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Cosmology

- 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
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
Jorrie
65 38,866
To have an enjoyable cosmo forum we needed a balance between mental freedom on the one hand and a shared knowledge...
Jul10-14 01:18 PM
marcus
491 154,178
There are two representations of blackholes that I see in the popular media. Could you help me find the answer to a...
Nov19-11 05:34 AM
Hjarloprillar
7 1,652
What do we know about black holes swallowing dark matter? Dark matter exhibits gravitational effects, right ? So it...
Aug20-10 12:40 AM
Radrook
49 6,167
the title pretty much says it all. i am just wondering if dark matter (which doesn't interact with light i believe)...
Oct21-07 07:29 AM
Garth
12 3,637
Do antistars absorb photons? I read Feynman's Book, "QED - The Strange Theory of Light and Matter", there a while...
Jun5-07 06:09 AM
Nasher
6 2,640
I was wondering, if dark matter (DM) halos are spherical in nature and increase in density as a function of distance...
May21-07 02:19 AM
Wallace
2 1,396
I have been working hard to get the Dark Matter exclusion plots. In most of the papers (arxiv:0808.3607), I found...
Mar1-14 07:26 AM
mfb
1 457
How has subatomic particle homogeneity changed since cosmological redshift Z=1000? How much have particles maintained...
Sep17-13 02:29 AM
Mk
11 1,630
How is dark matter distributed (as far as we know)? Let's stay with a single galaxy like the Milky Way. I heard...
May6-14 11:51 AM
Mordred
4 672
The universe is observed to be flat. This is due to its energy density, and also due to purported inflation. How do we...
Jan1-10 10:17 AM
twofish-quant
12 1,775
Hi all, this is my first post; apologies if it seems a bit basic, I suspect there's something fundamental I'm not...
Mar12-12 12:50 PM
Chalnoth
17 2,210
Hello all, I'll start out by saying that I am a fairly new space/cosmology enthusiast with no real background in the...
Jul2-10 04:39 PM
Ich
1 817
I am just a layman who read that the farthest quasars (based on redshift) are about 13 billion light years away. Is...
Nov30-10 05:17 PM
marcus
11 5,668
If you care to, it would help if you would check my arithmetic. I may have made one or more mistakes. Thanks to anyone...
Jan8-12 09:41 PM
marcus
1 1,405
Hi , I need help from someone who has worked out the distance duality relation (between angular diameter distance...
Dec25-10 08:57 AM
aymer
1 1,213
Can we measure the distance between the first particle to enter the Bang event field and the last particle to enter? ...
Nov13-12 03:18 PM
mfb
1 998
I'm new here and my question could sound stupid but I'm a little bit confused. The Big Bang did happen 13.6 billion...
Aug24-10 03:31 PM
nismaratwork
7 910
Hi, I am trying to resolve a few questions concerning the measurement of cosmological distance and the determination...
Jul29-08 10:25 AM
JimJast
29 4,129
I am going to ask some questions based on my curiosity and my complete lack of knowledge and understanding of the...
Oct28-07 09:09 PM
Chris Hillman
3 2,514
If there are many universes , can it be possible that due to the presense of a universe the nearby Big Bang occurs in...
Apr2-12 04:03 PM
Drakkith
9 1,713
Hawaii Scientists Find Direct Evidence of “Dark Energy” in Supervoids and Superclusters superclusters & supervoids ...
Aug5-08 11:38 AM
jnorman
7 1,982
Hey folks, so perhaps some of you may have heard/read of Dietrich, et al, recent paper on dark matter "tendrils"...
Oct9-12 11:13 PM
Chronos
7 1,475
An interesting review paper of the search for DM particle(s): Direct Detection of Cold Dark Matter. The search...
Nov27-07 02:21 AM
Garth
0 1,610
In Weinberg's cosmology book, section 2.4 we have T' = \frac{T}{\gamma(1+\beta\cos{\theta})} He then claims,...
Jun21-09 02:04 AM
Chalnoth
2 1,100
In the distant past at bigbang the universe was very hot and dense. Can i say it was dimensionless then? If so did it...
Aug27-12 03:49 AM
twofish-quant
8 2,329
I watched astrophysical lectures by a scientist on the internet, and he claims that there are a total of twelve...
Dec3-08 05:09 PM
Janus
1 1,224
Is it within the realm of physics or cosmology to refer to a dimensionless void that may have preceded the big bang? ...
Oct7-13 11:56 AM
bapowell
7 5,956
Spectral redshift is currently understood to be of a variety of sources, velocity / doppler redshift, gravitational...
Nov15-13 05:26 AM
ConformalGrpOp
30 3,693
I assume that current experimantal data allows to exclude only some scenarios, for example, closed Universe: Big...
Oct11-09 06:39 AM
Chalnoth
6 1,406
Hello everyone. First off, I'm no astrophysist, but I'd been reading around and thinking about something. From what...
Jul31-06 02:35 PM
marcus
2 2,098
Acc. to general relativity time runs slowly near a massive body.So, i have a question bothering me from some time that...
Nov1-13 01:44 PM
Naty1
2 941
Basically as the questions says, can anyone explain what E and B mode polarisations are and hw they differ from temp...
Mar17-13 06:43 PM
Chronos
1 571
Here is a new, well-written explanation by R. J. Cook and M. S. Burns as to why the accepted physical attributes of...
May22-08 11:52 PM
pixchips
34 4,485
I wonder...
Oct24-12 10:29 AM
nicksauce
7 3,082
What is the difference between particle horizon and cosmological event horizon?
Feb9-06 01:29 AM
Chronos
5 2,342
What is the difference between a closed Universe and an open Universe? Please explain in layman's terms and describe...
Nov29-11 02:39 PM
bapowell
1 1,289
I read that the expansion of our universe is the expansion of space itself. Apparently, the phrase, expansion of...
Jul18-08 01:59 AM
Sundance
52 5,474
Can someone remind me what the difference between the Cosmological Constant (\Lambda) and Dark Energy (DE)? Doesn't...
Sep24-09 04:12 PM
Chalnoth
6 3,369
Hi Could you comment on Big Snap scenario briefly mentioned by Max Tegmark on page 12 (and I can't google more): ...
Sep14-13 03:41 AM
Dmitry67
4 1,169
That's title of the paper i've linked below. It's small paper that argues against an eternal universe. ...
May9-12 07:38 AM
skydivephil
15 2,126
Or could it be infinitely massive? I'm confused since both scenarios seem to be able to predict the same observations.
Oct20-09 10:12 AM
Wallace
5 1,583

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