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- The origin, evolution, structure and eventual fate of the universe.
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Quality answers to common cosmology questions
Jul23-14 11:07 PM Greg Bernhardt 
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Jan16-12 Greg Bernhardt
To have an enjoyable cosmo forum we needed a balance between mental freedom on the one hand and a shared knowledge...
Jul25-14 06:02 PM
492 158,335
The new A20 tabular calculator lets you look at changing geometry out to about 88 billion years according to the...
Jun11-14 11:00 AM
65 40,893
Greetings, I read a lot. It is often repetitious. Occasionally I read an idea or way of looking at something that I...
Mar13-11 09:45 PM
4 1,243
I don't know much about the big bang but if there was an explosion and the universe started expanding from a small...
Mar12-11 02:48 PM
12 1,436
Greetings, Is space made up of individual units like pixels on a computer screen? And the amount of space in the...
Mar12-11 08:56 AM
7 1,348
Is it possible to define a maximally rotating black hole? Could it be: 4\alpha^2 = r_s^2 (i.e....
Mar11-11 08:41 PM
10 2,717
is antimatter the same thing as dark matter? is antigravity the same thing as dark energy?
Mar11-11 01:26 PM
13 1,571
I wonder if someone has ever considered the following scenario: 1. "Standard" Big Rip model (phantom...
Mar11-11 05:21 AM
11 1,536
Now I'm using p=3H^2/8piG and I have H=70 km/s/Mpc, what is the critical density of the universe? now I'm plugging...
Mar10-11 08:35 PM
1 4,360
I know that H(t) = 1/a(t) x da/dt I know that a(t) is proportional to t^2/3 and da/dt is proportional to a^-1/2...
Mar10-11 08:14 PM
1 1,155
Can the speed at which galaxies separate exceed the speed of light?
Mar10-11 05:43 PM
5 1,297
Can someone give a clear definition of what we mean when we say the CMb spectrum is adiabatic and what it means for...
Mar10-11 08:25 AM
5 789
Wondering if anyone can help. Is there likely to be any difference in the gravitational properties of an event horizon...
Mar10-11 01:11 AM
19 2,952
Greetings, #1 - If all matter energy, and space were concentrated at the big bang, and the universe has been...
Mar9-11 10:16 PM
21 3,519
Greetings, The answer to a major question has raised another problem...then solution...then questions. Why...
Mar9-11 06:09 PM
2 796
First of all I'm a physics n00b so forgive me for intruding upon you people, whom I consider to be the pinnacle of...
Mar9-11 05:59 PM
2 776
Here is my understanding of how the anisotropies of the CMB are used to determine the geometry of the universe: The...
Mar9-11 07:04 AM
5 4,490
An estimate of 0.94/tPlanck for the maximum reached by the Hubble parameter was given by Ashtekar and Sloan here...
Mar9-11 05:13 AM
16 2,599
I know that the issue of cosmological redshift has been discussed in this forum before, e.g. click here, but I would...
Mar8-11 03:38 AM
9 2,459
In his theory, Stephen Hawking suggests that a black hole will give off thermal radiation. Radiation is light, so how...
Mar6-11 04:45 PM
2 1,563
-------------------------------------------------------------------------------- How the Scaler Field collapse,...
Mar6-11 10:21 AM
5 1,829
Our acceleration universe due to 'dark energy'. Do we have a mathematical equation to describe this? I want to know if...
Mar5-11 03:25 PM
3 2,641
Mar5-11 02:44 PM
0 720
Martin Rees in his book Just Six Numbers says that in the early universe there 1 billion antiquarks and a billion and...
Mar5-11 08:03 AM
2 830
OK I'm still new to cosmology and this question is bugging me: if a photon is emitted toward me from a distant galaxy...
Mar4-11 02:42 PM
11 1,993
There is a picture on this site that I don't understand. ...
Mar3-11 08:29 PM
9 2,958
Now this is my first post here but I've been a reader for some time. Now I have a basic understanding of physics and...
Mar3-11 12:41 PM
10 1,786
Simple question hopefully. What was the initial value for the hubble parameter immediately following the big bang (or...
Mar2-11 09:06 AM
15 1,919
Now Iíve been trying to read up on this Shockwave cosmology model and wanted to see if I have the correct view since...
Mar1-11 11:26 PM
0 694
Isaac Asimov, in his 1979 book A Choice of Catastrosphes: The Disasters That Threaten Our World, raised the...
Mar1-11 09:23 PM
9 2,610
would it be fair to say that Universes(??) on all scales, which consist of 'something', expand for the very simple...
Mar1-11 02:12 PM
1 632
I am curious about the red shift that is claimed to demonstrate that the Universe is expanding. Is there a...
Mar1-11 01:24 PM
Feeble Wonk
17 2,777
Hey I'm getting very muddled with my units, and would really appreciate some clarity :-) I have angular...
Mar1-11 06:55 AM
2 1,294
Hi, I was just pondering the moment of the Big Bang, and have been doing some reading on the subject, in which there...
Mar1-11 03:41 AM
6 2,362
I know that Hubble observed redshift which led to the conclusion that space was expanding. But why did redshift lead...
Feb28-11 03:13 PM
9 3,072
If our sun was replaced by a pulsar, would our solar system be sucked into it because of the increased gravity? How...
Feb28-11 09:44 AM
4 1,329
If the universe is 13.7 billion years old, then how can the observable universe reach out 46 billion light years,...
Feb28-11 12:50 AM
2 1,032
You probably know that there is a lot of evidence supporting the big bang, like the expansion of the universe, and...
Feb27-11 08:43 AM
10 3,769
I need help understanding the mechanics of expanding space. If I accept that EM field lines are correspondingly...
Feb26-11 09:35 AM
Feeble Wonk
0 1,035
Assuming that the whole universe is electric charge neutral, there are neutral atoms, unbound electrons (which play...
Feb26-11 06:22 AM
6 1,105
How was Einsteins understanding of the universe formed by his theory of relativity?
Feb25-11 06:42 PM
6 3,005
Hello, Firstly, i would like to say that i am by no means an educated person (as in taking specialty courses or an...
Feb24-11 05:56 AM
5 2,657

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