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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
492 161,658
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 42,546
peace upon u .. though it's a fantasy but it's a scientific one .. i've read about the generating energy from...
Feb11-09 01:02 AM
10 1,737
what are we seeing the present,the future ,or the past??
Dec6-07 08:46 PM
2 1,917
I am really puzzled. I have several questions about how Omega_M and Omega_Lambda evolve with time. Ultimately I want...
Apr26-09 06:08 PM
8 1,300
Quintessence fields are supposed to slowly roll down a potential V(\phi). Adding constants to the potential obviously...
May14-09 06:54 AM
1 1,184
Could somebody show me mathematically why/why not gravity could/couldn't directly be caused by expansion -everything...
Mar1-10 03:37 PM
7 1,240
As the universe expands... Is it that we are more on the surface of a balloon, so the expansion is similar for us...
Jan24-11 10:54 AM
0 873
What is catastrophic nova?Why have cosmologist chosen this characteristic for nova?
Jun20-07 01:42 AM
3 2,116
Two questions and theories... #1. Gravity The sun, a nuclear reactor, holds all the planets in orbit. However, if...
Dec18-07 07:29 PM
1 2,381
Sorry if this sounds a bit mixed up. When I was growing up, in the late 1990's, popular science books about...
Dec2-11 04:43 PM
Ken G
3 2,326
I was wondering, if inflation caused space to expand so rapidly, what happened to slow it down to the current rate?
Mar2-10 03:36 AM
8 1,679
If another galaxy were to be travelling towards us at the speed of light and as well as the Milky Way being ripped...
Feb23-12 11:42 AM
3 1,298
In the summer 2004 I read an article in New scientist discussing if lightspeed has changed during the last few billion...
Feb3-06 12:00 PM
Chaos' lil bro Order
4 1,711
Hi, anyone knows where I can find a BBN code to compute the cosmic evolution of light particles and elements?
Jul12-09 03:17 PM
0 1,489
Everytime I see a picture of the large scale structure of space with matter arranged in a web like form, I come to...
Aug17-12 08:38 AM
2 799
Hi, first of all I have to say that I know practically nothing about cosmology, though I know some basic physics. ...
Feb6-11 11:03 AM
2 950
Hi, I figured out a thought experiment/problem, here it is: A friend of mine is living in a galaxy far away. He...
Jul8-14 05:08 PM
7 534
I recently made a partially tongue-in-cheek remark on this board about cosmology being a bit like religion. I thought,...
Apr8-11 05:54 PM
22 3,858
I am interested in peoples opinion on the following papers, hep-th/0307026 Inflation and de Sitter holography...
Aug17-11 06:51 AM
0 1,098
Are inflation and expansion different phenomena and if so what is different about them. Both terms seem to refer to...
Apr9-11 09:09 PM
8 3,293
Hubble’s law, according to Wikipedia, says that the recession velocity of a distant object P comoving with Earth is...
Jun28-12 06:46 PM
16 2,262
I have just been reading about the Milne model of the universe, which is a version of the FLRW model with zero...
Jul1-12 08:09 AM
11 1,386
I was hoping somebody could point me towards a derivation of the following formula for cosmological redshift: z =...
Aug12-12 12:01 AM
32 4,748
The idea about the universe having zero net energy, as explained for instance in...
Jul10-12 08:27 AM
5 1,964
In Appendix A of Davis & Lineweaver (2003) proper distance to a faraway galaxy is defined as the distance along a...
Jul20-12 11:44 PM
7 1,588
Consider a light ray emanating from the origin of a FLRW coordinate system in a homogeneous, isotropic universe. The...
Aug11-12 08:08 PM
3 1,652
I have been trying to pin down a precise definition of large-scale homogeneity, in the context of saying, per the...
Sep10-13 09:22 PM
13 1,739
I was looking at the wikipedia article about cosmic inflation (you know, the first 10-32 seconds). It says that an...
Sep18-13 08:30 AM
12 1,613
I am looking for a derivation of Friedman's equations from the Cosmological Principle and Einstein's field equations....
Nov8-13 08:14 PM
22 2,627
I have been trying to derive the different ultimate 'fates' of the universe from Friedman's equations, for the...
Dec13-13 11:39 AM
George Jones
3 1,304
Hi, all! The camb code is available at in a web...
May26-09 07:55 AM
3 1,206
Hi, there! I'm trying to understand the derivation of (linearized) pertubation equations given in my lecture. As...
Jun4-09 06:07 AM
2 1,243
Okay, I'm not a physicist/cosmologist, but I was wondering about the expansion of the universe. Current theories...
May9-11 05:57 PM
57 6,624
I'm a physics grad student attempting to do a research paper on the social implications of the accelerating universe. ...
Apr7-07 05:57 AM
9 1,684
Hello everybody, (sorry for the eventual Engrish) I can't find any convincing answer for the following question : ...
May17-12 02:20 PM
George Jones
1 1,018
Hello everyone :) The CMB is polarized. I read in Dodelson's book "Modern Cosmology" that we can expect a signal of...
May18-12 08:10 AM
3 1,009
Hello here, I am currently working on the topic of inflation. It seems that at the stage of inflation, the...
Aug23-13 03:15 AM
0 643
Im very new to astronomy and astrophysics, so this may be a very simple question. I read somewhere that astronomers...
Nov18-11 09:27 AM
9 2,958
From what I understand, the expansion of the universe means that sub-lightspeed travel is sort of like running on a...
Dec27-12 04:16 PM
3 1,247
I know this question is quite off the track but while watching a documentary I came across terms 'Universe' and...
Jun20-09 10:30 AM
21 8,086
As the title says, my question is how do we know how old the universe is? Thanks
Mar21-14 09:33 AM
4 562

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