What is Cosmology: Definition and 918 Discussions

Cosmology (from Greek κόσμος, kosmos "world" and -λογία, -logia "study of") is a branch of astronomy concerned with the studies of the origin and evolution of the universe, from the Big Bang to today and on into the future. It is the scientific study of the origin, evolution, and eventual fate of the universe. Physical cosmology is the scientific study of the universe's origin, its large-scale structures and dynamics, and its ultimate fate, as well as the laws of science that govern these areas.The term cosmology was first used in English in 1656 in Thomas Blount's Glossographia, and in 1731 taken up in Latin by German philosopher Christian Wolff, in Cosmologia Generalis.Religious or mythological cosmology is a body of beliefs based on mythological, religious, and esoteric literature and traditions of creation myths and eschatology.
Physical cosmology is studied by scientists, such as astronomers and physicists, as well as philosophers, such as metaphysicians, philosophers of physics, and philosophers of space and time. Because of this shared scope with philosophy, theories in physical cosmology may include both scientific and non-scientific propositions, and may depend upon assumptions that cannot be tested. Cosmology differs from astronomy in that the former is concerned with the Universe as a whole while the latter deals with individual celestial objects. Modern physical cosmology is dominated by the Big Bang theory, which attempts to bring together observational astronomy and particle physics; more specifically, a standard parameterization of the Big Bang with dark matter and dark energy, known as the Lambda-CDM model.
Theoretical astrophysicist David N. Spergel has described cosmology as a "historical science" because "when we look out in space, we look back in time" due to the finite nature of the speed of light.

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  1. D

    Year 12 Cosmology extended research task

    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...
  2. Ken G

    Is the multiverse cosmology or metaphysics?

    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...
  3. wolfspirit

    The dereference between; astrophysics, astronomy, cosmology and space science

    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
  4. C

    I would like to learn more about cosmology

    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.
  5. D

    How Does Reheating Affect Temperature When Pions Exit Thermodynamic Equilibrium?

    Homework Statement Find the change in temperature due to conservation of entropy, which happens during reheating when pions ( \pi^{\pm},\ \pi^0 ) get out of thermodynamic equilibrium beneath 140 MeV. Homework EquationsThe Attempt at a Solution I tried to compare this to the exiting of...
  6. A

    Programs PhD research in particle physics and cosmology - Any advice ?

    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...
  7. H

    Newtonian cosmology vs relativistic cosmology

    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...
  8. dkotschessaa

    Cantor, infinity and cosmology

    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...
  9. MathematicalPhysicist

    Programs PhD in Theoretical Cosmology at damtp cambridge.

    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... :-(
  10. L

    What is the difference between Astronomy, Astrophyics and Cosmology?

    What is the difference between Astronomy, Astrophyics and Cosmology?
  11. C

    Where to do Cosmology or nanotechnology research over Summer in England

    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...
  12. A

    Good Cosmology Books: What You Need to Know

    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?
  13. B

    What Math and Physics Background Is Required to Study 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...
  14. J

    Cosmology: Expansion & Its Impact on Us - Jens

    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...
  15. J

    Advice on being mathematically prepared (QM Griffiths and Cosmology Ryden)

    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
  16. H

    1st year ugrad at UofT; considering cosmology.

    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...
  17. E

    Weinberg's Cosmology: Neglecting (1+z(eq)) in Denominator

    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".
  18. J

    Some repetitive mistakes and misconceptions about DM, MOND, TeVeS, and 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 ±...
  19. T

    What are some recommended Cosmology books?

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

    Age of Universe (Liddles Modern Cosmology)

    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...
  21. narrator

    Depth of fields in Physics, Cosmology etc

    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...
  22. T

    Where to study cosmology in Canada

    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...
  23. B

    Exploring the Problems in Cosmology: A Look at Conflicts with Standard Models

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

    Exploring the Cosmology of N=8 Supergravity

    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...
  25. M

    What is the Role of Cosmology in Our Understanding of the Universe?

    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...
  26. K

    Cosmology Conferences: Find the Perfect Fit for Your Paper

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

    Journal of cosmology and gravitation

    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?
  28. M

    Gravity, information, and cosmology (was Thoughts about the universe )

    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...
  29. COSMOSGEEK

    Should I study cosmology? Am I too old?

    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...
  30. Y

    Schools I want to study cosmology, which university should i apply ?

    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...
  31. DrChinese

    How unitary cosmology solves the inflationary entropy problem

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  32. TrickyDicky

    Does the Second Law of Thermodynamics Apply to Cosmology?

    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...
  33. wolram

    Loop quantum cosmology status report

    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...
  34. wolram

    Testing loop quntum cosmology

    arXiv:1108.0079 [pdf, ps, other] Gravitational wave generation in loop quantum cosmology Paulo M. Sá, Alfredo B. Henriques Comments: 7 pages, 8 figures, revtex4 Subjects: General Relativity and Quantum Cosmology (gr-qc) We calculate the full spectrum, as observed...
  35. A

    Open and Closed Models in 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...
  36. N

    In <Cosmology> written by Weinberg, in page 109

    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...
  37. J

    [cosmology] Find the comobile distance of a galaxy given redshift and H0.

    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}[...
  38. S

    Intergal result and quantum cosmology

    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?
  39. Greg Bernhardt

    How are time and distance measured in cosmology?

    How are time and distance measured in cosmology? Relativity says that time isn't absolute. For example, the rate at which a clock runs depends on its state of motion. Because of this, it's not trivial to define what is meant by phrases like "the age of the universe," or "three minutes after the...
  40. E

    Is Cosmology the Right Major for Me?

    Hello, My name is Eric, I will be starting college soon but it seems when it is time to decide on my future occupation I am at a loss. Due to the fact that I grew up in a Very sheltered town being surrounded by people who didn't really think college was something needed. I...
  41. B

    Help on Hubble Constant, H0, h100 & Critical Density Rhoc

    For the most part I've been using the Hubble constant of: H0 = 72 km/s/Mpc but I've started seeing it expressed as: H0 = 100 h100 km/s/Mpc. what is h100 and why is it coming up in this?? I've also seen the critical density for the shape of the universe (flat/open/closed ect) as: Rhoc = 1.879...
  42. E

    Some Simple Cosmology Questions

    Homework Statement Estimate the pressure of the CMB photons today. [You will need to choose a reasonable value for the present value of the temperature of the CMB. The radiation constant is α = 7.56 × 10−15erg cm−3K−4 Assume that a new population of stars is discovered, and their age is...
  43. E

    Jobs/funding in fundamental theory and cosmology

    Hi, I am a physics grad student, hoping to do theoretical cosmology. I've recently been thinking a lot about practical things like career tracks, postdoc jobs, etc. So I thought I'd ask a couple questions here to see what others think: 1) I hear that the job scene for fundamental theory...
  44. narrator

    Cosmology History: Timeline, Discoveries & Current Theories

    Hi all, Is there a timeline somewhere which shows a history of theories, breakthroughs, discoveries, especially with regard to cosmology. And is there a summary of the types of work being done in this area currently? It's probably a big question, but I'm keen to understand how some of the...
  45. L

    Sign of Lambda cosmology homework

    In question 4 of this paper, I am trying to find the sign of \Lambda Since we have the vacuum einstein eqns G_{\mu \nu}=-\Lambda g_{\mu \nu} we can just contract to get R-\frac{4}{2} R=-4\Lambda \Rightarrow \Lambda=\frac{R}{4} So \Lambda will have the same sign as R Now given the...
  46. A

    [Cosmology] Scale Factor Values

    Hello. I have been working through some questions and answers to do with cosmology. One of them asks you to consider a model where: \Omega_{MO}=3 \Omega_{\Lambda O}=0.01 \Omega_{RO}=0 and asks you to show mathematically that the model re-collapses. Following through the math, I get three...
  47. L

    Solving Cosmology Problem on Page 12 of Damtp.cam.ac.uk

    I'm looking through the solution to a problem and am stuck with some of the maths. The solution can be found here: http://www.damtp.cam.ac.uk/user/r.ribeiro/supervisions_files/Cosmo1sol_M2010.pdf The pages are numbered in the bottom right corner. I am on p12. We have an expression 1+z...
  48. narrator

    Practical Cosmology: Examples of How it Helps Our Ventures

    Not sure if this is OT for the cosmology forum.. pls move if so. I'm wondering about examples of where cosmology science has helped in a practical way. Not being facetious.. genuinely curious (and I think knowledge for knowledge sake is almost always a good thing). Cosmology has helped...
  49. W

    Is a Diploma in Cosmology the Right Path for an Aspiring Astronomer?

    Hi, I am 15 years old boy. I've just appeared from 10th grade exams. I am interested in cosmos. I like Stephen Hawking's shows too much, and other shows which are related wih cosmos. I want to become cosmologist or astronomoer. I've much curosity about cosmos. I am interested in...
  50. H

    Cosmology Books: Find Undergraduate & Graduate Books

    Hello everybody, I'am a new membre. I'am working on an introduction to cosmology, but I haven't yet the necessary documents:confused:, and hence I"ll be very thankful if you help me:smile:. I want a undergraduate and graduate (not very complex) books but not old if you can. thanks
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