July 28, 2004
Will Intelligent Alien Life Be Discovered Within 20 Years?

Search for Extraterrestrial Intelligence Institute astronomer Seth Shostak argues that computers and radio telescopes will advance enough in the next two decades that within 20 years we will be able to scan all stars for radio transmissions that are the signs of intelligent life elsewhere.

If intelligent life exists elsewhere in our galaxy, advances in computer processing power and radio telescope technology will ensure we detect their transmissions within two decades. That is the bold prediction from a leading light at the Search for Extraterrestrial Intelligence Institute in Mountain View, California.

Seth Shostak, the SETI Institute's senior astronomer, based his prediction on accepted assumptions about the likelihood of alien civilisations existing, combined with projected increases in computing power.

Astronomer and Panspermia theorist Chandra Wickramasinghe thinks Shostak's prediction is reasonable.

"The criticism of this group has been to say that we've looked for intelligence for close on half a century and nothing has turned up, therefore there has to be nothing.

"I think that's an extremely false position to take.

"Forty years is too short a time to expect anything. We would be greedy if we expect the first hellos to come in the next 10 years.

"Twenty years is a more reasonable time to took forward to."

Even if an alien civilization is discovered that is 1000 light years away (i.e. it would take light 1000 years to travel between here and there) there may be people alive right now that will live long enough to carry on conversations with aliens. Once we achieve engineered negligible senescence people will be able to live youthful lives for thousands of years. So while conversations with aliens may require thousands of years to conduct such conversations could be carried out between individuals rather than between successive generations as representatives of civilizations.

I think the biggest problem with a conversation with aliens is that both we and the aliens would change so much between transmitting messages and receiving responses that we'd have little in the way of a meeting of the minds or a convergence of beliefs or mutual understanding.

Of course, if we could live for tens or hundreds of thousands of years then that opens up the possibility of travelling to meet aliens. But the trip would be so boring and even if the aliens sounded friendly we'd have no way of knowing how much they'd change before we travelled through space to the alien star system. By the time we reached their planet they might be gone or overrun by artificial nanotech creatures.

The other big problem with travelling to meet them is that either their microbes might be fatal to us or ours might be to them or to some aspect of their ecology. They might not want to risk having us as visitors.

Share |      Randall Parker, 2004 July 28 02:31 AM  Space Exploration

Sam said at July 28, 2004 8:47 AM:

It's the most exciting thing I've heard today! If I can meet God face to face the one thing I ask him is to take me to the edge of the universe. Now it seems that we can do it ourselves soon.

Kelly Parks said at July 28, 2004 1:14 PM:

The only thing we'll be able to detect in the next 20 years are civilizations that just happen to be in that tiny window where they are big radio/TV beacons like we are now. Consider how small that window is compared to the length of time Earth spent with nothing but microbes (3.9 billion years) or the time Earth will spend being like Venus is now (over 6 billion years). Even in the 1.7 billion year window where Earth is "earthlike", consider what a tiny percentage the existence of our species represents (120,000 years or .007%).

I think microbes are common but multi-cellular life is very rare (see "Rare Earth" by Ward and Brownlee) and that intelligent life is vastly rarer still (the more you learn about human evolution, the more you see what a fluke we are). The number of planets in this galaxy with intelligent life that just happens to be at roughly our level of technology has got to be very, very small, billions of stars not withstanding. My guess is that we're the only one.

Randall Parker said at July 28, 2004 1:38 PM:


But intelligent life that is more advanced than our technology may decide to erect a big radio beacon or perhaps a light flash beacon in order to send out a message for other civilizations to find. So a civilization could reach our stage of development, erect a beacon, and then proceed to broadcast for hundreds of thousands or millions of years.

Of course an advanced civilization might decide to hide itself if it decided there will be too many hostile civilizations out there listening to identify other intelligent species to attack and destroy.

Fly said at July 28, 2004 3:11 PM:

“The number of planets in this galaxy with intelligent life that just happens to be at roughly our level of technology has got to be very, very small, billions of stars not withstanding.”

The only planet we truly know about is Earth. The only intelligent life form with which we have experience is man. We don’t yet know enough about the origins of life on Earth to calculate odds as to how unlikely it was that life would evolve on Earth. (I follow the theories on RNA based life and on the fatty membranes that may have formed spontaneously and provided a nurturing environment for RNA enzyme replication. Until we know all the steps we can’t know how likely each step was.) Nor do we know all the other pathways that could potentially lead to life forms.

Based on our one sample of Earth and based on how quickly the first life forms appeared on Earth, my guess is that life should be common on Earth-like planets. Based on recent discoveries of planets around many stars in our near neighborhood, I would expect many life-bearing planets. Given evolution and time I would expect many of those planet to produce intelligent life.

Given how rapidly human science and technology has progressed in the last hundred years and given the present prospects for much greater advancement in the near future, I would expect there to be technologically advanced beings who would drastically alter their solar systems in ways that should be evident from thousands of light years away.

From all the above, I believe we should already have seen evidence of intelligent life.

So where is it?

Is the “dog that didn’t bark” a strong clue as to man’s future?

Randall, yep. The killer aliens are one possibility. Even then I’d have expected to see solar system “ruins”. Or maybe supernovas are the preferred means of extermination.

Kurt said at July 28, 2004 5:06 PM:

I agree with the Rare Earth hypothosis. I think that Earth-like worlds are rare and that ETs are even rarer. The rare earth hypothosis adds the following factors to the famous Drake equation:

1) The presence of gas giants in the right orbits to screen out comets and asteriods to reduce the amount of impacts on the Earth-like world.

2) The presence of a large moon orbiting the Earth-like world (double-planet system). The moon stabilizes the axial tilt of the Earth-like world. Also the moon creates tides, which probably helps in the emergence of life from the sea up onto the land.

3) Plate-tectonics: These are essential for the reprocessing of the atmosphere as well as geo-cycles. However, I suspect that any Earth-size planet will have these.

Factors 1 and 2 probably drop the number of Earth-like world candidates by a factor of a thousand.

The other way to calulate the probability of ETs for any given number of Earth-like worlds is to calculate the ratio of time of human civilization (about 10,000 years) to the time that life has been on the Earth (about 4 billion years). This gives a factor of 1 in 400,000. This means to me that one out of every 400,000 Earth-like worlds, with the right sized moon and the gas giant planet being in the right place, is likely to have an ET civilization.

If you assume that 10% of the galaxy's stars are F, G, or K-type and 10% of those are in the galactic habitable zone. You get about 4 billion stars. If 10% of those have an Earth sized planet in the right orbit, that drops it down to 400 million worlds. So, there are probably 400 million "garden worlds" in the galaxy. Lets say that one out of a thousand of these garden worlds has a large moon and gas giant planets in the right orbits, this drops the number of garden worlds suitable for the emergence of ET down to 400,000. Since the time ratio of civilization to life on Earth is 1 in 400,000, this comes out to one civilization in the galaxy, which is us!

So, we are alone in the Milky way.

If the current csmological theories are currect, there are 10 to the 75 number of galaxies in our universe (the observable universe being a very small part of the total universe) and that there are probably an infinite number of other universes. So, the probability of ETs existing is unity.

To sum up, ETs exist and there is probably an infinite number of them. Its just that they are a lot further away from us than current SETI expectation calls for (the nearest ET civilization is probably in Andromeda - 2 million LYs away from us).

Kelly Parks said at August 3, 2004 12:08 PM:

Randall: Yes, there might be advanced civilizations that erect such a beacon. The hidden assumptions here is that an alien species would share our monkey curiosity (maybe). But if intelligent life is as rare as I think it is and technological civilizations rarer still (the appearance of intelligence is no guarentee that they will become technologically advanced) then such a beacon has avery low probability of a pay off. That doesn't mean such beacons would never be built but the odds look pretty long.

Fly: Yes, I'm hypothesizing from a single data point (Earth). The universe is undoubtably full of surprises and believe me, I'm eager to go take a look. But I didn't say life wasn't common. I think microbial life (the only form of life that existed on Earth for 85% of its history) will probably be found anyplace there's liquid water and any kind of energy gradient.

What I did say was that when you consider what a small "window" of Earth's life-span has conditions allowing multi-cellular life to exist (1.7 billion years out of 12 billion years) and that evidence suggests that planets like Earth are rare (http://www.nature.com/news/2004/040726/full/040726-14.html), it makes me think that planets with multi-cellular life (plants and animals) are truely rare. Then consider that, contrary to popular belief, there is no "force" in evolution making life more complex (see anything by Stephen J. Gould). If you can better adapt to an environment by becoming simpler then that's what happens (parasites, for example). In other words, the appearance of animal life is *no* guarentee that intelligent life will appear. If you look at the details of human evolution the thing you notice most is what an incredible fluke we are. How common are such events? Who knows? But I think that makes intelligent life several orders of magnitude more rare.

Kurt: Yes, exactly. The excellent book "Rare Earth" has, if nothing else, added quite a few more factors to the Drake Equation.

Kurt said at August 5, 2004 12:57 PM:


I left one factor out. A magnetic field. Earth has one, Mars does not. The "Rare Earth" authors believe that the tidal motions in the Earth's core caused by the Moon are responsible for the Earth having a magnetic field. I don't know enough about geology to comment on this. The rare Earth people believe that water and air molecules will tend to abblate away in the absence of a magnetic field, turning a proto-earth into a mars.

Your comments about evolution not favoring tyhe development of intelligence is interesting and is a view that I have had for a long time. The only thing that intelligence is usefull for, that I can thing of, is to get life off of planetary surfaces and out into space. We have not done this yet, so its not clear if intelligence will last a long time. Wings seem more useful than intelligence. Wings (flight) has been around for 200 million years. Intelligence has been around for, say, 500,000 years. Intelligence has a long ways to go before closing the gap with wings.

I know this is very cynical, but I have been known to be quite cynical.

This does remind me of an interesting SF short story by Bruce Sterling, called "Swarm". Its part of his Shaper/Mechanist "Schizmatrix". The theme of the story is that intelligence is not useful for long term survival of life and it is a good read. It is part of "Schizmatrix Plus".

There was an article today by a UK astrophysicist, who said he thinks that our solar system is quite rare as well.

David said at December 18, 2004 11:43 AM:

People that are convinced there cannot be extraterestial life are simply narrow minded.. Let your mind go to attempt to fathom infinity - infinity -parallel universes..
Infinity means you will never/ ever reach the end.. If so, what would be at the end of space.. Nothing in infinity is revolving around anything.. Planets revolve - Universes revolve - There is an infinite number of universes.. there is no end to it all !
The big bang is so narrow minded.. There are big bangs happening an infinite number of times // Black holes remember..

Kyle Janison said at January 23, 2005 9:37 AM:

There's a great new astrobiology blog, run by newspaper editor Rob Bignell, at http://alienlifeblog.blogspot.com/. It includes roundups of the latest news from the various scientific fields that form astrobiology and information about SETI. It disagrees wholeheartedly with the rare Earth hypothesis, and considering the number of articles the site reviews, the preliminary indications all seem to favor a universe full of life.

Ron Walraven said at February 24, 2005 12:16 AM:

I once saw in the newspaper a simple understandable calculation of the existance of life in other galaxy's. It was something like if there are 10 million galaxys, then there are approx 1 million which are inhabitabal, and so many that have intelligent life. I can't remember the whole equation. I was wondering if anyone else recalled what I was referring to?

Randall Parker said at February 24, 2005 10:05 AM:

Ron, You are thinking of the Frank Drake equation.

rupam said at March 20, 2005 3:04 PM:

i believe that life is a natural product of planetary evolution. Any system whether rocky or gaseous will with an energy source and chemicals. I support this with the following
$ Life on earth arose as soon as the crust cooled
$ Life on earth is found on many different (even assumed hostile) environments
$ Life is not defined as flesh and bones (though carbon seems to be the best element for a life base), there is no reason to assume sulphur, silicon, or other elements based life forms cannot exist
$ I agree that evolution doesnt necessarily mean intelligence but if the environment turns really bad, intelligence can cope better with it rather than real simple life forms..since intelligence has the capability of changing the environment around it while simple life forms (as tough as they may be) cannot do that. As a first comment, is life "evoloves" to the "perfect form", it will be intelligent rather than simple

Thus, I would suggest that life is just another phase is planetary evolution...maybe planets with no gaseous environment harbor strange life forms in their crust, or really hot planets harbor stranger life forms, but it seems to me that life is inevitable

as far as we finding it..

$ the idea that transmission capability is a small fraction of total life span on earth isnt convincing since if we look at some civilization a million years advanced than us, then thie ratio (viz. transmission capability versus total planet life) becomes bigger, so we can safely assume that there are other civilizations throwing out many many signals into space....maybe we just cant decipher then as of now but they are there...maybe on really high frequencies, high data rates etc

comments please.

haralambos said at March 27, 2005 10:11 AM:

i believe that extraterrestial life exists it can not be possible in so many galaxies not exist life.
it is not possible god that create life, create us to discover the other galaxies only. if He would create us only i dont think He would create the other galaxies and the whole system that we live rigt now.
the purpose of life i do not think that is the fancy cars,jewellery,money,etc...
it is more deep the meaning of life and only if we discover who we really are we will accept that life is anywhere in all galaxies not only in ours.

Kevin said at May 4, 2005 11:45 AM:

so if there are 1000 civilizations in our galaxy ... they should have there own GOD ? :P

Orflin G. Champion said at June 23, 2005 12:04 PM:

On the basis of present knowledge and the most likely explanation of the extraterrestrial hypothesis, we have been and are being visited by intelligent life forms who appear self disguising in and out of the narrow band of human perception. These continuous direct and indirect multifaceted alien manifestations demonstrate we are connected beyond the universe as we know it and are part of a much more profound cosmic process, the connecting of two species.

The web site listed below is devoted to human beings open to a sober examination and response to the big questions phenomenon that has occurred since the inception of the Internet.

Off The Grid Home Page

will said at November 2, 2006 2:08 PM:

it is absurd and arragant to think that we are alone in the universe, just because we are not technologicly avdanced enough to reach other star systems, and are too arragant to admit that there may be other laws of physics as we call it.our laws of physics are not the only laws in the universe, thats one big blind spot we have following old laws that were made up by observation of other scientists, we need to expand are thinking farther than that. for example, intellegence and education, one in the same, but we wouldnt have education without intellegence, it came first, then man with his own perceptions and opinions about his world decided to create subjects of education for all mankind,most of them hasnt been changed because in truth we are narrow minded by nature, in a sense followers not leaders, this is a new age we need to expand are thinking farther than are previous sceintists. maybe its how we are looking at it is why we cant figure out how to explore the galaxy,greed is another one of our weakneses, if we decided whole heartedly to give more to it than to take, we would already be on our way.but i guess its in our nature.we need to rethink the whole basic laws that we know.we need some extremely creative thinkers and people with high intellegance that are interested sincerely in expanding our world farther than earth.when we can figure out how to do away with money and greed also. we need to quit reading books other people wrote and stand on our own two feet, be doers instead of sayers.even if we reach our goal of efficient space exploration, find other intellegent life and civilizations,suceed in traveling through time, teleportation, telechanisis,eternal life. etc............ there is more in the iniverse as we no it or dont no it than we will ever understand.

Jase said at November 15, 2006 3:59 AM:

Yes but ironically we have to read your opinion and be told to make our minds up by you before we do it

George S said at August 28, 2010 1:27 PM:

SETI are searching for radio signals. An advanced species would not use any form of radio as it is extremely limited in it's capabilities. Assuming an advanced alien species mastered interstellar travel, they would want to communicate with their home planet in real time. Can radio do this? It cannot. SETI have only looked at a fraction of our region of space, with no success. Therefor, you have to conclude that intelligent life at roughly our level doesn't exist in that region. Until the technological singularity, we'll know nothing more than we do today.

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