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mag10

Is radio static from the Big Bang?

15 posts in this topic

Hello,

I know nothing of radio astronomy, but I heard that television and radio static are actually the background radiation from the big bang.

Is this true?

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Some of the static is, the Sun, stars and other objects add to it.

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No it's not the TV and radio static is due to lighting strikes here on earth. Andrew

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Yes it is true, i have heard this a few times however here is a section from the NASA website

Several members of the NASA Goddard COBE team work on WMAP. Like COBE, WMAP scans the sky over and over again, soaking up the ancient light from the Big Bang known as the cosmic microwave background. Microwaves are a low-energy form of radiation but higher in energy than radio waves. The cosmic microwave background blankets the universe and is responsible for a sizeable amount of static on your television set--well, before the days of cable. Turn your television to an "in between" channel, and part of the static you'll see is the afterglow of the big bang.

Edited by meteoriot

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The Cosmic Microwave Background (CMB) is the radiation from recombination (~300,000-400,000 years after the big bang). Its been stretched as the universe expands, and is now a thermal signature around 3K. This leads to a black body radiation curve like any "hot" object (if you can call something just above absolute zero hot!) centered around a peak.

In the case of the CMB its somwhere in the microwave region - 100-200 GHz. Tv typically receives in the MHz band - up to 200 Mhz or so. So its not a perfect match. Because its a black body spectrum though, its not a sharp peak, but more a rolling hill type of peak, so there are still bits of the CMB radiating in the MHz which TV picks up. BB radiation also tends to have more on lower frequencies than the higher frequencies of the peak too - as you can see from this plot.

cmb_intensity.gif

So the TV is not tuned to pick up CMB, but it does get a small fraction. When it is detuned from a TV station, the static you get is composed of all sorts of things, including stuff induced from sparks, lightning, stars, and the CMB.

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Yes, it's true, part of the interference is about 1% or less, the rest as Julian said is composed of all sorts of things, including stuff induced from sparks, lightning, stars. The same is true for FM radios - when the radio is tuned to an interstation setting, part of the hiss that you hear, called "white noise", is leftover radiation from the Big Bang. In fact, it was annoying "noise" that led to the discovery of the CMB. In 1965, Arno Penzias and Robert Wilson built a Dicke radiometer for Bell Telephone Laboratories to use in radio astronomy and satellite communication experiments.

Edited by Telrad

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No it's not the TV and radio static is due to lighting strikes here on earth. Andrew

Lightning strikes here on Earth are normally picked up locally as crackles, as anyone who listens to LW and MW broadcasts knows, yes they contribute to the noise at greater distances, but are below the normal noise produced by the CMB. Also the movements of electrons within the TV / Radio produce high levels of noise, unplug the aerial and see what they produce! Unfortunately or fortunately, with digital broadcasts, they noise doesn't make it to the screen or speakers, just a blue screen, or silence, mabe a slight hiss in the speakers from the power amplifier.

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Ok. Thanks.

I get the frequency thing for TV.

Now why only on FM (and only 1%, at that), and not on AM (which seems to generate a lot more static than FM?).

Also, I'm listening to a cheap AM radio right now at 130 KHz X 10 (that's what the dial says). And I hear a static pulse. Can you hear it also, and if so can you tell me if that's a pulsar? (It's been there for months).

I really appreciate any and all input you might have.

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The CMB is present in the higher frequencies which mostly use FM, now going over more to digital. The AM bands, from 40Khz to normally 30MHz, (Air Traffic still uses AM up to the low UHF range) are generally to low in frequency, for the CMB to be present.

The pulse that you get on AM at 1.3MHz (130 KHz X 10 = 1.3MHz) will not be a pulsar, you need a lot more equipment and better sensitivity than your radio can deliver. It is most likely local to you and I suspect a switching regulator, some thing that converts one voltage to another. Have a troll through this Google search and maybe you can identify the source of the interference, Google

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Thanks

It seems I got all excited for nothing.

But I'ts much better to be properly informed.

But now I'm curious!

I'm going to try to find a way to listen to a real pulsar!

I think that would be quite something!

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Ok. Thanks.

I get the frequency thing for TV.

Now why only on FM (and only 1%, at that), and not on AM (which seems to generate a lot more static than FM?).

Also, I'm listening to a cheap AM radio right now at 130 KHz X 10 (that's what the dial says). And I hear a static pulse. Can you hear it also, and if so can you tell me if that's a pulsar? (It's been there for months).

I really appreciate any and all input you might have.

Are you sure it's not Vengaboys or s club 7 or something?

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Sadly it is not true that the static on radio and TV is from the cosmic back ground radiation. All electronics generate noise of their own for various reasons, the main one is thermal noise. Anything above absolute zero generates increasing levels of thermal noise. What you can hear on an AM radio is mostly man made electrical noise and static from weather systems.

There are a number of signals from astronomic sources, sun noise, galactic noise and the background cosmic noise. You need something a bit better than your ordinary domestic radio and TV equipment to detect these. I used to be heavily into amateur radio a few years back and had a VHF setup that was good enough to hear the sun if the antenna happened to point at it. I think your average satellite TV set up is the closest to something that would be able to pick up cosmic radio signals.

Regards

Barry

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meteoriot says:

"Are you sure it's not Vengaboys or s club 7 or something?"

Hehe!

No I checked, and like I said, it's been at the same frequency for months.

Bazaar says:

"Sadly it is not true that the static on radio and TV is from the cosmic back ground radiation."

So. It seems there is no concensus on the subject (which is why I asked in the first place).

Thanks ollypenrice. The book you posted seems like a good place to start getting answers.

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