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Quality answers to common cosmology questions
Jun25-11 08:50 PM bcrowell 

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- The origin, evolution, structure and eventual fate of the universe.
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To have an enjoyable cosmo forum we needed a balance between mental freedom on the one hand and a shared knowledge...
Apr8-14 08:39 AM
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The new A20 tabular calculator lets you look at changing geometry out to about 88 billion years according to the...
Feb8-14 08:31 AM
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So two of the theories of the universe are the big rip and the big crunch or bounce. Big crunch being expansion of the...
May21-13 11:10 AM
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Why didn't the big bang just become a black hole? Thanks, Jake
May20-13 08:55 PM
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I don't know whether this has much general interest. I am interested by communication horizons in cosmology, or causal...
May20-13 11:31 AM
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Regarding the creation of the universe and the current model: Is it assumed that the universe, at the time of...
May20-13 01:10 AM
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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...
May19-13 11:11 PM
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By quantitative cosmology I mean with real times, distances, expansion rates, horizons, CMB stationary observers etc ,...
May18-13 12:36 PM
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Hi all, It is my understanding that a Doppler shift is the result of a change in wave frequency due to a change in...
May18-13 05:56 AM
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I'm not a big fan of quintessence, but, this paper is interesting - Quintessence with Hybrid Potential,...
May17-13 01:35 AM
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I have been watching Susskind's lectures on Cosmology which are great. There is something that I can't wrap my head...
May16-13 08:57 PM
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The basic equation of GR has a curvature constant Λ on the lefthand (geometric) side. The Friedman equation is...
May14-13 12:08 PM
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Everyday I sit and think about the universe, and after some thinking I always end up letting my imagination run wild...
May14-13 09:08 AM
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Where is the edge/boundary of the universe may sound like a simple question but I can see 3 possibilities. 1...
May13-13 05:09 PM
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There's a tutorial wiki for Jorrie's calculator. It needs exercises that beginning learners can do to help them get...
May12-13 01:36 PM
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Quick question: is there a general formula for the redshift zC for a photon travelled in a spacetime with arbitrary...
May10-13 06:11 PM
George Jones
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I tried out the new version of Lightcone today...
May10-13 03:45 PM
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In a sense the universe is its own clock and the pointer-hand is the scalefactor, as in: "when distances were 0.1...
May9-13 05:18 PM
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I was trying to find an updated view on the plausibility of the Big Freeze. I believe that a couple of years ago, it...
May9-13 06:57 AM
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Is it possible for technology to advance such that we can travel back in time and be the ones to set the universe into...
May8-13 05:13 PM
Vanadium 50
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The first stars formed when distances were 9% of their present size. The solar system began forming when distances...
May8-13 12:21 PM
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Developing a basic explanatory manual for the Light cone 1.0 calculator. This is as a supplement to give a basic...
May6-13 01:52 PM
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Hi. I read due interest papers in Arxiv. There is many times refereed to so called N-Body Simulations. Is that...
May6-13 10:25 AM
3 616 At about 7:00 he talked about imaginary time. Does that account for...
May5-13 09:24 PM
Simon Bridge
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When the universe was young, and everything was closer together, did the extra gravity cause time to run slower than...
May5-13 05:48 PM
20 1,804
Einstein discovered that general covariance allows his GR equation to have just TWO gravitational/geometric constants:...
May4-13 03:32 PM
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My question is what sort of material/matter existed to allow an expansion of the early universe? It had to be some...
May4-13 03:00 PM
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It seems as though the contemporary consensus among cosmologists is that the universe is basically flat and Euclidean:...
May4-13 02:11 PM
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Where did scientists reach so far about this matter? Any who had rejected it?
May4-13 05:11 AM
M. next
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Here is a new paper, and thorough discussion of dark matter: Non-Baryonic Dark Matter in Cosmology,...
May3-13 07:24 PM
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So if there are as many galaxies in the Universe as is claimed what's the role of interstellar combination of light...
May3-13 07:18 PM
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(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...
May3-13 05:12 PM
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Hi I rarely have a background in physics (yet!) But based on my popular knowledge I understand that the Universe...
May3-13 04:40 PM
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A new paper appeared on the arxiv today suggesting this possibility: I would not ...
May3-13 10:32 AM
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New release of Jorrie's tabular calculator....
May2-13 08:40 PM
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Hello everybody! This is my first post! I was wondering about the fact that we have measure our universe to be flat...
May2-13 01:47 PM
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The medium gravitational potential must have been higher in the past than today (assuming constant mass/energy and an...
May1-13 12:47 PM
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Experience and conventional wisdom say that whenever there is a really good idea ready to makes its entrance it often...
May1-13 11:39 AM
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Since Omega-lambda is very close to Omega-matter, what could it mean if we assume they are exactly equal to each...
Apr30-13 05:40 PM
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I'm interested in the history tables other PF members are getting as they try out Jorrie's online tabulator. What's...
Apr30-13 05:13 PM
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How can a black hole have a high entropy state if the matter inside it is in a supercondensed form with maximum...
Apr30-13 01:25 PM
14 1,061
"Normal" matter makes up about 5% of the mass/energy content of the universe. From studying this 5% we have discovered...
Apr30-13 12:55 PM
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