But it assumes that I have all day and nothing else to do... I dont. Lets not line by line nit-pick... why not choose a solid point and argue that....


This is why I didnt want to debate it..... Did I, at any point, say that every sf scenario is plausible? NO... so the fact that some are not does not prove that they are _all_ unreasonable.

Ok... lets agree on that... it still doesn't show that a) they are looking... b) they are looking here... or c) that whatever method they use works as well as simply receiving a targeted hello.

This is the area of imponderables that I don't want to go to... its too much like arguing how many angels fit on the head of a pin... all of our assumptions in this type of discussion are suspect.

Shoot me for stupidity... but I didnt understand this portion of your post at all. (I _know_ you want to reply... 'And thats why you are not qualified to speak on the topic....' )

Again, angels on the pin... I am not going to speculate on the imponderables....

Sure.. granted. But there still is a world of difference between being detected passively and going to a lot of trouble to actually get their attention.


Um... so do you reckon that if they have detected us there is still a possibility they haven't detected us?? A bit too existential an argument for me to follow....

And so we come back to... if the risk is small but the possible consequence is major... and you can avoid taking it (especially by simply NOT doing an action).. then do so.

Cant wait to see what those things are....

Its possible.... Have a look at my recent post... please feel free to point out any additional assumptions... or any flaws you see.

Um... I am not advocating doing anything.... the ones who are shouting are the ones who should prove the risk/benefit ratio is favourable. Also they should consult with those affected.

Yeah... I keep saying the risk is low. But I don't recall at any point estimating it.

Oh dear... a bit late now... the whole of society is premised on a number of implicit and explicit rules about behaviour. Take the one that you cant shout fire in a cinema. Your shout puts people at risk... you don't have the right to do it. Even if the risk is low....

Now we come to the 'By wanting to keep quiet till we know more, you are fearful and paranoid' point in the discussion....

Not suspicion... caution. Suspicion is such an emotive word. I think a bit of caution for kids is not a bad idea... Do you encourage yours to wander off in a crowd? The risk is low..... Most people out there will be helpful and considerate.

No.... intangibles can be very important.

I think the kids will be alright with 'we wont shout out just yet... we are still looking around the joint to see whats what'

I think you are right in that last paragraph. Sums me up exactly.


Also, haven't you repeated yourself enough?

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Evidence for what, that the "Precautionary Principle" is defined such as it is? Perhaps there is confusion about who has the burden of proof because people here are confusing science and politics. The issue of "who speaks for humanity" is a political question, not a scientific one, even if scientists are involved. The point of bringing up the Precautionary Principle in such a policy debate as this is to make the participants realize that the present or proposed activity in question is, infact, an (as yet) undefended affirmative proposition because their activity is not actually supported by the status quo.

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LOL!

I can imagine a line from a Jerry Bruckheimer remake of a Steven Spielberg movie:

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For myself, I do agree with your points, and it is dangerous to shout into the endless void in the way that we do; but the fact that radar is so much louder than our shouts makes it fairly pointless to worry about deliberate transmissions.

If we do detect an alien civilisation in the next few decades, one likely method would be a chance detection of their radar- they might use high powered active sensors to protect themselves against meteor impacts, for example. And if our planet develops similar anti-meteor technology in the near future we will be sending even stronger artificial radiation out towards any hypothetical eavesdroppers.

But a radar signal carries very little cultural information- we couldn't tell if a radar beam was coming from a race of intelligent lichen or a race of intelligent coke machines. Perhaps sending out a few data-rich messages might demonstrate to these hypothetical eavesdroppers that we are Mostly Harmless.

Or such messages might just whet their appetites.

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On the other hand, we might miss out on joining the 'Intergalactic Internet'. Interstellar travel is likely to be so difficult that perhaps no civilisation ever acheives it; however there may be a rich, yet fairly safe, flow of ideas and data from star to star between innumerable very different species. By remaining silent, we might miss out on all that.

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Thanks for the support... But I appear not to have convinced you that the radars are not as bad as targeted signals.

Was I wrong when I said that radars are generally intermittent and tend to be roughly in the plane of the eclipse [edit:bloody spell checker... gotta watch that... I started with 'ecliptic'] and therefore are not a guarantee that everyone out there sees them?

Whereas with a deliberate signal someone has gone to a lot of trouble to pick likely systems in whatever direction and targeted them? In other words in directions that may not normally have many, if any, radar beams. I could be wrong... but no one has pointed out the error, if there is one, in this sidebar of the argument.

In a way I feel I must be right since there would be no need to go active if our radar beams were already doing a good job of letting everyone know we are here. Apparently the active seti folk think they need to do more to get ETs attention.

Yes and no. Radars are usually aimed at specific Solar System bodies, and everything in the Solar System is in a Solar orbit, constantly moving. Unless you for some reason are aiming radar at a star, it'll never hit the same patch of sky twice.

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Um. I think the original radar fella was talking about military radars... but the astronomers' ones have roughly the the same constraints... if they are not aiming in the plane of the ecliptic they are not going to hit too many planets ....

Not saying there are none ever aimed elsewhere... just that the vast majority would be roughly in the plane of the ecliptic... and in fact, there is a bias towards the 'top' half of this imaginary, roughly ecliptic, plane. Most radars are in the northern hemisphere.

Astronomy radars would be in the plane of the ecliptic, but military radars would scan over a respectable fraction of the sky. The one near me scans mostly towards the east, which would be roughly in the plane of the ecliptic, but the one at Thule will be pointed north, so will often send beams out of the plane of the solar system.

Actually, this might not be so bad, as many nearby Sun-like stars which might be expected to hold life-bearing planets are in the Southern Hemisphere. Alpha Centauri, Tau Ceti, Epsilon Indi, Epsilon Eridani, Delta Pavonis, Gamma Pavonis, Nu2 Lupi...

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The point would be to look for indicators of things that are out of bounds for simple chemistry. There is far too much oxygen in Earth's atmosphere without some active process to sustain it.

Also, that is one of the simpler ways to find life, the sort of thing we can expect to do within a few decades. The theoretical possibilities of telescopic observation go far beyond that, and even far more impressive ideas (such as interferometric arrays of telescopes with an effective diameter of millions of miles) would be pretty simple compared to the technology needed for interstellar attacks.

If there is a paranoid star faring species, why would they wait for intelligent species to develop? It would be far safer (from a paranoid point of view) to keep any discovered life down to the level of bacteria (if that).

And that's my key point of disagreement: I expect that, assuming one existed, any technological species that cared could have detected and followed the development of life on Earth since long before we learned to use fire. If there was a paranoid species, I expect that they would have taken care of the "Earth problem" long ago.

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They don't have to be looking for any life signs at all to notice a planet with 21% free oxygen in its atmosphere! It would be a screaming red flag that something strange is going on here. It would be just as obvious as finding free chlorine or fluorine in a planetary atmosphere. Such electronegative elements simply do not occur as free elements naturally.

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This is the problem with long threads... you end up having to say the same thing over and over. Its not the fault of anyone.... not many of us have the time to read from the beginning if it is many pages long...

This was me a little while ago:
So... yeah... I know we stick out in this system because of our atmosphere... but as of this moment... as far as I know... we don't have any idea how many planets may have a similar situation. It could be, for instance that life evolves ubiquitously... so our atmosphere might not be as big a flag as you suggest. And the vast bulk, of the myriads of intelligent life forms, might be methane breathers... so who knew that a poison like oxygen, could have supported intelligent life... never woulda thunk it.

The whole point here is that we naturally tend to make assumptions about our own situation and figure everyone else must be the same. I can recall hearing definitive statements from respected scientists (who I fully believed at the time) that life would definitely require liquid water... that boiling water wouldn't support life... that sunlight, directly or indirectly, was the one absolute necessity for life.

I remember reading that there were 'theoretical' limits to the amount of bandwidth that could be gotten out of a copper wire... and now we routinely far exceed those 'limits' because of limitations in thinking of the scientists of the day.

So once again... it is dangerous to make any assumptions about alien intelligence. (dangerous in the sense that we will feel embarrassed if we are way off mark as often happens in a science as it explores new fields.... and dangerous in the sense of global catastrophe if we have made assumptions about alien behaviours and the worse case scenario, to our surprise, turns out to be true.)

Its hard to say global catastrophe without sounding dramatic... but its a small, non zero risk with a potentially disastrous consequence that is easy to mitigate... at least to some degree.

Ok... so if that is your key disagreement.... if you were to read:

So... Do you think that every single one of the possibilities I mentioned above have absolutely _no_ chance of being applicable? (and realise of course that I am only some dumb bum from down under... so that list is not an exhaustive one... or maybe even the best one) If you _do_ think that.... then what can I say...

But if you agree that there is _some_ chance that a belligerent, capable species might not know about us till we shouted at them then you would inevitably advocate silence. Unless my logic is faulty.

When and if we gain the technology to analyse the atmospheres of worlds in distant planetary systems, a whole new range of atmosphere types will no doubt be revealed to us. The mechanisms which could produce certain unusual types of atmosphere will no doubt be debated, but for certain types of atmosphere with very reactive components- for instance, oxygen, chlorine, perhaps fluorine - there must be an active process occuring to maintain that composition. Sometimes the active process will be natural, sometimes only biology would fit the bill.

Given sufficient observations of different worlds at long range, preferably reinforced by closer inspection by interstellar probe- an intelligent speces will gain the ability to determine whether a particular atmosphere is likely to be the product of biology, whether it is similsar to their own or not.

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