Can there be old radio waves broadcasted years ago still traveling in the air?












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$begingroup$


I was studying this radio receiver circuit
enter image description here
Then I read that radio waves broadcasted by radio stations will keep traveling in the air forever unless absorbed by something and that radio waves can penetrate most things. I wonder that if, some radio waves broadcasted some years ago are not absorbed by anything till now, can they still be traveling in the air now and like, be picked up by this radio circuit and we hear old broadcasted waves now?






waves electromagnetic-radiation







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$endgroup$

















    1












    $begingroup$


    I was studying this radio receiver circuit
    enter image description here
    Then I read that radio waves broadcasted by radio stations will keep traveling in the air forever unless absorbed by something and that radio waves can penetrate most things. I wonder that if, some radio waves broadcasted some years ago are not absorbed by anything till now, can they still be traveling in the air now and like, be picked up by this radio circuit and we hear old broadcasted waves now?






    waves electromagnetic-radiation







    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      I was studying this radio receiver circuit
      enter image description here
      Then I read that radio waves broadcasted by radio stations will keep traveling in the air forever unless absorbed by something and that radio waves can penetrate most things. I wonder that if, some radio waves broadcasted some years ago are not absorbed by anything till now, can they still be traveling in the air now and like, be picked up by this radio circuit and we hear old broadcasted waves now?






      waves electromagnetic-radiation







      share|cite|improve this question









      $endgroup$




      I was studying this radio receiver circuit
      enter image description here
      Then I read that radio waves broadcasted by radio stations will keep traveling in the air forever unless absorbed by something and that radio waves can penetrate most things. I wonder that if, some radio waves broadcasted some years ago are not absorbed by anything till now, can they still be traveling in the air now and like, be picked up by this radio circuit and we hear old broadcasted waves now?






      waves electromagnetic-radiation




      waves electromagnetic-radiation






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      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked 6 hours ago









      user3407319user3407319

      1157




      1157






















          2 Answers
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          $begingroup$

          In air radiowaves will eventually dissipate. The waves that escaped into space however are still speeding away from us, for ever. Much like the sunlight from the day the the dinosaurs were wiped out by an asteroid.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Why do they dissipate in the air?
            $endgroup$
            – user3407319
            5 hours ago










          • $begingroup$
            And if they do so, how do they reach the receiver circuit anyways?
            $endgroup$
            – user3407319
            5 hours ago






          • 1




            $begingroup$
            Just like you dissipate energy when walking in loose sand, radiowaves lose energy to the molecules in air. They also lose their coherence. So after seconds a radiowave is completely dissipated. However that is enough to be able to reach a receiver.
            $endgroup$
            – my2cts
            5 hours ago





















          3












          $begingroup$

          the radio waves that this particular radio was designed to receive are prevented from escaping into space by the ionosphere, and hence bounce around between the earth and the underside of the ionosphere. Each bounce dissipates some of the energy of the radio wave, to the extent that after the 3rd or 4th bounce, the radio wave's strength is less than that of the background noise at that frequency and the signal disappears into the noise. This is true even for extremely powerful transmitted signals.



          This means you cannot today pick up old radio broadcasts from the past.






          share|cite|improve this answer









          $endgroup$













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            2 Answers
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            2 Answers
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            active

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            active

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            active

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            2












            $begingroup$

            In air radiowaves will eventually dissipate. The waves that escaped into space however are still speeding away from us, for ever. Much like the sunlight from the day the the dinosaurs were wiped out by an asteroid.






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              Why do they dissipate in the air?
              $endgroup$
              – user3407319
              5 hours ago










            • $begingroup$
              And if they do so, how do they reach the receiver circuit anyways?
              $endgroup$
              – user3407319
              5 hours ago






            • 1




              $begingroup$
              Just like you dissipate energy when walking in loose sand, radiowaves lose energy to the molecules in air. They also lose their coherence. So after seconds a radiowave is completely dissipated. However that is enough to be able to reach a receiver.
              $endgroup$
              – my2cts
              5 hours ago


















            2












            $begingroup$

            In air radiowaves will eventually dissipate. The waves that escaped into space however are still speeding away from us, for ever. Much like the sunlight from the day the the dinosaurs were wiped out by an asteroid.






            share|cite|improve this answer









            $endgroup$













            • $begingroup$
              Why do they dissipate in the air?
              $endgroup$
              – user3407319
              5 hours ago










            • $begingroup$
              And if they do so, how do they reach the receiver circuit anyways?
              $endgroup$
              – user3407319
              5 hours ago






            • 1




              $begingroup$
              Just like you dissipate energy when walking in loose sand, radiowaves lose energy to the molecules in air. They also lose their coherence. So after seconds a radiowave is completely dissipated. However that is enough to be able to reach a receiver.
              $endgroup$
              – my2cts
              5 hours ago
















            2












            2








            2





            $begingroup$

            In air radiowaves will eventually dissipate. The waves that escaped into space however are still speeding away from us, for ever. Much like the sunlight from the day the the dinosaurs were wiped out by an asteroid.






            share|cite|improve this answer









            $endgroup$



            In air radiowaves will eventually dissipate. The waves that escaped into space however are still speeding away from us, for ever. Much like the sunlight from the day the the dinosaurs were wiped out by an asteroid.







            share|cite|improve this answer












            share|cite|improve this answer



            share|cite|improve this answer










            answered 5 hours ago









            my2ctsmy2cts

            5,3472618




            5,3472618












            • $begingroup$
              Why do they dissipate in the air?
              $endgroup$
              – user3407319
              5 hours ago










            • $begingroup$
              And if they do so, how do they reach the receiver circuit anyways?
              $endgroup$
              – user3407319
              5 hours ago






            • 1




              $begingroup$
              Just like you dissipate energy when walking in loose sand, radiowaves lose energy to the molecules in air. They also lose their coherence. So after seconds a radiowave is completely dissipated. However that is enough to be able to reach a receiver.
              $endgroup$
              – my2cts
              5 hours ago




















            • $begingroup$
              Why do they dissipate in the air?
              $endgroup$
              – user3407319
              5 hours ago










            • $begingroup$
              And if they do so, how do they reach the receiver circuit anyways?
              $endgroup$
              – user3407319
              5 hours ago






            • 1




              $begingroup$
              Just like you dissipate energy when walking in loose sand, radiowaves lose energy to the molecules in air. They also lose their coherence. So after seconds a radiowave is completely dissipated. However that is enough to be able to reach a receiver.
              $endgroup$
              – my2cts
              5 hours ago


















            $begingroup$
            Why do they dissipate in the air?
            $endgroup$
            – user3407319
            5 hours ago




            $begingroup$
            Why do they dissipate in the air?
            $endgroup$
            – user3407319
            5 hours ago












            $begingroup$
            And if they do so, how do they reach the receiver circuit anyways?
            $endgroup$
            – user3407319
            5 hours ago




            $begingroup$
            And if they do so, how do they reach the receiver circuit anyways?
            $endgroup$
            – user3407319
            5 hours ago




            1




            1




            $begingroup$
            Just like you dissipate energy when walking in loose sand, radiowaves lose energy to the molecules in air. They also lose their coherence. So after seconds a radiowave is completely dissipated. However that is enough to be able to reach a receiver.
            $endgroup$
            – my2cts
            5 hours ago






            $begingroup$
            Just like you dissipate energy when walking in loose sand, radiowaves lose energy to the molecules in air. They also lose their coherence. So after seconds a radiowave is completely dissipated. However that is enough to be able to reach a receiver.
            $endgroup$
            – my2cts
            5 hours ago













            3












            $begingroup$

            the radio waves that this particular radio was designed to receive are prevented from escaping into space by the ionosphere, and hence bounce around between the earth and the underside of the ionosphere. Each bounce dissipates some of the energy of the radio wave, to the extent that after the 3rd or 4th bounce, the radio wave's strength is less than that of the background noise at that frequency and the signal disappears into the noise. This is true even for extremely powerful transmitted signals.



            This means you cannot today pick up old radio broadcasts from the past.






            share|cite|improve this answer









            $endgroup$


















              3












              $begingroup$

              the radio waves that this particular radio was designed to receive are prevented from escaping into space by the ionosphere, and hence bounce around between the earth and the underside of the ionosphere. Each bounce dissipates some of the energy of the radio wave, to the extent that after the 3rd or 4th bounce, the radio wave's strength is less than that of the background noise at that frequency and the signal disappears into the noise. This is true even for extremely powerful transmitted signals.



              This means you cannot today pick up old radio broadcasts from the past.






              share|cite|improve this answer









              $endgroup$
















                3












                3








                3





                $begingroup$

                the radio waves that this particular radio was designed to receive are prevented from escaping into space by the ionosphere, and hence bounce around between the earth and the underside of the ionosphere. Each bounce dissipates some of the energy of the radio wave, to the extent that after the 3rd or 4th bounce, the radio wave's strength is less than that of the background noise at that frequency and the signal disappears into the noise. This is true even for extremely powerful transmitted signals.



                This means you cannot today pick up old radio broadcasts from the past.






                share|cite|improve this answer









                $endgroup$



                the radio waves that this particular radio was designed to receive are prevented from escaping into space by the ionosphere, and hence bounce around between the earth and the underside of the ionosphere. Each bounce dissipates some of the energy of the radio wave, to the extent that after the 3rd or 4th bounce, the radio wave's strength is less than that of the background noise at that frequency and the signal disappears into the noise. This is true even for extremely powerful transmitted signals.



                This means you cannot today pick up old radio broadcasts from the past.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered 4 hours ago









                niels nielsenniels nielsen

                19.1k52959




                19.1k52959






























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