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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
493 165,717
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 44,748
Yes, I have heard the theory Ė judging by the distance we know how old the coming picture is. However I donít...
Oct4-11 10:15 AM
11 2,092
Because AGN (active galactic nuclei) are so bright, it would be nice if we could tell their intrinsic luminosity or...
Oct2-11 06:00 PM
3 1,560
In today's Physics ArXiv: FROM TIME TO TIMESCAPE – EINSTEIN’S UNFINISHED REVOLUTION Dark Energy as simply a...
Oct1-11 05:27 AM
74 8,074
I'd like to understand accelerating expansion better. It seems that space is interjected proportionately where there...
Oct1-11 02:16 AM
Ken G
14 2,611
I came across a startling position on more than one occasion while reading "The Fabric of the Cosmos: Space, Time, and...
Sep30-11 04:58 PM
Jocko Homo
47 7,061
Somewhere, I read about the "Big Rip Theory". Has anyone here heard about the Big Rip Theory? Joe L. Ogan
Sep30-11 08:54 AM
10 4,319 quote: The velocity anomaly recently reported by the...
Sep30-11 08:02 AM
Vanadium 50
1 1,226
Does it make sense to visualize dark matter as roughly spherical, or oblate, around a spiral galaxy? Perhaps...
Sep30-11 02:08 AM
2 1,421
dear all, i want to know that is time exist before big bang , if yes then what is actual origin of time and if no...
Sep29-11 08:41 PM
Lost in Space
31 4,913
If the big bang occurs at the first moment of time, then how can there be a multiverse?
Sep29-11 07:21 PM
10 2,659
Please be patient with me. Cosmologists compute all the way back to the big bang when there was just a very...
Sep27-11 05:03 PM
40 4,250
I was just watching a television program about gravity today and it got me wondering what gravity was exactly. Most...
Sep27-11 07:55 AM
Vanadium 50
3 1,096
Hi, I read in a book by M. Kaku: "To describe the universe, cosmologists sometimes use the example of looking...
Sep26-11 09:01 PM
7 2,414
Present critical density of Universe rho_crit = 3 H^2 / 8 Pi G H = Hubble Constant = 2.2E-18 sec^-1 rho_crit...
Sep25-11 10:34 AM
3 1,877
The cause-effect relationship of timelike events is fairly self-evident. But I was wondering, do non-local effects...
Sep20-11 02:12 AM
1 1,793
Consider a thought experiment for a moment that hopefully does not violate Physics Forums rules... A sphere is...
Sep19-11 07:41 PM
2 1,608
Hello friends! Forgive me, I have another question for you physicists. We see those active galactic nucley which show...
Sep19-11 03:17 PM
5 1,603
I have read a few threads on here and acknowledge i am way out of my depth. Bearing in mind my limited knowledge can...
Sep19-11 01:00 AM
19 2,942
I've always wondered how they know all that stuff, you know, what happened in the first second of the universe. I've...
Sep18-11 06:04 PM
Vanadium 50
8 2,134
I realize BBC science news is not a totally reliable source, but I'm wondering if any of the knowledgeable folks here...
Sep18-11 11:44 AM
5 2,507
Life on earth has existed for around 3 - 4 billion years and Earth itself has been around for about 4.5 billion years....
Sep17-11 11:49 AM
1 1,812
I am in the process of putting together a presentation on the evolution of the universe for novices and beginners. In...
Sep17-11 09:07 AM
1 1,031
Hello, friends. I read that polar anisotropy of the CMB shows that the solar sistem is moving towards the Virgin...
Sep17-11 08:35 AM
20 3,280
Sep17-11 04:02 AM
3 1,547
I know that typical Black Holes dont feed on Dark matter because they are tiny, so the direct hit is unlikely. While...
Sep17-11 02:44 AM
8 1,915
Would gravitational waves act just like other types of waves? IE can they interfere, diffract, etc? I would assume no...
Sep16-11 05:36 PM
20 2,911
Hello guys/gals, I understand this is a probably a stupid/impossible question in yalls eyes, but considering that...
Sep16-11 06:46 AM
11 1,899
I haven't yet. I heard about it on the Cosmic...
Sep15-11 06:26 PM
3 2,338
I'm currently trying to reassess my image of the BB and the universe in general. I've been led to...
Sep15-11 08:21 AM
34 3,374
I have a puzzle when I study the hybrid inflation model. Suppose we have two scalar fields, \phi_1 and \phi_2...
Sep14-11 10:12 AM
5 2,018
Any galaxy that we can see, must have been travelling at less than light speed when the photons that we now see,...
Sep13-11 03:31 PM
57 9,373
In this thought experiment the sun does not run out of fuel and the earth is still here. So in 14 billion years we...
Sep13-11 03:06 PM
5 1,751
So, if space expands (measurements gets larger) in the presence of low mass, as between galaxies but not within...
Sep12-11 11:14 PM
2 1,223
There was a thread here a few minutes ago, posted by a new user, called "Thoughts about the universe". It contained...
Sep11-11 02:48 AM
mitchell porter
26 3,750
where did the freidman equation come from?
Sep10-11 09:52 PM
7 1,340
The title pretty much sums up what I am not comprehending. At about the time when atoms stopped forming I am asked to...
Sep10-11 11:03 AM
6 1,712
Had our observations shown shown that the Universe was not expanding, and was instead static, where would that have...
Sep9-11 07:20 PM
4 1,827
Is there a known quantity of CMb phtons? Presumably we can only recieve a finite amount in our detectors, but is that...
Sep9-11 02:28 PM
Cosmo Novice
8 1,813
Dear all, As u know, one of the best potentials for quintessence is V=^\alpha] \phi]^\alpha] They usually call...
Sep9-11 12:33 AM
4 1,769
Hi, I have lots of questions, they occured to me last year during the physic/chemistry class and I asked the teacher...
Sep8-11 06:06 PM
8 1,659

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