SETI - Search For Extra-Terrestrial Life

Mankind has long wondered if we are alone in the Universe. Since about 1960, a number of research projects have attempted to detect such other forms of intelligent life.

Whether or not alien life exists, those projects are certain to fail.

The projects that have been pursued in SETI (the Search for Extra-Terrestrial Intelligence) are based on several assumptions that are certainly wrong.

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It might be true that there is extra-terrestrial intelligent life. Actually, statistically and scientifically, it is a virtual certainty. It may also be true that we could some day find a way to detect it, and we may someday even find a way to communicate with them. To accomplish these things, attitudes and experiments must be very different from present efforts.

All existing efforts are based extensively on many egocentric assumptions. We on earth generally use modulated radio waves to transmit information from one point to another. This is an EXTREMELY inefficient approach! We send such power in all directions, which is called isotropically. Enormous amounts of radiant energy are therefore needed to transmit signals that carry rather minimal amounts of information. In the first few decades of our having discovered radio waves (about a hundred years ago), yes, it was the only idea we had in this regard. Even now, our technicians are aware of MUCH more effective and efficient ways of transferring information from one place to another. In only fifty years, we discovered Masers and then Lasers, and in only another fifty years, now, we have learned how to send information on modulated Laser beams. Instead of having to send out a billion Watts of radiant energy in all directions, we now know how to send as effective a communication with only five Watts of radiant power, due to the extremely narrow beam of a Laser beam. Of course, this can only work IF we happen to know the exact direction of the target! Over the upcoming centuries and millennia, it is certain that our scientists will discover FAR better methods of communication that we cannot even imagine now. Such extremely advanced communication methods would certainly be used by advanced life forms in the Universe. They would be foolish indeed if they choose to use very primitive methods like ours.

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We, on earth, only discovered the existence of radio waves about one hundred years ago. For all the thousands of years of previous human societies, we were completely ignorant of the existence of the many forms of electromagnetic radiation that always surround us.

Less than one hundred years ago, we discovered how to create radio waves. Soon afterward, we discovered how to "modulate" those waves with lower frequency electrical signals that carried the information of sounds, and later pictures. These technologies of radio and television only came into existence during the lives of some people who are still alive today! In other words, our knowledge and experience in creating and detecting such waves are extremely primitive!

Even though we have accomplished a lot during this century, with radio and television and many similar technologies now surrounding our lives, we have only the most minimal understanding and experience in such fields. Come back to me in ten thousand years, and I will acknowledge that you then pretty much understand the subject! This present human arrogance regarding the belief that ALL is already known about electromagnetic radiation is one of the central incorrect assumptions involved in the SETI efforts.

A second incorrect assumption involves something called "bandwidth". This is related to the amount of information that can be transferred by known methods of modulating radio waves. Using modulated radio waves is a very crude method of transmitting information signals. For example, a modulated light signal can carry over ten billion times as much information as an FM radio signal, and our technology already has learned much of that technology, in our first hundred years of being capable of creating modulated Laser and Maser signals.

A third assumption that is almost certain to be wrong is that signal makers would be creating and radiating truly phenomenal amounts of energy fairly indiscriminately as to direction. Even our primitive hundred-year-old technology has already discovered extremely narrow beam radiation methods such as Lasers and Masers. A precisely directed Laser beam could transmit a message to a specific destination while using less than one-billionth of the radiative energy of conventional radio signals.

If the Earth had a colony on a planet in the Alpha Centauri system, four light-years away, consider the possibilities. Would we generate and then radiate trillions of watts of radio signal to send our indiscriminately aimed messages, or would we use a few hundred Watts of extremely narrow directed laser signals exactly in that direction? Would we tolerate that low band-width of 10 MHz of modulated radio waves when we knew that a single sentence of exchanged information "conversations" would always take 8.6 years round trip? Doesn't it seem obvious that we would already be using carefully aimed Laser narrow modulated light beams to maximize the information transmitted and minimize the power needed?

And this is just after our first hundred years of learning about creating and transmitting electromagnetic signals. Imagine what technology we might be using a thousand years from now? Ten thousand years from now? A million?

However, all of the ongoing SETI projects have assumed that the signals that we should listen for are simple modulated radio signals. It is the equivalent to if we would have teams of reconnaissance personnel watching the horizons for smoke signals, in the hopes of learning what neighboring enemies might be doing. A couple hundred years ago, that would have been worthwhile, but it is probably true than most enemies in the modern world have developed more advanced communications methods. Our personnel that would be now watching for smoke signals would certainly be wasting their time. Not because it wouldn't still work, but because far better methods are available. And that those others would likely have learned enough to not NEED to be sending smoke signals to exchange information. Today, they probably would just pick on their cel-phones, and no smoke would appear!

A Little History

The earliest successful transmissions of signals and information via radio waves was done on a "carrier wave frequency" of a few hundred thousand cycles per second (hertz). That carrier frequency was capable of being modulated with an electronic equivalent of a SOUND signal of a few thousand hertz frequency. In the jargon of the subject, this would be referred to as having extremely LOW BANDWIDTH.

Within just a few years, our technologies advanced to being able to create and control and detect carrier wave frequencies of a few hundred MILLION hertz (which we now use for television transmission). This bandwidth subject can get fairly technical, and numerous electronic textbooks cover the subject. The important result here is that this carrier wave frequency of one thousand times higher has about one thousand times higher BANDWIDTH which means that one thousand times as much modulated information can be carried on it. This is what enabled the technology of television, because a complex television image requires MANY more times the amount of information of simple radio transmission of voice, music or other sounds.

Later advances involved slightly higher modulating frequencies that enabled transmitting COLOR television signals (which require about three times the amount of electronic information as a black-and-white signal). Technology continued to advance, and soon UHF and microwave technologies came into existence. With even higher carrier frequencies, bandwidth became even broader, so even more information could be carried on a transmitted electromagnetic (radio) carrier wave. Soon, the technology of "multiplexing" MANY desired signals together allowed sending hundreds of sound signals together on a single microwave carrier wave.

Recent advancements have extended these technologies to modulating light waves, especially laser or maser generated light waves. Light is actually very similar to radio and television and microwave in that they are all electromagnetic radiation. Their (carrier) frequency is the main difference. In the case of light, the frequency is on the scale many millions of times higher than any of the others.

This means that the BANDWIDTH available for signals being carried on a carrier light wave is so broad that many millions of times as much information can be sent from the source to the destination! Our earth-based technologies are already developing these areas, and optic cables are becoming common. These are cables that do not even include metal but rather special glass fibers. A light signal is sent through the cable that is modulated with astounding amounts of multiplexed signals. This field of technology is another one where many textbooks describe the field, but which is rather advanced and beyond what we need here.

Carrier Frequency

During the early thinking regarding SETI, an assumption was made. In the 1950s and 1960s, it may have sounded like a good assumption, but it is clearly incorrect now. As radio telescopes explored and charted the skies (since THAT technology was invented in the 1930s) it was noticed that natural signals of every imaginable frequency seemed to exist, but that there was a particular microwave frequency (about 1.4 Ghz) that seemed generally clearer. That frequency is associated with a characteristic of the Hydrogen that makes up much of the material of the Universe. (Another technical subject!)

In any event, it was decided that any extra-terrestrial civilization would probably use this frequency (because it was clear and not subject to static or other signal disruption from other natural sources). In the 1950s and 1960s, this microwave frequency was right at the edge of our technologies, and there was the assumption that the OTHER intelligent life was exactly as intelligent as we were! Again, our arrogance led us to believe that we knew ALL the answers! Any TRULY advanced civilization would know just what WE knew (and little more!)

In just a few decades, our technology has discovered how to put millions of times as much information on light waves. This begs a question! Why would the OTHER intelligent life form use an inefficient and even antiquated carrier frequency as microwaves, when they could use light as a carrier, with millions of times the signal carrying ability? They WOULDN'T!

Energy Efficiency

Another obviously incorrect assumption is related to the inefficient use of energy. During the Twentieth Century, earth societies went berserk in using (and wasting) phenomenal amounts of energy in almost every field of endeavor. The list of negative consequences is a long one, which includes global warming, innumerable types of pollution, and many effects that will not be noticed or documented for years to come.

This attitude of having unlimited energy available and not having to worry about any unintentional "collateral damage" that might be caused by massive radiation, extends to the field of SETI. A REALLY illogical assumption has been made that an intelligent society would send omni-directional or broadly directionalized radiation throughout the Universe when they would certainly be actually interested in sending a message in one very specific direction, like to a colony on another planet or to a spacecraft. Why would they create a transmitter that would radiate a BILLION watts of electromagnetic radiation in all directions, when, by carefully directing it, a ONE-WATT signal would have the same result of contact with their colony? Why would they waste the time and effort and expense to build such a transmitter, and why would they continually waste a billion watts of energy when one watt would do the job? They WOULDN'T!

Even earth-based technologies have already learned these things. When NASA scientists try to communicate with a spacecraft they sent to Mars, do they send billions of watts of signals in all directions? No! They use a special transmitting antenna that directs a fairly narrow signal toward Mars. And the spacecraft has its own directional antenna to receive those signals and to send back its own messages. These things only make sense, because they are tremendous improvements in power usage efficiency. Some day, NASA will figure out how to use even narrower laser beam light waves as the carrier waves, and energy efficiency will be enhanced far better yet!

If we actually BELIEVE the word INTELLIGENT in the concept of SETI, we should conclude that an intelligent civilization would not long squander astounding amounts of energy in communications methods. Given our present knowledge, the best guess is that modulated laser light beams would be a FAR more efficient method of communication that any method assumed related to SETI projects. Why would an advanced (more so than us) civilization use such a crude method of communicating as a limited bandwidth microwave, omni-directional method? They WOULDN'T!

And MORE!

All of our speculations on the methods used by alien life forms include DOZENS of assumptions! WE have only even KNOWN ABOUT electromagnetic radiation for about one hundred years. What new and more advanced phenomena will we learn about in the future? Will we ever learn the mechanism of ESP? If so, the phenomenon may have nothing to do with electromagnetic radiation but some entirely new field that we have no clue about! What if the INTELLIGENT beings in the Universe use such a system for communication. We could have no experimental way of knowing about it! (Yet!)

Imagine people of two hundred years ago speculating on how we would communicate today. They knew nothing of cars, airplanes, light bulbs, electricity, computers, phonographs, CDs, radio, television, or thousands of other common parts of our lives. How accurate are our speculations likely to be about our own society two hundred years from now? Or two thousand? Or two million? Or some alien society that doesn't even resemble us, fifty million years advanced of us? No chance! We can only make wild guesses regarding these things. So, believing that we understand what kind of equipment they will be using and what kinds of signals they will transmit is really just a demonstration of our great arrogance!

It MAY be worth attempting some sort of SETI project. If so, that project will certainly have to be VERY different from efforts made so far, if there is to be ANY hope of success.

The civilizations on earth have taken billions of years of evolution and many thousands of years of social development to get to the level of knowledge we have today. If some other planet's development was just one percent ahead of ours, they would be millions of years more advanced than we are. If that planet's development was just one percent behind ours, their "intelligent life" would still be hunting and gathering. It is totally illogical to assume that the other end of ANY long distance conversation would be exactly at our stage of development (or within 50 years or so).

There's another implicit assumption in this. If the other planet's civilization was a million years ahead of us, what could they POSSIBLY learn from such a primitive civilization as ours? If we today could locate a community of primitive earth men from a million years ago, would we try to talk to them? Why? They would not have a significant language, and they would have few concepts they even understood. Eat, sleep, cave, warmth, survive, and maybe fire. Would you go out of your way to try to get a conversation going with someone with so little to share?


There is actually an even more practical problem related to SETI. Say that we somehow discovered a planet circling some small star in the nearby region of space that we commonly refer to as Orion or the Orion Nebula. In Universe terms, those stars are VERY close to us, only around 600 Light Years away. Let us now consider several possible situations.

Say that there are people on that planet which have learned the technology of radio and television, and that THEY initiate a SETI program, in an attempt to find others such as us. So they build massive and expensive equipment and start sending out SETI type radio signals. Those signals would travel at the speed of light, which means that they would arrive here around 600 years from now, around 2600 AD. Whatever our technology then, would anyone on Earth actually still be LISTENING for extremely crude and extremely weak radio signals? About the only realistic possibility I see is that MAYBE some small child might need to create a Science Fair Project, but no one else would possibly still be listening for simple radio waves 600 years from now. So there is NO realistic chance that SETI could possibly work, even regarding a NEARBY planet which was occupied with intelligent beings.

Consider the reverse situation. That the planet just described had discovered radio and television technology 700 years ago, and that they decided to send out SETI type radio signals around 600 years ago. IF we developed sensitive enough radio receivers, AND if we could analyze what we received well enough to realize that they were artificial signals sent from a planet in the Orion region, what would WE do then? We must note that we are considering a civilization that is 600 years Ahead of us, and that RIGHT NOW, they would no longer see any value in radio communications. Would any of the beings then even KNOW about a brief experiment in SETI that was done thirty generations (or 600 years) earlier? But more significantly, WOULD any of their descendants of 30 generations later still be interested in such ancient history to even listen for or care about any response that we might send, which could only arrive back there after another 600 years of the radio waves traveling back from Earth to their planet? There seems zero chance of that. IF a civilization is so backward to have not progressed in technology for 1200 years, they must not be progressing at all. In other words, it seems most likely that they might have exterminated themselves, as the BEST chance of possible communication!

So the idea of SETI is extremely dependent on BOTH civilizations involved being willing to stick with an obsolete technology for at least 1200 years, just in order to become aware of each other! In other words, no realistic chance whatever, and the basic idea of SETI can be seen as extremely foolish.

Now, extend these science fiction dreams further and speculate about actually GOING there after we had established communications. Nearly everyone seems to immediately jump on board such ideas, probably because they trigger the imagination. But when we examine the actual FACTS, we can see how silly that idea is.

We DO know that with CURRENT technology, we can send small robot spacecraft to Mars in a year or two of flight (one way). At those times, Mars is actually only about 3 Light Minutes away from us. Our technology would require massive improvement to even remotely travel much faster, and there is NO CHANCE that we will ever be able to commute to Mars in a three-minute flight at the speed of light!

WHY is that so impossible? Because of biology! We have lived all of human existence in a situation where we are forever in the Earth's gravitational field. Our heart must always be able to pump blood up to our brains and return blood from our feet, and the biological construction of tissues is such that the heart, heart valves, arteries, blood vessels, and the delicate blood passageways in the brain all do that pretty well. But when a Jet aircraft pilot really accelerates, he may momentarily cause his body to endure G-5, meaning a situation where is body experiences five times the normal force of Gravity. Many early Jet pilots died of brain aneurisms or of blood vessels bursting or of all their blood pooling in their feet and therefore dying from lack of blood elsewhere, that G-suits had to be invented such that pilots could survive.

G-2 is more easily survivable, but it still puts immense stresses on the body. For example, if you are currently an adult man of 200 pounds like I am, during G-2, the body would behave as though it weighed 400 pounds. It would be like me having to carry an entire second person on my back, constantly and continuously. My movements would be far slower and more difficult. If that was only for a few seconds, we can do that. But what if you were required to endure that continuously for a year or for ten years? The fact that your heart had to continuously work twice as hard to pump blood, alone, would reduce your likelihood of survival.

Why these comments?

So say that YOU were selected to go in a rocket ship to that planet in the Orion region that we discussed earlier. You would need to ACCELERATE to get up to a fast cruising speed. Let's examine that. Say that your rocket was designed to have its rocket engine fire constantly for years, and that it provided an acceleration of 64 ft/sec/sec or 2G. This means that you would have to endure that 2G environment (for probably half of the entire trip, which we are about to calculate, and then the rocket would need to be turned around and the rocket fired backwards for the second half of the flight, to slow you down so you would be able to stop and visit once you got there. So your body would have to endure the 2G for the second half of the trip as well.)

So, every second, your speed increases by 64 ft/sec. After an entire day (86,400 seconds) of that acceleration, you would be traveling at slightly over 1,000 miles/second. After a month of such acceleration, you would be traveling at about 30,000 miles/second. There are some effects of Relativity which would eventually occur, but in around a year of this flat-out acceleration, you would then be traveling at a speed that was fairly close to the speed of light. Assuming that your heart and body survived that full year of extreme stress, your rocket engine would then shut off and you would COAST for 600 years. Then another full year of extreme stress during deceleration at the other end.

This is NOT like how science fiction describes space travel! To have to endure physical hardship which might not even be survivable for an entire year, and then coast for 600 years and then another year of extreme physical stress, just for a NEARBY trip??? You noticed the 600 years part. Yes, even if you survive the G-force stresses, you will not live 600 years. So it would actually be a descendant of yours, around 30 generations after you, who might actually arrive there!

You might have realized from the above that severe acceleration is NOT a good idea. In fact, it is nearly certain that the ONLY rocket acceleration which would ever be designed would be where G-1 exists. This WOULD take around two years instead of one, but your body would then not have to endure the immense biological stresses. It actually would only extend the (one way) trip from 602 years up to 604 years, and so it IS the logical thing to do!

Still, what will the future hold 600 years from now? What if that other planet decided to send this rocket toward Earth, due to a communications between our two civilizations? Can they really be sure that Earth civilization will not have had a nuclear war and everyone dies before 600 years? Or the effects of global warming where all the plants and therefore all the food supply dies, meaning the deaths of all animals and humans? Or what if we all die from drug-resistant TB or from Ebola or from Bird Flu or a hundred other reasons? To have invested 600 years and massive expense to make such a trip, and then find that there is noone at home? See the bigger issues and bigger questions?


This discussion seems to suggest that the many SETI projects that are listening for modulated radio waves are doomed to total failure. The only REMOTE possibility is regarding a distant civilization that also had just discovered radio waves (at some distant time in our past), and didn't then know any more about the field than we now do!

Given our current knowledge, it seems FAR more reasonable to look for modulated light signals. Even then we would have to be somewhat lucky to receive one. We would have to be exactly on line and behind the target for such a communication signal to arrive in our location. But such a signal would not have a simple mathematical sequence as its modulation. It would certainly have a VERY high frequency modulation signal, so as to best use the available band width. Such a modulation signal would likely be so high a frequency on its own to be above the ability of any sensing equipment we now can build. So the signal would just appear to us to be a monochromatic light source.

A future civilization MIGHT modulate some really obvious pattern into their carrier wave, to make sure that their intended target looks in the correct direction. We certainly see a number of very peculiar light patterns in some objects that we believe are stars. What we call Pulsars, are certainly impossible by the laws of science as we know them. Could any giant star ROTATE so fast as to appear to flash 30 times every second? The surface velocity of such a rotating star seems to violate the limit of the speed of light! What if such very distinct flashes are NOT natural at all, but instead ARTIFICIAL pulses, which were added by a transmitter just to ensure that their much fainter communication signal was found in that specific direction? In other words, that things that we describe as Pulsars (and other rapidly pulsing optical or radio signals) are meant to get our attention?

So, in the future, if WE decide to try to send a narrowly directed communication signal toward Alpha Centauri, in case there might happen to be an inhabited planet in that system, should we also send brilliant flashes of distinctive light or radio in that exact same direction, sort of as a Beacon, to alert any people near Alpha Centauri that they should look for a much fainter signal that might contain an information message? Seems to me a FAR more thoughtful way of trying to pursue SETI, in both directions, receiving AND sending!

The conclusion is then that we are probably just not yet technologically advanced enough to create a decent SETI project!


See also: Discovering Alien Life Signals in Space


This text was first assembled in 1994. This presentation was first placed on the Internet in April 1998.

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C Johnson, Theoretical Physicist, Physics Degree from Univ of Chicago