Captain... every time I point out an error in any of your thinking you take either of two courses... reply with personal attack or ignore and wait for a later chance to speak to a different topic.

Maybe I am wrong... but it seems to me that logic doesn't carry much weight against your cherished belief in our safety.

It seems that you feel that all sapient life forms have only good intentions, or they do not have the capacity, or that the debate is mute becuase we have already alerted everyone to our presence.

Read back and you will see that all of those assumptions have flaws... and that there actually is no guarantee that we have already given ourselves away (else why bother shouting?), or that if we did, it would be safe to so so.

You seem incapable of grasping the fact the natural selection favours the strong... and that what seems insurmountable to you could be no big deal to a long lived, capable life form.

Or you believe that we have advertised enough already that everyone knows we are here. You need to study the science a little bit... the atmospheric clues that 'give us away' are only apparent to any civilisation on very specific lines of sight... etc etc... radar lobes... etc etc...

You keep whatever warm and fuzzy beliefs that you want.... but please refrain from bad mouthing me repeatedly...

1) it's Kaptain! (You seem very careless with other poster's handles. For instance, it's Eburacum, not eracom!).
2) I have no "cherished belief in our safety". I simply disagree that a few, short transmissions to a few randomly selected target areas of the sky are significant when we are continually sweeping a large fraction of the sky with gigawatt radar arrays!
3) If you take disagreement as attack, that's your problem, not mine. Deal with it!
4) If I had been bad mouthing you repeatedly, I'm sure I would have heard from a mod by now. In fact, if you are convinced that I am treating you so badly, why don't you PM one and complain?

BTW, you see my join date? That's just the date that the old BABB went from a single undivided thread to a forum similar to what this is now. I actually started posting on the BABB in the mid nineties. Oh, and my post count? Way short! The old BABB didn't keep track (I also lost a few in the merger).

My point? In all that time and in all those posts, I have never been admonished by a mod! So, that would be a first.

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

Oh... its the appeal to authority... I am the senior here so I must be right... yeah sure.

Yes I am... sometimes for the sheer whimsy of slightly changing it... sometimes through carelessness... But you should note that I am not at all careless with content... and I always have a full handle quote at the start, or close to it.

Yes... we have discussed your belief that sweeping a large fraction automatically notifies _every_ species that we are here.... Have you considered the numbers? Even a small portion of the sky unswept is a huge number of stellar systems... and Murphys law says that if we hadna woke em with a shout, the bad guys woulda been in one of those unswept sections... (irony seems built into the fabric of spacetime).

No.. disagreement is fine... its you piping up unasked, appropos of nothing, to indicate your belief in my bloody-mindedness that I find annoying.

So you reckon they ruthlessly sweep on every instance of snide swipes?.... remarkably efficient of them....

No need, I am sure that you will be slightly more temperate in future...

I posted something pertinent in another thread

Sending signals is hard. It's not something likely to be done accidentally. We'd basically have to build a huge array broadcasting on a short-wavelength band with absurd amounts of power, and focus it at a specific planet orbiting another star if we want to be "heard" by instruments specifically pointed back at our planet.

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Yes... that is in accord with what I have read a number of times down through the years... So it does still seem to me that a directed shout by astronomers targeting high probability systems with best of breed signalling equipment is likely to have more chance of being noticed that our current leakage.

Thank you for the detail in your post.

And that probability still rounds to zero.

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Douglas Adams

Rounding to zero is a lovely mathematical concept, but it doesn't offer much comfort to the person who contracts the one in a billion rare cancer...

Blase acceptance of risk is ok if you cant control it... but if you can avoid it by simply putting your impatient companions in a holding pattern for a while.... then why not?

I would love to hear why there is an urgent need to shout out just as we are starting to get a boost in our knowledge of some of the factors in the Drake equation.

I think there is are a few assumptions in this that need pointing out. You assume that because the trip takes 'thousands' of years it wont be done...

Firstly the trip may not take thousands of years at all... a bussard ram jet type craft or a ion drive might make the trip in a period at least an order of magnitude less than your premise.

Secondly the 'time' that it takes is relative.... to the beings making the trip it may be significantly less due to relativistic time dilation.

Thirdly there is the possibility that in a worst case scenario... even if it did take thousands of years, that might not be a significant factor to the travellers. It may well be only us humans that are bothered by those time scales... and in a few hundred years it might not even bother us...

Now... sure... if it did take a few decades, centuries, or more, to suffer the ill effects of waking the wrong folk then it likely wont be you or I suffering. But I would bet that our descendents in that scenario would wish that we had been slightly more cautious and just waited a decade or so before sending... so that we would have found out more and realised our error before we made it...

And you are assuming some things also.

1. That traveling between star systems is cost-effective. It is not. Even getting to our closest neighboring star would take a tremendous amount of energy. Any civilization that survives will have to make intelligent decisions regarding energy invested versus energy returned. Interstellar colonization makes no economic sense.

2. Regarding time dilation, as has been pointed out several times in this thread, any such ship will take thousands of years to make the trip based on our frame of reference. A civilization capable of such a journey will know this. They'll also know that either our civilization will have collapsed before they arrive her, thus making the trip superfluous, or we will have advanced so far technologically that they are no threat to us.

3. Physical laws are the same throughout the universe. Any civilization that survives long-term will do so only after learning to use energy wisely, which returns me to point 1. Interstellar colonization makes no economic sense. Interstellar conquest makes even less sense. Yes, that makes it negative. Interstellar travel is a losing proposition.

4. Space is huge. The proverbial needle in a haystack is a slam dunk compared with finding and communicating with an alien civilization. even if we do detect alien signals (or they detect ours), decoding the signal, identifying the source, and sending a response will take many, many years.

5. The universe is old. If there were an alien civilization out there with the technology and motivation to travel between the stars they would be here already.

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"There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened."
Douglas Adams

It does occur to me that, as we are considering various outcomes of low probability, we might do well to attract the attention of the Culture before the Affront notice us.

So can any of the capable astronomers on this forum come up with a Drake-like equation for the probability of alien life having detected us already. Most of the universe is excluded since the limit is how far our signals could have traveled from the first produced until now. So there is a radius I believe someone said was about 70 light years, which is probably close if you are going by television broadcasts and not all radio signals in general. But within that radius there are X number of stars with varying probabilities of developing planets, and there is probably some estimate somewhere of the quantity of interstellar planets that could be added in, and then if we assumed that life could start on some percentage of them, etc. etc.

I also wonder if the question of receiving a single frequency is valid. We are broadcasting, collectively, across a wide spectrum. If you looked at Earth with broadband receivers would you see a bright radio star? It is my understanding that we outshine the sun in the radio spectrum. Would not that collective power be more detectable than the single narrowband broadcasts that have been mentioned. Does it make more sense to view our transmissions as a whole rather than individually? And if you have the ability to detect individual photons (skipping the obvious problem of selecting which ones are noteworthy among the gajillions received) could you not reconstruct a signal no matter how weak it is? Let's just ignore noise for a moment, or at the very least look at transmissions in ranges that have a greater likelihood of not being clobbered by noise, would it matter how far the photons traveled? It seems to me that it wouldn't, and if you had a good way of discriminating noise from the signal that you could get those transmissions no matter how far away you are (assuming again that interstellar particles don't deflect so many of the photons that all intelligence is lost).

Isn't our inability to use weak transmissions really mostly limited by the sensitivity of our receivers? For instance, if you had line of sight between two points with nothing but pure vacuum in between, the transmitter can be as weak as is possible and the only thing limiting your reception of it would be the quality of your receiver to amplify the photons that reach it. I'm not certain this statement is entirely accurate, but if it is then it seems it might be important to the ability of a distant race receiving our signals.

Now the next big question is: I imagine radio signals as being like expanding bubbles that inflate away from the source. Now depending on whether the signal is a bunch of photons standing shoulder to shoulder racing outward or all traveling like a wave, then it seems that in one case there would eventually be space between the photons as they diverged with spreading, and in the other case the wave might grow continually weaker as it thins out. I probably have this all wrong, so if you know better, feel free to jump in and spell it out. (Where's Ken G... he always knows the answer to these sorts of questions).

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The only way of finding the limits of the possible is by going beyond them into the impossible.

Arthur C. Clarke

The Brain Science Podcast

No doubt... it is inevitable... I agree that we need to check them out... so...

I will assume that you mean in the most broad definition of economic sense... (not that you are assuming a capitalistic system for some species that we know nothing at all about).

Cost effective? No I dont care about that... maybe they dont either... but if they do lets look.... Ok.. so how do you figure it? If you have a starship then the only things you need are the will, time, supplies and a propulsion source... if you are able to build a starship... then fuel is probably not going to be a problem for you. If you want to go then you can. If time is not an issue as I mentioned earlier then that is ok... Supplies... who knows... maybe they hibernate... Maybe they are experts at closed systems... who knows... but I am sure that it is not impossible. Propulsion systems have been postulated here on earth that would do the job... and maybe we haven't thought of them all yet.

(I started with... 'if you have a starship'... ok... that's a big if... but if you have been sentient and civilised for 4 million years then maybe that's not a big deal... I don't buy the theory that we all collapse after a few centuries.... maybe they splinter... and spread out. Or maybe they have worked out, or are, by their very nature, a stable system of mutual survival)

Ok... so you figure that all that is a large 'cost'... so what is the 'benefit' that will make that worth the effort? I will mention a couple of earthly motivations but don't forget to add in an 'x' factor or two of unguessable alien ones...

• On earth the paintings of aboriginal peoples are highly valued... maybe 'art' is a new concept...
• If you don't want any future competition then, like weeds in the lawn, its better to get right onto them.
• The food from another culture may be interesting... lets hope its not us
• Curiosity... it seems natural selection favours it...
• To be the first... put another notch on your light sabre...
• Research into extraterrestrials

My point is that there are lotsa potential reasons... and this is not the place to elaborate them all.... read some good, 'hard science' fiction.


No... I think you must agree that the actual trip time may vary widely depending on the distance and the velocity... certainly that's the time scale for _our_ near-future tech, from any but the very nearest stars. But high fraction of C velocities are possible... lets imagine even only .25c which brings thousands of stars into the one or two hundred year trip range. But its angels on a pinhead... the numbers are wildly speculative and don't actually matter once you drop human lifespan assumptions out of the equation.

And... we might not collapse, they might not care what state we are in, they might not assume a collapse because its rare... I dunno and neither do you.


Why do you say that?... energy is available in this universe in abundance... and possible with 'zero point' it might even be unimaginably so....

I was gonna just ignore this... but I cant... no.. no.. no.. no...

Yeah... sure... but how does that affect the premise?

Yes... its a bit of a paradox isn't it.. lets call it the 'Fermi paradox'....

Look, I can see that you have thought a bit about all this... but it is in our very natures to always assume that the other is somewhat like us...

If you can get past that, and take on board the stupendous numbers involved, then you can appreciate that any assumptions that we make are almost certainly bound to be sus. If you look at any of the proclamations of wise folk who came before us, you can see many examples of stupendous blunders made on assumptions of sameness.

Bill Gates... are you still sure that no computer will ever need more than 512k of memory?

I'm curious. Arthur C. Clarke wrote a book called Rendezvous With Rama a very long time ago. I'm going to borrow heavily from the construction of Rama for these questions, so I'm mentioning it in advance for those who may be familiar with the book.

Create a very large cylinder and rotate it for simulated gravity. Use however many nuclear power plants you might need to put energy into the system I'm going to describe. Inside the cylinder, which is hollow, people could live and farm on the inside surface with very bright grow lamps running down the axis. The lamps would provide light and heat and you could probably have a sustainable population living generation after generation inside the cylinder as long as you recycled everything. While this may be a big engineering project it doesn't seem beyond the capability of the human race now. So if we discovered transmissions from an alien race we could build one of these things and send them off. If it took a couple hundred years to get there you would have a steady supply of babies to carry on the voyage (lets leave ethical issues out for now).

If we felt hostile toward those aliens we could send a spartan selection of space marines to go kick their butts or wipe them out so we could use their planet.

So, if we could do it, why couldn't they do it to us? There isn't an incomprehensible expense to do this. You just have to have enough nuclear fuel to sustain the population for as long as it takes your drives to get you there.

And what if it isn't even the entire race of aliens that wants to do us in but only a select population that wants to move away from home and wants our apartment. There is nothing that says an entire alien population must be good or evil. They could be just like humans where some people are real boneheads and some people are nice.

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The only way of finding the limits of the possible is by going beyond them into the impossible.

Arthur C. Clarke

The Brain Science Podcast

The precautionary principle (that we take no action unless we are 100% certian there is no risk) is suicidally restrictive. Though many people preach it (because it's absolutist and simplistic), no one follows it, because no one can follow it consistently and maintain enough activity to live.

Yeah, there might be other life out there. Yeah, it might be intelligent. Yeah, it might be aggressive. Yeah, it might have the means of interstellar travel (nevermind the billions of years worth of development on either end of that small randomly placed blip in time where they would even be interested in us). But adding all those "mights" up - you recieve an absurdly small probability surrounded by a whole lot of other rough-order-of-magnitude equally plausible alien contact scenarios surrounded by an even larger region of scenarios where our signal just peters out before it reaches anything capable of detecting and understanding it, and looking in the right place in the right time.

As for the other plausible alien contact scenarios:
1. They can hear us, but aren't interested/don't have the resources to make the trip.
2. They just aren't looking hard enough for our signals and completely miss us.
3. They are out of range.
4. There are a few hundred million earths to look at in a galaxy, and only a billionth of them have intelligent life - hence no competitive population pressures, and a needle-in-haystack problem of finding us in the first place.
5. They have much more important things to fight about than little blue water covered rocks, and are only interested in us as cultural curiosities - the same way we aren't desperately trying to exterminate the head-hunters of Borneo. (You know - to steal their infinitely valuable bug infested holy sites and arrest their development to a transcendent superpower)
6. The even more extreme case of #5 - they are so different from us that they look at us like we look at squirrels, and don't care on an entirely different order of magnitude.
7. They may even want to enlist our aid/provide assitance of some sort - it doesn't even necessarily have to be altruistic. (example - maybe they want to let us know we are about to be swallowed by their nasty-neighbors empire and will provide us the means to defend ourselves, thus placing a stumbling block in their path - of course this assumes a lot of things I personally believe unlikely)


Another way to look at it is that this whole thing is somewhat analogous to Pascal's Wager - yeah the creator of the universe might be a sadistic monster who likes torturing his creations beyond the dreams of any earthly tyrant, and demands servile self abasement and strict obedience to his priests - but at base it's just a trick to try to overwhelm the near-zero probability backed by absolute-zero data with a hypothetically infinite consequence, and thus override your reason. Not enough data to do something = not enough data not to do something = not enough data to base any sort of conclusion on.


PS - I agree with you that there are probably more efficient ways of conducting interstellar travel than using pure rockets, even limiting ourselves to completely non-controversial physics. The bussard ramjet is one possibility. I have a few ideas along these lines myself. It wouldn't take thousands of years to go ten or twenty light-years, maybe only a hundred or so.

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Yep... quite correct. The generation ship, (and don't forget we don't know how long a 'generation'...) is a perfectly possible scenario... and there are lots of others.

I think that the real reason people think my concern is not valid, is because they fundamentally, and intuitively, don't really accept the possibility that there are others out there. I can certainly understand that.

The universe continually seems to be counter-intuitive, and the gut instincts that served us well as we progressed from the days of mastering fire, may not serve as well to inform our thinking about a universe with more suns than there are grains of sand on earth.

If you do come to believe that there is a possibility that we are not unique... if you let that dwell inside for a while..... and then see the various objections from a 'prodigious universe, non-human' standpoint, then you must accept the fact that our cosy assumptions could be wrong... and that shouting just as we are starting to know a little something about the neighbourhood is soooo _typically_ human. And possibly fatally, (or maybe just dramatically,) foolish.

Splitting the atom might have been dramatically foolish too - we didn't know - we just started playing with radium and uranium. Messing around with lightning might have angered the gods too (and in some superstitious countries, the lightning rod was banned for half a century because it was "thwarting the will of God")- we did it anyway because nothing efficacious or worthwhile has a zero risk.

Furthermore, not doing something carries all the costs and risks which are never accounted for under precautionary principles. Stagnation. Rigidity. The decline into obsolescence o