Be vewwwwy vewwwwy quiet….

By Julianne Dalcanton | January 16, 2008 1:49 pm

I have no independent knowledge of the veracity of this report, but a local TV station in the Bay Area is reporting rumors that the SETI program running at the upgraded Arecibo radio telescope has detected an anomalous signal (or in the very high tech language of their reporting, a “mystery signal”). The report includes some quotes from Dan Wertheimer, the director of the program, so presumably the reporter talked to someone with verifiable science cred before writing the piece. The quotes from the project’s scientists are guarded enough that I’m guessing this is just a lousy job of science reporting in the local news.

The part that got my blood pressure going was the follow-up about what we should answer back. The idea that our backward, technologically impaired civilization should jump up and down and wave its arms around saying “LOOKY HERE!!!! LOOKY HERE!!!! PICK ME!!!!”, is,….what’s the word….oh….batshit crazy. History is not exactly awash in cases where the technologically less advanced civilization wound up the winner when two cultures collide. Usually, it gets rolled.

In spite of this, some crazy optimists in Russia are actually beaming signals out to nearby stars, right now. This “active SETI” program strikes me as completely foolish, and has already caused a rift within the SETI community (so apparently, I’m not alone in my abject fear of being spotted by a more advanced civilization). While this issue hopefully has less urgency than figuring out the political response to planetary climate change, we need to eventually get our collective goverments organized into a treaty about how to deal with this issue. Suppose someday we actually detect some alien space ship whizzing through our local neighborhood. Do we let the Raelians and Scientologists invite them down for a drink, even if the rest of us think it’s better to lay low?

In the meanwhile, Earth should just STFU.

(UPDATE: Link to timesonline changed to the original reporting that they swiped from a much better article by David Grinspoon at Seed.)

(AND ANOTHER UPDATE: Phil Plait did some actual reporting (you know, calling and actually asking), and yup, it’s just bad journalism, as expected.)

CATEGORIZED UNDER: News, Science and Society, World
  • rillian

    Doesn’t all the radio and optical noise our civilization emits give us away regardless? I mean, if they’re looking for someone to roll.

    Of course, if you thought getting people to think sufficiently long term to deal with climate change was a problem…

  • Julianne

    We’re plenty noisy on our own, true, but the detectable range can be significantly further when you beam a specific, easy to distinguish signal in the exact direction of a nearby star.

  • Sirhcton

    I always have mixed feelings about the proper attitude for actual detecting signals from another civilization. I used to think that given the distances and times involved, communication would always be a long-term affair, with only messages and little chance of physical exchange. Also, any civilization able to actually assemble the resources for a physical visit (either in person or via machine proxy) would be advanced enough to be both non-hostile and circumspect.

    As I have aged, I have come to agree that maybe it is better that we should be circumspect and learn to take a longer term view of this. If an alien civilization is anything like the human ones, calling attention to ourselves might be just what we want to avoid.

  • Wilfred

    Come on, the defense satellites are a dead giveaway already and those have been beaming for years, and guess by which country? It has one letter less than ussr…

  • rooshi

    Very thought provoking post!

    I was also wondering about the flipside: If we detect another civilization because of them being noisy (as opposed to wanting to contact us) what should we do?

    It would be more than ‘batshit crazy’ to contact them, more than it would be to respond to a beamed, intentioned signal from them. Maybe they won’t be ready for contact with us, maybe they will be less civilized, more martial.. whatever.

    Assuming that is wise, the problem becomes a more existential one. Just WHY do we want to contact another civilization again?

    I can understand wanting to *find* other life in the universe (SETI). But just how risky would it be to get in touch? Will the benefits ever outweigh the risk?

  • George

    Is it necessarily certain that we will detect a more advanced civilization? Certainly if they can come here they are more advanced, but we can be getting radio noise from a civilization that’s just about right where we are, and even if that civilization has been around hundreds of years since that message was sent, their society could have stagnated or regressed in that time (or maybe not even exist anymore).

    Bottom line is, it’s rather hard to make a decision when we really have no idea what the risks and benefits might be — and you can’t really make a policy based on facts that you don’t know.

  • Low Math, Meekly Interacting

    Wouldn’t it likely take anywhere from thousands to millions of years for them to get the message and then get here and blow up the Earth (insert Marvin the Martian joke here)? I mean, when they set out, they may be more advanced than us, but their technological development would probably be arrested in transit, giving us plenty of time to build a BFG powerful enough to blast ’em from a safe distance.


  • TomR

    I’m curious if anyone knows of a rigorious treatment of the whole “aliens are watching old I Love Lucy eposodes” idea. I feel like I’ve read somewhere that if there was a civilization just like ours around Alpha Centuri, we still wouldn’t know about it. Any idea if that’s true or not?

    Back-o-the-envelope says that a powerful AM station is down to 1 photon/m^2 in about a light year, which makes it seem like it would be pretty hard to distinguish from sunspots/thermal noise/auroras/lightning/pigeon poop at intersteller distances.

    Are there any radio astronomers out there who could weigh in on this? I’d love to learn more about the limits of detectors, how much info you need to tell a technological signical from noise, what the intersteller medium absorbs, etc. ,etc…

    Oh yeah, that “news” story looks more like bad journalism than anything else. Still, we can hope.

  • Matt

    OK, I’m really, really hesitant to bring this up at such a reputable place as Cosmic Variance, but … here goes.

    Julianne – if you’re willing to consider the possibility that spaceships could one day buzz the earth, why not consider the possibility that it could already be happening? In the last 50 years, hundreds of thousands of witnesses have reported seeing objects in the sky with capabilities far beyond what we could hope to build ourselves.

    I know witnesses are the least reliable form of evidence available, but doesn’t the sheer number of accounts at least count for something?

  • David Grinspoon

    The Times Online article you link to steals quotes, unattributed, from my recent SEED Magazine article on the active SETI debate.


    David Grinspoon

    Also, see interesting recent discussion on this debate on Centauri Dreams:

  • George Musser

    Julianne, STFU is not an option. Our photosynthetic friends have been broadcasting their presence for 2 Gyr or so.

  • Low Math, Meekly Interacting

    Matt, I’m reminded of the MIB gag, where Tommy Lee Jones explains to Will Smith that the sorts of tabloids that publish stories about Batboy and his ilk contain the finest investigative reporting on Earth.

  • Pingback: Centauri Dreams » Blog Archive » Dubious SETI Report Claims Reception()

  • chuck

    “The idea that our backward, technologically impaired civilization”

    Compared to what? Imaginary space aliens from science fiction?

  • TomR

    George, what you say is true, but by the same argument, the vast majority of planets with life won’t have technological civiliations. Seems like you’ve got to be awfuly paranoid to wack 99,999,999 algae planets just to get the 1 with tool builders. (This always strikes me as funny. I’d be willing to bet that in the next 10-30 years we build telescopes that are able to detect spectral signs of life around other stars. The dissapointment is that the life we find will almost certanly just be space seaweed).

    That being said, I don’t think we can dismiss the chance that other civilizations are hostile. By physics as we know it (TM), it’s a lot easier to sterilize a planet than it is to visit it. We can at least imagine how to accelerate a projectile up to a few percent of c, where it has more energy than the rock that killed the dinosaurs. Building something that can slow down when it gets where its going is many orders of magnitude harder. It’s not too hard to imagine ETs with cold-war style thinking: “Well, they could destroy us if they wanted to, so the only logical action is for us to do it first….”

  • Icelander

    Why would an advanced alien civilization want to invade and conquer Earth? If they need labor, they’ve probably got AI and robotics by now.

    If they need raw materials, why not harvest them from somewhere they don’t need to conquer and destroy us. Why not mine Mars or the asteroid belt for raw materials? There are things there, like heavy metals, that are in short supply on Earth and you don’t need to pack your ray gun.

    If they need living space, I would ask why? They’d need some sort of self-sustaining space vehicle to get here in the first place, so why not live on those? And wouldn’t they know of millions of other worlds that don’t have life on it?

    And if they’re a warlike species, how would they have survived? We’re still at risk of blasting ourselves off our own rock, and I don’t think our first reaction to the news of a less-developed civilization would be to hunt it down and kill it, especially if it meant figuring out how to cross interstellar distances to get there.

    Finally, any species sufficiently advanced to travel between the stars would have to realize that life is rare and intelligent life doubly so. So why go around destroying it, even if it’s not nearly as advanced? They would have their own history to remind them that we are like them.

    Indeed, an alien civilization would probably more interested in studying us as indicative of how they used to be, than invading.

  • Odani of the Mysterious Voice Patrol

    LMMI’s hypothesis works if our current theoretical speed limit–lightspeed–remains valid. What if it isn’t? I have no idea what the work-around might be like, nor do I have any basis for believing there is one–but the possibility does exist, just as there exists the possibility that some other life-like form is Out There, monitors the electromagnetic spectrum for communications, and would be interested in us.

    So, I’m writing a letter to my UN delegate today, urging him to make all countries in the world aware of the possibility of this latest crisis, and urging world-wide laws outlawing deliberate messaging to outer space. That’ll fix them ruskies.

    Well, others may not be into reacting to alien contact or global warming, so how ’bout something closer to home? The following is from a comment to tristero’s January 16, 2007 post, “Cause And Effect, Perhaps?” at

    “I’m a cell/developmental biologist. Recently I attended a lecture series sponsored by a new “think tank” called Reason to Believe. This group promotes a brand of “scientific” creationism that is remarkably like Intelligent Design, only the Reason folks think the ID people are cowards for not going there and naming the Designer. There were two lectures. One was by a physicist/cosmologist who claimed he was “proving” that God/Jesus/the Creator created the world, that the Bible predicted Special Relativity 12 times, and that the chances of, I don’t know, some such thing, happening spontaneously was 1/10 to the 1032 power. He flashed some equations, and some Bible verses, threw around a lot of big physics words, agreed with the estimate that the universe is 13.7 billion years old, plus or minus 200 million, and that life on earth began about 4 billion years ago. He claimed that the Bible proved the Lambda-CDM concordance model.

    “Like I said, I am a cell/developmental biologist. I last took a physics course when Reagan was president. It was physics for pre-meds, and I worked my ass off for a B. So, like, no way in hell was I going to challenge this guy on the content of what he was saying. But I was extremely bothered by the fact that he would claim that the Bible “proved” something and then not take us through the proof. Or flash a big multivariable equation on the screen and not explain it in terms that the average person with high school or college math/science exposure could follow. In my Bio department, we sometimes have seminar speakers using computational models to explain interesting biology, and they always walk us dumb biologists through the equations so we can not only follow the seminar, but also evaluate the work. That’s science-critical evaluation. But this guy made no attempt to convince anyone of what he was saying, he just wanted to dazzle the uncritical with “science”, which is, to too many people, big words and incomprehensible math. “

  • Icelander

    I also forgot to add that we’ve been transmitting our location with increasing strength for almost 100 years now. Any alien species sufficiently advanced enough to destroy us is probably also advanced enough to find out where we are, considering we’re within 100 light years.

    And since they’ve got to cross interstellar distances to get here, they’ve got no guarantee that we won’t be advanced enough to destroy them by the time they get here.

  • Jobe Roberts

    I don’t understand why you’d equate more advanced as more hostile and hell bent on killing us all. Maybe they’re simply intelligent enough to communicate and give us some needed advice on how to prevent us from killing ourselves.
    As pointed out, they probably already know we’re here and are hiding from us.

  • Sean

    I’m with Julianne. History has not been kind to less technologically advanced cultures.

    But really, it’s a matter of risk. To simplify things, let’s say there is an x% chance that an alien culture wipes us out/enslaves us/eats us for appetizers, and a (100-x)% chance that they lift us beyond our current petty squalor. What is an acceptable value for x, that you would take the chance? 10? 2? And just how confident are you in your estimate?

    I think we have a long way to go before we can play with the galactic big boys, presuming there are any.

  • Julianne

    I’m not assuming that they’re hostile — I’m assuming that I have absolutely no way of knowing. In that circumstance, I’d rather be quiet and watch until I do know.

    Intent aside, even if our new alien buddies wish only the best for us, it doesn’t guarantee that we wouldn’t be the losers in the exchange. Colonialism as practiced by humans was not always done with bloodthirsty conquest in mind, but was sometimes motivated by noble (sounding) justifications. Still didn’t mean it went well.

    And with regard to the relative difficulty in working out treaties for alien contact vs global warming, I’d argue that it’s easier to do the first now, before anyone has any skin in the game. With climate change, there are real immediate obvious costs that one has to pay. With alien contact, however, it’s not a big deal to make concessions. The groups making the treaty really need to be primarily governmental, however, not SETI-dominated, since self-defense and enforcement of treaties are not yet the purview of our SETI overlords.

  • Z

    The timescales involving interstellar travel are so huge (relative to fixed observers) that I don’t think it matters if we’re alone in the universe or not. What are aliens going to do after they receive our signal in a few thousand years, waste enormous amounts of energy accelerating space vessel just so they can enslave or destroy us? Nevermind we will probably be long dead by then anyway.

  • Eugene

    But we all know we will eventually wipe out the eveel aliens with our unstoppable microbes, the real rulers of Planet Earth!

    (Just kidding).

  • Low Math, Meekly Interacting

    What a timorous bunch…

    I, for one, welcome our new Type III overlords!

  • spyder

    Not that there is an age disparity here, but it seems that most have forgotten (or are perhaps just unaware) that we had this discussion a few decades ago (35+ years now). Now this current argument is predicated on the apparent risk of broadcasting a signal into space that may entice some as yet undescribed non-earth-based lifeform to invade the planet. Since that actually requires proximity of matter (getting to within the boundaries of our solar system), we would be at greater risk if we spread our “signals” throughout the solar system, as well as the nearby, local, surrounding galactic space. Yet we have done that already. The Voyager spacecrafts are way out there, and they both contain very specific, very detailed messages about human beings on planet Earth. Thirty years ago my father, who helped design and build launch vehicles, gave each of us children our own copies of those messages, maps, and cultural information. Not many years ago, i transferred the analog information from its original cassettes onto a hard-drive for safer longterm storage. There is even a book (published in 1978 under Carl Sagan’s name, along with others) titled MURMURS OF EARTH, that discusses the messages, the intentionality, and potential interstellar access of the Voyagers.

    I suspect it might be a little late to be arguing this point.

  • Low Math, Meekly Interacting

    Eugene, it’s even worse than that. I’ve heard that, despite having mastered interstellar travel, they can’t figure out the basics of atmospheric spectroscopy, or even how to make a decent raincoat.

  • Count Iblis
  • Ellipsis

    I’m not sure any treaty could be general enough to cover all the hypotheticals on that one.

  • Low Math, Meekly Interacting

    So somebody actually resigned their position in an “elite SETI study group” because this Russian dude is beaming messages at more-or-less random stars? That seems about as reasonable as complaining to the authorities that your neighbor is disturbing the peace by talking to his plants.

  • TomR

    BadAstronomy is reporting that they’ve spoken with people at SETI, and the story is basicaly confused reporting. From that blog:

    Basically, Dan Wertheimer, a radio astronomer who is affiliated with SETI, detected a pulse from space. The source is certainly extragalactic, and is most likely some sort of natural event. It’s unclear exactly what kind of event, but there is a long list of things it could be. Aliens phoning us is pretty far down that list. But since Dan does do some SETI work, the reporter just botched things up a bit and misattributed the source. The news article reads oddly, like he took a mishmash of topics and wrote them all up into one article, so this misunderstanding doesn’t surprise me much.

    The signal was detected quite some time ago, and had it been alien, believe me you would have heard from the folks at SETI!

  • The Almighty Bob

    Any reasons to invade involving slave labour or resources have the old problem of extraction to deal with; Earth may not have a very deep gravity well, but it’s still there. Much better to mine asteroids and build Cylons.

    But they don’t need to invade to destroy us; there’s the old phenomenon of “culture shock,” which has nearly destroyed the human race a hundred times over in science fiction. I can’t think of any specific real-world examples off the top of my head, but I have vague inklings that they existed… Aboriginal (the non-specific definition) cultures running headlong into a civilisation that completely overawed them and wrecked their way of life.

  • The Almighty Bob

    Of course, then there’s Fermi’s Paradox to deal with, and (more damaging to SETI, in my view, because it lands a blow on the technological rather than philosophical assumptions) Shannon’s work on information entropy (that article’s very dense; the best summation my [limited] understanding gives is that any optimally encoded signal will be indistinguishable from noise).

  • Count Iblis

    If civilizations typically evolve to become machine civilizations that go on to colonize the galaxy, then it may be dangerous to transmit signals. When a machine civilization gets started on some planet, there will be a very strong competition between different cyber entities. It is not clear at all that such a competition will lead to superintelligent entities.

    It may well be the case that many generations of machine evolution leads to a ruthless entity who destroys any intelligent competitors in order to use all the resources for itself.

  • andy

    Don’t worry folks, chief “crazy optimist in Russia” (to use your words) Alexander Zaitsev apparently UNDERSTANDS that active SETI is not dangerous (presumably he knows the exact criteria the berzerkers are using and has long experience with interstellar politics), anyone who suggests otherwise is acting on an unsubstantiated BELIEF.

    Furthermore, he is qualified to speak for all humanity because of his “sovereign right on The freedom of speech, The freedom of broadcasting, The freedom of expression…”

    Oh yes, these people are so keen to talk to aliens that they believe talking to humanity is irrelevant.

    All hail our wise (and let us not forget, sovereign) ambassadors to the cosmos!

  • Moshe

    Interesting reasoning, especially when applied in reverse: maybe we are not discovering any civilization because everybody is hiding from us. One look at our atmosphere may suggest we are some kind of ruthless civilization running a colony, who knows what will happen to the next ones to be discovered…

  • Low Math, Meekly Interacting

    No ET after all. Bummer.

    (And I’m still quietly weeping inside that there was no Uranium Pew-36 Explosive Space Modulator reference, given the wide-open opportunity, and the Elmer Fudd quote above…sigh…)

  • Elliot


    I think you are misinterpreting the information entropy as defined by Shannon. It should be distinguishable from background noise.


  • George Musser

    Julianne, Sean, TomR: The risk of sending out a signal is completely moot. A TPF-class instrument easily detects our presence out to a certain distance, and the average civilization will have been around for millions or billions of years longer than we have, which is plenty of time to conduct a thorough survey of the Galaxy.

    If they’re out there, they know we’re here.

    Our unwillingness to send out a signal will only reflect on our own paranoia, and other civilizations will recognize that, to our own detriment.


  • anonymous

    Well, according to the Star Trek chronology, we will make first contact in the year 2063. Maybe this is the start of it. And don’t worry about possible hostilities: they’re vulcans.

  • John Merryman

    Given our exponential rush toward the edge of our little petri dish, interstellar invasion seems pretty far down the list of worries.

    My theory for saving civilization from its own predation is to recognize that virtual currency, ie. tax based, not asset based, is a public utility, like a highway system and treat it as such. Not only would this tend to distribute wealth more evenly, but it would reduce the obsession with currency, since it would always be viewed as a form of public property and one’s responsibilities would be increased by possession of a surplus. This would serve to slow and congeal economic prospects somewhat, but given that resources are ultimately limited, this would be a long term benefit. We might even go back to fixing things and growing more of our food. There could even be local currencies, just like there are local governments. Banking profits would be a form of community income.

    While this may seem to be more suited to an economics discussion, the ultimate goal is to make earth one large organism, with humanity as its central nervous system, not simply its top predator. If we are the embryo in the egg, we have about finished consuming the supply of protein and it’s about time to hatch.

    As it is, economic discussions don’t get much past whether we are headed for a recession, or not. The view here is at least long term.

    Sorry to interrupt, back to SETI.

  • chris

    ouch – some basics seem to be missing in this discussion.

    first, the classical argument for the difference in technology level: our ‘space age’ is hardly a century old by now. this is epsilon compared to cosmic distance scales, so the possibility to contact a less advanced civilization which is still in the space age is also epsilon.

    second, a civilization which is millions of years into the space age has to at least have the property of not having self-destructed meanwhile. this hints at the fact, that they won’t just destroy us. but i agree, this argument is not too convincing.

    in any case, i am willing to make any bet that we are alone. probability speaks grossly against a second civilization somewhere.

  • Arush Kishore

    “History is not exactly awash in cases where the technologically less advanced civilization wound up the winner when two cultures collide. Usually, it gets rolled.”

    Not quite true. Tipu Sultan in India used rockets against the English centuries before they were discovered in the west. Indian navy was significantly superior to that of the English, and Indian culture was without parallel. But India was quite successfully mauled by the British, simply because the British were beastly dickheads intent on spreading what they thought was superior.

    Moral: your technological superiority does not matter, only your will to kill, maul and subjugate other people. THAT is the lesson the West has taught us for centuries.

  • Reginald Selkirk

    Lacking other models, we should consider the possibility that at least a portion of other civilizations, if they exist, also contain crazy optimists who are foolishly engaging in “active SETI” by beaming out LOOKY HERE!!!! LOOKY HERE!!!! PICK ME!!!!”

    Since we have not detected any such COBIETI* activity, we should reduce our estimates of the probability of the existence of other civilizations.

    * Crazy Optimist Batshit Insane Extra Terrestrial Intelligence

  • Pingback: SETI and other stuff « Dad2059’s Blog of Science Fiction/Science Fact and Random Acts of Weirdness()

  • NoJoy

    I, for one, welcome our new Type III overlords!

    Isn’t this really a decision for President Executron and the Robot Congress?

    I think we have a long way to go before we can play with the galactic big boys, presuming there are any.

    Don’t you mean big girls?

  • John Ramsden

    There’s a 300-page book devoted to the so-called Fermi paradox, summarized in the book’s title: “If the universe is teeming with aliens . . . where is everybody?” by Stephen Webb (Praxis Publishing Ltd, 2002, ISBN 0-387-95501-1)

    As far as the many unknowns permit, this is a scientific analysis rather than a load of flying saucers and Roswell rubbish, and it discusses dozens of reasons, with the author’s quite plausible conclusion at the end.

  • Grima Wormtongue

    I’ve been wondering who sends the faxes I’ve been getting for the last few years. They’ve definitely helped me advance my scientific career.

    I’ve been working on the latest set of blueprints in my shed for quite a while now. Actually, I’ve had to rebuild the shed around what I’ve been working on – whatever it is.

    Can’t way to power it up and press the button with the strange squiggly symbol on it.

  • Albatross

    I’ve always thought the SETI concept a tad quaint. While it’s certainly the best bet we have at the moment, I suspect that Radio would be to the putative aliens what Smoke Signals are to us.

    As we can see in our own technological development, the period of inefficient (from a power use POV) broadcast lasts only long enough for a digital infrastructure to be established. Digital provides more control over communications, and simultaneously contains the signal. Assuming civilization still exists in 100 years, I suspect we’ll be LESS noisy on the RF scale than we are now.

    So looking for alien species in RF seems as wrongheaded as peering across the horizon looking for smoke signals. Of course, it’s the only technology we presently have, and if the aliens ever showed up I’d be the first one to sign aboard their ships, but I think the chances of SETI finding something are even slimmer than they seem to be.

    On the other hand I am hopeful that sometime soon someone will think to hook a speaker up to a quark, and discover that there’s an FTL communications channel already trasmitting “KLGM 17000 – News/Talk Betelgeuse.”

    “Here’s a tip: keep banging the rocks together, guys!”

  • John Ramsden

    Albatross wrote [#48]
    > Assuming civilization still exists in 100 years, I suspect we’ll be LESS noisy on the RF scale

    Exactly, and much less obviously informative too, what with all the compression and packet switching and frequency hopping elaborations that will undoubtedly come into use before long to squeeze every ounce of capacity out of all the frequency bands.

    To paraphrase Arthur C Clarke “Any sufficiently advanced comms technology is indistinguishable from noise” *g*

    If intelligent life is very rare, that raises the question of what is special about our environment (if one chooses for the sake of argument to disregard the the “here just because we’re here” explanation).

    Aside from the habitability zones round the galaxy and the sun, and the fast rotation rate of Earth, and its large moon to stabilize the direction of Earth’s rotation axis, and many other considerations discussed by Webb [cited in #46], I was quite persuaded by an idea in New Scientist a couple of years ago that the existence of multi-celled life here might be largely due to unusually large abundance of iron in the Earth’s crust (combined with plate tectonics to churn it to the surface).

    If the iron on Earth was able to absorb oxygen for longer than it might on most other otherwise comparable planets (and it does appear to have taken 3 billion years), then maybe that somehow gave early single-celled life forms here the opportunity to reach and head down an obscure but in the long term more productive evolutionary byway, whereas with the usual smaller quota of iron leading to a more rapid iron “oxygen saturation” and subsequent dispersal of atmospheric oxygen some other more stable but less felicitous evolutionary endpoint is the almost inevitable result.

  • Lawrence B. Crowell

    This is likely chimeric, just as the recent Texas UFO was likely an atmospheric optical effect from a temperature inversion.

    Communicating with an ET is likely to be about as difficult as trying to talk to an octopus. Some octopi species have brains the size of basketballs. An ET might have smarts and even be able to build devices such as radios, but a decryption algorithm for converting their “language” into ours is most likely a very non-trival problem.

    Also I suspect that if we do manage get communications from an ET they will be in our galaxy, or in the 1000 light year neighborhood. It would be nice for we could compare scientific notes on the structure of the universe. Yet frankly I suspect this is not likely. ETs may well be out there, where maybe the nearest are in the M81 galaxy or tens or hundreds of millions of light years away.

    Don’t worry, I doubt they are coming here. If our space program is any clue space offers little for us and probably little for them outside of science. I doubt we are going to colonize space and the StarTrek dream will remain on DVDs.

    Lawrence B. Crowell

  • Count Iblis

    Moshe #35, :) :)

    I agree with Lawrence that communication may not be possible for us. However, you can imagine different machine civilizations communicating over many millions of lightyears distance to make their equipment compatible and then uploading themselves from one civilization to the other.

  • Lawrence B. Crowell

    If any ETs are out there broadcasting messages, and if their conditions are at all parallel to ours I would imagine if we could decrypt their message it might amount to “Help!” As I read our situation these days we are in one hell of an entropy pickle, and it is getting worse.

    Sagan’s cosmic connection is an entertaining idea, and I would love it if we could plug into it. Yet if the averate distance between intelligent life is too large, galaxy to galaxy instead of star to star, the interstellar internet may never get off the ground anywere in the whole universe.

    If we end up promoting something into space and the stars it will more likely be nano-bots or vonNeuman probes.

    Lawrence B. Crowell

  • Peter Mexbacher

    Julianne, why do you assume that the aliens would have to be hostile? I think that every species which has made it to a technological level that includes space travel and has not annihilated itself in the process has passed beyond _our_ apish ways.

    Your fears, alas, are human, all too human.

  • Lab Lemming

    Dear Julianne,
    Perhaps your difference of opinion with the active SETI Russians is merely a reflection on the conditions under which you live. For example, life as a slave race in the Pan-Galactic Hegemony may be less desirable than life in modern, democratic Seattle. But is it really that much worse than eeking out an existence in Putin’s Russia?

  • Craig Whitman

    The best reason for contacting another civilization is the technology boost.
    Contact would lead to enormous technical advancements and probably to
    something similar to the Star Trek Society.
    After all we can not start trouble till we figure out how to get there.
    Given the history of the human race it is not us that would actually be in trouble.

  • Lawrence B. Crowell

    Any direct contact with life from another planet is more likely to lead to microbial horrors. Our immune systems, as those of every living thing on Earth, have evolved for life on Earth. StarTrek always had Kirk, Spock, McCoy beaming down in their uniforms. Any life form on that planet, say a single-cell like organism, might see them as lumps of proteins, lipids carbohydrates free for the taking. This assumes life elsewhere is at least carbon based and similar enough to life here. The immune systems of Kirk et al will respond to the presence of foreign molecular compounds, metahistones will present them to T-cells and so forth. Yet I suspect our immune systems might be completely lost in trying to manage an invasion by “bugs” with radically different biochemistries. The captain and crew of the Enterprise might end up as defenseless as loaves of bread again mold. Of course the reciprocal would be the case as well. This also leads to the problem of cross planetary bio-contamination, which would mirror our problems here with invasive species.

    Lawrence B. Crowell

  • Count Iblis

    I have a little more faith in our immune systems. Our bodies can actually deal very well with agents that cause “random” damage. Things tend to go wrong when we are under attack from agents that undermine very specific defense/repair mechanisms of our body.

  • Hal S

    I agree with Julianne that we should not assume that aliens will be benevolent. However, the fact that we haven’t been destroyed by an alien civilization, gives us a few real options.

    1) We are alone
    2) The difficulties and technology required to travel in interstellar space is beyond most civilizations
    3) Some benevolent, indifferent or really scared civilization is allowing us to exist (ignore us and maybe we’ll go away)
    4) Advanced civilizations in our universe are evolving at about the same rate or;
    5) It is very unlikely that contemporary civilizations would arise close enough in space and time for them to overlap.
    6) They are mired in a bureaucratic process (the Vogon problem)

    Option 6 is the most interesting, and perhaps the most depressing. I sometimes shake my fist at the heavens when I think of all the bureaucratic nonsense we will bring with us if we ever conquer interstellar space travel.

    Interstellar real estate developers, and space preservation societies, that I fear is the future of mankind in space.

  • Lawrence B. Crowell

    I doubt that interstellar travel will ever happen. Now, to tout a book I just published, last month it came out “Can Star Systems Be Explored? — The Physics of Star Probes. pub — World Scientific. I do think it is possible to send probes and robots to nearby extra-solar planetary systems. I wrote the book as an entertaining format to discuss issues of basic mechanics, relativity and some aspects of physics. You will also see why I think warp drives and wormholes are not likely, and I suspect ruled out by quantum gravity.

    So for the naunce I will assume that anything we send to another star will be a photon said, relativistic rocket, EM accelerated nano-probes, etc all of which travel at velocities v

  • Lawrence B. Crowell

    This system does not like the carrot symbol and cut this off

    a photon said, relativistic rocket, EM accelerated nano-probes, etc all of which travel at velocities v

  • Lawrence B. Crowell

    travel at velocities less than c. Let’s be conservative for now. For the purpose of probes I assume velocities that have gamma factors gamma = 1.05 to 2.0, for velocities about 9% to 87% the speed of light. Since these are meant to send information back there is little purpose in going faster than gamma = 2, going a bit closer to light speed takes a whole lot more energy and buys you little. It takes a lot of energy to do this as well, even for these “pokey” velocities compared to our usual Sci-Fi ideas of warp drives.

    To travel to another star would require people spend a lot of time on board. There is an idea called the bussard warp drive, which accelerates and uses the time dilation factor to get a crew very far in a limited time. I discuss this idea in my book, but this is a bit extreme. So interstellar space takes a long time to cross and it is damned cold. It is full of hazards as well. A tiny particle which slams into your relativistic spacecraft can explode like a 100lb bomb. So you make the thing needle shaped, I mean really needle shaped, and have some sort of energy screen ahead of the craft to deflect these. An ultrathin solar sail which is very wide to the direction of approach needs to be designed so that such micrometeoroids would pass through with minimal damage.

    So I doubt people are going to travel to other stars. It is just too much for us. I suspect the same for any ETs as well. So I doubt that ETs are coming here, or that we are going there. I doubt there will be any cross contamination of life forms, unless we have a returning probe that brings them back from some other problem. If so, and that goes awry, well we only have ourselves to blame. We might consider this question with a planet in our epsilon neighborhood — Mars.

  • Hal S

    Lawrence B. Crowell

    I was wondering if you addressed the “Omega drive” or rather the pulsed thermonuclear detonation drive. It seems that if we develop sufficiently intelligent computers (not necessarily sentient, I am still not convinced sentient AI’s are possible); we really already have the technology for interstellar exploration by machines.

    I agree that humans are likely to be to frail to travel through space, but a 50 or 100 year industrial program is beginning to be bureaucratically possible, as long as it were justified.

  • Lawrence B. Crowell

    I would compare our ideas about ET or ETIs to the Greek pantheon of gods. Consider our science fiction portrayals of ETs. Some benevolent, Spielberg’s “ET” and “Close Encounters,” the old “My Favorite Martian,” and some of them less so, such the campy film “Independence Day,” where these guys had exploitive designs on Earth, or the shock horror aliens of the “Alien” films. StarTrek gave us the wizened Vulcans, the warrior Klingons, cyber-organic BORGs, pompous Romulons, fascistic Cardasians and so forth The Greek gods ranged similarly, Hermes the god of war, Jove the King of Olympus, Apollo the muse of reason, Aphrodite the goddess of eros, and Pluto the god of the underworld and Cerebres the viscious three headed hound which guarded its gates.

    The ETI is really a modern version of human anthrotypic ideations of gods or demiurgic beings. I think these sprung from our evolution of lingustic thought and speech, where we used spirits, totems and other anthrotypes as a way to communicate information from one generation to the next in a tribe about the local environment. Tribal religions are nature religions, and stories about spirits in the forest or bush are a way of passing on local survival information. The ETI has some connection to science, and is not quite the fantasm we see with angels, demons and for that matter God. After all it is certainly possible that ETIs exist elsewhere in the universe. What we don’t know is the average density of ETIs, such as ET per galaxy. Think of f(x) as a function which describes the distribution of ETI in the universe. We might be tempted to see this as some function that ranges everywhere with peaks and valleys in regions more likely to have life and other regions not so likely. The question is whether or not this function might not be a delta function that is peaked at one point in the universe — here on planet Earth. And if we keep looking out and never find ETI, they might always exist billions of light years out beyond possible reach. If so then how can we ever know?

    To be sure, if ETI is out there they would have an obvious interest in us if they get our radio messages. Assuming physical contact or travel between us and them is possible, it is likely that their interests are their own, and they might not any more moral qualms (assuming that is the appropriate term) in killing a human than we do in killing an octopus with a soccor ball sized brain, which is obviously in some way intelligent. We might ponder how we might behave towards them, given our own history of treating humans with differences of one sort or the other in malicious manners.

    Lawrence B. Crowell

  • Hal S

    Lawrence B. Crowell

    Just bought your book “Can Star Systems Be Explored?”

    Looking forward to reading it!

  • Lawrence B. Crowell

    Hal S on Jan 20th, 2008 at 1:12 pm
    Lawrence B. Crowell

    I was wondering if you addressed the “Omega drive” or rather the pulsed thermonuclear detonation drive.

    Interstellar exploration by machines I argue is possible, but we are a bit behind the power curve. Robert Forward’s Starwisp is probably a decent idea for a first start. This could get to alpha centuri in about 50 years. In my book I do explore the Orion spacecraft concept, which is a 1950’s idea of nuclear bombs pushing a craft through interplanetary space. It was a big idea, headed by Stanislaw Ulam (the real father of the H-bomb over Teller) and had all that boldness of that post WWII era. The test ban treaty of 1963 put the kabbosh on Orion. I discuss a range of propulsion and power systems, mostly here somewhat qualitatively, such as ion, VASMIR, inertial confined fusion (Daedalus), anti-matter and so forth. Pulsed nuclear drives could reach about 10% the speed of light relative to Earth.

    The criticial factor is specific impulse, which I work the physics of in my book, which comes from the so called rocket equation. This is the velocity of the rocket plume or reaction mass divided by one Earth gravity s = V/g. The fastest V is the speed of light, so your rocket shoots out a high flux beam of light. There is a more passive version of this with photon sails, which are more practical than an anti-matter rocket. A photon sail I find can pretty easily reach a near gamma = 1.5, or about 50% the speed of light. There are some upper limits to this. As the photon sail craft reaches higher velocities the photons pushing it forward are more redshifted which give less acceleration. I work that stuff out.

    Interstellar craft imply a change of scientific culture. Most research programs are guided by the culture of urgency, rush, the need to publish NOW! and so forth. I think it is possible to explore the interstellar neighborhood out to 20 or maybe 50 light years, but they would require time. These programs would be many decade, multigenerational or even multicentury programs. It is similar to Catheral building in high-Medieval Europe. Those who designed them and started building them often never lived to see their completion. Our modern culture operates on the fast food culture — gotta have it now, and science is not that different in many instances.

    Lawrence B. Crowell

  • Hal S

    Lawrence B. Crowell #65

    I think your right about our fast-food culture and its general impatience. As much as we all dislike bureaucracy; it does provide certain stabilizing effects to planning cycles.

    Currently we have both civilian and military programs that will exceed the 100 year mark. A civilian example is social security, a military example is the Nimitz class carrier program. Although at some level, comparing those two is comparing apples and oranges; they do provide us the ability to understand multigenerational management problems.

    So in a way, one of the biggest hurdles is having a bureaucracy mature enough to cope with long range planning and support, and we might be reaching a point where we can handle a 100 year planning cycle for a major spending program…the real question is how to justify the expense.

  • John Ramsden

    Lawrence B Crowell wrote:
    > You will also see why I think warp drives and wormholes are not likely, and I suspect ruled out by quantum gravity

    I’ve ordered your book Lawrence, and look forward to reading it. Sounds like it will nicely complement Webb’s Fermi Paradox book.

    From your preceding posts, it appears you naturally assume that an advanced civilization is confined to spreading star by star within our Universe. However, I gather that jumping into a large rotating black hole need not be the fatal error commonly assumed, and an intrepid adventurer doing so could end up intact in a new Universe inside, rather as our Universe, with its cosmological horizon, can itself be construed as the interior of a black hole.

    If the evolution of intelligent aliens is common (and many would say that’s a big if) then perhaps, partly in view of the very limitations on interstellar travel you describe, those that survive come to think of the present Universe as no more than a nursery, and that to spread themselves far and wide in one fell swoop they must migrate to a universe at the “next level down” by a coordinated leap into a rotating black hole.

    Of course, like many hypotheses of how aliens behave, it’s expecting a lot to believe that *every* civilization would reach the same conclusion and migrate in its entirety. Also, on the same assumption, one might expect aliens to “drop in” on our Universe from levels above; but there are no more obvious signs of their presence than of “indigenous” aliens.

    On the same “nursery” principle, at a more modest scale, I think it’s quite probable that one day, if mankind survives, then in a few thousand years a decision will be made for mankind to fly the nest so that another civilization can evolve on Earth in its own time as we did. Doubtless they will leave bots to obliterate any signs of our former presence and to prevent backsliders trying to sneak back, a kind of high-tech Angel Gabriel guarding the gates of a refurbished Garden of Eden awaiting its next tenants …

  • Lawrence B. Crowell

    Thanks for buying my book, and the same to Hal S. I talk about rotating black holes in the book. The discussion is not at all in depth discussion compared to something in a GR paper. The rotating black hole is a realistic propulsion system, but with a big hitch. The rotation of the black hole in effect drags space (or points of space) around with it. This can cause a mass to be frame dragged around with the rotation. A weak gravity version of this is the Lense-Thirring effect, which has been detected by the LAGOES satellite in the case of the Earth, and the Gravity-B probe is set to make more sensitive measurments. This also has in the weak gravity field limit analogues to a magnetic field. A rotating charge is associated with a magnetic field.

    For a rotating black hole this frame dragging becomes large the closer you are to the hole. Then at some radial distance you are dragged with the black hole rotation and you can’t prevent it, no matter how much you fire your rocket to stay stationary. This static limit corresponds to the r = 2GM/c^2 of the Schwarzschild black hole. You are in a region (ergosphere) where in order to remain stationary you have to effectively travel faster than light, which is impossible. There is a region further in where the actual event horizon is. You really don’t want to cross that! This process of being dragged along is due to a symmetry (isometry) of space which preserves momentum. This symmetry is given by a Killing vector. Now if your rocket has a spent bottom stage you can jettison that to the black hole and this isometry preserves momentum (similar to Newton’s third law) and your top stage portion will be given a huge momentum boost out of the black hole ergosphere. You have in effect abosrbed some energy rotation from black hole that is larger than the mass-energy you dumped into it. This can be a huge energy boost for a space craft.

    There a lot of stuff with black hole thermodynamics involved and the black hole entropy increases. I will spare that for later.

    What is the hitch? You have to get to the black hole first. Not only that the black hole has to be huge so the Weyl curvature or tidal forces on your craft are not so large as to rip it apart. A standard 10 solar mass black hole would turn your spacecraft into scrap metal before you got within 10 or 100 times the horizon radius, and not only that your body would be pulled into thread (a’la the Inquistion’s rack) before you reached the ergosphere. The closest identified black hole you could navigate this way is the big one in the galaxy center, many thousands of light years away.

    What about jumping in, going for broke!? Well many of us have seen those Penrose conformal diagrams with patches, the spacelike region bounded by the horizon and then an inner timelike region which shrouds a ring singularity. In principle you could fly through this and do some hoop shots around that ring singularity and come out somewhere else, either in our universe or some other one. Nifty, right! There is one problem. The inner horizon may only exist in this mathematical solution. This is an eternal black hole — a pure mathematical artifact. If you just assume that during the life of this black hole there has been light or matter falling into it when you would reach that inner singularity you would do so with all that stuff blue shifted “to infinity.” Now heap on the fact the black hole is not eternal, but formed by the implosion of a star — you’d crash into all of that stuff blue shifted to infinity. In other words this horizon does not look stable, and in fact likely the real singuarity of the black hole. You couldn’t get into that inner region where you might be able to sail to other worlds or whatever. You die instead as you and your craft are crushed utterly into Planck mass oscillators.

    There are of course other exotic spacetimes, wormholes and warp drives and other things. These violate some energy condition set down by Hawking and Penrose, the energy is in effect negative. If you assume that there is a quantum field which is the source of these spacetimes, the violation of these energy conditions means the quantum field is not bounded below (no minimal quantum state) and all sorts of horrors emerge. So these are not likely real. A final verdict of course has not been issued, but I think these things are not likely. They also lead to causality violations, such as you going back in time and killing your parent before you were born. Kip Thorne keeps hammering away at the wormhole idea, but I seriously doubt this is real physics. Kip Thorne’s work is not in vain, for it keeps us asking questions.

    Lawrence B. Crowell

  • Hal S

    TomR #8

    I am not a radio astronomer, but I do have a working knowledge of radar/radio theory and operation. I will not claim I am an expert in the specifics of SETI or modern radio astronomy, but I can put you on the right path at least.

    I know I have read more complete descriptions of these problems in the past but I haven’t been able to relocate them on the web.

    The basic problems with ET’s watching our TV is both a signal strength problem (as you alluded to), and a technological “evolution” problem.

    The simplest, and least informative way of explaining the technological “evolution” problem, is that ET would have to know some specifics of how we have designed our radio and TV transmitters and receivers in order to watch “I love lucy” or any other TV program.

    Without writing an entire book, (and if you look online you can probably find some good one’s about radio theory and construction), the first guess ET would have to make about our approach to radio and TV, is that we use superheterodyning to transmit and receive information.

    Superheterodyning is basically saying we “mix” our modulating information signal with a constant amplitude/frequency carrier signal. For simple AM radio, when we do this we produce 2 new frequencies.

    One frequency is the sum of the carrier frequncy and modulating frequency (the upper side band), and the other is the difference between the carrier frequency and modulating frequency (the lower side band). The side bands carry identical copies of the information, and the carrier contains no information (since it is of constant freq and amplitude)

    When we transmit a simple AM radio transmission, we actually transmit 3 seperate signals, the lower side band (LSB), the carrier signal, and the upper side band (USB). The bandwidth of the signal is the difference between the USB and LSB.

    This is a horrible waste of power and bandwidth, and in most applications of AM, we actually use a single side band (SSB). This means we filter out one of the two side bands and the carrier frequency, and just transmit one frequency. The reciever is then equiped with its own oscillator in order to remix with the transmitted side band and produce an intermediate frequency (IF), which is then demodulated to produce the original modulating frequency.

    This picture gets more complicated for FM and TV signals, where side bands actually contain several frequencies instead of just one.

    The point of this excercise is to demonstrate that although there is nothing that says ET can’t watch TV; not every civilization will necessarily use the same approach in designing their TV sets, and ETs would have to spend a significant amount of time trying to feel their way in the dark.

    The signal strength issue is also very real, and other than pinpointing our location, ET would not get a consistent signal that would be intelligible. Even if ET had a huge reciever with perfect filtering technology, it would be hard to get a clean signal mostly because not every place in the world respects the same standard in frequency band allocation (although they are getting better)

    Hope that helps, and sorry if this isn’t new info for you, I just didn’t know how deep into theory I had to go.

  • Hal S

    just a correction

    “Even if ET had a huge reciever…”

    should be

    “Even if ET had a huge antenna…”

  • Craig Whitman

    Not to pick at what may not happen but when I was born we had just begun the jet age, fastest thing out there was still less than a thousand miles an hour. Fifty years before that they were sill locking people up that thought human flight might be possible and the fastest thing on the planet was about seventy miles an hour. Today we have space craft moving in excess of forty thousand miles an hour. If advances continue along those lines we could be exploring other stellar regions in about a hundred years.
    Remember that in 1900 science said the atom could not be split.
    I would never underestimate human greed or the capacity to find a way to do something.
    As for the ET thing I might consider that if they are here or have been here the fact that we have not already been destroyed or enslaved would say it all. If they were as hostile as the human race they would have already conquered us.
    That seems to be our nature to insist on control of anything or anyone we find.
    And only our own arrogance would lead us to assume that we are the cream of the crop when considering intelligence in the rest of the universe.
    The fact is that as a species we are only just now learning some of the right questions to even ask.
    I suspect that in a hundred years not only will the universe look very different but I believe we will see our selves very different.

  • Lawrence B. Crowell

    To Hal S., I am not a radio astronomer either. Yet RA signal processing involves lots of transformations, where the Fourier transform is the most basic of course. There are of course other signal techniques such as wavelets and the like. So if there is a signal in a wave form it can be extracted by some convolution technique. If there is a bit stream, or some signal embedded in there which imparts physical information it can be extracted. Even without ET considerations physical processes that generate EM radiation can have surprising forms, such as maybe some unknown energetic process which modulates the polarization of waves.

    As for Craig’s comments, this might be the case if there is some unforeseen breakthrough in our understanding of things. A look back at the 20th century reveals that its fortunes were built largely on one thing, petroleum. This black gold was the refined energy source that took us from the coal/steam age into the age of internal combustion engines, which is what founded the American 20th century rise to ascendency. We are going to be facing some very serious problems on this front. Of course there is nuclear energy, but fission power plants have not exactly materialized the way people thought in the 1950s. Fusion? Well that frankly is a long way off, and the D-T process being most intensively worked on sends 80% of its energy in a neutron. The energy in a neutron is not easily harnessed. Petroleum represented the last major improvement in refined energy, but what we may be facing in the future may be a step backwards in some ways.

    Sending people into interstellar space will require energy, and lots and lots of it. This is not even to mention exotic ideas of warp drives, wormholes, Kraznynov tubes and related things. Progress in “speed” took off expnentially from the early 20th century, from 100 mph to 30,000 mph by the 70s. Yet in the last 30-40 years that progress has largely stopped. If you extrapolate previous growth we would already be sending craft or travelling at 1000km/sec or so. The same thing is observed with life span improvements. Life spans went from the mid-40s in the early 19th century to the mid-50s by 1900 to now in the upper 70s. But most of that 20th century gain was made before 1970. Life spans have improved from the low 70’s to the high 70’s over the last 30-40 years. The progress is hitting a ceiling.

    In effect we may have plucked the low hanging fruit. We also appear to be going in other directions as well. Usually instead of working hard to get the high hanging fruit, we go off and pick the low fruit on another tree. Instead of travelling off into outer space we seem to be going into virtual reality, and the cell-phone is a clear indication of how our information technology is becoming rapidly integrated into us. People are wearing head pieces these days like Lt. Uhruh on StarTrek. Before long it will be glasses or contact lenses which raster scan retinas with virtual reality overlays, then implants, brain-cyber connections and so forth. By 2050 human brains directly cyber-connected may be the dominant nodes on the internet.

    Sure enough things will change in the future, but I think it will be very different from the future of the past, and even what we can maybe foresee of the future is at best a murky idea of things.

    Lawrence B. Crowell

  • Hal S

    Lawrence B. Crowell #72

    I agree with you on your point.

    What I was implying with the “evolution” comment is that as our technology progresses and our communications become more digitized, compressed and encrypted, the ability for ET to watch our TV becomes even less likely.

    A few years back, npr did a very successful april fools joke that highlighted some of the issues with the rapid changes in technology. Its worth a read, and good for a chuckle.

    Shellac, the Sound of the Future
    An April Fool’s Day Treat from All Things Considered

  • Lawrence B. Crowell

    Some years ago I made a similar comment about information in general. I argued that baked tablets were the ideal way to store information for thousands of years. After all the Akkadian to Chaldean cultures are known for their records they left on these. They are hard to destroy in large numbers, they don’t burn, heat will not degrade them like magnetic media, and so forth. So we might if we wanted convert all our great cultural works into clay tablet form so they could last for long periods of time. These could be stored in vaults which might in due time be dug up.

    Lawrence B. Crowell

  • TomR

    Hal S #69 & 72,

    Thanks for an informative reply. I was being a little flip with the “watching I Love Lucy” comment, and you’re right, I completely neglected how hard it is to figure out what a signal’s actual message is. It’s funny, we seem to think that there’s some “natural” relationship between radio waves and sounds/images, when in fact its the result of decades of engineering. And, as other people have pointed out, the more advanced your technology, the more your signals resemble static.

    Still, I think we can sweep that problem under the table, at least at a first cut for two reasons: First, determining that signal is from a technological source is (I think) a much easier problem than actually decoding it, and second, once you think you’ve got a technological signal, pretty much every curious mind on your planet is going to be working on decoding it. That being said, I defy anyone to figure out how to pull a video stream out of a compressed TCP WiFi signal…let alone figuring out things like that RGB encoding is based on quirks of human eyes, MP3 on our hearing, etc…

    So, to give a better defined problem, what would you need to distinguish our broadcasts from natural signals? As a start, you’d need enough resolution to seperate the Earth from the Sun–the back of my envelope says that get a resolution of 1 light-minute, using a 100Mhz signal, you need an antenna of 1923KM/light year. Not infeasable with interferemotry just a little better than ours.

    For most signals we emit now, I assume that if you got a broadband recording and did a standard bunch of FFT’s on it, they’d pop right out. That is, it’s not too hard to realize you’re seeing a narrow band, complexly modulated signal–are those assumptions correct? Also, I since a radio antenna’s aren’t omnidirectinal, they’d have a pretty distinctive modulation over a 24-hour period. (Assuming that ET can figure out how long our day is).

    The big unknowns for me are what kind of S/N ratio you’d need to figure out you’ve got a technological signal, and what the sources of noise are. I guestimate we’re putting out a few GW ERP of RF ( Any idea how what natural emissions there are in the various broadcast bands?

    And, sort of related, does anyone know if the power grid leaks significant amounts of 50/60Hz radiation? Hard to detect something that low, but even a fraction of a percent leakage would probably be brighter than the intentional broadcasts.

  • TomR

    Followup–If anyone else is interested, there’s answers to some of the questions I asked at

    The short version is “Even a 3000 meter diameter radio telescope could not detect the “I Love Lucy” TV show (re-runs) at a distance of 0.01 Light-Years!” But, it does turn out that radars have higher power and relatively narrow bandwidth, and might be detectable at a few light years.

  • Count Iblis

    Tomr, the 50/60Hz radiation won’t propagate far. The reason is the presence of the insterstellar plasma. In a plasma, all static electric fields are screened. The electic field of a charge falls of like
    exp(-r/lambda)/r^2, where lambda is the so-called Debye screening length of the plasma. When a plasma is suddenly perturbed, it will oscillate a characteristic frequency. This frequency can be thought of how fast the plasma is able to react to perturbations.

    This then has the effect that frequencies roughly below the plasma frequency are screened by the plasma just like static fields and the signal strengths will decay exponentially with the distance. Only signals of frequency higher than about the plasma frequency can propagate through the interstellar plasma.

    If I remember correctly, the plasma frequency of the interstellar medium is about 1 MHz…

  • Lawrence B. Crowell

    I am pondering this a bit. This is a skin depth phenomenon as well. The Debye screening length here clearly must has a frequency dependency, something I am not knowledgable of. We do get radio frequency radiation from very distant sources. I will have to confess that this is a lot of physics that is outside my domain of deep experience.

    As for figuring out a WIFI TCP/IP signal, the ETs don’t need to do that to figure out that there exists a signal and that there is some sort of information content. Actually communicating with ET, or ET figuring out what we are transmitting (imagine how much porn they would get on those Wifi signals) would require some serious decryption work. With elliptic variety coding structures (Goppa) there is a wide range to work in, and this can be extended to more general algebraic or projective varieties. The Golay, hexacode to M_{24} might work and M_{24} code have 196560 roots or possible state configurations, but this might not be enough to get a Hamming measure on an ET code.

    BTW, I have been working on quantum gravity as a quantum code system.

    Of course to cap it off ETI might be more different from us than the brainiest octopi is from us. An ETI might know about electromagnetism, but their mathamatics might be da-da poetry to us, assuming we figure out where their math is encypted in the signal. Of course Sagan had them sending prime numbers in pulses, but if there sense of numbers is completely different than ours, they still might send information we would have a hard time decrypting.

    Lawrence B. Crowell

  • windy

    Just to be contrary…

    I’m with Julianne. History has not been kind to less technologically advanced cultures.

    So we should stay on the reservation and preserve our traditional way of life, secure from the temptations? :)

    It’s not just a bad thing that history hasn’t been kind to less technologically advanced cultures, since otherwise we’d be living like most of our ancestors did. The problem is that usually history hasn’t been kind to the people involved (which I’m sure what you had in mind). But the analogy might not be very accurate, if the dangers are not likely to be the same as from some of the actual historical contacts on Earth:

    -they want land or slave labor: the implausibility of this was pointed out by Z and others.

    -they seek to convert us to the one true religion: it might make interesting sf but…

    -they want resources: again, why go the distance, unless it’s something that’s only found here, like biological resources (and we could share the genetic material)

    -disease: actually we would be unlikely to catch diseases (as such) from ET’s because of the phylogenetic gulf. An invasive lifeform that competes with Earth life would be a more likely danger.

    -one of the less advanced cultures uses tech/contacts from the more advanced culture against its neigbours (this has historically been a major danger and could be still, but it’s one that humans would control themselves!)

    I think we have a long way to go before we can play with the galactic big boys, presuming there are any.

    Why do you assume we are advancing faster than them? If you want to apply the historical analogy, there’s also the fact that the cultures that stayed isolated longest (like the Tasmanians) didn’t do any better at first contact, they did worse…

  • Lawrence B. Crowell

    I would not worry about cosmic imperialism. Seriously ETIs are not going to use vast sums of energy to send themselves here so they can use our puny muscle power as slaves. They might come here in order to use the planet for themselves, where we’d be swatted away. But then again can they really get here? Interstellar space is vast, even if it is a little bubble region compared to cosmological distances. A light year is about 10^{13}km, the solar system extends out about 3×10^9 km, the moon is about 5×10^5 km from the Earth. It takes years to travel these distances. Even if ETI used relativistic time dilation to reduce their trip time that would take vast amounts of energy. To cut the trip time in half requires the spaceship have as much mass equivalent in its kinetic energy of motion as the mass of the ship. Then use E = mc^2 to figure out how much energy that is. This might be possible with a modest probe, but is problematic for a 10,000 ton spaceship.

    I’d say that we might consider instead of “hiding this little light of mine,” that we let it shine. We might consider instead sending out powerful signals directed at G-class stars announcing ourselves and revealing what we have discovered. Maybe some ETI will get our signal 2000 years from now and be grateful for being able to compare their ideas about the universe with ours. As I have written a book about sending probes to other stars I think that something similar to AC Clarke’s monolith should be send along as well. The probe craft might set up a durable structure that contains information about ourselves and what we have learned. In particular this would be done if the probe explores a bio-active planet. Maybe millions of years in the future some ETI might evolve and they discover this thing and learn about us and our science.

    The Fermi paradox does indicate that actual travel between stars is unlikely. Under the exceedingly small probability they come here they probably would be no threat. After all, if the Apollo astronauts were greated by a tribe of angry stone aged “fuzzy-wussies” they would have been in big trouble. So we can play the turtle and pull into our shell, or we can come out and be seen. If we get an ET message they might do much the same.

    Lawrence B. Crowell

  • Lawrence B. Crowell

    Quick note about

    windy on Jan 22nd, 2008 at 8:38 pm

    -one of the less advanced cultures uses tech/contacts from the more advanced culture against its neigbours (this has historically been a major danger and could be still, but it’s one that humans would control themselves!)


    Before the Iraq invasion I thought about a Sci Fi story where Saddam got interstellar military technology from some ET. The USA starts its war and within a day the entire US military is destroyed and the Iraqi flag is flying over Capital hill.

    Lawrence B. Crowell

  • martin g

    Reading about Tesla’s attempts to broadcast usable electric power through the atmosphere from his Colorado lab I wondered if the high power/high frequency broadcasts that he created would be detectable to an ETI. That was a little over a hundred years ago and the broadcasts were just raw energy, but they were artificial and apparently very powerful (able to kill cows at a considerable distance). Should we be looking for a reply? Should we be looking for another Tesla out there doing crazy dangerous experiments trying to see how much he/she/it can get out of there primitive electromagnetic apparatus?

    Another thing: Dead cows, Colorado, ET. Think about it.

  • Hal S

    Windy 79, Lawrence 80

    Lawrence has an excellent point here which can be extended to point out that any civilization that has access and control of the levels of energy needed to conquer space would likely view the resources of Earth as miniscule…a speck of dust.

  • Hal S

    Martin 82

    Maybe Tesla inadvertantly killed cows on ET’s home world and in a case of tit-for-tat are doing the same thing to us…or maybe they think that’s how our civilization communicates…with dead cows 😉 lol

  • Hal S

    maybe we should be hurtling dead cows in space, to the far reaches of the cosmos…the interstellar dead cow network…what’s the decay rate of a dead cow in space? LOL 😉

  • Lawrence B. Crowell

    Ultimately the problem with the Science Fiction idea of some beings or madman trying to conquer the universe is that there is really nothing to conquer.

    Human activity on Earth might be detectable “out there.” Some SETI types arrgue that EM transmissions will travel out and be detectable. We will never know if Sagan’s Cosmic Connection exists or not unless we look. Even still we might facilitate it if we transmit information ourselves, or erect AC Clarke’s Sentinel or Monolith on moons in extra-solar systems so that maybe in the distant future ETI will find our announcement to the universe and what we know about it. Sagan’s cosmic connection might just amount to distant ETI’s sending bits of information here and there, receiving some in return and each ETI might end up as a rather transient actor in the web.

    Lawrence B. Crowell

  • Andre

    Given the content of the radio and television broadcasts from earth over the course of the past century, any eavesdropping ET civilization would be more than justified in concluding that earth should be rid of its human presence as soon as possible, before humans have the technological ability to escape and do the same to possible other life-bearing places in our vicinity that we have been doing both to ourselves and to other lifeforms on this planet. In fact, there is a good argument that earth would be better rid of our presence even if we do not travel.

  • Lawrence B. Crowell

    I think that humans will do a perfectly good job of annihilating themselves. Ponder that we have today politicos who advocate starting world war III to bring Jesus back. That will be something really special, particularly if or when it goes nuclear. Our species is essentially engineering the next mass extinction. Life on the planet will survive, and within a few million years evolution will have replaced econiches with new species. We will be fossilizing, or some of our more durable objects will be around for a long time. In particular ceramics, with one big item we make which might exist for many hundreds of millions of years, the toilet.

    Lawrence B. Crowell

  • Pingback: Aliens Found! News At 11 « In Other Words()


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

Cosmic Variance

Random samplings from a universe of ideas.

See More

Collapse bottom bar