Cosmology Definition and 915 Threads

Is CCC killed by BICEP2 or there is a way in which it survives?

Hi, Are the multiverses that come up in some cosmological theories, e.g. inflation, in any way related to the worlds in the many-worlds interpretation?

Is there a difference between cosmology and physical cosmology? The two have separate wikipedia pages which seem to say essentially the same thing. Also, cosmology is obviously a branch of physics, so is "physical" redundant?

The ideal gas has the following requirements. 1) there are no intermolecular forces between the molecules. 2) the volume of the gas is negligible compared to the volume of the container they occupy. 3) the interactions between the particles and the container is perfectly elastic (total kinetic...

I am wondering whether discussions of inflationary cosmology in these forums generally includes or explicitly excludes prior Plank era and GUT era dynamics. I never gave it any thought until reading the following. The Wikipedia article provides a perspective I just don't remember from other...

The radical Smolin thread left me wondering if other similar ideas could not be applied to other areas of Cosmology and even Particle Physics. Every complex system I can think of in our lives, and in nature, forms part of a complex multifaceted control system or process, with various feedback...

I am quite a stranger to cosmology, so please go easy on me if what I say below is actually very stupid/ignorant! From the little exposure I've had to cosmology, it seems to me that in cosmology, a lot of approximations are taken, as well as a lot of huge assumptions made. For example, I've...

I wonder, whether cosmology come to an end as quantum, ie. M-theory?

Karami's talk is scheduled for Tuesday 29 October in just a few days. http://relativity.phys.lsu.edu/ilqgs/ The title has not yet been posted. It is a good bet that it will be about one or more of the active topics in Loop cosmology of which there are quite a few. Karami's recent work...

Homework Statement Suppose the sun weighs ##2 \times 10^{30} kg##, calculate the maximum possible number density of stars in the present universe, if all the baryons in the universe were assembled into solar mass stars, and ##\Omega_b = 0.05## today. Homework Equations ##n=\frac{N}{(4/3) \pi...

Most people here I think will agree that in order to understand what happened at the big bang we most likely need a quantum theory of gravity. There do appear to be models of cosmology such as CCC or Baum/Frampton that seem to try and sidestep this requirement, but looking at quantum gravity...

This is a phrase I keep seeing dicussed in cosmology papers, can anyone give a summary of what "Galileon cosmology" is ?

Hi all, first post, just a mechanical engineer with an interest in theoretical physics. I have a few questions about inflationary cosmology that I was hoping some people could help me with. First what exactly is the bowl that inflationary cosmology talks about, I read Brian Greene's Fabric of...

I recently read an article (http://vixra.org/abs/1308.0143) written by an acquaintance, Dr Dimitar Valev and wanted opinions on its relevance . Basically, dimensionless ratios are derived from equations based on both the Planck constant and the Hubble constant. Thus, Quantum Mechanics and...

Hi, everybody. I have some problem with Wald's statement shown in the picture. This is from the last paragraph in Page 178. He claimed that there are only solutions with two of the p_{\alpha} positive and one negative. But it's easy to find out that if two of the p_{\alpha} are negative while...

"Cosmology is the scientific study of the properties of the universe as a whole." That definition seemed concise and straight to the point for both scientist and the public. Everything else cosmology contains seems would be included within that definition. Does anyone here have a better one...

Author: Ta-Pei Cheng Title: Relativity, Gravity & Cosmology: A Basic Introduction Amazon Link: https://www.amazon.com/dp/0199573646/?tag=pfamazon01-20 (submitted by serllus reuel)

This week Skydive Phil released an outstanding 40-minute special on quantum cosmology. It's different. What makes it different from, say, slick science cinematography you get on "Nova" and commercial channels is the Skydive team's "realness"---their intelligent probing interview style. Phil's...

Tom gave an honest assessment just now in another thread of the real situation with LQG which in effect includes the several roads from there to cosmology (eg. Agullo, Alesci, Barrau, Engle, Vidotto, Wilson-Ewing and others). He made a very good point which is that the problems are not...

Hi everyone, I was wondering if you guys could suggest me some good books in cosmology with finely explained WKB method and Perturbations especially in Structure formation area. I have "The early universe" by Klob and Turner and "Cosmology" by Weinberg , but they seem unpalatable at first...

Hey everyone, I wanted to share this new interview I found with Roger Penrose wherein he discusses his theory of conformal cyclic cosmology: http://www.ideasroadshow.com/issues/roger-penrose-2013-07-12 I was wondering, are you convinced by his theory? I find it intriguing but I'm...

Hello folks, I am from Hong Kong studying in a university in HK, major in Physics. Next year will be my final year of undergrad (3 yr undergrad program) and I am considering applying for graduate schools in the US. My major research interests lie on particle physics and particle physics...

I approach this cautiously but with interest. (How often do ideas like this work out?) http://arxiv.org/pdf/1307.1848v1.pdf and suggest you jump immediately to page 24 where there is a suggestive graph, Figure 1. ==quote page 24 of Bars Steinhardt Turok 1307.1848== Fig.(1) is an...

So we know that at the moment of the big bang the universe was relatively low in entropy; as the universe has expanded entropy has increased, but what about further down the line? What about when the universe is so cold that it's nothing more than a collection of black holes, and further more...

The Philosophy of Cosmology is a new field of study at Oxford and Cambridge in Europe, and Rutgers, Columbia, NYU, Yale and UC Santa Cruz in the United States. Apparently they got a million dollar grant from Templeton foundation to create this new field of study. I am asking if this...

I am following up Weinberg Cosmology book, but I have one question. In chapter 3.1, we have Eq (3.1.3) and (3.1.4) s(T) = \frac{\rho(T) + p(T)}{T} T\frac{dp(T)}{dT} = \rho(T) + p(T) In Eq (3.1.5), we have the Fermi-Dirac or Bose-Einstein distributions. n(p, T) = \frac{4 \pi g...

In this post, I am going to assume the truth of the standard model of cosmology, which says that the universe is expanding as time progresses from some infinitely compressed state. The paradox[/size] Has anybody heard anything like this? Any thoughts on how to "solve" it?

I'm currently reading "Three roads to Quantum Gravity" by Lee Smolin. In the book he describes attending a presentation by Fay Dowker and James Hartle about the consistent histories approach to quantum cosmology. He describes that, "there were worlds that were classical now that were arbitrarily...

A brief question: I am an armchair cosmologist - or maybe a "wannabe" cosmologist...it's a fine line. I am 47 years old with most of my career in software behind me but, without returning to college to become involved professionally in Astrophysics and Cosmology, I'd like to contribute to the...

I discovered that I have a very strong interest in cosmology and astrophysics but the field seems to be extremely competitive and jobs are very limited. I am thinking of doing aerospace engineering + science combined degree just because doing science alone seems like a gamble as I might end up...

What are the greatest mysteries in Cosmology? Please comment on my list. 1 Complete explanation of black holes, what happens to time and space (worm holes?). 2 Process of symmetry breaking during initial stages of the of the big bang (includes matter/antimatter unbalance). 3 Source and...

I need integrate "over heavy momenta" the following equation \sigma v>= <\sigma v>= \frac{1}{n^{(0)}_1n^{(0}}_2 \int \frac{d^3p_1}{(2Pi)^3 2 E_1} \int \frac{d^3p_2}{(2Pi)^3 2 E_2} \int \frac{d^3p_3 }{(2Pi)^3 2 E_3} \int \frac{d^3p_4}{(2Pi)^3 2 E_4} e^{-(E_1+E_2)/T} \\ \cdot (2 Pi)^4 \delta^3...

By quantitative cosmology I mean with real times, distances, expansion rates, horizons, CMB stationary observers etc , derived from the standard model fitted to data. I don't mean ideas about conditions shortly before or after the start of expansion, although that is very interesting too. The...

This is quite an entertaining 15 minute video that provides a high level discussion for a general public audience. [A physics teacher and childhood friend uses the video in her advanced placement HS physics classes in New York. Her students are one group of US kids that I know get a good...

New release of Jorrie's tabular calculator. http://www.einsteins-theory-of-relativity-4engineers.com/LightCone1.0/LightCone.html this is clearly the best on-line cosmology calculator for the general user on the web. Hands down. Lightcone rules. that's all there is to say. Check it out...

Hello folks My name is Mike. I am into Cosmology ever since I was a kid. Throughout the years I strayed away from Cosmology unfortunately but I am very very fond of Cosmology...and thus...call me an amateur Cosmologist :D Anyway... These days couple of questions puzzle me in the...

Homework Statement The assignment is to find the energy loss constant for the theory of tired light. If redshift isn't caused by the expansion of the universe but from a loss of energy, how much of a photons energy is lost per unit distance(MegaParseC) for some set Hubble constant. Homework...

I am an aspiring physicist. My main interests are Particle Physics, Cosmology and Black hole physics. I am going to join a college this year for the same. I applied to two colleges and got selected. University of Lancaster and University of Birmingham. I have applied for the course - Physics...

This paper; 'What have we learned from observational cosmology ?', http://arxiv.org/abs/1304.4446, provides a good overview on the evidence supporting the LCDM model and why it is currently favored by mainstream scientists. It also offers considerable discussion on the motivation for Dark Matter...

Conspiratorial cosmology - the case against the Universe Sounds pretty serious to me... Garth

I've been looking for a few websites good for Cosmology and Physics, maybe you guys can help? I'm in 8thgrade, but I can comprehend a lot, just try to stay away from websites that have excessive technical math please. All posts are appreciated.

Homework Statement i i am trying to derive \dot{\rho_{R}}+4H\rho_{R}-\Gamma_{\phi}\rho_{\phi}=0 as in Kolb an turner (Boltzmann describing reheating). Is the correct approach to, use the 1st law dU=dQ-pdV, but what would dQ be?

Can anyone explain: why COBE measured IR and microwave as opposed to visible light, when surely we are measuring photons that have decoupled? why Planck is measuring light polarisation?

http://www.perimeterinstitute.ca/seminar/rethinking-cosmology In five days Paul Steinhardt (Princeton) will give a colloquium talk at Perimeter. He has a 90 minute timeslot. Steinhardt has been a proponent of "brane-clash" cosmology. Sometimes called Cyclic or Ekpyrotic. Two spatial...

Is the key difference between coasting and static cosmology models the presence of a linear acceleration, or are there other major differences? Regards, Noel.

I was reading Weinberg's book Cosmology. When I went to chapter 2, under the subsection 2.1 "Expectations and discovery of the microwave background" I could not understand one statement. ---Quote--- The work done by pressure in an expanding fluid uses heat energy drawn from the fluid. The...

In Mukhanov's Physical Foundations of Cosmology p348, he writes "Decoherence is a necessary condition for the emergence of classical inhomogeneities and can easily be justified for amplified cosmological perturbations. However, decoherence is not sufficient to explain the breaking of...

Author: William Lewis Burke Title: Spacetime, Geometry, Cosmology Amazon Link: https://www.amazon.com/dp/0935702016/?tag=pfamazon01-20 Prerequisities: Level:

"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...