# Thread: Wavelength of the Cosmic Microwave Background?

1. ## Wavelength of the Cosmic Microwave Background?

It must have one, but I am unable to find out how long it is. Or even its frequency in hz.

2. ## Re: Wavelength of the Cosmic Microwave Background?

My Finals are done so I'm in a strict "No calculations" phase, but you could plug the frequencies on this chart into our good friend λf=c.

3. ## Re: Wavelength of the Cosmic Microwave Background?

From Wikipedia:

"The CMB has a thermal black body spectrum at a temperature of 2.72548±0.00057 K. The spectral radiance dEν/dν peaks at 160.23 GHz, in the microwave range of frequencies."

It's a black body curve, not a single frequency, but the peak is at 160 GHz.

4. ## Re: Wavelength of the Cosmic Microwave Background?

So, 1.871 millimeters.

5. ## Re: Wavelength of the Cosmic Microwave Background?

That's still really short, but it is a distance we can actually see.

6. ## Re: Wavelength of the Cosmic Microwave Background?

Technically yes, although in terms of radiomagnetic waves I´m not sure if "the wavelength is something I could see if it was a physical object" is the most useful criterium for how relatable something is.

7. ## Re: Wavelength of the Cosmic Microwave Background?

Originally Posted by Lvl 2 Expert
Technically yes, although in terms of radiomagnetic waves I´m not sure if "the wavelength is something I could see if it was a physical object" is the most useful criterium for how relatable something is.
Well, it is when you're building antennas by hand, or building reflectors or Faraday cages for that wavelength. That's all I've got off the top of my head, though.

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