Cosmology Definition and 915 Threads

: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 Apart from BBC Space (which is somewhat outdated now), all the rest are as if scientists are talking to 5 year olds trying to make them understand with ludicrous...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.

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...

can anyone give me any information on some good books, online books or lecture notes to help me with university introductory cosmology i have my lecture notes but they are very poor and i find it difficult reading and interpreting what is going on thanks

Here is the Penn State press release http://www.eurekalert.org/pub_releases/2007-07/ps-whb062907.php called "What happened before the big bang" the press release evidently covers much of what you need a subscription to read in Nature Physics magazine, or else have to get it at your university...

By quantum cosmology QC I mean research using a quantized version of the familiar classical Friedman-LeMaitre model used in mainstream cosmology. Quantum cosmology is beginning to have an impact on regular cosmology. It offers answers to certain puzzles and also prospects of testing QC...

If you want an accessible overview of quantum cosmology try this TOC: https://www.physicsforums.com/blogs/hellfire-3727/category/interesting.html Hellfire covers different attempts made since the 1960s, and by comparing them (and showing historical development) makes the whole subject...

From the Review of Mainstream Cosmology thread. Here I have started just such a thread. This thread is not the place to discuss a multitude of speculative ideas, rather it is intended as a discussion of observations that may raise questions about the consensus \LambdaCDM model. I start...

Edit: Thread started at the same time as Garth's on the same topic, go https://www.physicsforums.com/showthread.php?t=170753" instead!

Hello, I am 17 and from England. I have never really been good at maths, I find equations and such difficult to comprehend - this was the reason I decided not to take physics in college but rather art subjects, and luckaly enough for me I have always had an apparent gift when it comes to...

Hi marcus! It seems to me that there are many different approaches, from around the world, that are converging at an accelerated pace. Maybe not? … It might just be my desire to understand minimum length. http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.2397v1.pdf The Quantum Configuration...

CONGRATULATIONS TO Martin Bojowald! http://arxiv.org/PS_cache/arxiv/pdf/0704/0704.1137v1.pdf Lattice refining loop quantum cosmology, anisotropic models and stability Martin Bojowald∗ 09 April 2007 Standard Theory SU(3)xSU(2)xU(1).…. String …. Have not done it. He is the first to...

There's no debate which post-SM approach the vast majority of HEP/particle physicists prefer: string theory. While I don't know what the vast majority of post-SM, post-GR approach cosmologists, astrophysicists, astronomers prefer, loop quantum cosmology or string cosmology, in solving a...

i have 2 questions: 1. what is the difference between astronomy, astrophysics and cosmology? 2. what did Alan Guth mean when he said, "The universe is the ultimate free lunch"?

mm k. So. As lots of other students are at the moment, I am currently preparing for a presentation. My chosen topic: alternatives to the FRLW model. What I'd appreciate from you guys is simple; I've been coming here long enough to notice that everyone has their own little deviations and...

Homework Statement Reading about the raditation dominated era I saw that the radiation energy density today was given by: \rho_r = \frac{\pi^2}{30} g_* T^4 = 8.09 * 10^{-34} g/cm^3 where g_*=3.36 is the degree of freedom of the radiation (equivalent) and T=2.75 K is the CBR...

People might be interested in a new paper, namely Cosmic clocks, cosmic variance and cosmic averages David L. Wiltshire 72 pages, 5 figures http://www.arxiv.org/abs/gr-qc/0702082 which demolishes DE (yet again!).

I am an public health/environmental student... I'm never taken any philosophy or anstronomy courses in my life. I am taking a course this semester that I thought was going to be more about the environment and turned out to be very abstract and philisophical. My first assignment is due this week...

Hi, I'm new to this forum, but saw that everyone was so kind and helpful, so was wondering if anyone could help me with a couple of things.. How does one calculate the age of the universe using Hubble's constant, if the constant is in km/s/Mpc? Do we know the critical density of the...

her new url is http://faculty.cns.uni.edu/~morgan/ajjar/Cosmology/cosmos.html her cosmology calculator is a handy resource especially since Ned Wright modified his cosmology calculator earlier this year----July sometime. Now, with Wright's, you can't input a redshift z. You have to input a...

I was intrigued by this paper and the approach: http://arxiv.org/abs/gr-qc/0611090 Cosmology as a search for overall equilibrium Authors: Carlos Barcelo Comments: 9 pages, 1 figure "In this letter we will revise the steps followed by A. Einstein when he first wrote on cosmology from the...

I've just been reading some of these threads, as i am quite interested in cosmology. I was wondering about a possible cosmology of the universe that i haven't really seem written about anywhere. What if, each point of the universe is both the centre AND edge of the universe? If the...

How would our cosmology change once we have the ability to significantly escape our planet, our solar system, or our galaxy? Must we evolve socially or genetically to realize extended space travel? Might we first attain the ability to transform virtually through the cosmos? Would the...

Hello, I am a non-science student with a huge interest in cosmology and modern physics. I've read Micheal Greene's "Elegant Universe" and "Fabric of the Cosmos" a couple of times, and I loved them. What else do you recommend? (I know about Stephen Hawking's 2 books, and I hope to read them...

Just a quick note to say that Riofrio now has evidence of a changing speed of light. See her blog: http://riofriospacetime.blogspot.com/ :smile:

Hello all, This is my first post here and so I hope I am posting in the appropriate section. My question is actually related to both Physics and Discrete Mathematics. I'm writing a very general essay (no rigorous derivations or extremely involved mathematics) about Markov chains as they are...

This may not be a new idea, I haven't read it anywhere else. Imagine the big bang scenario. Imagine an expanding sphere, like a bubble. Imagine that the "skin" of the sphere is thick, say thirty billion lightyears and as the sphere expands, the "skin" gets thinner. Imagine a coordinate system...

http://arxiv.org/abs/astro-ph/0608644 Wolfgang Priester: from the big bounce to the Lambda-dominated universe James Overduin, Hans-Joachim Blome, Josef Hoell 12 pages, 7 figures, optimized for A4 paper. Partly biographical, partly historical review of subjects to which Priester contributed...

This link is to (popular) cosmology books, http://www.astro.ucla.edu/~wright/cosmobib.html Which would you buy/not ?

http://arxiv.org/PS_cache/astro-ph/pdf/0310/0310808.pdf uses the term "proper distance", but doesn't define it. Presumably this must be a standard defintion. So far, though, I have not been able to track down a definitive defintion (I'm still looking). My guess is that this distance is...

I want to buy Barbara Ryden's Cosmology book. Has someone read it already and could say a few things about it? On amazon it gets nice reviews but what do you think? thanks

Entropy, information and Omphalos cosmology Roger Penrose, in The Road to Reality, discusses the Second Law of Thermodynamics and the Universe’s entropy. He floats (section 27.13) an order-of-order-of magnitude argument that the entropy of our Universe has increased from mighty big (10^10^88)...

Gday, I'm currently doing a major yr 11 assignment on cosmology for physics. One of the questions in this assignment was about the historical developments of various models of the universe over time. I've mentioned the geocentric and heliocentric models but the question also asks about the...

Hi I'm new here, I found this forum while trying to plan my career in cosmology. So far to have a good career in this field you must have a Bachelor, a Masters, and a PhD. So far I know what college I'm going to go for my Bachelors, which is Angelo State University. I already have a four-year...

Whenever a diffuse gravitating system condenses into a stable and more compact object, energy must be removed from it. This is a consequence of the Virial theorem, which mandates that in a stable system of gravitating particles there must be a proportional balance between the magnitudes of...

Hi all, I'm going to spend my summer doing some self-study in the subjects which I'll be covering in the future and I think it'd be a great time to dive into relativity. I've had some education in special relativity but I've never dealt with general relativity. I'd like a good, thorough...

[FONT="Fixedsys"]-> = implies Dark Energy -> Repulsion Inflation -> Repulsion Gravitation -> Attraction (Repulsion = Attraction -> Steady Region) & Euclidean Universe -> Light can travel on parallel lines that remain the same distance from each other :: matter, light, and energy...

Is NASA doing anything to advance the science of cosmology? my personal veiw is that this agency is a total waste of money, money that could be spent, doing robust scientific cosmological related experiments, what do you think?