HomeLatest ThreadsGreatest ThreadsForums & GroupsMy SubscriptionsMy Posts
DU Home » Latest Threads » Forums & Groups » Main » General Discussion (Forum) » Astronomers discover thre... » Reply #25

Response to G_j (Original post)

Mon May 2, 2016, 08:32 PM

25. Outside a relatively small distance from us, They don't love Lucy

While it’s interesting to imagine how far our radio signals have traveled into space, it’s 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 Layman’s term, it’s 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.


Reply to this post

Back to OP Alert abuse Link to post in-thread

Always highlight: 10 newest replies | Replies posted after I mark a forum
Replies to this discussion thread
Arrow 35 replies Author Time Post
G_j May 2016 OP
Egnever May 2016 #1
cherokeeprogressive May 2016 #2
tk2kewl May 2016 #14
ChisolmTrailDem May 2016 #8
Egnever May 2016 #12
KelleyKramer May 2016 #18
Stuckinthebush May 2016 #32
felix_numinous May 2016 #3
ProfessorGAC May 2016 #4
lagomorph777 May 2016 #6
ProfessorGAC May 2016 #15
felix_numinous May 2016 #7
ChisolmTrailDem May 2016 #9
ProfessorGAC May 2016 #16
JesterCS May 2016 #28
Ichingcarpenter May 2016 #34
meow2u3 May 2016 #24
longship May 2016 #27
malaise May 2016 #5
felix_numinous May 2016 #10
ChisolmTrailDem May 2016 #11
HuckleB May 2016 #13
captainarizona May 2016 #17
pinboy3niner May 2016 #19
ladyVet May 2016 #20
Pakhet May 2016 #22
Fumesucker May 2016 #21
aggiesal May 2016 #23
LineReply Outside a relatively small distance from us, They don't love Lucy
IDemo May 2016 #25
G_j May 2016 #30
MisterP May 2016 #31
Oneironaut May 2016 #26
Lint Head May 2016 #29
wildbilln864 May 2016 #33
glinda May 2016 #35
Please login to view edit histories.