From the March 2015 issue

Is the cosmic microwave background a shell around us? Or are the microwaves everywhere in the universe?

Barry Berman, Sparks, Maryland
By | Published: March 30, 2015 | Last updated on May 18, 2023
Cosmic microwave background

The cosmic microwave background (CMB) radiation fills the universe and travels in all directions. As we see it from here in satellite maps, it is about equally bright in all directions, and that’s one of the main reasons we know it’s cosmic. The Greek word is isotropic, which means the same in every direction.

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