ta152h0 wrote: ↑
Fri Apr 13, 2018 11:03 pm
And all this began 13.8 billion years ago.
Where there is light, there is speed of light.
Where there is dark, there is speed of darkness.
The cosmic microwave background (CMB) basically represents a specific point in time (about 380,000 years after the Big Bang).
Hence, ever since that time our observable CMB has been receding from us at the speed of light
The 'Dark Ages ages' directly front of the CMB represents a relatively dark shell from 380,000 years to 150,000,000 years ago.
This shell, too, is receding from us at the speed of light.
The actual individual physical objects we observe at any given time (e.g., the UDFy-38135539, EGSY8p7 & GN-z11 galaxies
and currently observed CMB features) will never move at the speed of light
... but they will slowly evolve over time until their internal clocks grind to a halt as they approach the speed of light due to the exponential expansion of the Universe.
<<The "Dark Ages" span a period from about 380,000 years after the Big Bang, when the universe had cooled enough to allow light to travel long distances, but light-producing structures such as stars and galaxies did not yet exist. During the Dark Ages, the temperature of the universe cooled from some 4000 K down to about 60 K. During this period, the universe was "dark" in several ways. Before the start of the Dark Ages, it was opaque because it was filled with a hot plasma which prevented light from travelling far. The effect was similar to being filled with a glowing fog. During recombination/decoupling, the plasma cooled and formed neutral atoms, and the universe became transparent for the first time. However it was still "dark" for many millions of years, because stars, galaxies and other light-giving structures did not yet exist. Only two sources of photons existed: the photons released during recombination/decoupling, as hydrogen atoms formed, which we can still detect today as the cosmic microwave background (CMB), and photons occasionally released by neutral hydrogen atoms, known as the 21 cm spin line of neutral hydrogen. There was no other light since stars and galaxies had not yet formed. The Dark Ages ended gradually as structure formed, during a period from around 150 million years after the Big Bang to around 1 billion years.
The October 2010 discovery of UDFy-38135539, the first observed galaxy to have existed during the following reionization epoch, gives us a window into these times. The galaxy earliest in this period observed and thus also the most distant galaxy ever observed is currently on the record of Leiden University's Richard J. Bouwens and Garth D. Illingsworth from UC Observatories/Lick Observatory. 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. More recently, the UDFy-38135539, EGSY8p7 & GN-z11 galaxies
were found to be around 380–550 million years after the Big Bang and at a distance of around 13.4 billion light-years.There is also currently an observational effort underway to detect the faint 21 cm spin line radiation, as it is in principle an even more powerful tool than the cosmic microwave background for studying the early universe.>>