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zankaon
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If the Hubble parameter is always decreasing for very early stages of Big Expansion of manifold (i.e. Big Bang), then what was it decreasing from?
zankaon said:If the Hubble parameter is always decreasing for very early stages of Big Expansion of manifold (i.e. Big Bang), then what was it decreasing from?
jonmtkisco said:Hi Wallace,
Actually I made a boo boo. At redshift z=10000, I have H around 85-90 million km/s per Mpc.
My source is Jorrie's spreadsheet which integrates critical densities backwards from the present.
Jon
jonmtkisco said:Marcus,
I'll be happy send it to you. Can I send it through the forum?
I'll ask Jorrie if it's ok to distribute it.
Jon
jonmtkisco said:Hi Wallace,
Actually I made a boo boo. At redshift z=10000, I have H around 85-90 million km/s per Mpc.
My source is Jorrie's spreadsheet which integrates critical densities backwards from the present.
Jon
marcus said:...
Let me compare what Morgan's cosmos calculator says
http://www.uni.edu/morgans/ajjar/Cosmology/cosmos.html
Now I will try 10,000-------the calculator says 37 million km/s per Mpc.
...
I don't know which is right. I don't trust Morgan calculator at such high redshift. Could well be that your figure is better.
...
marcus said:It is probably really for use with redshift z < 10.
But i want SOME idea of the rough magnitudes.
Here's what I was using, if you want to try it for comparison.
marcus said:Now I will try 10,000-------the calculator says 37 million km/s per Mpc.
...
I don't know which is right. I don't trust Morgan calculator at such high redshift. Could well be that your figure is better.
...
Jorrie said:...
It looks like the Morgan calculator ignores radiation energy density (as it should at 0 <= z <= 6, it's specified regime). When I set Omega_r = 0 in my spreadsheet, I get H ~ 37,000 million km/s per Mpc at z ~ 10,000.
Jorrie
marcus said:Nice! Neat inference. Thanks. I see you have an ebook at your website that you wrote, Relativity 4 Engineers. Could be a very enlightening book 4 anybody, if this is a fair sample.
jonmtkisco said:Jorrie,
Do you have any sense as to whether the universe was likely to have been expanding more quickly, or less quickly, than the Friedmann equations calculate, during that first second?
Jon
pervect said:The trick is to find out which a(t) corresponds to a P(t) and rho(t) that has the desired relationship between P and rho.
The bigger trick is to figure out some theoretical grounds for some "equation of state" that one expects P and rho to satisfy.
Wallace said:What would solving the Friedmann equations for T<1 second tell you anyway?
The Hubble parameter, denoted as H, is a measure of the rate at which the universe is expanding. In the early universe, it was much larger compared to its current value, indicating a faster rate of expansion.
The Hubble parameter is calculated by dividing the rate of expansion (measured in kilometers per second) by the distance to the observed object (measured in megaparsecs). In the early universe, the rate of expansion was determined by observing the redshift of distant galaxies.
The Hubble parameter is significant as it helps scientists understand the evolution of the universe. By measuring the expansion rate at different points in time, we can determine the age of the universe and the amount of matter and energy present during the early stages of its formation.
In the early universe, the Hubble parameter was larger compared to its current value, indicating a faster rate of expansion. As the universe continues to expand, the Hubble parameter decreases and the expansion rate slows down.
The Hubble parameter is a crucial component of the Big Bang theory. It provides evidence for the expansion of the universe and supports the idea that the universe began with a big bang and has been expanding ever since. The Hubble parameter also helps scientists understand the early conditions of the universe and its evolution over time.