Cosmology Definition and 948 Threads

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. B

    Cosmology Raw Data: Access Unanalyzed Experiments

    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...
  2. M

    How Do Observers Measure the Universe's Age and Size in Cosmology?

    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...
  3. E

    What is most influential candidate quantum cosmology today?

    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...
  4. N

    M branes in Cosmology, PhD inquiry

    I'm considering a PhD in cosmology, but the university I'm interested in focuses particularly on models based on branes. I'm finding it difficult to get information on the specifics of this topic, but for the moment i'd just like to know whether it is entirely based in string theory. In...
  5. M

    What is the boundary of the observable universe in the Milne universe?

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

    Astronomy vs Cosmology: Understanding the Differences Explained

    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).
  7. S

    Future in Cosmology: College Requirements & Pay

    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...
  8. MathematicalPhysicist

    Programs A phd in pure maths and postdocs in theoretical physics (cosmology).

    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...
  9. putongren

    Quantum Cosmology - Imaginary Time

    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...
  10. O

    Multiverse Cosmology: Exploring Physicists' Views

    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...
  11. J

    How Can Beginners Learn Physics and Cosmology Effectively?

    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:
  12. marcus

    Exploring the Language of Cosmology Basics: Introducing Terminology to Newcomers

    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...
  13. E

    Recommend a textbook of cosmology

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

    Difference between Astronomy and Cosmology is?

    What is the difference between Astronomy and Cosmology?
  15. T

    Exploring the Limits of the Balloon Analogy for 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...
  16. marcus

    What causes the research interest in cosmology?

    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...
  17. T

    Why Are Primes Used in the Electromagnetic Signals Equation in Cosmology?

    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...
  18. P

    Theoretical Cosmology: PhD Programs & Math for UK Students

    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...
  19. J

    Recommendations for Cosmology DVD for Kindergarteners

    Can someone please recommend a cosmology dvd? In Amazon, I see very good review for Carl Sagan's cosmos dvd set. But I'm wondering since it was made in 80's, the the graphics would be inferior. Has anyone watched it? I would like to show it to my daughter (kindergarten), hoping she would develop...
  20. C

    Programs Cosmology PhD in oxbridge - what are my chances?

    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...
  21. nicksauce

    Cosmology Book Suggestions: Upper Undergrad/Grad Level

    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.
  22. Q

    Cosmology Question: Finite Universe with Overdensity & Cosmological Constant

    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...
  23. T

    Connecting with Fellow Cosmology Enthusiasts in Brisbane

    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...
  24. E

    Can information be transmitted faster than c in inflationary cosmology?

    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?
  25. marcus

    Path Integral formulation of Loop Cosmology (a first)

    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...
  26. I

    Exploring Cosmology with Balloons and Foam: A New Perspective

    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...
  27. marcus

    Tests of LQG in cosmology (proposals, prospects etc)

    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...
  28. Dadface

    Do Cosmologists Truly Believe in Their Theories?

    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...
  29. Fredrik

    Definitions (continued from the cosmology forum)

    This is a reply to a comment made in the cosmology forum. That's not correct. Do you really believe that physicists are that dumb? The real story goes something like this: The speed of light is a constant in the real world. Therefore, we define a mathematical model in which the speed of...
  30. wolram

    Cosmology: Futility of Exploring Beyond Our Solar System

    Since the speed of light has been proven to be an absolute limit on the speed of travel, it is obvious humans will never reach beyond our solar system, humans may do some fantastic parallax measurements, but beyond them we will never have any thing other than a rubber ruler to measure with...
  31. wolram

    Critique of relativistic cosmology

    arXiv:0901.1956 [ps, pdf, other] Title: A Critique of the relativistic cosmology Authors: R. K. Thakur Comments: 8 pages, Comments welcome Subjects: General Physics (physics.gen-ph)
  32. P

    Cosmology Question that I really don't have a clue on.

    Homework Statement a) Using the Robertson-Walker metric, write down an expression for the proper distance in terms of the coordinate r. For objects moving with the expansion of the universe, show that the proper distance increases with time in the manner described by the Hubble Law. b) Use...
  33. turbo

    SDSS Quasars & Cosmology: Challenges to Current Models

    SDSS is perhaps the most ambitious astronomical survey ever undertaken, and it has provided a wealth of new data. Unfortunately for cosmologists (or fortunately, if cosmologists are willing to re-group), some of the findings are quite inconsistent with their expectations. Scroll down to Nov 2...
  34. marcus

    Tighter bounds on cosmo parameters (Chandra Cluster Cosmology Project)

    http://arxiv.org/abs/0812.2720 Chandra Cluster Cosmology Project III: Cosmological Parameter Constraints A.Vikhlinin, A.V.Kravtsov, R.A.Burenin, H.Ebeling, W.R.Forman, A.Hornstrup, C.Jones, S.S.Murray, D.Nagai, H.Quintana, A.Voevodkin ApJ, in press: Feb 10, 2009 issue (Submitted on 15 Dec...
  35. marcus

    Ways to accommodate modern cosmology

    People find their own ways of making sense of modern cosmology. Unless they are utterly unable to get comfortable and reject it whole hog (as some do quite vehemently :biggrin:). If you have a way of making your peace with cosmology, feel free to describe how you do it. Or try this recipe and...
  36. R

    I Deciding Cosmology or Astrophysics?

    First i need someone to help break it down what's the difference. Instead of just saying the origins of space is cosmos. Ima tell you what I am interested in and let me know which one i will do better in. I am interested in learning about space and how it was created, not only I am interested in...
  37. wolram

    What Are the Six Puzzles Challenging LCDM Cosmology?

    [37] arXiv:0811.4684 [ps, pdf, other] Title: Six Puzzles for LCDM Cosmology Authors: L. Perivolaropoulos Comments: 9 pages, 3 figures. Invited article to the TSPU anniversary volume "The Problems of Modern Cosmology" on the occasion of the 50th birthday of Prof. S. D. Odintsov Subjects...
  38. M

    Cosmology Paper Ideas: Need Help!

    I have to write a 4000 word paper for my Astronomy 302 (Foundations of Cosmology) class and I really do not know what to do. I was thinking about doing it on the effects black holes on the furture of the universe but I can not find any scholarly peer-reviewed journal articles on it to write a...
  39. G

    Cosmology, K=0, Matter dominated, energy density

    Homework Statement For K=0 of matter dominated universe, i.e at z>>1, find the energy density of starlight if f portion of matter condensed in solar type stars and the stars are uniformly distributed in space. Homework Equations Friedman eqn: \rho_m = \frac{3H^2}{8 \pi G} The...
  40. T

    Comments about an issue in cosmology?

    Learned Gentlemen, My Doctorate is in Medicine, so my questions and comments might be below you. Where can I ask questions and make comments about an issue in cosmology? Thanks, tfb
  41. F

    Cosmology and Energy Quantization in Matter

    Quantum Wave Cosmology is a niche in cosmology that consists of a group of “not easily refuted” protoscience ideas about a universe composed of nothing but energy. A few QWC ideas include: The universe is composed of one commodity, energy. Energy cannot be created or destroyed and so...
  42. wolram

    ICosmo: an Interactive Cosmology Package

    arXiv:0810.1285 [ps, pdf, other] Title: iCosmo: an Interactive Cosmology Package Authors: Alexandre Refregier (1), Adam Amara (2), Thomas Kitching (3), Anais Rassat (1) ((1) CEA Saclay, (2) ETH Zurich, (3) Univ. Oxford) Comments: 5 Latex pages including 2 tables and 4 figures. Submitted to...
  43. wolram

    Practical cosmology and cosmology physics

    arXiv:0809.1084 [pdf] Title: Practical cosmology and cosmological physics Authors: Yu. Baryshev (1), I. Taganov (2), P. Teerikorpi (3) ((1)Astron. Inst. St.-Petersburg Univ., (2)Russ. Geograph. Soc., (3)Tuorla Obs. Turku Univ.) Comments: 16 pages, summary of the conference "Problems...
  44. WCOLtd

    3 questions on Physical Cosmology

    First question: According to Hubble's Law, the redshift observed by distant galaxies are proportional to their distance. This is what I already know: It says on wikipedia that Hubble observed cepheid variable stars in a spiral nebulae to calculate their distance, cepheid variable stars are...
  45. 8

    Finding Cosmology Resources for Beginners

    I would appreciate some guidance. I don't get very far in reading peer-reviewed papers before I'm really confused --- they're way beyond my level. Even some posts on this forum are a little beyond me. And "popular" books can be misleading or just plain wrong ---and there are LOTS of...
  46. marcus

    Observing Quasar Accretion Disks: Scientists See Standard Cosmology at Work

    Nice picture of quasar accretion disk---pat on back for standard cosmology in Nature The 24 July issue of Nature reports some beautiful observational work, using a polarized light filter. Actually able to SEE the hot blue accretion disk whirling around a supermassive black hole at the center of...
  47. marcus

    The physical meaning of expansion in cosmology

    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...
  48. S

    Suggest good articles on Loop Quantum Cosmology

    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
  49. Y

    Entropy & Cosmology: Arrow of Time Paradox

    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...
  50. N

    Cosmology: Equation of state parameter

    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...
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