Are we transmitting?

[Ralph]

I've been waiting for this category to turn up!

I've got the SETI@home screensaver on this PC which, as you probably know, scans through background noise looking for alien transmissions. Also, things like the movie 'Contact' seem to suggest that intelligent life would transmit on a unique frequency such as "hydrogen times pi" so we would see it for the message it is.

All well and good, but are WE routinely transmitting signals for them to pick up or are we the universal equivalent of a voyeur, sitting back letting someone else do all the work?

[booksworth]

Even if there isn't any intentional transmission, I should think that the combined output of the world's broadcasters must be pretty obvious all over the universe.

[bernardo]

Yes they are doing.

[JohnPPotts]

I don't believe we are deliberately sending anything, partly because the returns are so unlikely to be seen on any reasonable timescale (bear in mind any signal will take over 4 years just to reach our nearest star - Proxima Centauri - which doesn't have any planets we can see) so it's unlikely that we could meaningfully communicate. Of course, we are "accidentally" beaming out into space all our TV and radio transmissions, but given how hard it is (in some areas) to receive them even in areas they are attempting to reach, it is doubtful it would be anything other than very faint background noise to ET

[CharlieP1973]

But don't forget, booksworth, that our broadcasts will have travelled less than a hundred light years from Earth - a pinprick in the vastness of the universe!

[Closer]

4 years for broadcast signals to get to the nearest star ? If any one is out there, they'll be a bit behind on their EastEnders

[Calvesy]

No doubt if another intelligence were to invent TV, radar, satellites and mobile phones they would face similar engineering problems to us and would probably end up using the same frequencies for these purposes. There is no economic or survival advantage in deliberately informing galactic civilisations of our vulnerability (Species 2, Von Neumann's paranoid galaxy theory), but leakage of our signals may be detectable if they are louder than the background noise from space.

[Diablod666]

well i pretty much agree with all the answers, but one line in the question is quite stupid really. i think you have been watching too many movies ralph! lol i dont know where you got "hydrogen times pi" from, but hydrogen is a chemical and pi is an infinite number. you cant times hydrogen by pi! lol its like saying "what is the square route of a chair?"! lol

and you certainly wouldnt get a frequency if there was some way you could times it by pi.

[Diablod666]

Ralph, you have just been outsmarted by a cocky 14 year old ;)

[Dagman]

Careful Diablod666, Ralph is perhaps referring to a term used in the film Contact, not something he dreamt up!

I have heard that there are deliberate broadcasts into space's densest areas but don't know in what context or who funds it!  

[Ralph]

Dagman, you are right about the 'Contact' reference and you have also renewed my intrigue with the subject after saying that there may be targeted broadcasts by forces unknown. Hmmmm. Now I'd like a Conspiracy or Government Secrets category!