Cosmology Definition and 917 Threads

"APS Physics" view of pre-inflation cosmology article The APS has an online periodical that publishes "Viewpoints" on current research, for instance http://physics.aps.org/articles/v5/142 is an interpretive explanatory viewpoint, written for non-specialists, on the article by Agullo Ashtekar...

I have a few questions so I hope it is okay if I ask them all here in this thread. They are all related somewhat. According to brane cosmology, our 4-D universe is embedded inside a higher dimensional space, a hyperspace if you will, called the bulk. The reason we cannot perceive or interact...

Homework Statement Decide the density parameter from the following data: z=0.04, m= 17.38 and σ=0.19 Homework Equations Definition of the density parameter: Where p0 is the current density and pc is the critical density. The Attempt at a Solution I feel like I don't...

Homework Statement Show that by using the Friedmann-equation you can determine the scale factor for a Universe in it's early stages (starting with the Big Bang) to: Homework Equations The equation for the scale factor: Where r(t) is the distance from us to a given galaxy to the time t...

In brane cosmology how can there be no such thing as inflation. I was watching a lecture with Neil Turok and he said he made a bet with Hawking that says that the new Planck satellite will give us information that could prove against inflation. So, my question being, instead of inflation in the...

Hi there, the full question is as follows: Suppose omega_m = 0.2. If we observe cosmic acceleration at z=0, what is the possible range of values of q_0? What is the minimum value of lambda? What is omega_total? so I'm having trouble with the relationship between q_{0}, \Omega_{m,0}, \lambda...

The recent report from the South Pole Telescope seemed to several of us to be exceptionally interesting making one think we might have a thread that just lists recent papers, as they come out, which seem as if they might be important to cosmology. Here are a few. http://arxiv.org/abs/1210.7231 A...

There's an interesting conference taking place this month at the NORDITA institute for theoretical physics in Stockholm. It brings together, from a number of different areas, researchers working on various models of what was happening around the start of expansion--replacing the "singularity"...

A friend of mine was reading Penrose's new book on CCC; I do not want to discuss this story here but a rather interesting detail which could be relevant w/o the whole CCC stuff. SR and GR rely on (global and local) Lorentz invariance. From these symmetries one can derive invariant mass M² and...

Starting with the Robertson-Walker metric \large ds^2 = -dt^2 + a^2(t) [ \frac{dr^2}{1-kr^2} + r^2(d\theta^2+\sin^2\theta d\phi^2] Consider a light ray emitted at the Big Bang traveling radially outwards from our position. Therefore we have: ds = 0 d\theta = d\phi = 0 Substituting...

When talking cosmology what exactly is a manifold, is there any observational evidence that we live in one ?

I’m a layman new to the Cosmology Forum and just finished reading through the very helpful, “Effort to get us all on the same page (balloon analogy anyone?)” by Marcus et. al. followed by “Look 88 billion years…”. [If you’re in a hurry see the nice summary by Mark M at cosmo.pdf.] Along the...

Hi. I'm an undergraduate student interested in cosmology. Initially, it was astrophysics, and I know it's a large field and I'm generalizing, but I felt a lot of the work was statistical analysis and letting the computer crunch images and letting it do things for you. I know a lot of...

In a serious thread, a newbie brought up Carmelian cosmology and clearly thinks it's meaningful but in the brief look I gave it, it looks like nonsense, which is why I put this post in Skepticism & Debunking. Any thoughts? Thanks EDIT: Never mind. I spent a few more minutes looking at it...

Hey guys, I am currently in year 12 and have been asked to develop a thesis on cosmology for an Extended research task (ERT) and I am bewildered. Nothing is coming to mind at the moment and I am struggling. I have no idea what to do mine on. the teacher gave us a list of topics that we might...

There have been a few threads of late on the multiverse concept in cosmology, and whether it can be viewed as a viable, albeit currently underconstrained cosmological theory that is leading us to demonstrably correct discoveries about our universe, or if it is essentially a fairly arbitrary...

hi i am looking at uni courses and i a a bit confused between the differences between; astrophysics, astronomy, cosmology and space science in terms of what is covered in each . Can anyone help please. Ryan

Hello, I am a 12 years old in 6th grade. It's been my dream (since I was five) to become a cosmologist. Sadly at school we do not learn about cosmology, because of "religious" reasons. I would greatly appreciate it if anyone would know where there is a beginners area for cosmology.

Hello everyone, I am a student in particle physics and cosmology in some Belgian university. I'll finish my master degree in June of this year. I am searching for PhD studentships in Europa or US, but it is very difficult to get a place somewhere. I applied to some universities, I'm still...

I am working on an introduction to cosmology, I have began by the Newtoniant one (the Hubble law, the Friedmann, fluid and acceleration equations), and some of the aspects of the relativitic one. I want to relate the tow parts by mentioning the shortcomings of the first, and then mentioning the...

I should start a new thread for my questions rather than hijack others... Posted this on another thread but it didn't get any response, so bear with me if you've seen it. Has anybody looked into Cantor's works on infinity and seen how they relate to the question of an infinite universe...

Besides having the best academic record and publications, what else can one do to improve his chances to be accepted to this prestige club? Just a dream... :-(

What is the difference between Astronomy, Astrophyics and Cosmology?

I'm a Physics Senior in the United States. I would like to participate in an Undergraduate Research Program in the UK this summer. I've applied to several here in the US, but I'd enjoy a pretense to both further my studies of novel space-time geometries using non-FRW models and visit some some...

Hello. What are some good books for learning cosmology? I know GR (At the level of Schutz) And /some/ QFT. So...How much particle physics/QFT are required for a book like Weinberg or Dodelson? Should I do my QCD and Electroweak theory and particle physics before doing cosmology?

What do I need to know before I can study Cosmology. I think I'm going to read this text: https://www.amazon.com/dp/0198526822/?tag=pfamazon01-20 Cosmology by Steven Weinberg. I'm going to read this College Physics text first by Serway...

Hi, I have one question about the expansion of the universe. Say, that there is a part which is that far away that we can't see it any more more because the speed of light is succeded. Wouldn't this mean that those part of the universe has no more influence on us at all? In ohther words...

I was wondering whether I should brush up on ode's/pde's or just go through the math appendix of Griffiths to prepare myself. How much ode's/pde's is needed for Griffiths and Ryden? Thanks

Hello, I am a first year undergraduate student at University of Toronto planning to pursue cosmology as a field of study in the future. There are currently two specialist programs being offered that relate to my interests (unfortunately, I was unable to find a direct link to the programs, so...

In equation below 〖H₁〗^2/〖H₀〗^2 =Ω₀(cri) (R₀⁴)/(R₁⁴(1+z(eq))) Why is the term “(1+z(eq))” negligible in denominator according to the term “ R₁⁴ ” ? Weinburg did it in his book named "Cosmology".

First MOND was the first to predict the cosmic background radiation, as repeated in this recent article (2011) http://prl.aps.org/abstract/PRL/v106/i12/e121303 in its page 121303-3: Whereas the LCDM-1999 prediction was falsified (A1:2 = 1.8). Only after the WMAP data was known (A1:2 = 2.34 ±...

Hello, Has anyone read any good or interesting Cosmology books lately? Thanks

Hi, I am currently reading Liddles Introduction to Modern Cosmology (2nd Ed) and having trouble with problem 8.4, about the age of the universe with a cosmological constant. The question asks to derive the formula for the age by first writing the Fridemann equation in such a model as...

As someone trained in IT, having spent 15+ years as a network consultant, it sometimes surprises me that people expect you to be an expert in other areas of IT. I know networks and subnets, protocols, infrastructure, network security, data packets, switching, wireless and related things - that...

I am currently in first year physics at university. I have looked at lots of courses that my university offers (u of Manitoba), and at many others, and I can't find any many undergrad courses, just astrophysics courses. None of the other universities that I have checked have degrees in physics...

Is there a current list of the major problems or conflicts with the standard cosmology models?

My ongoing study of https://www.physicsforums.com/showthread.php?t=483871" that this has something to do with the fact that the shear viscosity to entropy ratio of a strongly coupled N=4 super-Yang-Mills plasma is 1/4π. Sheppeard has her own program of deriving field theory from categorical...

Once I read a famous quote from a science book, but I do remember the name of the book, neither the name of the speaker. The general idea of the famous quote is that, "All the knowledge we have are in principle some parts of cosmology." It implies that since all the phenomena we see are parts...

Hi all, I am new here. Can you please give me a list of good conferences for publishing cosmology related papers?

which journal specifically i have to hope a little time for a response of acept or reject? and , where the time of to hope is big?

Gravity, information, and cosmology (was "Thoughts about the universe") There was a thread here a few minutes ago, posted by a new user, called "Thoughts about the universe". It contained reflections about gravity, information, and the universe, that were probably inspired by the holographic...

Should I study cosmology? Am I too old?? Hello eveyone, Im 24 years old. I wasted a lot of time before. I've just finished the 1st of university. Then I left. I regreted what I've done before. Cuz I looked for wrong things all the time. Since last year, i started reading lots books about...

i want to study cosmology,and i am going to apply this year. i am not qualified for the top 20 universities' Ph.D program, and i think i should apply some universities ranking from 30 to 100, i mean , ranking of physics, but still strong enough in theory cosmology. however, i have no idea...

Just curious as to what you think about this recent paper from Max Tegmark: How unitary cosmology generalizes thermodynamics and solves the inflationary entropy problem Abstract: "We analyze cosmology assuming unitary quantum mechanics, using a tripartite partition into system, observer...

Since the second law of thermodynamics builds upon the first, if the first law doesn't apply to cosmology like it keeps being repeated around here, it would seem to follow that that the second law doesn't apply either. Could this be clarified by someone tat actually knows about cosmology...

Sorry if this has already been discussed, i couldn't find any thing.arXiv:1108.0893 (cross-list from gr-qc) [pdf, ps, other] Loop Quantum Cosmology: A Status Report Abhay Ashtekar, Parampreet Singh Comments: 136 pages, 15 figures Subjects: General Relativity and Quantum Cosmology...

Let us consider the cosmological metric: {ds}^{2}{=}{dt}^{2}{-}{[}{a}{(}{t}{)}{]}^{2}{[}\frac{{dr}^{2}}{{1}{-}{k}{r}^{2}}{+}{r}^{2}{(}{d}{\theta}^{2}{+}{sin}^{2}{(}{\theta}{)}{d}{\phi}^{2}{]} -------------- (1) For closed models k is positive We shall consider here a closed one: We write...

In <Cosmology> written by Weinberg, in page 109, it says that \epsilon=\alpha_{B}T^4+\frac{3}{2}n_{B}Nk_{B}T p=\frac{1}{3}\alpha_{B}T^4+n_{B}Nk_{B}T \alpha_{B}T^4is the average energy density of black-body radition, then what does \frac{3}{2}n_{B}Nk_{B}Tmeans? the energy density of...

Homework Statement Calculate the comobile distance of a galaxy with z=7.3, H_{0}=72 km/s/Mpc, universe with \Omega_{0}=\Omega_{0,m}=1 Calculate the scale factor when the galaxy emitted the light we receive today. Homework Equations Friedmann equation (\frac{\dot{a}}{a})^{2}=(H_{0})^{2}[...

This article : http://www.sciencedaily.com/releases/2011/06/110630111540.htm claims to rule out "some" string and loop models but doesn't really elaborate, I couldn't find that claim in the original article: http://arxiv.org/abs/1106.1068 anyone care to discuss?