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Are Photons Noisy?


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#1 hazelm

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Posted 15 June 2017 - 07:34 AM

If I read right,  the Cosmic Microwave Background is the spot on the spectrum where photons peak at expending their energy which enhances our visibility.  So far, so good?  However, the interference that  Arno Penzias and Robert Wilson got was noise.  This noise was later identified as the CMB.  So, are those photons dancing to a noisy band?  Or, seriously, from where does the noise come?  Can the movement of photons make sound?  Can there even be sound in space?



#2 Super Polymath

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Posted 15 June 2017 - 07:52 AM

There was no oxygen back then to produce sound.

What you're talking about is the static from the electronic equipment they were using to decipher signals from the Holmdel Horn Antenna.

#3 billvon

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Posted 15 June 2017 - 08:27 AM

If I read right,  the Cosmic Microwave Background is the spot on the spectrum where photons peak at expending their energy which enhances our visibility.  So far, so good?  However, the interference that  Arno Penzias and Robert Wilson got was noise.  This noise was later identified as the CMB.  So, are those photons dancing to a noisy band?  Or, seriously, from where does the noise come?  Can the movement of photons make sound?  Can there even be sound in space?

When the term "noise" is used in EM radiation, it refers to a non-pure spectral signal; there is a fundamental with a lot of other frequencies around it.  For the CMBR it peaks at about 160GHz, but extends far to either side of that; in physics terms it is a noisy signal.  If you pointed an antenna at it and downshifted it to audio frequencies it would sound like white noise with an emphasis on whatever frequency represents 160GHz.

What you're talking about is the static from the electronic equipment they were using to decipher signals from the Holmdel Horn Antenna.

 

It has nothing to do with the noise in the receiving equipment.



#4 hazelm

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Posted 15 June 2017 - 08:57 AM

Thank you, Billvon.  "When the term "noise" is used in EM radiation, it refers to a non-pure spectral signal; there is a fundamental with a lot of other frequencies around it.  For the CMBR it peaks at about 160GHz, but extends far to either side of that; in physics terms it is a noisy signal.  If you pointed an antenna at it and downshifted it to audio frequencies it would sound like white noise with an emphasis on whatever frequency represents 160GHz."

 

Are you saying that sounds coming in at different frequencies interfere with each other, creating what we call noise?  I am reminded of the old radios but best not go there.  Different frequencies at different speeds creating interference (noise) I think I see.  For sound, we need particles bouncing off something.  Does that mean mass?  Photons have mass but coming out at different frequencies creates the noise?  Much like the instrumentalists of a band each practicing his own parts without playing together?  Does this mean the spectrum has more than light waves; it also has sound waves?

 

I hope I am not getting confusing.



#5 Super Polymath

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Posted 15 June 2017 - 09:16 AM

When the term "noise" is used in EM radiation, it refers to a non-pure spectral signal; there is a fundamental with a lot of other frequencies around it.  For the CMBR it peaks at about 160GHz, but extends far to either side of that; in physics terms it is a noisy signal.  If you pointed an antenna at it and downshifted it to audio frequencies it would sound like white noise with an emphasis on whatever frequency represents 160GHz.

It has nothing to do with the noise in the receiving equipment.

You just explained how it does, dude.

#6 Super Polymath

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Posted 15 June 2017 - 09:22 AM

Thank you, Billvon. "When the term "noise" is used in EM radiation, it refers to a non-pure spectral signal; there is a fundamental with a lot of other frequencies around it. For the CMBR it peaks at about 160GHz, but extends far to either side of that; in physics terms it is a noisy signal. If you pointed an antenna at it and downshifted it to audio frequencies it would sound like white noise with an emphasis on whatever frequency represents 160GHz."

Are you saying that sounds coming in at different frequencies interfere with each other, creating what we call noise? I am reminded of the old radios but best not go there. Different frequencies at different speeds creating interference (noise) I think I see. For sound, we need particles bouncing off something. Does that mean mass? Photons have mass but coming out at different frequencies creates the noise? Much like the instrumentalists of a band each practicing his own parts without playing together? Does this mean the spectrum has more than light waves; it also has sound waves?

I hope I am not getting confusing.


Think about it like the earth equipment translating spectral analyses into frequencies. The radiation itself makes no noise, space is soundless.

Edited by Super Polymath, 15 June 2017 - 09:25 AM.


#7 billvon

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Posted 15 June 2017 - 10:51 AM

 

Are you saying that sounds coming in at different frequencies interfere with each other, creating what we call noise?  I am reminded of the old radios but best not go there.  Different frequencies at different speeds creating interference (noise) I think I see.  For sound, we need particles bouncing off something.  Does that mean mass?  Photons have mass but coming out at different frequencies creates the noise?  Much like the instrumentalists of a band each practicing his own parts without playing together?  Does this mean the spectrum has more than light waves; it also has sound waves?

 

I hope I am not getting confusing.

Not exactly.  Acoustic noise IS sounds at all different frequencies.  Sometimes they interfere, sometimes they reinforce.  Because of how our ears work we perceive that as noise.  "White" noise means that every spectral slice has a similar power of sound energy within it.  It is somewhat analogous to white light, which contains a wide variety of light frequencies that we perceive as white.  You could consider white light "noisy" and be fairly accurate.

 

Note that acoustic noise is made up of many different frequencies, as opposed to one pure tone at one frequency.  Similarly, white light is made up of many different frequencies, as opposed to a single frequency that you would get from a red laser diode, for example.

 

You cannot "hear" white light (or any EM frequencies) directly.  You need some apparatus to turn the EM frequencies into audible sounds, and then translate them down into a frequency you can hear.  If you did that with CMBR you would hear a noisy signal with an emphasis around 160GHz.



#8 billvon

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Posted 15 June 2017 - 10:53 AM

You just explained how it does, dude.

No.  A perfect (i.e. very high fidelity, zero noise) radio receiver/downconverter/amplifier would still produce a sound like white noise - since the CMBR, not the apparatus, is the source of the noise.



#9 exchemist

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Posted 15 June 2017 - 10:56 AM

If I read right,  the Cosmic Microwave Background is the spot on the spectrum where photons peak at expending their energy which enhances our visibility.  So far, so good?  However, the interference that  Arno Penzias and Robert Wilson got was noise.  This noise was later identified as the CMB.  So, are those photons dancing to a noisy band?  Or, seriously, from where does the noise come?  Can the movement of photons make sound?  Can there even be sound in space?

No.

 

There are two issues: what the cosmic background radiation is and whether photons make a sound.

 

The second is easy: they do not. Sound only occurs in a material medium that can transmit sound waves, such as air or water - or indeed a solid. Photons, however, are waves in the electromagnetic field, which is not a physical medium at all, which is why they can indeed travel through space. 

 

Regarding the first issue, about the CMBR, it is not a spot on any spectrum. The CMBR is radiation that comes from all directions in the sky and is thought to be what is left of the radiation emitted during the expansion of the universe after the big bang. It has a spectral distribution (i.e  the proportions of the various different frequencies of radiation that make it up) which is the same as that given off by a black body at about 3K, 3 degrees Celsius above absolute zero. While the big bang would have been very hot, the expansion of space since the time the radiation was given off has stretched the waves out and lowered the frequency - and thus the apparent "temperature" associated with the CMBR.

 

Some people call the CMBR an "echo" of the big bang, which is a slightly unfortunate metaphor as no sound is involved.



#10 hazelm

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Posted 15 June 2017 - 11:21 AM

I am stirring all this together and I think seeing where I was going wrong.  There is no "cause" from where I was looking.  The cause is in where the waves are finally received - something material to bounce off of?  Radio equipment might be called a cause but doesn't it  still need your ear before there is really sound.  No?  (The old famous forest and tree question?) 

 

I shall ponder a while.  I have never, to my knowledge, heard "white noise".  I have no idea what that is like.  But I think I am getting the picture.  Let me re-read.  Thank you.


Edited by hazelm, 15 June 2017 - 11:22 AM.


#11 DrKrettin

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Posted 15 June 2017 - 12:11 PM

  I have never, to my knowledge, heard "white noise".  I have no idea what that is like.  But I think I am getting the picture.  Let me re-read.  Thank you.

 

You can "see" white noise when the TV is on but no signal is being received. It's the weird black-and-white fuzzy image which you see before some terrifying and mysterious paranormal message appears when nobody is looking.



#12 hazelm

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Posted 15 June 2017 - 12:39 PM

You can "see" white noise when the TV is on but no signal is being received. It's the weird black-and-white fuzzy image which you see before some terrifying and mysterious paranormal message appears when nobody is looking.

Well, I do not have a television set but I do know that image from times past.  If I turned the sound up I got static?  Seems I did.  Thanks.



#13 exchemist

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Posted 15 June 2017 - 02:28 PM

I am stirring all this together and I think seeing where I was going wrong.  There is no "cause" from where I was looking.  The cause is in where the waves are finally received - something material to bounce off of?  Radio equipment might be called a cause but doesn't it  still need your ear before there is really sound.  No?  (The old famous forest and tree question?) 

 

I shall ponder a while.  I have never, to my knowledge, heard "white noise".  I have no idea what that is like.  But I think I am getting the picture.  Let me re-read.  Thank you.

I believe it is quite trendy at the moment to play recordings of white noise as an aid to meditation.  



#14 billvon

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Posted 15 June 2017 - 02:41 PM

 I have never, to my knowledge, heard "white noise".  I have no idea what that is like.  But I think I am getting the picture.  Let me re-read.  Thank you.

If you've ever heard static from a TV or AM radio - that's very close to white noise. 



#15 hazelm

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Posted 15 June 2017 - 02:50 PM

I believe it is quite trendy at the moment to play recordings of white noise as an aid to meditation.  

I have never tried it but I'm not a meditator in the trendy style.  However, I do think that tells me what white noise is.  I have seen ads for recordings of white nse to aid in sleeping. 

 

I have read and re-read all your answers and I think it is falling into place.  Fascinating what goes on overhead and round about?   Even more fascinating is how we manage to learn of it without making the trip.  Thank you all again.



#16 Super Polymath

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Posted 15 June 2017 - 03:25 PM

If you've ever heard static from a TV or AM radio - that's very close to white noise. 

1% of static on an untuned analog TV is from cosmic background radiation.



#17 Super Polymath

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Posted 15 June 2017 - 03:26 PM



No.  A perfect (i.e. very high fidelity, zero noise) radio receiver/downconverter/amplifier would still produce a sound like white noise

That's what I said. 

 

 

 

since the CMBR, not the apparatus, is the source of the noise.

 

This is why Hazelm thought photons can make noise. Don't be overly pedantic to the layman. 

 

A photon is smaller than a single molecule of any medium, Hazelm. Sound is produced by molecules, changes in air density, particles don't even register. Same reason why the speed of light is far faster than the speed of sound. 


Edited by Super Polymath, 15 June 2017 - 03:30 PM.