I think that Radio signals are irrelevant, because alien civilisations did detect us back in 6000 years ago when we started agriculture and destroyed forests to the crops in larger scale due to urbanisation. Perhaps cities are directly visible from space?
Thus Alien's do not need radio frequencies for spotting a civilisations, but they can do it with normal optical wave lengths. We could already spot ourself nearby civilisations directly if we had build permanent colony to the moon 30 years ago as was planed. When industrial revolution happened, also the chemical composition of atmosphere started to change into artificial, so this signature would also be easy to detect some 200 lightyears away from here, even for primitive Earth like civilisations, who has better sense for investing science and space exploration. I think that we could differentiate continent sized details, and of course we could detect traces of artificial chemical components from atmosphere. ―Jouni Sent from my iPad On 21 Feb 2012, at 17:55, David Roberson <[email protected]> wrote: > Radio transmissions might be an ancient form of communications to an advanced > civilization. It could be like us talking to each other with smoke signals. > > At this point it can only be speculation as to what future technology will be > invented. Before radio, all we had was wire lines. Who predicted modern > digital communications over vast distances 100 years ago? I am not more > capable of this than the next guy but I leave the probability open for future > advances since I have seen many during my lifetime. > > Dave > > > -----Original Message----- > From: fznidarsic <[email protected]> > To: vortex-l <[email protected]> > Sent: Tue, Feb 21, 2012 10:18 am > Subject: Re: [Vo]:100 years 1912 beep beep beep and aliens > > I don't know, but the first beeping signals have now reached 12,500 stars. > The fact of the matter is any civilizations out there able to receive our > signal should have been transmitting at least 100 years ago and we should > already have detected them. It appears that we are unique. Many are > predicting we will not be around to receive any answer. > > > http://www.physorg.com/news196489543.html > > > Frank Znidarsic > > > So besides SETI attempts, what would be our best chance to detect ET life? > At least, i think they should emit low amounts of infrared (You've got to > stay warm in winter, right), some kind of heat signature, but to see > something you must be inside their cone, what do you think ? > > > > Dont know.
