h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Why haven't we heard anything? You present a few possibilities. But the other side may be playing with a different set of (Physics) rules. As I wrote in my comments, the other day, under 'UFOs -What Conspiracy', the foreign objects that are entering our atmosphere and air space seem to be operating under different rules. They hover; they reverse; they make 90 degree turns; they accelerate and seem to disappear immediately. Could it be that they are operating on 'digital' while we are still operating on 'analog'? We are trying to send linear signals while they may have found dimensional doorways through the time-space continuum. There can be no doubt that something foreign has entered our planet's space. There is no definitive proof that these objects, while definitely controlled, are occupied by 'beings'. Maybe, to make contact, we should look in a different direction - either very close, or with different technologies.

Surely an advanced a civilisation as you propose would suddenly not stop monitoring the 'analog' frequencies just because they had gone 'digital'?

And if they wanted to send messages to other lifeforms surely they'd have the common sense to realise that other lifeforms may have not done the cosmic equivalent of junking their walkmans for MP3 players and send the message in as many ways as they could (including the electro-magnetic spectrum)?

Why havent we heard anything?
Well possibly because the nearest life forms able to reply are 4 light years away (since that is our nearest stelar neighbour) and have either passed through our current stage of developement, have not reached it yet, or, and this is always possible, do not exist.
If a species has progressed to the ability to be able to traverse interstellar distances it must either have developed communications technology which travels at the same speed or faster than its spacecraft or it must send all messages by probe or drone. The remaining possibility is to return with the message at the end of the mission after being incommunicado for the trip.
Any one of these options means that Seti is listening on the wrong frequencies, with the wrong equipment and in a random hope of picking up their equivalent of the Jimmy Young Show or Neighbours.
Now I don't say that this will not happen but think about this, if we assume that the alien technology advances at roughly the same rate as our own we need to catch them in the 100 year window when they were starting to transmit in the RF frequencies and that these have to be the same as the ones we use. If a species sees in the infra red and hears in the hypersonic what would they transmit that we would even consider to be a communication signal? Why send a lightspeed signal if it's faster to go and have a look? There is no reason whatsoever to assume that a species capable of Faster Than Light (FTL) travel is remotely interested in those that are not. We would be but we are insatiably curious but we must not ascribe our values to another species, "man assumes that because he has invented digital watches, and all that the dolphins have done is muck around in the sea enjoying themselves, that man is the more advanced species. Strangely enough the dolphins consider themselves more advanced for precisely the same reasons." Nuff Said.
Anything Seti recieves will be too late to communicate with but we still need to listen to give us a clue where to go.
Dragonsinger