Harte wrote: Anaxagoras wrote: Harte wrote:
A guy on ATS just forced me to do the calculation. A 20 gigawatt signal one light year away would reach us with the undetectable power of around 20X10^-22 watts.
IOW, no way Jose.
Try it yourself: link
Don't forget to:
1) convert light years to meters,
2) square the distance
Plus, wouldn't stuff like the nearby star also mask this signal with lots of electromagnetic noise?
Absolutely. But it could be handled by using frequencies that can stand out from the nearby star.
Everyone should stop and think about a signal strength of 20 GW. The highest powered signal we use to my knowledge is with certain high power radars which are
directed but have a power density of one to five gigawatts.
Anaxagoras wrote:I forget, but isn't SETI looking for aliens that might be intentionally sending us a message? It might be hard to pick up their signals if they aren't pointing them right at us, right? Because, why do that anyway? Yeah, perhaps we've done it once or twice ourselves, but we're weird.
I guess they do it because there isn't anything else we can do at the present time and (apparently) we don't want to just sit around wondering and not trying in some way to find out.
This negative screed got me thinking. Back in pre-cambrian days, when I was in grad school, we used a thing called a Computer of Average Transients".
Idea was that if a signal was lost in noise and was repeatable and could be synced, all you had to do was create intervals within which the power of the signal was averaged.
So, if you were using scalp electordes to measure an evoked visual potential, the eeg on each trial was random, noise. But the evoked response was not, it was the same each time. When you average random you get a constant, when you average the signal you get
seems to me that the same sort of thing might apply with signals from ... space