To have an enjoyable cosmo forum we needed a balance between mental freedom on the one hand and a shared knowledge...

Apr814 08:39 AM
Jorrie

483 
125,152 
The new A20 tabular calculator lets you look at changing geometry out to about 88 billion years according to the...

Feb814 08:31 AM
mfb

61 
23,397 
So two of the theories of the universe are the big rip and the big crunch or bounce. Big crunch being expansion of the...

May2113 11:10 AM
Mordred

2 
778 
Why didn't the big bang just become a black hole?
Thanks,
Jake

May2013 08:55 PM
brianhurren

51 
8,047 
I don't know whether this has much general interest. I am interested by communication horizons in cosmology, or causal...

May2013 11:31 AM
Chalnoth

11 
875 
Regarding the creation of the universe and the current model:
Is it assumed that the universe, at the time of...

May2013 01:10 AM
marcus

19 
1,398 
Hi there
Am to teach a lesson on stars and galaxies to my year 7 class on Monday...
Want to brush up on a few...

May1913 11:11 PM
Chronos

8 
748 
By quantitative cosmology I mean with real times, distances, expansion rates, horizons, CMB stationary observers etc ,...

May1813 12:36 PM
Mordred

13 
813 
Hi all,
It is my understanding that a Doppler shift is the result of a change in wave frequency due to a change in...

May1813 05:56 AM
mfb

1 
572 
I'm not a big fan of quintessence, but, this paper is interesting  Quintessence with Hybrid Potential,...

May1713 01:35 AM
Chronos

0 
590 
I have been watching Susskind's lectures on Cosmology which are great. There is something that I can't wrap my head...

May1613 08:57 PM
marcus

4 
735 
The basic equation of GR has a curvature constant Λ on the lefthand (geometric) side.
The Friedman equation is...

May1413 12:08 PM
Mordred

12 
968 
Everyday I sit and think about the universe, and after some thinking I always end up letting my imagination run wild...

May1413 09:08 AM
Forensics

6 
1,186 
Where is the edge/boundary of the universe may sound like a simple question but I can see 3 possibilities.
1...

May1313 05:09 PM
Spourk

133 
7,423 
There's a tutorial wiki for Jorrie's calculator. It needs exercises that beginning learners can do to help them get...

May1213 01:36 PM
marcus

7 
773 
Quick question: is there a general formula for the redshift zC for a photon travelled in a spacetime with arbitrary...

May1013 06:11 PM
George Jones

52 
3,788 
I tried out the new version of Lightcone today...

May1013 03:45 PM
marcus

8 
965 
In a sense the universe is its own clock and the pointerhand is the scalefactor, as in:
"when distances were 0.1...

May913 05:18 PM
Mordred

10 
1,097 
I was trying to find an updated view on the plausibility of the Big Freeze. I believe that a couple of years ago, it...

May913 06:57 AM
bapowell

2 
897 
Is it possible for technology to advance such that we can travel back in time and be the ones to set the universe into...

May813 05:13 PM
Vanadium 50

4 
841 
The first stars formed when distances were 9% of their present size.
The solar system began forming when distances...

May813 12:21 PM
Mordred

20 
1,207 
Developing a basic explanatory manual for the Light cone 1.0 calculator. This is as a supplement to give a basic...

May613 01:52 PM
Mordred

1 
574 
Hi.
I read due interest papers in Arxiv. There is many times refereed to so called NBody Simulations.
Is that...

May613 10:25 AM
phyzguy

3 
616 
http://www.youtube.com/watch?v=VZiWKmhuaZE
At about 7:00 he talked about imaginary time. Does that account for...

May513 09:24 PM
Simon Bridge

1 
747 
When the universe was young, and everything was closer together, did the extra gravity cause time to run slower than...

May513 05:48 PM
petm1

20 
1,804 
Einstein discovered that general covariance allows his GR equation to have just TWO gravitational/geometric constants:...

May413 03:32 PM
marcus

5 
837 
My question is what sort of material/matter existed to allow an expansion of the early universe?
It had to be some...

May413 03:00 PM
spark802

8 
785 
It seems as though the contemporary consensus among cosmologists is that the universe is basically flat and Euclidean:...

May413 02:11 PM
WannabeNewton

33 
1,848 
Where did scientists reach so far about this matter? Any who had rejected it?

May413 05:11 AM
M. next

11 
911 
Here is a new paper, and thorough discussion of dark matter: NonBaryonic Dark Matter in Cosmology,...

May313 07:24 PM
Chronos

6 
700 
So if there are as many galaxies in the Universe as is claimed what's the role of interstellar combination of light...

May313 07:18 PM
Chronos

6 
271 
(c^4/(8 pi G))*3*(17.3e9 light years)^(2)
Paste that in the google window, and see what you get.
When I paste...

May313 05:12 PM
marcus

9 
798 
Hi
I rarely have a background in physics (yet!)
But based on my popular knowledge I understand that the Universe...

May313 04:40 PM
marcus

3 
665 
A new paper appeared on the arxiv today suggesting this possibility:
http://uk.arxiv.org/abs/1305.0498
I would not ...

May313 10:32 AM
Mordred

3 
671 
New release of Jorrie's tabular calculator....

May213 08:40 PM
Mordred

4 
778 
Hello everybody! This is my first post!
I was wondering about the fact that we have measure our universe to be flat...

May213 01:47 PM
vattoman

11 
961 
The medium gravitational potential must have been higher in the past than today (assuming constant mass/energy and an...

May113 12:47 PM
Mordred

7 
886 
Experience and conventional wisdom say that whenever there is a really good idea ready to makes its entrance it often...

May113 11:39 AM
Mordred

76 
9,635 
Since Omegalambda is very close to Omegamatter, what could it mean if we assume they are exactly equal to each...

Apr3013 05:40 PM
ftr

7 
913 
I'm interested in the history tables other PF members are getting as they try out Jorrie's online tabulator. What's...

Apr3013 05:13 PM
Mordred

26 
1,927 
How can a black hole have a high entropy state if the matter inside it is in a supercondensed form with maximum...

Apr3013 01:25 PM
jambaugh

14 
1,061 
"Normal" matter makes up about 5% of the mass/energy content of the universe. From studying this 5% we have discovered...

Apr3013 12:55 PM
Haelfix

2 
618 