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Revision as of 04:45, 9 November 2014

Cosmology:

Hello Jayron32,

I hope you are well.

Thank you for helping me yesterday. I have few more questions I would like help on, could you kindly help me please, or direct someone who would be able to help.

1)

Dark Ages

Before decoupling occurred, most of the photons in the universe were interacting with electrons and protons in the photon–baryon fluid. The universe was opaque or "foggy" as a result. There was light but not light we can now observe through telescopes. The baryonic matter in the universe consisted of ionized plasma, and it only became neutral when it gained free electrons during "recombination", thereby releasing the photons creating the CMB. When the photons were released (or decoupled) the universe became transparent. At this point the only radiation emitted was the 21 cm spin line of neutral hydrogen. There is currently an observational effort underway to detect this faint radiation, as it is in principle an even more powerful tool than the cosmic microwave background for studying the early universe. The ‘Dark Ages’ are currently thought to have lasted between 150 million to 800 million years after the Big Bang.

Reionization, 150 million to 1 billion after the Big Bang

In Big Bang cosmology, ‘reionization’ is the process that reionized the matter in the universe after the "dark ages", and is the second of two major phase transitions of gas in the universe. As the majority of baryonic matter is in the form of hydrogen, reionization usually refers to the reionization of hydrogen gas. The primordial helium in the universe experienced the same phase changes, but at different points in the history of the universe, and is usually referred to as ‘helium reionization’.

They found the galaxy UDFj-39546284 to be at a time some 480 million years after the Big Bang or about halfway through the Cosmic Dark Ages at a distance of about 13.2 billion light-years.

I’m confused, with the highlighted bits. When did the reionization occur and when was the dark ages?

2)

I don’t know from which article I got the following, let me know if you know the link please:

The dark matter clump together under gravitational attraction due to the initial density perturbation spectrum caused by quantum fluctuations. This derives from Heisenberg's uncertainty principle which shows that there can be tiny temporary changes in the amount of energy in empty space. Particle/antiparticle pairs can form from this energy through Mass-energy equivalence, therefore enacting a gravitational pull, which will cause other nearby particles to move towards it, disturbing the even distribution and creating a centre of gravity. The gravity of these denser clumps of dark matter then caused nearby matter to follow suit, and start falling towards the centre. This resulted in a clouds of gas, predominantly Hydrogen to form, and within these clouds began to form the first stars. These clouds of gas and early stars, many times smaller than our galaxy, were the first protogalaxies.

I don’t understand this highlighted bit, hydrogen was there from before, right? During the “Dark ages”.

3)

View the link (https://en.wikipedia.org/Star#Classification) and explain please why this is the second time it defines a white star occurs twice during its evolution phase . I actually don't get it. The diagram you told me to look at earlier in the other discussion does not have a white star line during its evolution phase.

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Hello,

I don’t know from which article I got the following, let me know if you know the link please:

The dark matter clump together under gravitational attraction due to the initial density perturbation spectrum caused by quantum fluctuations. This derives from Heisenberg's uncertainty principle which shows that there can be tiny temporary changes in the amount of energy in empty space. Particle/antiparticle pairs can form from this energy through Mass-energy equivalence, therefore enacting a gravitational pull, which will cause other nearby particles to move towards it, disturbing the even distribution and creating a centre of gravity. The gravity of these denser clumps of dark matter then caused nearby matter to follow suit, and start falling towards the centre. This resulted in a clouds of gas, predominantly Hydrogen to form, and within these clouds began to form the first stars. These clouds of gas and early stars, many times smaller than our galaxy, were the first protogalaxies.

Hi Russell. It's from Protogalaxy. For future reference, if you take a portion of unique text and run it through Google in quote marks you can determine this for yourself. It literally took me less than ten seconds to find the answer. Best regards--Fuhghettaboutit (talk) 04:19, 9 November 2014 (UTC)

Thanks Fuhghettaboutit. Nice user name btw..lol -- (Russell.mo (talk) 04:29, 9 November 2014 (UTC))