How quickly was the CMB made?

[repoman]

So, the CMB was made when the universe was about 380,000 years old. But, how fast was the phase change from plasma to non-ionized monoatomic hydrogen?

Have a percentage range definition would be sensible, say the time from 95% of hydrogen being ionized to 5% being ionized. Not sure what numbers to use. The numbers used will give different clearing times.

Did the "clouds clear" in a year, week, hour, minutes?

 

[repoman]

Did a google search and surprisingly found some info on quora.com

pretty cool stuff

https://www.quora.com/How-large-was-the-universe-at-the-moment-of-recombination-in-Big-Bang-cosmology

took 110,000 years to go from fully ionized to non ionized?

 

[steve_bank]

The model is based on our Earth bound definitions of time and space, seconds and meters. The model uis very successful is that it predicts today's particles and macro scale galaxies.

In reality we have no idea if using our meter and second definition makes any sense as the BB cosmology developed. That is how I see it.

I do not know the theory in detail, does it take into account velocity and gravitational time dilation as the universe as we see it formed? Given the high density of the starting conditions does our second here on Earth have any meaning there?

 

[Bomb#20]

The model is based on our Earth bound definitions of time and space, seconds and meters. The model uis very successful is that it predicts today's particles and macro scale galaxies.

In reality we have no idea if using our meter and second definition makes any sense as the BB cosmology developed. That is how I see it.

I do not know the theory in detail, does it take into account velocity and gravitational time dilation as the universe as we see it formed? Given the high density of the starting conditions does our second here on Earth have any meaning there?

An excellent question. According to Wikipedia, 1 second is defined to be exactly "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom". It seems to me this definition presupposes a universe capable of containing cesium. Cesium couldn't exist in the first "second" after the big bang -- protons and neutrons were all constantly being created and then annihilated by antimatter too quickly for nuclei to form. For that era we need a hotter clock.

 

[repoman]

hmm, interesting points.

On another note, does the 13.6 eV (not sure how many decimal points there are to this and will assume that 13.60000 eV is exact for now) ionization energy dictate an "exact" frequency photon? I am not sure how much spread is allowed for a photon to be able to ionize a neutral hydrogen atom. Would 13.599, 13.59, 13.55 eV photons work for this?

Because as the universe was expanding what was the drop in energy of these photons per year?

something like this on a linear approximation

E = (13.6 eV)*b*t

Where b = fractional decrease by year and t= years

b would be something like 0.99xyz... which would need some modeling to figure out.

 

[steve_bank]

The model is based on our Earth bound definitions of time and space, seconds and meters. The model uis very successful is that it predicts today's particles and macro scale galaxies.

In reality we have no idea if using our meter and second definition makes any sense as the BB cosmology developed. That is how I see it.

I do not know the theory in detail, does it take into account velocity and gravitational time dilation as the universe as we see it formed? Given the high density of the starting conditions does our second here on Earth have any meaning there?

An excellent question. According to Wikipedia, 1 second is defined to be exactly "the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium-133 atom". It seems to me this definition presupposes a universe capable of containing cesium. Cesium couldn't exist in the first "second" after the big bang -- protons and neutrons were all constantly being created and then annihilated by antimatter too quickly for nuclei to form. For that era we need a hotter clock.

I do not know that there is an exact number of trasitions per unit time. Time and frequency should invoke the Uncertainty Principle.

A simplified description. A detector and electronic counter count transitions . When the counter reaches the max count it resets to 0 toggling a signal and restarting the count. This essentially creates a square wave. A high frequency oscillator is locked to this signal by a phase locked loop which acts like an average or smoother.

A common output of a a commercial atomic clock is 10 Megahertz. For a 1 second reference it is divided digitally. Back in the 80s a Hew let Packard cesium clock secondary standard cost around $10k. You could pick it up and carry it.
https://science.howstuffworks.com/atomic-clock3.htm
https://en.wikipedia.org/wiki/Atomic_clock