Aliens in 1500 years

[magnemoe]

7 hours ago, PB666 said:

That's a problem, but my prediction is that it will take 600+ years with perfect technology, it could take 15000 years without any active efforts on our part to reach out to aliens, we would be waiting for them to broadcaste signals. 

If anybody listens in the time frame, its more likely that we will broadcast less in the future, more use of low power cell networks on earth and lasers in space. also limit how far away you can detect signals and you will have to listen over geological time spans to have an chance to pick up something. First issue is that at some point the signal get weaker than the noise level, second is that its limited how many square kilometers of antennas you bother to use for this. 

Of the numbers of technological civilizations, just an subset will be willing to do an seti program over geological timescales. 
Say 1 of 10 if you are very optimistic. 
Still see my first contact scenario as most plausible   http://i.imgur.com/Mo00fXb.png

[PB666]

2 hours ago, magnemoe said:

If anybody listens in the time frame, its more likely that we will broadcast less in the future, more use of low power cell networks on earth and lasers in space. also limit how far away you can detect signals and you will have to listen over geological time spans to have an chance to pick up something. First issue is that at some point the signal get weaker than the noise level, second is that its limited how many square kilometers of antennas you bother to use for this. 

Of the numbers of technological civilizations, just an subset will be willing to do an seti program over geological timescales. 
Say 1 of 10 if you are very optimistic. 
Still see my first contact scenario as most plausible   http://i.imgur.com/Mo00fXb.png

See my other thread on gaming aliens, playing the game first encounter is made when we are colonizing as we are about to explore a new system at which point we decide to explore a different direction or about to colonize and we have to make choices about how to manage an encounter. So assuming we can manage a new star system at the frequency of 0.002/T² until some galactic barrier is reached, and assuming we while move out like fingers on a hand there's a pretty good chance this would happen within 1500 years, but because of the way preferential stars are distributed it might happen faster or because IS travel is harder much slower. 

[DBowman]

On 6/17/2016 at 4:38 AM, Scotius said:

Maybe, instead of looking for modulated signals (that degrade with time and distance covered) we should simply look for stars that produce more electromagnetic "white noise" than they should? Sure, it's not foolproof, but if we find a Sun-like star that generates twice the amount of radio static that G class star should, it could mean something's afoot

Also our tech direction wrt copyright protection and the general move to encryption by default means that makes sense, an advanced civilization's  comms is likely to be indistinguishable from noise so we'd have to do traffic analysis.

[magnemoe]

On 17.6.2016 at 1:24 PM, PB666 said:

See my other thread on gaming aliens, playing the game first encounter is made when we are colonizing as we are about to explore a new system at which point we decide to explore a different direction or about to colonize and we have to make choices about how to manage an encounter. So assuming we can manage a new star system at the frequency of 0.002/T² until some galactic barrier is reached, and assuming we while move out like fingers on a hand there's a pretty good chance this would happen within 1500 years, but because of the way preferential stars are distributed it might happen faster or because IS travel is harder much slower. 

Problem is that the aliens will be stone age or vastly more advanced than us. Just not at our technological level, that is as likely as they looks like us  So it would not be an interesting conflict. 


 

[PB666]

26 minutes ago, magnemoe said:

Problem is that the aliens will be stone age or vastly more advanced than us. Just not at our technological level, that is as likely as they looks like us  So it would not be an interesting conflict. 

Right, but how do we test star systems for intelligence, listen or probe? Right now our strategy is to send out 100 probes at 0.1c, if it works and you did this once a year, if aliens were doing the same the probes would pass through a pre-explored system and never see each other. The only reason there might be a encounter if a probe malfunctioned and coincidenrally sent its signal in the direction of the other space probes. In terms of listening, what if the aliens are not talking. So we are left with aliens being in a system and we don't know they are there.....we send out probes and detect them, do we try to talk to them via our probes, or do we avoid them. But there is also a chanc we don't detect them; a very rare chance encounter that will happen if we move out of this system. How do we respond tonthe obvious precense of some other sentient in contested territory. Eventually we will be those aliens, with any hope. And then we have to make the decision how do we respond to a colonization in a system we think is under our SOI or some attempt to communicate with us. 

My opinion is that we don't talk, we avoid, passive observation, they would do the same. If the are more advanced they would learn more about us than we about them. 

Edited June 20, 2016 by PB666

[kerbiloid]

A telescope needs much less (at least twice, but not limited) time than a probe to deliver results.
And any life, especially a technologically advanced one, means structure instead of chaos. Also in a planet specter,
So, you should first study how to distinct a presumably "structurized" planet specter from a natural, "chaotic" one. And should increase telescope resolutions.

Only after you will have listed the planets with strangely "structurized" specter and gotten a high-resolution photos of its continents, you would decide either send there a fireship probe, or emit there a gamma-ray radiosignal.
Because you will know more exactly, whom you can face. And because while this study lasts, your growing fleet of star destroyers can change weights of decision cases.

(Otherwise you a risking to get a antimatter bomb under a mask of embassy)

Edited June 20, 2016 by kerbiloid

[PB666]

37 minutes ago, kerbiloid said:

A telescope needs much less (at least twice, but not limited) time than a probe to deliver results.
And any life, especially a technologically advanced one, means structure instead of chaos. Also in a planet specter,
So, you should first study how to distinct a presumably "structurized" planet specter from a natural, "chaotic" one. And should increase telescope resolutions.

Only after you will have listed the planets with strangely "structurized" specter and gotten a high-resolution photos of its continents, you would decide either send there a fireship probe, or emit there a gamma-ray radiosignal.
Because you will know more exactly, whom you can face. And because while this study lasts, your growing fleet of star destroyers can change weights of decision cases.

(Otherwise you a risking to get a antimatter bomb under a mask of embassy)

Your message makes no sense. 

[magnemoe]

11 minutes ago, kerbiloid said:

A telescope needs much less (at least twice, but not limited) time than a probe to deliver results.
And any life, especially a technologically advanced one, means structure instead of chaos. Also in a planet specter,
So, you should first study how to distinct a presumably "structurized" planet specter from a natural, "chaotic" one. And should increase telescope resolutions.

Only after you will have listed the planets with strangely "structurized" specter and gotten a high-resolution photos of its continents, you would decide either send there a fireship probe, or emit there a gamma-ray radiosignal.
Because you will know more exactly, whom you can face. And because while this study lasts, your growing fleet of star destroyers can change weights of decision cases.

(Otherwise you a risking to get a antimatter bomb under a mask of embassy)

First you look for planets with life, then you look closer also after radio signals, None and no mega structures or similar and you assume no technical civilization. 
next would be to send an probe, note that an probe who brakes to enter orbit would be discovered by anybody advanced, an flyby would be harder to detect if done carefully so you do this first is paranoid, an flyby will catch an civilization but probably not an base or small colony depending on radio noise or rocket engines. 
You would want to land probes first if you want to set up an colony anyway. 

Now any alien within 1500 ly with interest in space is likely to know about Earth as in an planet with plenty of life. Probably also searched for civilization and found nothing. An flyby the last thousands years would probably show primitive civilization an earlier landing might show intelligent life however both require that they are so close they would detect us anyway soon.or we detect them if they have low interest in space. 


 
 

[kerbiloid]

3 minutes ago, magnemoe said:

None and no mega structures or similar and you assume no technical civilization. 

I don't mean megastructures themselves.
I mean: the signal itself is less chaotic, more structurized. Modulated signals, modulating frequencies, regular reflections from artificial objects, infrared anomailes, etc.

Not signals themselves, but anomal regularities in chaotic by nature things.

Sending a probe is mostly useless without exact knowledge — where to look, what to search. There are many planets around.

[wumpus]

13 hours ago, DBowman said:

Also our tech direction wrt copyright protection and the general move to encryption by default means that makes sense, an advanced civilization's  comms is likely to be indistinguishable from noise so we'd have to do traffic analysis.

Never mind encryption, efficient coding makes things indistinguishable from noise.  Typically this involves compression (either lossless or lossy) but also efficient coding means your receiver is just barely getting the signal/noise ratio needed to decode the signal and anyone (from outside that solar system) is getting uncoverable garbage.

Roughly 100 years after first creating radio, I'd expect any "off planet" signal to be roughly at the limit for Shannon coding (older probes excepted, but Voyager was one of the first to be re-programmed with (then) advanced coding).  This means that *barely* losing a few dB of signal means it is *impossible* to recover (perfectly, anyway) the signal and is likely to be completely indiscernible from background noise.  Note that such techniques are quite possible for terrestrial use: the catch is they often take a lot of computation which introduces lag.  Of course when you have the speed of light lag from Mars (or even GSO) this isn't a big deal.

Don't really expect to find radio use on a planet as anything other than a slightly higher (if that) emission of EM radiation.  And even then it will likely be uneconomical and replaced by something else.

[PB666]

Ah yes, voyager will travel for millions of years before it encounters anywhere near close to habitable space, by then it systems will be dead it will have accumulated space ice, been hit by space objects, little space-r-roids, so that would hardly matter anyway.

Aside from the natural unintelligability of the signal, see my thread on gaming aliens. Is it in any alien best interest to 'reach out and touch' some other alien species, other than the occasional 'oh explicative we just killed ourselves, here fellow aliens of the universe, don't do "[silence, followed by a blip in the LIGO experiment].

 

[DBowman]

7 hours ago, wumpus said:

Never mind encryption, efficient coding makes things indistinguishable from noise.

true, I neglected that.

Is there any way to use propellant exhaust cloud as an indicator for a tech civ? I mean any big system wide civ will be using propellant to move stuff around, so you'd expect to see 'too much/un-natural amounts of xenon' for example. Also the distribution would be un-natural; in plane (maybe natural) at velocities characteristic of an ion drive (for example, not natural). If there were planets / asteroid belts at inclinations then you'd expect to see exhaust distribution from plane changes also (very not natural).  

[magnemoe]

11 hours ago, kerbiloid said:

I don't mean megastructures themselves.
I mean: the signal itself is less chaotic, more structurized. Modulated signals, modulating frequencies, regular reflections from artificial objects, infrared anomailes, etc.

Not signals themselves, but anomal regularities in chaotic by nature things.

Sending a probe is mostly useless without exact knowledge — where to look, what to search. There are many planets around.

You know its an planet with life else you would not go, an cloud of probes on an close flyby would give way more information than an +10 ly study. 

[PB666]

41 minutes ago, magnemoe said:

You know its an planet with life else you would not go, an cloud of probes on an close flyby would give way more information than an +10 ly study. 

 

41 minutes ago, magnemoe said:

You know its an planet with life else you would not go, an cloud of probes on an close flyby would give way more information than an +10 ly study. 

There strategy is to send 1000 probes to centari-a, you don't have to be very far from something tondetect it with 1000 ships. Kerbaloid is being argumentative because he thinks direct confontation is the best way. 

[magnemoe]

11 hours ago, DBowman said:

true, I neglected that.

Is there any way to use propellant exhaust cloud as an indicator for a tech civ? I mean any big system wide civ will be using propellant to move stuff around, so you'd expect to see 'too much/un-natural amounts of xenon' for example. Also the distribution would be un-natural; in plane (maybe natural) at velocities characteristic of an ion drive (for example, not natural). If there were planets / asteroid belts at inclinations then you'd expect to see exhaust distribution from plane changes also (very not natural).  

An large rocket engine is pretty easy to detect inside the solar system as i understand, part of the no stealth in space.
Over interstellar distances it get hard, its hard to get light from exo-planets, engines produces far less energy than is reflected from an planet. 
 

[DBowman]

34 minutes ago, magnemoe said:

An large rocket engine is pretty easy to detect inside the solar system as i understand, part of the no stealth in space.
Over interstellar distances it get hard, its hard to get light from exo-planets, engines produces far less energy than is reflected from an planet. 

I wasn't thinking of an individual engine, more the whole stellar system level pollution from thousands or millions of drives running over hundreds of years - not the fires, all the old smoke.  For example if some extraterrestrial had spectroscopically detected chlorofluorocarbons in Earth's atmosphere ( via the absorption spectrum of an observed transit say ) in the 1970s then they'd probably conclude Earth had a tech civilisation (because the gas is un-natural and would need to be constantly renewed to have that level in the atmosphere).

Whatever waste gas the exo-civ produces could lie between us and it's star (depending on inclination etc) and so should leave some (low signal for sure) artefacts in the stellar spectrum, similarly it's likely the stars radiation would cause the gas to make some emission spectrum artefact as well.

I've not even tried to quantify any effect you'd expect but that's the idea in principal.

Edited June 21, 2016 by DBowman
spelling

[PB666]

1 hour ago, DBowman said:

I wasn't thinking of an individual engine, more the whole stellar system level pollution from thousands or millions of drives running over hundreds of years - not the fires, all the old smoke.  For example if some extraterrestrial had spectroscopically detected chlorofluorocarbons in Earth's atmosphere ( via the absorption spectrum of an observed transit say ) in the 1970s then they'd probably conclude Earth had a tech civilisation (because the gas is un-natural and would need to be constantly renewed to have that level in the atmosphere).

Whatever waste gas the exo-civ produces could lie between us and it's star (depending on inclination etc) and so should leave some (low signal for sure) artefacts in the stellar spectrum, similarly it's likely the stars radiation would cause the gas to make some emission spectrum artefact as well.

I've not even tried to quantify any effect you'd expect but that's the idea in principal.

 The flux of solar wind and photon pressure would drive it to the dark edge of the system. 

Edited June 21, 2016 by PB666