Cosmology Definition and 952 Threads

The aim of the thread is to offer a non-technical concrete way of understanding the standard model. Usual metric, equations, parameters are in the background but the focus here is on unmathematical presentation, indicating how key physical quantities could (ideally!) be measured. When I talk...

please suggest good articles on Loop Quantum Cosmology If you have links of good articles and review papers of Loop Quantum Cosmology please post here

The question of the "arrow of time" and increasing entropy is not as clean cut as one might imagine. I think it it R.Penrose that pointed out that while a simple application of thermodymanis predicts the "heat death" of the universe where everything is cold and in thermal equilibrium, there is...

Homework Statement Hi all. The pressure in a multi-component universe is additive, just as the energy-density is: P = \sum\limits_i {w_i \varepsilon _i } \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{\rm{and}}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\varepsilon = \sum\limits_i {\varepsilon _i } But...

Recently the expansion of the Universe has been found to accelerate. When studying Hoyle, Gold and Bondi's Steady State Cosmology, it clearly predicts an acceleration like this. I realize that this theory has been 'put to bed', and abolished, and all the other colorful language people like to...

LQC is the dominant approach to quantum cosmology these days, if you gauge by recent peer-review publication and citations in the professional literature. So anybody who wants to know about quantum cosmology could be well advised to get an introduction to LQC. Parampreet Singh is one of the...

Homework Statement Hi all. When looking at a graph that shows the proper distance at the time of emission as a function of the redshift z in a model-universe with only matter, the proper distance at time of emission has a maximum at about z ~ 1.7. What does this maximum mean? I can see...

I have long been interested in cosmology, and I took a course with the same title in undergrad. We used Liddle's book An Introduction to Modern Cosmology which I thought was pretty good, but it was relatively short. I have knowledge of mathematics and physics up to early graduate level (got my...

[SOLVED] Astrophysics homework: Cosmology Homework Statement I have to show that during the Big Bang Nuchleosynthesis, the scalefactor is approximately given by a(t) = \left( {4H_0^2 \Omega _{r,0} } \right)^{1/4} \sqrt t The Attempt at a Solution Ok, since the BBNS is during the first ~3...

I find myself very interested in Cosmology and would consider doing a PhD in the field, however I am not sure if I would like to be an academic or not. Given the relatively few technical applications of Cosmology, would it be wiser for me to enter a field with greater possibilities for...

I think string theory and quantum loop theory are the instigators in destroying public interest in cosmology, pop articles promised so much ,but nothing emerged, i also think that funding of cosmology projects will decline with diminishing results, it is no fault of the scientist, just bad luck...

Penrose has given this Before the Big Bang talk repeatedly over several years and it has developed. Some new thoughts, new cartoon drawings. Here on YouTube is a version he gave 31 October 2007 at George Mason University (Fairfax, Virginia, near Washington DC). It comes in several segments. The...

Hi! I'm interested in alternative cosmologies and the variable mass hypothesis developed by arp and narlikar seems to explain better the discordant redshifts: but I can't understand how this theory calculates cosmic distances according redshift and time. Narlikar says that " We have here a flat...

Have you read this book (2nd edition), and if so, what do you think of its approach to cosmology? Personally, it is one of my all-time favorite physics books - joyfully understandable, beautifully imaginative and lastingly philosophical.

It is conjectured that we are at an historic watershed when people will stop thinking of the big bang as the Beginning of time or our universe, but will see it as a step along the way. The frontiers of science---what we can model and test---are being pushed back to conditions prior to the onset...

Hi there, I was wondering if anyone had any recommendation on a good grad level cosmology book. Something dealing with more astrophysical things like structure formation. I'm using the Cole & Lucchin book for my class now and am not really a big fan of it. The other books I've found are either...

When I went through a course on Relativity, the professor said that relativity was at its foundation based on the philosophy of logical positivism (i.e., the only meaningful discussion is of observations, no discussion of a larger reality is meaningful), which seems to preclude larger...

The other day I read a rencent article in Scientific American entitled "The End of Cosmology." I have a simple question that I hope someone can clarify for me. Let me first give a brief summary and my understanding of the article. In every direction the universe is expanding, and this...

Greetings, I was an avid amateur cosmologist for a few years, but lost interest 2 years ago. What I recall is a few basics like: 1) Univ is ~13.7 billion years old 2) Univ is accelerating in expansion 3) WMAP measured ~2.75 Kelvin vacuum temp. 4) Space is indeed flat Euclidean...

Is there a modern cosmology textbook as good or better than Scott Dodelson's?

Is cosmology an attempt of the church to highjack science? Is this cosmology the beginning of a new breed of "science" where belief is protected and taught under the name of science?

Hi guys, I'm in a pickle here with an assignment. I'm required to find the redshift at which the energy density in radiation equals the energy density in matter. The following are the givens we were...well, given: 1) assume 1 baryon = 10^9 photon 2) assume all photons have energy to the...

I don't know if this is the appropriate forum for my dilemma, but here it goes: Second law of thermodynamics says that the entropy in the universe increases. In every texbook I have learned, ice is considered to have low entropy. When it melts, entropy increases. When that water becomes water...

Here is the homepage of the event -- to be held from Jun 19 to Jul 05 2008, in João Pessoa, Brazil: http://www.fisica.ufpb.br/eventos/friedmann2008/friedmann2008new2.htm http://www.fisica.ufpb.br/eventos/friedmann2008/friedmann2008new2_arquivos/page0016.htm" are the current scheduled...

Homework Statement So the other day in my cosmology class we talked about whether smaller objects like a solar system, a star or a galaxy expand with the rest of the universe. While the answer is obviously no, since local gravitational forces can overcome that expansion, our professor...

hi. this is probably in the wrong place, but what is the difference between cosmology and astrophysics... i only ask because i wanted to be an astrophysisist, but before i make up my mind for sure i just want to know what cosmology is... thankyou dan

Here is what I have learned ,….. the experiments on “warm dense matter” (WDM) will have impact on Cosmology. Ionized might be a good word to describe the universe prior decoupling. There will be new calculations to try to understand the universe before decoupling (400,000 years) Prior to...

This could be good http://pirsa.org/08010033 ==quote== PIRSA:08010033 Title: Lecture 1 ( Windows Media , Macromedia Flash , MP3 Audio , PDF) Speaker(s): Lee Smolin Abstract: The Problem of Time in Quantum Gravity and Cosmology Date: 09/01/2008 - 7:00 pm Location: 405 URL...

My posts have been rude i am just annoyed that all though i have learned a lot about cosmology i have learned nothing that matters, you guys spend years of hard work doing things only you can, i wish you had a bigger budget to work with, so that theory could be tested, i know you would like...

Our college has just established a new department: laboratory of high energy physics and cosmology. And it is the first in our country. We are first students,too. Can you help me have a general view on cosmology and astrophysics? We only know little about some constellations and solar...

I got as far as Calc 2 in college, took some college physics and read lots of popular cosmology books. What if I want to get technical now? What specific math do I need to know to fast track it without learning things that are irrelevant? It's too late to go back to school now.

well, dear all first i want to introduce myself, i am a mechanical engineer working professionally as a piping stress analyst in a multi-national firm, well cosmology and the things abt the origin of time and space etc seems to be very nice things to study and i am new to them, can u please tell...

At the risk of annoying some people but hopefully also interesting others I would like to mention my new book on the periodic table, which has just been named as one of 7 "outstdanding academic books of the year 2007" in the category for chemistry But the book is as much about physics as it...

I found a video called "how the sun really works" on youtube. Link: http://www.youtube.com/watch?v=ihVaL-FHUyk" Well. This did not make much sense for me. Is there something to be debunked?

:confused: could anyone please help me with this coursework,i am soo confused with maths,thanks 1) Start with friedmann equation for case for flat universe k=0 with mass density total p =p(m) + p(cosmo constant). how can i derive integral relating scale factor to time in form...

Hello, Recently I've been trying to spark my friend's interest on Cosmology, and thus have been browsing the net for documentaries. Apart from BBC Space (which is somewhat outdated now), all the rest are as if scientists are talking to 5 year olds trying to make them understand with ludicrous...

To begin with, I'll let you know I am a student. I am prone to theoretical physics and philosophy over cold, hard, mathematical fact. That being said, I was recently intrigued by a few things I learned regarding the Big Bang Theory. I'm still really shaky on the topic, though, and I could use...

You are given a chance to fly back in time with no worry over changing history in bad ways. Knock knock and you enter a college looking for famous Isaac Newton, age 45, in person. He's a real fun in every way - mechanics, theory of gravity, celestial mechanics, calculus, the queen. Also he...

Hello, I am looking for some of the best books regarding cosmology, parallel universes, time travel, dimensions, quantum mechanics, theoretical physics, etc. for a layman. I am interested in the subject and would love to learn more about it. Any advice of where to get started would be...

MTW section 27.7 states: It then proceeds to derive the relationships: \rho_m a^3 = constant and \rho_v a^4 = constant that pervect has shown before. My question: does this mean one cannot push the basic Friedmann equations that were discussed so exhaustively in the locked thread...

https://www.amazon.com/dp/0198526822/?tag=pfamazon01-20 I wonder if this is an update of his book Gravitation and Cosmology.

Why haven't cosmology and philosophy been formerly combined? They both deal with the beginning of the universe and what it happened, at least one certain field of philosophy. So why not?

The electric universe http://video.google.com/videoplay?docid=4773590301316220374 many claims that challenge main stream cosmology.

Is it possible that a sufficiently intelligent and technologically advanced civilization, at some point in the future, could colonize the entire universe and control it? I mean, could it stop the accelerating expansion of the universe, entropy, proton decay, black holes, etc? Could it create...

Can anyone tell me how far cosmology has advanced beyond Enstein?

arXiv:0709.3102 [ps, pdf, other] Title: Cosmology and the Unexpected Authors: Edward W. Kolb Comments: Two lectures presented at the International School of Subnuclear Physics, "Searching for the 'totally unexpected' in the LHC era," Erice, Italy 2007 Subjects: Astrophysics (astro-ph)...

Ok. I've got to know what you guys think of my pet theory. << URL snipped >> There are some things I'll never understand, like quantum gravity, and the like. But I'm an engineer so I can piece some things together. What I want to know is, what is wrong with my pet theory? There's GOT to be...

American Scientists Online: see full issue: September-October 2007 Other Formats: PDF Modern Cosmology: Science or Folktale? Current cosmological theory rests on a disturbingly small number of independent observations Michael J. Disney...

Hi all, First post here, so hello! Anyway, I am a 16 year old high school student. I have always had an interest in astronomy which led to, over the last few years, an interest in cosmology. I have read a whole lot of 'popular scientist' type material on cosmology, Brief History of Time, ect...

How would the Universe evolve under differing values of c? c being the speed 3 x 10^8 m/s as defined, being the speed electromagnetic, and other massless forces propogate. I'm interested in scenarios where c varies relative to the other constants of nature, I'm wondering if or how the...