DaveM
Paranormal Adept
Chris O'Brien mentioned on the Paracast + that he wondered how far radio signals have traveled since their inception here on Earth. I searched around and the information is sketchy at best. Here is one quote I found on the Reddit website:
Radio waves are just another form of electromagnetic wave like visible light, and so they move at the speed of light, and will have traveled 103 light years since 1910.
However...
Radio waves lose power the further you get from the source. Anyone who's been on a long road trip and had to change radio stations can attest to this. Specifically, they follow an inverse-square law: doubling your distance from the source means that the radio waves will be 4 times less powerful, tripling your distance means the waves will be 9 times less powerful, etc. Because of this, even at the nearest star to us, our radio transmissions would be indistinguishable from background noise. So the idea that alien civilizations could someday pick up our radio and TV broadcasts is, unfortunately (or fortunately, depending on your views), impossible.
If Every transmission, radio signal etc... leaves Earth, How far has earth's broadcasts reached since the first? : askscience
Radio waves are just another form of electromagnetic wave like visible light, and so they move at the speed of light, and will have traveled 103 light years since 1910.
However...
Radio waves lose power the further you get from the source. Anyone who's been on a long road trip and had to change radio stations can attest to this. Specifically, they follow an inverse-square law: doubling your distance from the source means that the radio waves will be 4 times less powerful, tripling your distance means the waves will be 9 times less powerful, etc. Because of this, even at the nearest star to us, our radio transmissions would be indistinguishable from background noise. So the idea that alien civilizations could someday pick up our radio and TV broadcasts is, unfortunately (or fortunately, depending on your views), impossible.
If Every transmission, radio signal etc... leaves Earth, How far has earth's broadcasts reached since the first? : askscience