Cosmology Definition and 915 Threads

What exactly is going on in physics and with the standard model of cosmology? We had a model that seemed to describe in absolute perfection the workings of the universe, but over the last few decades observations have been made that explicitly counter what's expected from general relativity...

Hi all. I have been applying for graduate (research) studies in Astrophysics (I am interested in cosmology - CMB, SNIa, models...) at some UK universities - Imperial College, Durham, Glasgow, Manchester. All of them have research groups in the field of cosmology. So far I have received an...

I have been reading Kip Thorne's marvelous book ""Black Holes and Time Warps" to familiarize myself with general relativity. Along the way, I have found he discusses many fascinating cosmological topics that I would like to explore further. I am looking for books about the various types of...

OK, I have a plan to learn this summer after all of my exams will end, some subjects in physics and maths (GR,QFT, measure theory,DG and some random matrix theory, not sure if this plan is tangible, I'll try), so for GR I think of using Wald's and A First course in GR, maybe I'll also look at...

Henderson gives a good talk. He's been working with Abhay Ashtekar on reformulating loop cosmology as a spinfoam-like path integral---also using GFT (group field theory) where a parameter shows up that may have physical interest (possible connection with the cosmological constant). He got...

Is evolution (Darwinian) considered part of the science of cosmology? or would that be another subject entirely?

I'm confused a little bit by this and have a few questions. I wasn't sure where to put this because it's kind of a relativity question (time dilation) and a cosmology question combined. From what I understand, all galaxies are moving away from us. But isn't the Andromeda galaxy eventually...

cosmology strings vs loops How well does string cosmology account for inflation, CMB, gravitational waves, evolution classically using FRW metric? does string cosmology offer either qualitative or quantitative predictions? This paper addresses these in the loop framework...

Curvature Cosmology is a cosmology based on two hypotheses. The first, curvature redshift, is an interaction between photons and curved spacetime and produces the observed Hubble redshift. It can also explain the anomalous Pioneer 10 acceleration. The second, curvature pressure, is a...

¿Cosmology or Theoretical Physics? I have a dilemma. I have an offer for Cosmology and I have an offer for Theoretical Physics. I'm ofcourse aware of both fields, but I would like to know from you what their main differences are. Thank you!

2 galaxies are "moving" away from each other due to the expansion of space, if each is moving away at 3/4 the speed of light relative to the other would they not be moving faster than light relative to each other? Is the expansion of space limited to 1/2 light speed ? Does the law of non...

Homework Statement The fluid equation in cosmology is given as: \dot{\epsilon} + 3*(\dot{a}/a)*(\epsilon+P) = 0 Where \epsilon is the energy density and a(t) is a scale factor. Using the equation of state, P = w*\epsilon, show how \epsilon change with a(t). Homework Equations...

A pretty loaded title for the thread (I know). I would like to know what are everyone's perceptions/opinions regarding the beginning of the universe (of time) as it relates to the notion of a god or God?

Entropic gravity and cosmology The considerable impact of Verlinde’s recent paper in which he suggests that gravity is nothing but an entropic force has familiarised many with this type of force. Verlinde wrote: The examples he mentions involve constituents in thermal equilibrium with...

What exactly is the difference? The latter does not seem so popular to me? On average how much does the latter earn?

Hey! Can you please recommend me some good and up to date cosmology books? Thanks!

Hi everybody, I would like to chat about the physics of loop quantum cosmology. Let me list a few broad topics I'm interested in understanding better: 1. What simplifications/approximations make loop quantum cosmology a solvable simplification of full loop quantum gravity? 2. How is...

What exactly are the differences between Astronomy, Astrophysics, Cosmology, Planetary Science?

What are the best "2nd tier" physics PhD programs known for cosmology? Thanks

I have a friend asking for ideas for an A or C oriented gift, including things that might be a bit of a scam, like having a star named after you. I know that you can buy land on the moon but that is expensive. Any ideas?

Homework Statement This is what the question says exactly: Assume the universe today is flat with both matter and a cosmological constant but no radiation. Compute the horizon of the Universe as a function of \OmegaM and sketch it. (You will need a computer or calculator to do this).Homework...

Homework Statement At the time of decoupling the universe was 1/1000 of its present size. How for could light have traveled in the time up to decoupling? (assume that the universe was dominated by radiation until then) Homework Equations The Attempt at a Solution I'm a little...

So, I'm interested in the big questions. I guess that leads me towards cosmology - though, quantum or particle physics, or string theory are also tied to the stuff that I want to find out. I'm doing my BS in physics right now and I'm trying to figure out where I want to go for the PhD. I...

My lecturer has written the following:Given \frac{4 \pi \rho a^3 c^2 }{3} and V = \frac{4 \pi a^3}{3} , then substituting \frac{dE}{dt} = -p\frac{dV}{dt} we have: \frac{d(\rho a^3)}{da} = -\frac{3pa^2}{c^2} \leq 0 (1) Ok that part is fine - substitute and use the chain rule: So, if we...

I was reading Roger Penrose's book and he mentions that there are huge amounts of raw data from experiments that haven't yet been fully analysed. Is there a way I can get my hands on this raw data, for cosmology experiments or any other experiments with large amounts of raw data? I know that...

Forgive me if these questions are asked here a lot, but I couldn't find any posts answering them in the first few pages... I'm just starting to learn a bit about cosmology...because I'm currently learning general relativity. I'm just curious, what does it mean to say that the universe has a...

What is the most influential candidate quantum cosmology today? By influential it (a) reproduces known observation, (b) offers speculative ideas in the Planck epoch, (c) professionally researched and published in peer-reviewed journals. I suppose the time line should be 2007-2009 The two I am...

What is the difference of cosmological horizon and particle horizon in cosmology?

Hi all, This question may seem innocent, but I can't see a clear boundary between the two. Who could explain it please. (as short as possible).

Alrite I am sure this question has been asked many times. What do i need to take in college for a future in cosmology? i don't want to waste too much time in school but if i have to I am willing to do it, and i was wondering if a job in cosmology paid well? if so or not how much?? I've also...

Is this unheard or a lot of people do such a thing? I mean if someone like me would like to do research in both areas, but knowing that doing 2 phds is too much (although I have read of a few who have done two phds one in CS and one in maths), I think my compromise would be to do first in pure...

I have trouble understanding the concept of imaginary time. As I understand it (by reading other online sources), imaginary time was developed by Stephen Hawking and Hartle in their theory of quantum cosmology. Quantum cosmology is applying quantum mechanical principles to cosmology as a...

I really know nothing whatsoever about cosmology although I find it very interesting. It seems that a lot of physicists nowadays reckon there's a multiverse. I don't particularly want there to be a multiverse. WHAT DO YOU FOLKS THINK. Also, if there was a multiverse, would the laws of physics be...

Hi everyone, I'm a new member. Just joined tonight, actually. I'm new to physics & cosmology. I'm here to learn as much as I can because it all feels natural to me. Hopefully some of you can better help me understand the basics and help me learn all I need to know. :blushing:

In this PF Cosmo forum context we have to be sensitive/practical about language. How to state cosmo basics, especially to newcomers who may not have assimilated technical terms like "scalefactor" yet. This does not mean we dumb everything to the max! Introductory terms should lay a basis of...

I am a graduate student. I want to study the cosmology, now. Can someone recommend a textbook of cosmology?

What is the difference between Astronomy and Cosmology?

The analogy always used is to draw two points on the surface of a balloon and then blow air in the balloon. The points move away as the balloon expands. The issue I have with this is: now draw a "meter stick" on the surface of the balloon. It expands too, at the same rate, so that the number...

I just happened to notice a way to gauge the degree of research interest in cosmology---which I think has something to do with its importance in uncovering new physics. What this does is search Stanford's Spires HEP database for the overall most highly cited physics papers that have appeared...

Homework Statement Title should be: ELectromagnetic signals in cosmology. \int\frac{d\rho}{\sqrt{1-k\rho^2}}>=-\int\frac{dt'}{a(t')} The integrals being from r1 to r and t1 to t respectively. I can't understand the need for the prime here. Could someone explain to me the significance of...

Hey people. I hold an Astrophysics Msci (undergraduate masters) at 2:1 in the UK, and I'm currently preparing to apply to PhD programmes in 6-7 months time. I have a few questions. I'm interested in theoretical cosmology, and theories of galactic evolution - I'm looking for good universities...

Hello everybody! I'm about to make an important decision concerning my PhD, and I'm totally lost. Here is my situation: I'm about to finish my MSc in physics (cosmology) in my home country (which is neither in the USA nor in Europe). I suppose my university is quite good by international...

I'm looking for a comprehensive introduction to cosmology at the upper undergrad or grad level. Any suggestions? I took out Narlikar's (An introduction to cosmology) book from the library, and it looks alright, but I would like some suggestions on other books as well.

Hi All Let's assume the Universe's topology is a standard hypersphere (i.e. it's finite) and it's only a bit over-dense (Ωo = 1.02 - 1.01.) Say it has a mass-energy break-down like our own, 27% matter and 73% cosmological constant. In that case how do we work out its current radius? Can it...

Hi! I'm a law and business student in Brisbane, Australia and have recently developed a keen interest in cosmology, physics and all the rest of it! I am sorry to not pose an intellectual question of the calibre of the other "newbie" :) but I am feeling somewhat disconnected from my peers at...

can information be transmitted faster than c in inflationary cosmology where with a large positive cosmological constant, space is itself expanding in an exponential faster than c manner?

Today (17 March) we got our first news of a Path Integral formulation of LQC. Adam Henderson is a PhD student in Ashtekar's group at Penn State. He gave an internationally distributed seminar talk on his research. http://relativity.phys.lsu.edu/ilqgs/henderson031709.pdf...

Hi, to pick up on marcus' https://www.physicsforums.com/showpost.php?p=2015482&postcount=67" in the sticky thread: Recently, I tried to see where this analogy could bring us if evaluated properly, and I was surprised to find that it is actually far better than what marcus pessimistically...

In the last couple of years there'v been several papers on this, often by people I hadn't heard of before. The question came up in another thread "can you summarize in a single post" the various ideas being discussed? Personally I couldn't but I can dig up some links. Toss them out for you to...

Armed with a mass of observations and mathematical equations cosmologists tell us that the universe started with a big bang and that its ultimate fate is,as yet,unknown.Fair enough but now the ordinary person in the street is starting to believe the big bang theory and that we will soon have a...