On 31-3-2010 4:40, Nicolas Alvarez wrote:
> andrel wrote:
>> On 30-3-2010 18:11, Darren New wrote:
>>> andrel wrote:
>>>>> How about the fact that the stars of the universe are all red-shifted
>>>>> the farther they get from *us*?  Or the fact that we seem to be the
>>>>> only creatures in the entire *universe* that broadcast radio signals?
>>>> For the latter see the Drake equation.
>>> I'm familiar with it. What about it?
>> All we know that there are no radio signals broadcasted from a place
>> exactly the right time ago to be just reaching us now, send towards us,
>> and in a format that we recognize. Which is quite a long way away from a
>> conclusion that no signals are send at all.
> 
> I keep wondering... Is humanity *constantly* broadcasting radio signals in a 
> simple format to nearby solar systems? What if aliens have a program exactly 
> like SETI@Home, trying to find intelligence in noise from received radio 
> signals, but neither party is sending anything?

The major things we have been sending is FM (and AM) modulated radio and 
TV. This is effectively a big signal in a very small bandwidth. If you 
make a spectrum it will turn up as an unexpected peak above the 
background. If you then become interested and look closer you will see 
that the spectral contend is not compatible with a line originating from 
an exited atom or molecule. So, if these aliens are at the right time 
and place and have a SETI project running they will detect us in a 
couple of centuries when the signal reaches them.
If they are listening but expect a different modulation scheme they 
might just skip the lucille ball show as a strange artifact.

ATM AFAIK nobody is sending a deliberately simple encoded message. I 
think the jury is not out on the question if that would be a good idea 
at all.

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