Can there be old radio waves broadcasted years ago still traveling in the air?
$begingroup$
I was studying this radio receiver circuit
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
asked Feb 15 at 18:36
user3407319user3407319
1277
$endgroup$
add a comment |
$begingroup$
I was studying this radio receiver circuit
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
asked Feb 15 at 18:36
user3407319user3407319
1277
$endgroup$
add a comment |
$begingroup$
I was studying this radio receiver circuit
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
asked Feb 15 at 18:36
user3407319user3407319
1277
$endgroup$
I was studying this radio receiver circuit
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
asked Feb 15 at 18:36
user3407319user3407319
1277
asked Feb 15 at 18:36
user3407319user3407319
1277
asked Feb 15 at 18:36
user3407319user3407319
1277
asked Feb 15 at 18:36
user3407319user3407319
1277
asked Feb 15 at 18:36
user3407319user3407319
1277
1277
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
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.
answered Feb 15 at 19:15
my2ctsmy2cts
5,8742719
$endgroup$
$begingroup$
Why do they dissipate in the air?
$endgroup$
– user3407319
Feb 15 at 19:22
$begingroup$
And if they do so, how do they reach the receiver circuit anyways?
$endgroup$
– user3407319
Feb 15 at 19:23
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
Feb 15 at 20:06
add a comment |
$begingroup$
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.
answered Feb 15 at 20:38
niels nielsenniels nielsen
21.6k53062
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add a comment |
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2 Answers
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active
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2 Answers
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active
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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.
answered Feb 15 at 19:15
my2ctsmy2cts
5,8742719
$endgroup$
$begingroup$
Why do they dissipate in the air?
$endgroup$
– user3407319
Feb 15 at 19:22
$begingroup$
And if they do so, how do they reach the receiver circuit anyways?
$endgroup$
– user3407319
Feb 15 at 19:23
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
Feb 15 at 20:06
add a comment |
$begingroup$
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.
answered Feb 15 at 19:15
my2ctsmy2cts
5,8742719
$endgroup$
$begingroup$
Why do they dissipate in the air?
$endgroup$
– user3407319
Feb 15 at 19:22
$begingroup$
And if they do so, how do they reach the receiver circuit anyways?
$endgroup$
– user3407319
Feb 15 at 19:23
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
Feb 15 at 20:06
add a comment |
$begingroup$
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.
answered Feb 15 at 19:15
my2ctsmy2cts
5,8742719
$endgroup$
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.
answered Feb 15 at 19:15
my2ctsmy2cts
5,8742719
answered Feb 15 at 19:15
my2ctsmy2cts
5,8742719
answered Feb 15 at 19:15
my2ctsmy2cts
5,8742719
answered Feb 15 at 19:15
my2ctsmy2cts
5,8742719
5,8742719
$begingroup$
Why do they dissipate in the air?
$endgroup$
– user3407319
Feb 15 at 19:22
$begingroup$
And if they do so, how do they reach the receiver circuit anyways?
$endgroup$
– user3407319
Feb 15 at 19:23
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
Feb 15 at 20:06
add a comment |
$begingroup$
Why do they dissipate in the air?
$endgroup$
– user3407319
Feb 15 at 19:22
$begingroup$
And if they do so, how do they reach the receiver circuit anyways?
$endgroup$
– user3407319
Feb 15 at 19:23
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
Feb 15 at 20:06
$begingroup$
Why do they dissipate in the air?
$endgroup$
– user3407319
Feb 15 at 19:22
$begingroup$
Why do they dissipate in the air?
$endgroup$
– user3407319
Feb 15 at 19:22
$begingroup$
And if they do so, how do they reach the receiver circuit anyways?
$endgroup$
– user3407319
Feb 15 at 19:23
$begingroup$
And if they do so, how do they reach the receiver circuit anyways?
$endgroup$
– user3407319
Feb 15 at 19:23
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
Feb 15 at 20:06
$begingroup$
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
Feb 15 at 20:06
add a comment |
$begingroup$
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.
answered Feb 15 at 20:38
niels nielsenniels nielsen
21.6k53062
$endgroup$
add a comment |
$begingroup$
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.
answered Feb 15 at 20:38
niels nielsenniels nielsen
21.6k53062
$endgroup$
add a comment |
$begingroup$
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.
answered Feb 15 at 20:38
niels nielsenniels nielsen
21.6k53062
$endgroup$
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.
answered Feb 15 at 20:38
niels nielsenniels nielsen
21.6k53062
answered Feb 15 at 20:38
niels nielsenniels nielsen
21.6k53062
answered Feb 15 at 20:38
niels nielsenniels nielsen
21.6k53062
answered Feb 15 at 20:38
niels nielsenniels nielsen
21.6k53062
21.6k53062
add a comment |
add a comment |
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