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SharkFart86 t1_jb203b1 wrote

Reply to comment by Ralph_Shepard in Does the age of the universe depends on where you are? by _bidooflr_

What you’re asking is kind of a weird question, you can use anything you want as your reference frame. The CMB is often used as the reference frame because it has some convenient qualities that make it more a “fair” reference in cosmology, but there isn’t anything inherent about it that makes it more absolute than any other frame of reference.

And keep in mind that the reference frame matters within the context of the subject. Using CMB as a reference in regards to the orbit of the planets in our solar system makes way less sense than using the sun as the frame of reference. The frame of reference should be whatever makes the model clearer to accurately understand. The CMB works great when looking at the movement or rotation of galaxies, because otherwise those values are very difficult to describe in a clear way.

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TaiVat t1_jb2cwhd wrote

I think the question there in terms of "absolute" is that the CMB is "special" in the sense of being the most distant observable "object", and thus is kind of "absolute" in the sense that its the most encompassing of all possible frames. I.e. all of the rest of the observable universe is within it. Kinda like a skybox in a video game.

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Ralph_Shepard t1_jb2epci wrote

That is why I used the quotation marks and "better than", but I can't think of any other better reference point

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