[QUOTE=ewmayer;538965]...
and the further reasonable surmise that not all those advanced alien races are friendly,
...[/QUOTE]I have always wondered : everybody thinks about anything in term of economics of the financial kind these days. But when ET is discussed the possible hostility of the others is always considered.
The only contact we could have at the moment spans huge distances and thus a huge time lapse.
Hostility implies an entity spend huge efforts (nothing comparable with "discovering America") to go somewhere and try to obtain something through force.
If some ET might be in a position to communicate (not over astronomical time-spans, but with a reasonable lag) they might decline because it doesn't interested them or because they were busy. They might also be curious. But would they immediately start hostilities, an occupation ?
Another aspect always swept under the carpet, the distances and the time involved would mean "civilisations" eons apart : fists, teeth and nails versus nuclear arms (to give known examples.)

Uncomprehension, misunderstanding, probably. I think it reasonable to expect at least goodwill not "unfriendliness" of hostility.

Jacob

[QUOTE=S485122;538975]I have always wondered : everybody thinks about anything in term of economics of the financial kind these days. But when ET is discussed the possible hostility of the others is always considered.
The only contact we could have at the moment spans huge distances and thus a huge time lapse.
Hostility implies an entity spend huge efforts (nothing comparable with "discovering America") to go somewhere and try to obtain something through force.
If some ET might be in a position to communicate (not over astronomical time-spans, but with a reasonable lag) they might decline because it doesn't interested them or because they were busy. They might also be curious. But would they immediately start hostilities, an occupation ?
Another aspect always swept under the carpet, the distances and the time involved would mean "civilisations" eons apart : fists, teeth and nails versus nuclear arms (to give known examples.)

Uncomprehension, misunderstanding, probably. I think it reasonable to expect at least goodwill not "unfriendliness" of hostility.

Jacob[/QUOTE]It doesn't have to be actively hostile. Even just visiting with benign intentions can unintentionally cause major problems. For an Earth analogy think about the spread of disease. The early settlers of many places didn't even know that they would bring about death through diseases. And not just to other humans that might have been already there, also plants and other animals suffered.

[QUOTE=ewmayer;538970]Not at all - but can you think of a more bit-efficient one? DNA sequences, or even viral RNA ones, tend to be rather longer than the mere ~1kbit needed to encode all known-to-us M-prime exponents.[/QUOTE]
Sagan had the aliens thumping out plain primes on the bass drum for Jody Foster to hear. Once she caught the beat she tuned in for the disco experience on the side channel. This was an obviously more advanced civ sending their version of an ASCII uudecoder prog.
With MP's a civ could shout out M2-M127. This would show several things:
1. We have intelligence/know about math (we recognize primes)
2. We know about more complex math and have the ability to dedicate time to it and value it enough to do so (6h x 52w x 19y)
3. We have the means to broadcast.

So that puts us up in the the early twentieth century. If someone replies with say the next 8 or 10 terms, then we respond with 8, then they know that we have computers and have further progressed from mechanical (relay or geared) systems to electronic ones and have moved on to more complex systems. After that a back and forth of 4, then 3, then 2, then 1 at a time would figure out who is in the lead.

As was pointed out. MPrimes are efficient. One could tap them out as just beats. Then when responding, tap out to 127, then switch to a binary code for the next batch. Doing all of this would be a bit like modems doing their thing negotiating the highest known protocol.

[QUOTE=ewmayer;538965]I've long argued that under the assumption ...[/QUOTE]
:tu: :goodposting:
The best post on this forum this year, by any user, by far!

:laurv:

Assuming the ET has bad intentions, or, in the large extent, that something bad for us will come from meeting them, or even realizing their presence, is not unrealistic. Think about the history, what the conquistadors did when they found new lands? they killed the people there; What Romans did when they found Egypt? They killed them and enslaved them. What Magellan did when he found new populated islands in Pacific? He killed the people there. What Brits, French, Ottomans, Dutch (in southern Africa), did when they found people there? They killed them. Australia? New Zealand? They only now are arguing about their "Anzac Day", because some of them have remorse, why? They killed all the natives... Most of the time on purpose, but sometimes just accidentally, even if the conquerors had good intentions (i.e. spreading of virusues and diseases unknown to the locals, on which their bodies were not immunized by evolution - and this worked most of the time both ways, the conquerors also had to suffer and die, due to the local diseases - and how did they "took revenge"? You guessed, they killed more locals...)

This is not mine, it was said by people who knew better, in the past (Carl Sagan is one of them). So, be happy we are lucky enough to be so far away from each other...
Nothing good can come from meeting them, unless they are REALLY more advanced than us (like we are, when compared to monkeys, or ants), and therefore inclined to compassion towards us. And in that case, who would want to meet them? :shock:

A moderate difference in technology, or as well as just a little difference in technological advance, will undoubtedly result in wiping out of one of the two civilizations, the one less advanced. And who will that be, assuming THEY are the one coming here? (we, with whole our current technology, still have no known way to go there, except being bored to death traveling for thousands of years in a spaceship, so guess who the most advanced is, in case we meet...).

[QUOTE=Uncwilly;538982]After that a back and forth of 4, then 3, then 2, then 1 at a time would figure out who is in the lead. ... Doing all of this would be a bit like modems doing their thing negotiating the highest known protocol.[/QUOTE]

A wonderfully clear way of saying it! :tu:

And now we have another excuse (I mean reason) to justify why we invest so much of our time and energy into this project.

We're preparing for our first interactive encounter with extraterrestrial life! :wink:

[QUOTE=Uncwilly;538982]
So that puts us up in the the early twentieth century. If someone replies with say the next 8 or 10 terms, then we respond with 8, then they know that we have computers and have further progressed from mechanical (relay or geared) systems to electronic ones and have moved on to more complex systems. After that a back and forth of 4, then 3, then 2, then 1 at a time would figure out who is in the lead.[/QUOTE]
I think the message would be staged. First, attract attention with a signal unlikely to be of natural origin. Like say the counting numbers. Then, a sequence of all primes over a short interval from 2. Then, Mersenne exponents. Transition from counting taps of the telegraph key, to base two, at some point. Message loops.
That's assuming that sending at all is considered a wise move. A healthy paranoia might lead to lots of listening and little or no sending. Breeds prone to developing bullies might take a signal source, particularly one that embarrasses them by knowing 10 more Mp exponents, as a place to direct a largish asteroid or comet to with a little nudge by laser beam and big negative consequences to the recipient of the incoming biosphere-buster.

That a completely different planet would go through the stages of technical progress that we had is an assumption. An aquatic intelligent species is unlikely to do things like smelt ore to build metal gears, electrical wire, silicon foundries etc. Their tech may be biotech from early on, or unguessably different from any of ours.

There are many reasons for an intelligent species to conclude the trip or conversation is not worth the time or cost.

[QUOTE=kriesel;539035]That's assuming that sending at all is considered a wise move. A healthy paranoia might lead to lots of listening and little or no sending. Breeds prone to developing bullies might take a signal source, particularly one that embarrasses them by knowing 10 more Mp exponents, as a place to direct a largish asteroid or comet to with a little nudge by laser beam and big negative consequences to the recipient of the incoming biosphere-buster.[/QUOTE]Have you read "The Three Body Problem" and its sequel "The Dark Forest"? If not, hit pause now and go do so. (You can listen to them instead.)

[QUOTE=kriesel;539035]I think the message would be staged. First, attract attention with a signal unlikely to be of natural origin. Like say the counting numbers. Then, a sequence of all primes over a short interval from 2. Then, Mersenne exponents. Transition from counting taps of the telegraph key, to base two, at some point. Message loops.[/QUOTE]Given that the closest alien life is most probably a minimum of many hundreds of LY away (and probably much much further) then holding a multi-stage dialogue to establish our relative e-peen sizes would be time consuming and difficult. Would we even have the patience to last it out over the many millennia that would take?

And the equipment required for both the receiver and transmitter still hasn't been invented here.

[QUOTE=retina;539075]Given that the closest alien life is most probably a minimum of many hundreds of LY away (and probably much much further) then holding a multi-stage dialogue to establish our relative e-peen sizes would be time consuming and difficult. Would we even have the patience to last it out over the many millennia that would take?

And the equipment required for both the receiver and transmitter still hasn't been invented here.[/QUOTE]
ONE hello message, with multiple parts, transmitted repeatedly, if at all.
Taking our own technological evolution as an example to learn from, analog radio transmission at high power is in a sense a passing fad. The bubble of radio and TV signals we have emitted has an outer radius now of 50-100 light years. Changing regulations and technologies have led to the switch to digital TV and putting more of the traffic on cable and fiber. Picking a message out of the wide EM spectrum and many terrestrial sources from any plausible distance would take a lot of luck, and resources, and excellent receiver sensitivity. NASA uses some pretty hefty high gain antennas and knows where to point them to pick up the faint signals from our interplanetary probes, which are still very close compared to Alpha Centauri.
After contact is established, communication could be operated full duplex; send whatever's thought safe to share and possibly of use. Not only is latency very long, the feasible bit rate is likely to be very low. [url]https://en.wikipedia.org/wiki/Channel_capacity[/url]

[QUOTE=retina;539075]And the equipment required for both the receiver and transmitter still hasn't been invented here.[/QUOTE]Not true.

A pair of radio telescopes comparable to our largest steerable devices, 50m to 100m aperture, could maintain communication to a kiloparsec or more.

Arecibo or Tianyan could talk to their counterparts pretty much anywhere in the galaxy.

The SKA will be able to communication with its peer anywhere in the Local Group.

Two laser boosters, as suggested for the Breakthrough plan for interstellar probes attached to light sails, could maintain megabit communications over a gigaparsec on the assumption that a filled array of detectors of comparable size was also installed. Admittedly, the ping time would be rather lengthy.

(Incidentally, I'm a co-author of a paper which discusses using sneakernet for communication up to a kiloparsec; this time the light-sail probes themselves would be used rather than their propulsion system.)

I do not yet know how far two E-ELT / TMT telescopes could communicate using currently available high-power optical or near infrared lasers. I would be surprised if it is markedly less than a kiloparsec. I will try to find out.

All the above have been invented. The first two have been in operation for decades, the third and fifth are under construction but the fourth does not yet have a plausible construction date.