Timeline of the Universe question

[dogjones]

Was reading this (http://www.guardian.co.uk/science/2008/apr/26/universe.physics) and a question popped out at me.

In the intro the article says:

Combined with studies of the radiation left over from that primordial explosion, they have found that the universe was born 13.7bn years ago, give or take 200m years. (Bolding mine)

However, it then gives a timeline measured in 10^-n seconds after the big bang. I'm having difficulty reconciling the 200m year margin of error with this kind of precision. Could someone enlighten me here?

Looking at this:

300,000 years

The universe has cooled to about 1,000C - cool enough for electrons to pair up with nuclei to form the first atoms. By the end of this so-called Recombination Era, the universe consists of about 75% hydrogen and 25% helium. With the electrons now bound to atoms, the universe finally becomes transparent to light - making this the earliest epoch observable today.

200m years

Small, dense regions of cosmic gas start to collapse under their own gravity, becoming hot enough to trigger nuclear fusion reactions between hydrogen atoms. These are the very first stars to light up the universe.

Is it something to do with we can only really look back to 200m years or so post big bang, and everything before that is more along the lines of mathematical proof? The 300,000 year post BB era is apparently the earliest epoch observable - is this the CMB? I guess we can't use red shift to measure the distance and therefore exact age of this or something?

My brain is a kaleidescope of jumbled thoughts. Can someone please order it.

[Pixel42]

"How did the universe evolve in the first few seconds after the big bang?" and "How old is the universe?" are completely different questions, in the same way that "How does a baby develop in the womb?" and "How old is that guy over there?" are completely different questions. Knowing the answer to the first question tells you nothing about the answer to the second.

[Ziggurat]

Is it something to do with we can only really look back to 200m years or so post big bang, and everything before that is more along the lines of mathematical proof?

It's probably more useful to think in terms of fractional uncertainty. 200m years out of ~14 billion years is around a 1.5% uncertainty. If you think about the model having about this level of uncertainty in the duration of each stage, it's quite consistent that the absolute magnitude of uncertainty in the age of the universe can be significantly larger than the duration of certain early stages of the universe.

The 300,000 year post BB era is apparently the earliest epoch observable - is this the CMB?

Yes.

I guess we can't use red shift to measure the distance and therefore exact age of this or something?

Not without some uncertainty, because the amount of red shift is related not only to the age of the light, but also the expansion rate of the universe.