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Basic mathematics is something common to all lifeforms with advanced technology so the generally accepted route to communication is via mathematics. this allows the generation of basig symbols which are developed and elaborated to enable communication. This would apply to any lifeform however it was constructed. A good example of this process is described in the book and film "contact" by Carl Sagan.
Doesn't Voyager 1 have a naked scientist type logo on the side and there is some mathimatical progression involved somewhere. This was done incase some aliens came across it.Voyager 1 is a real hero. It's still going and is expected to keep sending back data until at least 2020...that's 43 years after it launch! I'll be happy if my 76 merc lasts that long.
There has been threads on radio communication over vast distances and the calculations show that transmitters thousands of times more powerful than we have now would be required.
We cannot even be sure how large the aliens would be. Is the voyager going to look like a speck of sand, or like something the size of a mountain, in which case, at what scale will they view what they see (maybe they will pay more attention to the surface texture of the metal than to the symbols writ large on the side).
Actually, if we assume basic life processes as being similar to ours then we can.
We do have some idea about upper and lower size limits. Any creatures of fly size would be, necessarily, limited in brain power (numbers of cells / memory elements) and, for engineering reasons, they would need to build ships around the size of human's space ships in order to leave a planet of Earth-like size.
Also, there are upper limits to size, based on strength of materials available for skeletons etc.
I could imagine a range of body masses spanning a ratio of, perhaps, ten to one? Certainly not more than 100:1.
Trees, that do not rely on bone, are capable of growing much higher. Even life that does rely on bones, in particular, marine life, is also not so constrained on size.
Blue Whales are up to 170 tonnes, and heavy as I may be, I am still well under 1% of that body mass.
Not flies, but bees, are also strongly cooperative, and so can achieve far more than any single bee or fly could attain on their own (although their is no doubt that the number of cells in a human society exceeds the number of cells in a single bee society)
QuoteTrees, that do not rely on bone, are capable of growing much higher. Even life that does rely on bones, in particular, marine life, is also not so constrained on size.But they don't need to carry enough muscle to move them around!
Woops - I forgot about sea organisms. However, their technology could be a bit limited if, as with humans, they need fire to get started.
This is true, but there are many more possible interconnections between the cells of a complex brain than between the brains of 'simple' individuals. I think this is relevant where sophisticated ideas and tasks come into play.
There is something else to consider about aliens. The more different they are, from us, the less 'interested' we would be in what they had to say to us. It is probably true to say that, if they looked a lot like us, we would be much more empathic (or, possible suspicious). The conspiracy theorists would just love it if they looked like people dressed up.
Initial 'messages', would have to be extremely simple - prime numbers sent in binary form or musically related frequencies. etc. etc.
Organisms evolve to fit their surroundings in competition with other organisms.
OK you can move a tree with human muscles but that's not a big organism; it's a small organism doing some work on a big object.
Humans can also run around, defend themselves and chase prey. A 10m human would be no use as a predator; it would have to photosynthesise and would need no brain.
'Intelligence' develops where it is necessary / advantageous; carnivores and omnivores do better when they are intelligent. 'Too much' intelligence is wasted on herbivores so they don't tend to be that smart -just be strong or run fast, which isn't a good starter for 'civilisation' or technology.
Where there has been evolution in isolation - Australia / Galapagos Islands / the sea etc. we find that species develop in parallel fashion, with predators and prey all taking up equivalent roles. There are certain optimum arrangements for given circumstances and these are what develop favourably.
There is no reason to suppose that carbon-based life on another planet with 'Goldilocks' conditions would end up developing in a wildly different fashion. I agree that you can dream up all sorts of life forms but Chemistry has to rule. You need complex molecules for 'life' and there is nothing quite so useful as Carbon for this under Earthlike conditions. Is there evidence of alternative complex molecules existing under wildly different conditions in the same way as we can detect the presence of Methane etc. all over the place?
Speculation is only worth while when it is based on a hint of reason or we'll have fairies at the bottom of the garden.
Wales and Fingers: We didn't do well BECAUSE we had fingers; our evolutionary path gave us rudimentary fingers and a crude ability to use them, all in the same process and we ended up with what we have now. Whales' ancestors actually DISCARDED what could have been fingers when they took to the sea and needed flippers, not hands. It seems that organisms. once committed to a particular path, carry on in that direction, changing only when circumstances change radically.
Potential candidates for Alien civilisations need to have gone through similar processes to what we have been through and in similar timescales, too.
Any 'top' organism has to reach a level before there is some extinction event which gives another organism the chance to get to the 'top'.What do I mean by 'top'? I suppose I mean to be successful reproducers and to want to and to be able to communicate with other similar organisms. There are loads of other prolific species which don't give a monkey's about the others except as potential danger of dinner.
On the subject of brain size, there is a definite upper limit on human brain size and that is imposed by the restrictions of the female birth canal and on the necessity of having and supporting a skull to protect it whilst we are walking about.
The only meaningful conversations across interstellar distances would be between 'aliens' that had a much longer lifetime than us and a vastly different concept of time.There is a remote chance that if we were in the right position between two systems that were communicating we might eavedrop on such a conversation but would we recognise it as such ? as the data rate would be very low by our standards
There is one unicersal way in which all beings that we consider intelligent could communicat. If we found aleins that we considered intelligent there is an extremely high probability that they would know about atoms. Thus we could communicate using atoms. Both us and the aliens would need to be able to detect various atoms. We could then develop a language like thisHydrogen could be the equivalent of Hello.If we detected Hydrogen being emitted by an alein this would be 'Hello'. However this would requiere both side to be coincidently using this metheod.Another possibility is that because of the extremely long time scales of the universe it is also extremely likely that any aleins we encounter will be millions possibly even billions of years a head of us in terms of technology. Such an advanced species will most likely have encountered other life and may have ways of communicating with aleins.Yet another way that would be a little more difficult is using the positions of stars. If we send them data with the position of a particular constelation with positions of that constelations stars relative to earth and sent them data of earth's position relative to their locations and maped out the stars we gave them relative to their position we could use various grouping of stars as communications. for instance:Equuleus star constellation means the equivalent of 'Hello'Another way we could communicate with aleins is by communicating using universal constants. However this may be a bit more risky because many universal constants are constantly changing. Such as the grvitational Constant which has changed some over extended periods of time.Another way, which would be unblievably difficult and requiere computers so powerful that its like nothing we can imagine. In about 600 hundred years it has been predicted that we will have computers that will be able to simulate the universe. Also this last one here is pure theory. Now using this computer we would enter everything we know about these aleins that is naturally occuring about them, such as their quivalent of DNA and the environment of their planet, moon, star, or whatever other object they live on then have a the computer run a simulation giving data on all possible combinations of what this species could come up with. And I am everything down to at least one of these simulations would give us the exact date they discovered the atom. Then amoung this data would be there language. Then this next part would take a very very very long time depending on their computing power and wether or not they are attempting to communicate with us to, which if we know about each other they may be interested in doing so. We will send them a steady stream of all this data we communicated from our simulation then if they responded using lets just say radio waves to keep it simple we would look for that peice of data amoung our database from the simulation and match it up. At that point we could confirm that to be some kind of a word. After that this process would be reapeted until we discovered many more of their words or rather word equivalent. Then once we have a reasonable number like at a point that we stop discovering additional words then we start sendng the words back to them that we discovered in random orders. Then we wait for a response. If the response sent back contained the same words only in a different order then we could know that their response was the correct order of the words. We keep on doing this until we get more snetances. Then we plug these sentances back into the data we got from the simulation. The simulations would have picked up the positions of the aleins lifeform at everystage of their timeline. We then try and look for situation in which one of these sentances that are correct was spoken by one of the aleins when first interacting another another alein after a period of time. Such as a 'Hello' you may give to a co-worker when arriving at work. Then after all that we will have successfully discovered what is MOST likely some sort of a greeting. At least in theory. However this metheod requires that the aleins have a greeting perhaps the aleins do not greet each other.I can think of many other possible communication methods and at the same time I can think of holes in any of the above communication methods. That is why if we truly wished to communicate we would need to attempt hundreds of methods.
What will they make of The Beatles' "Across the universe" - an all-out declaration of war? Have NASA really thought this thru??
There is a limit to which special transmissions and processing at the receiver end can improve the situation.
I would have though once a signal is well below the noise there is nothing you can do no matter what you do. Integration of a period of time will have its limits.
Take it from from there are no working systems which can rescue signals which are well below the noise.....and we are talking 60 - 80 - 100 dB ++ below noise.
You can dream up fanciful schemes to extract a tiny bit of info from a signal with massive redundancy and take a 1000 year to do but it wouldn't be much use would it?
There are other problems with long distances which space agencies have to deal with. Even at the record distance we have received a signal fom a spacecrft which is only 1/600 of a light year signals tends to arrive garbled due to group delay. There are very slight differences in the speed of popagation at different frequencies so bits of a signal (which apart from sinple 0n-off keying - Morse has a spreed of frequencies) arrive before others.
It is getting too esoteric and too 'science fiction'.
I am just making the point that huge transmitter powers would be needed to communicate at distances of the order of one light year never mind hundreds of light years.
Group delay is a separate question and there is a considerable difference between the 'rough note' pulsar etc and a communications signal.
Owing to their extraordinarily rapid and stable rotation, MSPs can be used by astronomers as clocks rivalling the stability of the best atomic clocks on Earth. Factors affecting the arrival time of pulses at the Earth by more than a few hundred nanoseconds can be easily detected and used to make precise measurements.
To think there could be any technique that could retreive signals which are millions of times below noise...not only receiver noise but cosmic noise is a bit like me saying that I could make my ordinary car do 100,000 MPH and 50,000 MPG (at the same time).
Anyone looking towards Earth would also be looking at our Sun and receive its radio noise.
At some point there will be no signal..at some distance..when there are just no electrons being stimulated in a aerial by our Earth transmitter.