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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...
Aug2-14 07:51 PM
marcus
493 167,757
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 45,915
How much is it feasible for us to send some probe/s to the event horizon of a black hole? Perhaps Voyager will...
Oct19-13 08:10 PM
mfb
5 2,337
Hi everyone, Can anyone point me into the right direction on how to compute the deceleration parameter (##q_0##)...
Oct19-13 06:11 PM
roam
5 884
Now I think there are arguments for the Fine Tuning of the universe. I like Martin Rees' book but I know there are...
Oct19-13 05:49 PM
MrAnchovy
12 1,089
Hello, We know that according to Hubble's law V=HD that velocity of distant galaxies are proportional to distance...
Oct18-13 03:02 PM
mfb
3 795
I recently received a private communication that raised this question? I find that I personally cannot imagine the...
Oct18-13 09:16 AM
us40
31 26,271
Hello, According to Stephen Hawking no boundary condition universe does not have any boundary in space time.If it...
Oct17-13 01:21 PM
bapowell
5 1,042
I've tried to google the answer but either I'm not reading it clearly or there is no actual answer, but is space...
Oct15-13 04:08 PM
Tanelorn
30 46,280
If space is expanding like balloon and it disappears wrinkles on surface than after sometimes surface will become...
Oct15-13 12:11 PM
Adam_Smith
4 925
After the Big Bang the matter of the universe started to condense and we ended up with matter built up of neutrons,...
Oct15-13 11:49 AM
mfb
1 1,192
Hi all! In Ruth Durrer's book "The Cosmic Microwave Background" there is this picture (Fig. 5.2 page 193) about the...
Oct13-13 05:06 PM
fairy._.queen
10 2,355
Hi Guys, Just finished watching an episode of Through the Wormhole, where they discuss the Big Bang Theory. I must...
Oct12-13 08:01 AM
D H
27 19,517
Why is photon gas pressure = photon energy density (per volume) divided by 3? Thank you
Oct11-13 08:07 PM
andrewkirk
5 3,647
If the universe is a 3 dimensional (plus time) space expanding into something, what is that something? Am I correct...
Oct9-13 11:40 PM
Genocide
2 1,220
] arXiv:1310.2072 Intermediate inflation from rainbow gravity John D. Barrow, Joao Magueijo Subjects: Cosmology...
Oct9-13 09:17 PM
UltrafastPED
1 946
Is dark flow evidence of other universes?
Oct9-13 08:37 PM
Chronos
2 804
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 7,126
Suppose gravitons do leak into Calabai Yau spaces thereby dragging 3 dimensional space in with them and suppose in the...
Oct7-13 04:13 AM
ZapperZ
13 2,989
Does a FRW universe with the equation of state: $$p = -\frac{\rho c^2}{3}$$ have a singularity at the Big Bang?...
Oct5-13 12:42 AM
Chalnoth
2 2,245
I'm confused about the relationship between two seemingly different concepts of flatness of the universe. 1....
Oct4-13 05:27 PM
Chalnoth
7 4,480
Why Yab=Xab-kHab+k2HacHcb-... and not Yab=Xab-kHab+(1/2)k2Haccb-...? Y is the curved space-time metric X is the...
Oct4-13 04:00 PM
maica
6 1,784
When we 'look' at blackholes, we see matter being sucked into it and compressed to an infinitely dense point, a...
Oct4-13 12:00 PM
mfb
1 1,071
Most people here I think will agree that in order to understand what happened at the big bang we most likely need a...
Oct4-13 02:04 AM
skydivephil
2 1,585
It makes no mathematical logic to say the universe started with a minute pinhead sized mass that suddenly exploded and...
Oct3-13 03:35 PM
Khashishi
3 1,656
Hi, I can't visualize how the universe could be infinitely flat according to the big bang theory... The only way...
Oct2-13 10:01 PM
Chalnoth
10 7,165
So for my physics class, we are trying to find modern applications for different areas of research. I know the HST had...
Oct1-13 04:05 AM
Bobbywhy
2 1,740
So the observable universe is flat overall but warped (compressed) in locations of gravitational fields. Is it the...
Sep30-13 05:13 PM
Drakkith
11 2,104
In the far distant future, will all of the stars in a galaxy be pulled into one giant black hole in the center? Are...
Sep30-13 10:21 AM
Chalnoth
2 2,280
If a small round black hole is traveling normal to the center of the major plane of a larger toroidal black hole, is...
Sep28-13 09:32 PM
Drakkith
34 11,733
Suppose space is expanding in the universe, then there must be void outside the universe. If this theory is true, what...
Sep28-13 02:36 PM
D H
7 1,310
Planck CMBR data...
Sep27-13 04:00 PM
mfb
6 1,406
Are gravitons and gravitational waves analogous to photons and EM radiation?
Sep25-13 08:28 PM
Drakkith
6 1,863
Not everyone likes the idea of Universe ​​created from a point singularity, so recently grows in popularity the cyclic...
Sep24-13 09:12 PM
bapowell
3 2,901
I'd just like to preface by saying that I'm not in any way an expert on high-level physics, but I would like to think...
Sep24-13 09:21 AM
Chalnoth
7 2,348
A short but interesting way of using the CMBR to test the quatization of gravity, what do you think ? Lawrence...
Sep23-13 04:29 PM
mfb
1 984
This is a phrase I keep seeing dicussed in cosmology papers, can anyone give a summary of what "Galileon cosmology"...
Sep23-13 08:59 AM
skydivephil
2 937
Dark Energy is said to be present in order to drive the observed acceleration of the expansion of the universe and...
Sep22-13 12:50 PM
Astronuc
9 2,067
http://arxiv.org/abs/1309.1487 Out of the White Hole: A Holographic Origin for the Big Bang Razieh Pourhasan,...
Sep20-13 12:41 PM
Chalnoth
8 2,655
Hi, Are Einstein's field equations without the cosmological constant scale invariant? If so does the addition of...
Sep20-13 07:17 AM
TrickyDicky
10 1,599
One version of the multiverse suggests that our bubble universe came from a progenitor universe and that our universe...
Sep20-13 05:05 AM
skydivephil
5 1,200
It could be possible for a driven vacuum bubble (like an Alcubierre drive,assuming that it could be possible to...
Sep19-13 01:41 PM
Chalnoth
1 943

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