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In reply to the discussion: Astronomers discover three habitable planets just 40 light years away [View all]IDemo
(16,926 posts)25. Outside a relatively small distance from us, They don't love Lucy
While its interesting to imagine how far our radio signals have traveled into space, its extremely unlikely that an alien civilization will be able to catch the latest episode of I Love Lucy. This is thanks to the inverse square law. In Laymans term, its a form of signal degradation.
As radio signals leave earth, they propagate out in a wave form. Just like dropping a stone in a lake, the waves diffuse or spread out over distance thanks to the exponentially larger area they must encompass. The area can be calculated by multiplying length times width which is why we measure it in square units square centimeters, square miles, etc. This means that the further away from the source, the more square units of area a signal has to illuminate.
Another way to think of it, is that the strength of a radio signal will be only 1/4 as great once you are twice the distance from the source. At ten times the distance, the strength of the signal would only be one hundredth as great.
Because of this inverse square law, all of our terrestrial radio signals become indistinguishable from background noise at around a few light-years from earth. For a civilization only a couple hundred light-years away, trying to listen to our broadcasts would be like trying to detect the small ripple from a pebble dropped in the pacific ocean off the coast of California from Japan.
http://zidbits.com/2011/07/how-far-have-radio-signals-traveled-from-earth/
As radio signals leave earth, they propagate out in a wave form. Just like dropping a stone in a lake, the waves diffuse or spread out over distance thanks to the exponentially larger area they must encompass. The area can be calculated by multiplying length times width which is why we measure it in square units square centimeters, square miles, etc. This means that the further away from the source, the more square units of area a signal has to illuminate.
Another way to think of it, is that the strength of a radio signal will be only 1/4 as great once you are twice the distance from the source. At ten times the distance, the strength of the signal would only be one hundredth as great.
Because of this inverse square law, all of our terrestrial radio signals become indistinguishable from background noise at around a few light-years from earth. For a civilization only a couple hundred light-years away, trying to listen to our broadcasts would be like trying to detect the small ripple from a pebble dropped in the pacific ocean off the coast of California from Japan.
http://zidbits.com/2011/07/how-far-have-radio-signals-traveled-from-earth/
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When you're talking cosmic proportions, 40 lys is just over yonder ---->
ChisolmTrailDem
May 2016
#8
We don't need there to be an "advanced civilization" there...hell we don't have that here! Anyway..
ChisolmTrailDem
May 2016
#9
This has the potential to be exponentially more exciting that it already is. If even simple life...
ChisolmTrailDem
May 2016
#11
You can detect an extrasolar transit with almost any telescope, the article is wrong on that
Fumesucker
May 2016
#21