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JohnF

communicating with an extraterrestrial civilisation

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If we were dealing with purely written or spoken language, foofighter would be correct. There is no way to decipher these without external clues. However, it is very likely that the signals would be the equivalent of television - carrying pictures. We could at least see the pictures. If the alien group was deliberately sending messages to unknown species, they would use a pictorial method which could be deciphered.

 

Anyway, we are at a stage well before the need for any deciphering. We are just trying to see if any signals exist. SETI has run a rough study of most of the galaxy and a more detailed study of some thousands of stars, and not seen any sign of a signal yet. There are lots of ways we can interpret this finding. In my very humble opinion, this result combined with the Fermi Paradox indicates that the simplest explanation is that intelligent, advanced alien species are very, very rare.

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There is a way to decipher messages sent from afar. The laws of physics are the same on a star 1,000 light years away as they are here. The trick, then, is to send a Rosetta stone that describes math, physics, and chemistry along with the signal. The signal would have to be low-bandwidth so we could distinguish it from noise. This alone rules out most broadcast techniques used today; our high-bandwidth broadcasts are nearly indistinguishable from noise. So, no pictures and definitely no TV.

 

Anything beyond a hundred light years or so is essentially one-way communication. Fortunately, that is not a problem yet; the SETI range is much shorter than than. Given the size of the universe, ET most is likely there somewhere. That is, however, completely irrelevant. Our search for ET is not only limited to our own galaxy, but to a very small part of our own galaxy.

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Since we have rocks picked up in Antarctica which are identified as having come from Mars, the reverse seems very likely.

 

Mars-to-Earth has the sun's gravity working for you. The other direction does not.

 

Assuming I've done my math right, it takes ~5x more energy to eject something from Earth and have it be gravitationally free than to do so from Mars. It takes ~5x of that to get it from Earth to Mars due to the Sun's gravity, meaning it takes 25x more energy to get from Earth to Mars as the reverse. So I wouldn't say that the reverse seems anywhere near as likely.

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To swansont

 

I read an article in New Scientist that claimed that the dinosaur killer 60 million years ago would have flicked lots of debris into space, so it is still possible. If the bacteria express happens to be fine dust, rather than large rocks, then there is the added factor of the solar wind that will drive the dust outwards, permitting some to reach Mars.

 

I doubt that the sun's gravity would help much in getting Mars debris to Earth. Anything in Mars orbit has to be decelerated to fall towards the sun, and that requires energy input. Some rocks DID reach the Earth, as I said before, but that would have been against the odds.

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To swansont

 

I read an article in New Scientist that claimed that the dinosaur killer 60 million years ago would have flicked lots of debris into space, so it is still possible. If the bacteria express happens to be fine dust, rather than large rocks, then there is the added factor of the solar wind that will drive the dust outwards, permitting some to reach Mars.

 

I doubt that the sun's gravity would help much in getting Mars debris to Earth. Anything in Mars orbit has to be decelerated to fall towards the sun, and that requires energy input. Some rocks DID reach the Earth, as I said before, but that would have been against the odds.

 

No, an orbit including Mars could intersect the Earth without any deceleration; it would be elliptical and would intersect the Earth's orbit twice. The reverse is not true without the energy input I described.

 

And (roughly spherical) particles bigger than ~ a micron feel a stronger gravitational force than the radiation pressure at the Earth's orbit.

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Swansont said

 

"an orbit including Mars could intersect the Earth without any deceleration"

 

Such an orbit achieved by a rock sitting on the ground on Mars would require substantial energy input. This comes from the impact energy of a meteor or asteroid striking Mars, and so the rocks get to Earth. In a similar way, with a large enough impact, rocks from Earth can be flicked into a Mars intersecting orbit, though, as you said, less frequently than the reverse. As I pointed out, the dinosaur killer was one such impact.

 

Fine dust can, indeed, be blown by the solar wind outwards, and bacterial spores can be a lot smaller than one micron.

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The trick, then, is to send a Rosetta stone that describes math, physics, and chemistry along with the signal.

D H is correct. The only way to decipher an unknown written language is to have a bi-lingual with a known written language. The most famous of these is of course the "Rosetta Stone".

 

Physics and Chemistry are the Rosetta Stone in this case. A good example of how this might work is in "Omniligual" by H. Beam Piper. "The Listeners" by James E. Gunn is a good novel about contact by radio.

 

I don't get those who think there is nothing to gain by talking. Even if we can't go there and they can't come here, a free swap of knowledge would enrich our world. The history, literature, philosophies, arts and sciences of another world would effectively double our own experiences.

 

How can the opportunity to see the Universe from a different perspective, not be worth the effort?

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I don't get those who think there is nothing to gain by talking.

There is nothing to gain if there is nobody to talk to, which is what the Fermi paradox is all about.

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To JohnB

 

The technique proposed here on Earth for sending radio messages to possible extra-solar listeners was to send a series of dots and dashes, in groups representing the result of multiplying two prime numbers. For example : you could send 77 dots and dashes in a bunch. Multiple of 7 and 11.

 

It is assumed that the receiver would know how special the number of dots and dashes was, and then rearrange those dots and dashes in a diagram, with the two primes as the values on the x and y axes. So one axis would be 7 and the other 11. Dots and dashes would be arranged accordingly and form a picture.

 

You can send an awful lot of data in pictorial form like this. If an alien species wanted to communicate by radio with a new civilisation, they might use that, or similar technique.

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You can send an awful lot of data in pictorial form like this.

Agreed. We just have to find someone to talk to.:D

There is nothing to gain if there is nobody to talk to, which is what the Fermi paradox is all about.

Personally, I think we simply haven't been listening long enough. If radio is the only way to find them, then we have to think (and fund) on generational, not annual or decadal scales.

 

If there is a civilization at our level a measely 200 LY away, we still won't find out about it for another hundred years. Someone only 50 LY away who might be looking us still hasn't had time for their message to arrive after detecting us.

 

For all we know, there may have been a high tech civilization near Alpha Centauri that destroyed itself in 1900 AD. We would never know as their transmissions ceased before we had the ability to recieve them.

 

We need to be patient, that's all. Rome wasn't built in a day and ET won't be found in a year.

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Do we really want to talk to aliens? I know people like to say that an advanced Race would be peaceful, but that may be only one race. They may be peaceful, but there could be more aggressive war-like races out there. I think that it is best if we just keep our heads down and try not to draw attintion to ourselves. Especially with we living in the United States being the strongest nation would more than likely be wiped out first as an example to the rest of the world. Think Independance Day without Will Smith being able to save us.

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Do we really want to talk to aliens? I know people like to say that an advanced Race would be peaceful, but that may be only one race. They may be peaceful, but there could be more aggressive war-like races out there. I think that it is best if we just keep our heads down and try not to draw attintion to ourselves. Especially with we living in the United States being the strongest nation would more than likely be wiped out first as an example to the rest of the world. Think Independance Day without Will Smith being able to save us.

 

I think that a race capable of building spacecraft capable of traveling the light years to reach Earth would not have achieved that level of technological advancement without being able to work with each other to learn how to build these, not to mention the prospect of spending the years, or, in most cases, generations in the vast emptiness of space together (with the same people for your entire lives) without killing each other before they reach Earth. They would almost have to be peaceful in order to us to find them.

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Sparky, there's no point in "keeping our heads down" as everybody within 70 odd LY already knows we're here. The increase in radio emissions from this system over that period make it obvious to any outside observer.

 

Also, unless FTL travel was cheap and fast for them, invasion would be problematic at best. You can't fight a war if it takes weeks or months for your reinforcements to arrive at the battle. And if FTL is cheap, it's easier to mine asteroids for any materials you want.

 

As to advanced races being friendly, I read an interesting idea some years ago. It was based on four basic assumptions:

 

1. All races could be grouped into three broad types;

A) Always friendly (Make Alliances)

B) Willing to be friends, but will fight if needed

C) Always fight

 

2. These three types will emerge in roughly similar proportions.

 

3. An alliance of races will always defeat a single race in combat.

 

4. A C type will always defeat a single race in combat.

 

So when A meets A or B we get an alliance of AA or AB. When A meets C we get a C.

 

When B meets A we get an alliance (BA), when B meets B we might get an alliance and when B meets C we get C.

 

When C meets A, B or C, we get C.

 

Taken to the next step, we now have a wad of AAs, ABs, BAs and BBs. When any of these meet, they form larger alliances and when they meet a C they wipe out the C.

 

You'll also notice that the C type races do a very good job of wiping each other out, thereby reducing the chances of us meeting one.;)

 

I'd add that anyone who has watched us closely enough to consider an invasion, would also be well aware that we would be more likely to hand them a ball of smoking rubble than a viable world. Humans would use thermo nuclear weapons to drive an invader off. Forget "Independence Day", to conquer a world you have to land and make a base and a suitcase nuke set off on the base perimeter can ruin your whole day.

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Sparky, there's no point in "keeping our heads down" as everybody within 70 odd LY already knows we're here. The increase in radio emissions from this system over that period make it obvious to any outside observer.

 

Also, unless FTL travel was cheap and fast for them, invasion would be problematic at best. You can't fight a war if it takes weeks or months for your reinforcements to arrive at the battle. And if FTL is cheap, it's easier to mine asteroids for any materials you want.

 

As to advanced races being friendly, I read an interesting idea some years ago. It was based on four basic assumptions:

 

1. All races could be grouped into three broad types;

A) Always friendly (Make Alliances)

B) Willing to be friends, but will fight if needed

C) Always fight

 

2. These three types will emerge in roughly similar proportions.

 

3. An alliance of races will always defeat a single race in combat.

 

4. A C type will always defeat a single race in combat.

 

So when A meets A or B we get an alliance of AA or AB. When A meets C we get a C.

 

When B meets A we get an alliance (BA), when B meets B we might get an alliance and when B meets C we get C.

 

When C meets A, B or C, we get C.

 

Taken to the next step, we now have a wad of AAs, ABs, BAs and BBs. When any of these meet, they form larger alliances and when they meet a C they wipe out the C.

 

You'll also notice that the C type races do a very good job of wiping each other out, thereby reducing the chances of us meeting one.;)

 

I'd add that anyone who has watched us closely enough to consider an invasion, would also be well aware that we would be more likely to hand them a ball of smoking rubble than a viable world. Humans would use thermo nuclear weapons to drive an invader off. Forget "Independence Day", to conquer a world you have to land and make a base and a suitcase nuke set off on the base perimeter can ruin your whole day.

 

While I do not think any violent space faring civilizations exist, if they were, and if they were to invade, I doubt that you would be able to adequately fight them anymore than all the animals in a forest would be able to adequately fight us with our bulldozers capable of totally demolishing their home.

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Re mention of Independence Day: Funny how in that movie, we managed to design a computer virus that would affect a totally alien computer. On the other hand, any invading alien would have an entire library of viruses capable of infecting us. So if we met a hostile invading alien race, we should expect to be hit really hard by a virus, or disease. We wouldn't be the ones infecting them with anything.

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There is no special reason to expect aliens to be hostile or friendly. They could be either.

 

I would suspect that, if an alien species came to our solar system, we would not know they were there - at least at first. An advanced species would have more advanced instruments than us, and they have louder electromagnetic 'noise' to listen to - a whole planet's worth. They would thus detect us while still outside our detection range.

 

Assuming no FTL propulsion, if they are hostile, it is logical that they would send a message to reinforcements - probably a laser beam, which would also be undetectable by us, to ask for more space craft. Some decades later, the armada would arrive, and humanity would soon afterwards cease to exist.

 

However, it has not happened yet, and this means it is seriously unlikely to happen any time soon. The galaxy is about 7 billion years old, and a hostile ET has had plenty of time to get here.

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How long would our radio transmitions remain distinguishable from noise when broadcast into space? I doubt the intensity of the wave would be detectable for more than a few light years (if even that far) away from Earth. If an alien can't detect our signals because we are too far away, I doubt that any aliens would even know we are here (unless there are some very close by).

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To noz

 

An aggressive, hostile but highly advanced alien species would not wait to detect us. They would be moving throughout the galaxy. As previous calculations have shown, it takes somewhere between 500,000 and 10 million years for a colonising species, using sub light speed vessels of cruising speed 0.1 to 0.2c, to colonise the galaxy to the point of overpopulation.

 

Since the galaxy is so old, they would already be here, and have already visited. Since we see no traces of any visit, it is reasonable to conclude that any such species is extremely unlikely to exist close to us (by astronomic measures) at this point in time.

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Well, I meant in general--not necessarily referring to "hostile aliens" (which I still doubt can exist, but will admit the possibility of), but any alien listening in. It would also seem somewhat uneconomic to send manned warships about the galaxy without having a particular destination, so I think they would, if they are smart (which, to have an interstellar empire, they would have to be) either send out probes or listen in on our communications (which is what I'm questioning--could an alien listen in on our communications?).

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... the delay in any communication effectively rendering such communication to be of no value.

Via quantum 'entanglement', quantum teleportation can communicate information, instantaneously, once a conventional signal link is established. Thus, although the initial erection, of an 'inter-stellar inter-net' would require conventionally-long periods of time; even so, once the 'galaxy net' had been established, information could, then, be communicated instantaneously.

 

 

 

I would suspect that, if an alien species came to our solar system, we would not know they were there - at least at first. An advanced species would have more advanced instruments than us, and they have louder electromagnetic 'noise' to listen to - a whole planet's worth. They would thus detect us while still outside our detection range.

Comparatively advanced human hunters use comparatively long-range weapons -- e.g. bow & arrows, fire-arms -- to target & kill comparatively primitive prey, from long-range, i.e. 'slay from a safe stand-off distance'. By analogy, advanced Super-Aliens would destroy us, while still outside our retaliation range.

 

 

 

I'd add that anyone who has watched us closely enough to consider an invasion, would also be well aware that we would be more likely to hand them a ball of smoking rubble than a viable world. Humans would use thermo nuclear weapons to drive an invader off.

Advanced Super-Aliens would derive more economic value, from the asteroid-sized blob of gold, which long ago gravitationally settled into the center of our world, than from any species, of earth's 'super-ficial surface bio-scum' bio-sphere of life-forms. Thus, rather than "landing", 'They' -- an archaic space-faring super-species (by assumed definition) -- would more probably rip apart our planet, and 'process' the same, much as humans contemplate 'space mining' smaller, but essentially similar, sub-planetary asteroids, i.e. simply smaller 'space stones'.

 

 

 

a race capable of building spacecraft capable of traveling the light years to reach Earth would not have achieved that level of technological advancement, without being able to work with each other to learn how to build these, not to mention the prospect of spending the years, or, in most cases, generations in the vast emptiness of space together (with the same people for your entire lives) without killing each other before they reach Earth. They would almost have to be peaceful in order to us to find them.

'They' would be friendly amongst 'Their' own kind. By complete contrast, comparatively primitive, planet-bound, pre-space-faring species, e.g. humans, would be (by assumed definition) utterly unlike 'Them'; and, hence, utterly un-liked by 'Them'.

 

 

 

...The laws of physics are the same on a star 1,000 light years away as they are here. The trick, then, is to send a Rosetta stone that describes math, physics, and chemistry along with the signal...
The technique proposed here on Earth for sending radio messages to possible extra-solar listeners was to send a series of dots and dashes, in groups representing the result of multiplying two prime numbers. For example : you could send 77 dots and dashes in a bunch. Multiple of 7 and 11. It is assumed that the receiver would know how special the number of dots and dashes was...

Signals from advanced Super-Aliens might involve 'numerological' references, to fundamental physical phenomena, e.g. "6" referring to carbon-based bio-chemistry; "26" referring to the nuclear iron peak.

 

 

 

an Alien race (more advanced than ours) decides to suppress any other race advancing too far... these Aliens would have to actively suppress these other races (which might include annihilation).

Inter-species competition is natural, and to-be-expected ("there's always a Bigger Fish"). Space-faring Super-Aliens, capable of colonizing space, would, therefore, naturally & to-be-expectedly assert 'Their' Super-Dominance, over that space habitat, into which 'They' were capable of entering. By analogy, then-earth-dominating dinosaurs naturally expanded, into every available terrestrial habitat (land, sea, sky), naturally displacing all sub-dominant, i.e. subjugated, species, to the maximum of dinosaurian competitive capability. Similarly, Super-Aliens would be capable of 'Supra-Natural' Super-Domination, over 'Their' entire surrounding space environment -- which would, eventually, come to include our star neighborhood. The ensuing annihilation, of earth, and earth-life-forms, would be a natural & to-be-expected example of extinction, a natural & to-be-expected evolutionary occurrence, quite common in earth's own fossil record.

Edited by Widdekind

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Some intelligent species might decides to forgo planetary life altogether. Such a species would be even more free to exploit the resources of the galaxy than a planet-bound species...
... large habitats - cities in space - will appear, and will become close to self sufficient
...the future will include planet bound people, and people living in space habitats or cities. The latter will be those who colonize the galaxy. Easy to move a space habitat since there is no need to fight a gravity well from a planet. Such people will be genetically altered to be immune to high radiation and to harm from zero gravity. They may well live very long lives so that a journey of 50 to 100 years holds no fears.

 

An alien species that reached that stage more than 10 million years ago would already have occupied the entire galaxy. Their space cities would be very visible...

Primitive humans inhabited natural structures, e.g. trees & caves. Advanced humans inhabit supra-natural, artificial structures, e.g. houses & apartment buildings. By analogy, advanced Super-Aliens would inhabit 'Supra-Natural', i.e. 'Superior-to-planets', artificial super-structures, e.g. Dyson Spheres.

 

Energy resources are precious. All human-known life-forms have evolved behaviors, e.g. hybernation & napping; and/or insulation structures, e.g. blubber, feathers, fur; in order to retain energy, and reduce energy wastage. Indeed, energy conservation is universally economically beneficial -- American corporations, seeking competitive advantage, have long been 'going green', reducing energy wastage, to cut costs (Stroup. Eco-nomics). Super-Aliens would be super-energy-efficient, i.e. 'They wouldn't leave Their lights on', er go 'Their' space super-habitats would be super-low-emission, super-low-surface-brightness, super-dim, super-dark, i.e. 'Biblically Black'.

Edited by Widdekind

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That ought to be detectable in the infrared. If you are using energy, as any civilisation must, then there will be waste heat. The error in thinking here lies in the presumption that aliens would continue (or have in the first place) the uncontrolled desire for expansion of numbers.

 

Widdekind, your responses in post #70 and likely many other posts in this thread all demonstrate a simple fact: you have not understood the meaning of the word alien. You are describing beings whose behaviour is similar to ours, or what ours might become. In other words they are not, in your mind, aliens - but familiars. Alien means alien. Strange, different, not like us.

 

One of the better attempts to capture this in SF were the moties in Pournelle and Niven's The Mote in God's Eye, and I suspect that doesn't even come close. Follow that thinking and the answer to Fermi's "Where is everyone?" becomes evident.

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..unless FTL travel was cheap and fast for them, invasion would be problematic at best. You can't fight a war if it takes weeks or months for your reinforcements to arrive at the battle.

 

Apex Aliens, millions or billions of years more advanced than modern mankind, would seem 'God-like', i.e. 'They' would be 'Super-Natural', i.e. Superior-to-Natural. Thus, 'They' would have artificial, space-habitation super-structures, that were Superior-to-Natural, i.e. superior to planets, i.e. "better than our asteroid", eg. Dyson Spheres. By analogy, advanced humans construct artificial land-habitation structures, e.g. houses & apartment buildings, that are superior to natural alternatives, e.g. trees & caves.

 

Therefore, by the time a 'Super Cortez' actually did cross our cosmos -- i.e. 'the Sun-rise Sea', 'the Big Water' -- then, that 'Super Cortez' would arrive with Superior-to-Natural space super-crafts, which were as superior to our planet-world, as an apartment building is to a cave or tree, i.e. 'God would have better than our asteroid-space-stone'.

 

Er go, humans would have no 'home-field advantage', any more than european neanderthals, lacking comparably advanced modern human technology, were able to keep their caves, against encroachment, from cro-magnons (Churchill 2009). Instead, outmatched, humans would need the reinforcements; and, like the neanderthals, humans would have none, and die -- i.e. suffer extinction, before more advanced life-forms, as has ever been a natural part, of life, evolving on earth, for billions of years.

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That ought to be detectable in the infrared. If you are using energy, as any civilization must, then there will be waste heat. The error in thinking here lies in the presumption that aliens would continue (or have in the first place) the uncontrolled desire for expansion of numbers.

 

'They' could 'dump' waste heat, into our space environment, at any temperature, above ambient background, i.e. >3K.

 

Meanwhile, humans cannot detect brown dwarves, radiating at oven-temperatures T~1000K, i.e. several hundred times hotter, from farther than a few light-years. And, radiation intensity scales as the fourth-power of temperature.

 

Thus, 'They' should show up, on thermal scans of space... of currently supra-human super-sensitivity. By comparison, humans currently cannot observe whole (dwarf) galaxies, in our own galactic neighborhood (Local Group). Thus, 'They' could be coming, inbound, to 'blast' earth... in a fleet of billions of star-sized super-ships... each of whose drive-exhaust flares was as bright as a (small) star... and 'we monkeys of earth' would be as oblivious, as all of our planet's other advanced life-forms, e.g. peregrine falcons, great white sharks, lions.

 

Again, theoretically, whole fleets of Alien super-star-destroyers could be decelerating through our own galaxy halo, at this very moment, and we would know nothing. To do better, we would have to be looking, in the right direction, with super-sensitive IR scanners, well beyond our ability to develop, much less deploy (in space, too), at present.

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