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Don't Shout

David Brin has a warning for irresponsible astronomers.

When in danger, most people in a group recognize the responsibility to be quiet, and not give themselves away to an enemy by making noise, sometimes to the point that a crying baby will be stifled, and even suffocated. I think that this is a similar case where people should be enjoined, by force if necessary, because we cannot know the consequences. I see very little potential benefit to this, and a great deal of risk. The apparent insularity of the SETI folks cannot continue--we are all on this planet, not just them.



Paul breed wrote:

I've given a lot of thought to the Fermi Paradox and
the active destruction of emerging technological civilizations is clearly one of the possible
answers to the Paradox.

I've just finished reading Weber's "Off Armageddon Reef"
and I'm eagerly awaiting "Schism Rent Asunder" books in an ongoing series about man kind trying to hide from such a destroying force.

Karl Hallowell wrote:

I think the concern is unwarranted. If I were organizing a galaxy-wide stomp of any radio-using civilization, my apparatus would have already stomped humanity back to the stone age. A number of asteroid impacts to the technological and industrial centers, say Europe or the US in the 40's. That's because I'd already have prepositioned some mass drivers in the asteroid belt (or at least the machines to make those mass drivers). And it's a lower entropy solution than waiting till humans have colonized the Solar System and then getting rid of them.

K wrote:

Well thank goodness you're not the Galactic Overlard, then Karl.

Astrophysics and astronomy routinely assume that if an effect is valid in the Earth's physical space that it's valid throughout the universe. Anyone who's camped unarmed in an area where predators prowl would take it as a general principle to not go out of your way to make yourself obvious. And anyone who has a modicrum of knowledge about human history would take it as a given that sapience makes first contacts any less dangerous.

The notion that advanced civilizations are "peaceful" and "wise" in a human sense is a religious one, not a scientific one.

Peter wrote:

Consider the character old old style analog transmission vs. the new digital transmission. Analog transmissions have a spectral profile that's readily identified as artificial. And an alien intelligence detecting it could probably engineer a receiver, even if they didn't understand the speech carried. Modern digital signals, on the other hand, look far more like noise, and would be more easily missed, and be impractical to make any sense of if somehow identified. So a civilization that's advanced to mostly advanced digital radio effectively disappears from distant radio observations.

I'm wondering if an alien civilization listening to out radio signals will think we've been hit by a massive disaster when our radio from Feb. 2009 gets to them.

ken anthony wrote:

"To Serve Man" -- it's a cookbook! One of the best twilight zone episodes ever.

If we are not alone, the probable assumption is that alien life varies in disposition. It is always strategically wiser to look before you leap. Shouting in the dark is the monster movie scenario and just as stupid if we do it for real.

So far our radio is probably in the noise and not too easily heard. To intentionally shout into the unknown is just plain stupid. However, I suspect no harm. God loves idiots, he made so many of them.

Ric Locke wrote:

I think Peter's observation is valid. It's an insight I had when I first learned about "spread spectrum" radio techniques.

An advanced civilization based at least somewhat on our pattern will need a lot of bandwidth. One way (I won't say the only way) to do that is to use modern techniques, and the result of those is that the signal is indistinguishable from noise if the receiver doesn't have information not transmitted in the signal itself. The same techniques allow spectrum sharing among many users, and the total detectable signal thus becomes closer to random noise. Not only that, the same techniques allow reduction of power levels, both at any given frequency and overall.

It therefore follows that SETI is futile. A civilization advanced enough to teach us anything will be undetectable. We used analog radio techniques for about a century. Plug that into the Drake equations and the probability is so close to zero as to be not worth the trouble.

Note, too, that as time passes we have fewer and fewer receivers capable of detecting an analog signal. It could be that Brin's cautiousness isn't necessary. The purple people eaters of zeta Aurigae IX-3 (or the Posleen) don't have analog receivers either, so won't hear the "shout".


Dennis Wingo wrote:

God loves idiots, he made so many of them.

Now that is funny beyond words.

mpthompson wrote:

Given the sum total of all foolish things mankind has done through the centuries, I would rank purposely transmitting messages into interstellar space at just about near the absolute bottom of things to be concerned about. If the METI folks want to waste photons on such transmissions let them do it if it encourages them to keep moving forward with SETI which has itself a near zero chance of picking up extraterrestrial signals.

Besides, provoking extraterrestrial contact (or conquest depending on how you look at it) would make our great-great-great-great-great-great-grandchildren's lives much more interesting.

Tom W. wrote:

I believe the main point of his article was not necessarily that we should not consider 'shouting' to the stars, but that the idea may affect so many and is being discussed by the relatively few.

I think that SETI is a waste of time and that sending radio noise into the universe equally a waste of time. It is all based on the assumption that there are worlds out there that transmit (and listen) in the same sense that we do. We are constrained by our limits and knowledge of a few thousand years on one planet in an vase universe. IMHO, any species capable of galactical travel would have far, far more advanced systems of communication.

The bigger issue is that while this is my belief, I do not have the moral authority to put the rest of the planet at risk, especially without at least some discussions at a higher level than just a few of my friends.

B.Brewer wrote:

What type of transmission are they proposing anyway? A broad spectrum that's higher in power than anything else on the planet that's omni-directional?
I don't think they have the funds for something of that magnitude.
They're best bet is to transmit a narrow beam in the direction of where the "WOW" signal was received for a couple of decades (or at least the round trip travel time of light to it)

Charles Miller wrote:

Since you can't prove a negative, it is impossible to prove that there is no risk in actively transmitting signals to the Galaxy saying "We are here!"

So, logically, we have to accept there is a non-zero level of risk, even if the level is unknown.

Now some of you may want to debate whether the risk of catastrophic consequences is high (say >20%, or small 5-10%, or very small ~1%, but there is still some non-zero risk of the destruction of all human life.

One of the problems in discussing this is that most people have a hard time thinking about small probabilities with high consequences. Our brains are not wired for it.

I will try to clarify the issue, as well as the ethical dimension.

Let us assume you think the probability is really really small -- let's posit a highly skeptical position -- that the probability of catastrophe is 0.01%. If you multiply that by 6 billion people (which assumes global population levels off for the long-term), it means that somebody is taking an action that has an expected casualty impact of 600,000 human deaths.

Does anybody here think that a few people should be allowed decide, on their own and without debate or permission, to do something that has an expected casualty impact of 600,000 human deaths?

Is this ethical?

Please note, that if you think the probability is ...

- 0.1%, then the expected impact is 6 million deaths.

- 1%, then the expected impact is 60 million deaths.

- 10%, then the expected impact is 600 million deaths.

This is an important ethics in science issue. Kudos to David Brin for his essay, and to Rand for posting on it.


- Charles

tcobb wrote:

I suspect that listening for radio transmissions from alien civilizations will pretty much be futile. The closest analogy I can think of is a bunch of stone age people on an isolated island in the present searching for smoke signals on the horizon. Finding none, they conclude that no other people exist.

Who knows? Maybe we ought to be looking for pulsed neutrino emissions instead.

Any aliens that were sufficiently advanced to build an interstellar spaceship would certainly be able to build huge space-based telescopes with which to examine potential life-bearing planets. Even if they couldn't see any detail on Earth they could still use spectroscopy to measure the composition of our atmosphere, to look for the gasses required by life (in any form that they would recognise) or evidence of industrial activity. If they wanted to find other forms of life - whether for communication, conquest or lunch - surely the most effective way to do it would be a systematic telescopic survey of every system that they could potentially reach? For that matter, isn't that what we should be doing as soon as we are able? I suspect that in a few decades time all this messing about with radio signals is going to be remembered as a rather embarrassing waste of time.

However, I do agree that it is reckless to be shouting a "to whom it may concern" message at the stars when we have no idea what, if anything, is actually out there.

memomachine wrote:


Shouting to the heavens that you're here? Isn't that advertising? Of course the only question then is what precisely are you advertising?

We can hope it's not the All You Can Eat Humanorium.

Jon Card wrote:

It does seem like there's something lacking in a plan where the worst possible outcome would be success.

It has, however, inspired me to rewatch Tim Burton's Mars Attacks. So, it's got that going for it.

tps wrote:

Excerpts from The Killing Star (1995) by Charles Pellegrino and George Zebrowski

"Imagine yourself taking a stroll through Manhattan, somewhere north of 68th street, deep inside Central Park, late at night. It would be nice to meet someone friendly, but you know that the park is dangerous at night. That's when the monsters come out. There's always a strong undercurrent of drug dealings, muggings, and occasional homicides. It is not easy to distinguish the good guys from the bad guys. They dress alike, and the weapons are concealed. The only difference is intent, and you can't read minds. Stay in the dark long enough and you may hear an occasional distance shriek or blunder across a body. How do you survive the night? The last thing you want to do is shout, "I'm here!" The next to last thing you want to do is reply to someone who shouts, "I'm a friend!" What you would like to do is find a policeman, or get out of the park. But you don't want to make noise or move towards a light where you might be spotted, and it is difficult to find either a policeman or your way out without making yourself known. Your safest option is to hunker down and wait for daylight, then safely walk out. There are, of course, a few obvious differences between Central Park and the universe. There is no policeman. There is no way out. And the night never ends."

From another board:,7025.0.html

Relativistic Kill Vehicle

An advanced civilization would travel the stars at near-light speed. An object only the size of the space shuttle going 70% the speed of light would end life on earth. But that's not very efficient. I'd have the object split in two, have the second half brake slightly, then both halves pancake out to discs the radius of the Earth. One half of the earth would be obliterated, giving Tokyo some time to wonder why New York went silent until 24 hours later the other side of the earth is fully exposed and the second wave sterilizes that half.

Traveling at near-light speed, there would be a doppler effect. When you think they are a light year out, they are actually a light month out, when you think they are a light-day out, they are already on top of you. Even if you could shoot such a fast-moving object, it would simply become debris which would still hit you at 70% lightspeed.

Charles Pellegrinoís Three Laws of Alien Behavior:

1) Their survival will be more important than our survival.
2) Wimps donít become top dogs.
3) They will assume that the first two laws apply to us

If another race can travel at near light speed, they can kill all life on our planet. There may only be a CHANCE that they would, but any chance of total species not to mention planetary life death ought to be brought to zero. Anything less is an intolerable risk. I can't see them seeing it much differently. Therefore, if they are there, and they know we are here, and they can build it, they WILL kill us. Maybe the RKV is already on its way. The earth does shine brighter than many stars in various radio frequencies. It is very like a bullseye.

There is no way to distinguish a near-lightspeed exploratory mission from a RKV entering the system to kill us all. Not that, with the relativistic time lag, it will do us much good.

Akatsukami wrote:

"Traveling at near-light speed, there would be a doppler effect. When you think they are a light year out, they are actually a light month out, when you think they are a light-day out, they are already on top of you."

But the Doppler effect will also tell us how fast it is moving, and therefore what correction to make in the calculation of its position from the signal.

"Even if you could shoot such a fast-moving object, it would simply become debris which would still hit you at 70% lightspeed."

Impossible to say, without knowing too many other things, but rather unlikely, IMO. Hit a RKV with anything of respectable mass, and it becomes a cloud of plasma. Depending on how far away it is, that cloud may or may not diperse and/or decelerate by the time reaches Earth. Even more to the point, it becomes an unguided cloud of plasma...and the Earth is a moving target.

"If we can see it, we can hit it; if we can hit it, we can kill it." We can't see it now; but an solution to the problem of RKVs requiring orders of magnitude less energy (and therefore expense) is 360x360 skywatch, and some Saturn Vs boosting a few dozen kilos of ball bearings to escape velocity.

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This page contains a single entry by Rand Simberg published on July 12, 2008 7:07 AM.

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