[enraged_camel]

I've never understood such assumptions of intelligence. "If a civilization could do X, they could also do Y and Z." Says who? It's not like we're experts in alien intelligence. How can we be, when we have never encountered one?

[lutusp]

All true, but applying common sense still has a point. For example, do we want to broadcast the fact of our own existence across interstellar distances? This is actually an active debate topic among those who think about stuff like this.

Ironically, after a brief spell of broadcasting our existence with powerful radio and radar waves, we're gradually shutting down the big transmitters for reasons of economy and efficiency. Satellites allow us to accomplish the same end with much less power than the old high-powered transmitters, and GPS-guided aircraft makes more sense that long-range radars for all but military purposes.

There are those who argue that we should transmit the basic facts of our existence with high-powered radio transmitters and lasers, and await a reply. Others argue that we shouldn't. Both arguments have merit.

[kamaal]

>>do we want to broadcast the fact of our own existence across interstellar distances?

We are already doing it(http://en.wikipedia.org/wiki/Arecibo_message). We are also sent a probe with heck lot of details on it(http://en.wikipedia.org/wiki/Voyager_Golden_Record).

>>This is actually an active debate topic among those who think about stuff like this.

True, but we have always been sending radio signals in space and probably will continue to.

[lutusp]

> We are already doing it ...

Yes, absolutely. It is said that, because of radar, we're the brightest object within several light-years in those wavelengths. Add to that the periodic nature of radar, and we're signaling with an obviously unnatural beacon for anyone willing to listen.

I'm just saying the debate goes on, even though we're providing quite a beacon for anyone interested in detecting signs of semi-intelligent life. :)

> True, but we have always been sending radio signals in space and probably will continue to.

I wouldn't say "always". The first reasonably strong, narrow-band radio signals commenced in the 1920s. Not even 100 years. And we're quickly reducing our EM radiation footprint for economic reasons unrelated to anything resembling policy.

I see the point of both arguments -- that we should, and shouldn't, broadcast our existence. I actually prefer the "should" argument overall, considering the difficulty that an alien species would have getting here. We might learn something remarkable from a safe remove.