrant ambitious colonization efforts. An alternative suggestion that would explain our apparent solitude is that the Galaxy is urbanized, and were in a dullsville suburb.

One question that I've often wondered is what makes us think we're worthy of contact by far advanced civilizations? If they are capable of interstellar travel, we'd be no more than chimps with simple tools to them.

When we study "lesser animals" in their natural setting, we do so in a stealthy and unobtrusive way. We simply observe. We don't interfere, or even wish to be seen. An advanced species capable of interstellar travel would probably act in much the same way.

The arrogance of our race makes us think that if they're there, they will contact us. We deem ourselves to be that important.

 

[amicus]

The big problem with SETI right now is data analysis. There are tons and tons of radiotelescope scans that have to be gone through and all the cosmic noise filtered out. It's very much like looking for a needle in a planet-sized haystack.

Aside from that, while radio signals do travel forever theoretically, (and *at* the speed of light, not "near" it. Radio waves and light are both electromagnetic radiatoin and differ only in wavelength), the strength of the signal weakens until it's virtually indetectable. So while we should be able to get most signals from within our own galaxy, we wouldn't be able to detetct extra-galactic signals, which is where most of your billions & billions or stars are. (The Milky Way contains about 400 billions stars)

And there's something else in the Drake equation, and that's the amount of time a technological civilization uses broadcast radio, which is quite inefficient. On earth, it's been about 150 years,and even now it's being phased out in favor of cable radio. Those "I Love Lucy" shows the aliens have been watching are about to be cut off.

What broadcast radio we use is also switching to digital, and if aliens have done the same and encrypted those digital signals, it might not be able to differentiate between them and random noise.

Stars, dust, anything that carries an electrical charge and moves generates EM radiation. The universe is a screaming cacaphony of radio noise. Finding some little signal in that racket is no mean feat.

Thanks, Mab...The most recent SETI institute information I have seen stated that the data analysis has improved exponentially with computer programs that scan millions of frequencies or channels and can instantly isolate that 'needle in the haystack' and immediately summon human attention.

The radio waves that travel at 'near' the speed of light, do so in earth's atmosphere; else where they are not attenuated by the vacuum of space and theoretically, so they say, can go on forever.

And yes, 'broadcast radio' as you say is a beginning step in electro magnetic wave generation. SETI researchers are now working on laser or maser technology which, as I understand it, will use digital light sources as a powerful beacon.

I tried not to color my thoughts with any social or earth centric bias. And although the SETI research is just in the beginning stages, it is my opinion it is sophisticated enough to detect any regular transmission of electro magnetic energy that is not naturally created. By that I mean to say, that if there are the number of intelligent civilizations out there that the probabilities suggested by Sagan and others, should be producing thousands of results.

It could well be the reasons you and others have suggested but I think one can not rationally dismiss the possibility that there just aren't any other civilizations out there.

That is one of the curses, if you will, of logic and reason. If there is no evidence pointing towards the existence of something, one is required to accept that lack of evidence as an indication that that 'something' does not exist.

It is not proof, of course, as one can not prove a negative. The huge size of the universe and the almost unimaginable number of galaxies and individual stars is so tremendous that the permutations and probabilities suggest there should be thousands of civilizations.

amicus...

 

[mismused]

delete