B CMBR: Is It Constant or Changing Over Time?

[Bill McKeeman]

My question is this: is the CMB constant or might it be changing with time?

 

[Ibix]

My question is this: is the CMB constant or might it be changing with time?

It's cooling. Very slowly, but it's cooling. It's the glow emitted by the Big Bang, more and more redshifted due to the expansion of the universe. It used to be really, really hot.

I expect the fluctuations will change over time too, but I don't know the timescale.

 

[EmileJ]

It is not constant. At some WMAP conference in 2013 it was estimated that the CMBR map will look totally different in about 1 billion years.
Very small changes might be detectable on the order of 100 years.

Link to blogpost about that conference.

It includes an animation of how those changes could look over time.