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. marcus

    Lightcone 1.0 tabular cosmology calculator

    New release of Jorrie's tabular calculator. http://www.einsteins-theory-of-relativity-4engineers.com/LightCone1.0/LightCone.html this is clearly the best on-line cosmology calculator for the general user on the web. Hands down. Lightcone rules. that's all there is to say. Check it out...
  2. C

    Cosmology questions, something that is puzzling me for days

    Hello folks My name is Mike. I am into Cosmology ever since I was a kid. Throughout the years I strayed away from Cosmology unfortunately but I am very very fond of Cosmology...and thus...call me an amateur Cosmologist :D Anyway... These days couple of questions puzzle me in the...
  3. M

    Can Tired Light Theory Explain Redshift Without Expansion of the Universe?

    Homework Statement The assignment is to find the energy loss constant for the theory of tired light. If redshift isn't caused by the expansion of the universe but from a loss of energy, how much of a photons energy is lost per unit distance(MegaParseC) for some set Hubble constant. Homework...
  4. S

    Schools Chosing College For Particle Physics And Cosmology

    I am an aspiring physicist. My main interests are Particle Physics, Cosmology and Black hole physics. I am going to join a college this year for the same. I applied to two colleges and got selected. University of Lancaster and University of Birmingham. I have applied for the course - Physics...
  5. Chronos

    Observational Cosmology & LCDM Model: What We Know

    This paper; 'What have we learned from observational cosmology ?', http://arxiv.org/abs/1304.4446, provides a good overview on the evidence supporting the LCDM model and why it is currently favored by mainstream scientists. It also offers considerable discussion on the motivation for Dark Matter...
  6. Garth

    Conspiratorial cosmology - the case against the Universe

    Conspiratorial cosmology - the case against the Universe Sounds pretty serious to me... Garth
  7. 4

    Looking for some good websites for Physics and Cosmology

    I've been looking for a few websites good for Cosmology and Physics, maybe you guys can help? I'm in 8thgrade, but I can comprehend a lot, just try to stay away from websites that have excessive technical math please. All posts are appreciated.
  8. M

    Ian Morisson's Introduction to Astronomy and Cosmology questions

    Hey there! I recently bought said book and would highly recommend it for any Astronomy and Cosmology undergrads. However, one little niggling thing about it (something that grinds my gears in general with textbooks) is that it features end of chapter questions yet no set of answers for the...
  9. P

    Solving Kolb & Turner's Reheating Problem with 1st Law of Thermodynamics

    Homework Statement i i am trying to derive \dot{\rho_{R}}+4H\rho_{R}-\Gamma_{\phi}\rho_{\phi}=0 as in Kolb an turner (Boltzmann describing reheating). Is the correct approach to, use the 1st law dU=dQ-pdV, but what would dQ be?
  10. P

    Questions on observational cosmology

    Can anyone explain: why COBE measured IR and microwave as opposed to visible light, when surely we are measuring photons that have decoupled? why Planck is measuring light polarisation?
  11. marcus

    Rethinking Cosmology (Steinhardt)

    http://www.perimeterinstitute.ca/seminar/rethinking-cosmology In five days Paul Steinhardt (Princeton) will give a colloquium talk at Perimeter. He has a 90 minute timeslot. Steinhardt has been a proponent of "brane-clash" cosmology. Sometimes called Cyclic or Ekpyrotic. Two spatial...
  12. L

    What is the difference between coasting and static cosmology?

    Is the key difference between coasting and static cosmology models the presence of a linear acceleration, or are there other major differences? Regards, Noel.
  13. K

    Questions arisen while reading Weinberg's Cosmology

    I was reading Weinberg's book Cosmology. When I went to chapter 2, under the subsection 2.1 "Expectations and discovery of the microwave background" I could not understand one statement. ---Quote--- The work done by pressure in an expanding fluid uses heat energy drawn from the fluid. The...
  14. atyy

    Interpretation of quantum mechanics in cosmology

    In Mukhanov's Physical Foundations of Cosmology p348, he writes "Decoherence is a necessary condition for the emergence of classical inhomogeneities and can easily be justified for amplified cosmological perturbations. However, decoherence is not sufficient to explain the breaking of...
  15. Greg Bernhardt

    Cosmology Spacetime, Geometry, Cosmology by William Lewis Burke

    Author: William Lewis Burke Title: Spacetime, Geometry, Cosmology Amazon Link: https://www.amazon.com/dp/0935702016/?tag=pfamazon01-20 Prerequisities: Level:
  16. marcus

    APS Physics view of pre-inflation cosmology article

    "APS Physics" view of pre-inflation cosmology article The APS has an online periodical that publishes "Viewpoints" on current research, for instance http://physics.aps.org/articles/v5/142 is an interpretive explanatory viewpoint, written for non-specialists, on the article by Agullo Ashtekar...
  17. K

    Brane cosmology and extra dimensions

    I have a few questions so I hope it is okay if I ask them all here in this thread. They are all related somewhat. According to brane cosmology, our 4-D universe is embedded inside a higher dimensional space, a hyperspace if you will, called the bulk. The reason we cannot perceive or interact...
  18. H

    Calculating the density parameter (Cosmology)

    Homework Statement Decide the density parameter from the following data: z=0.04, m= 17.38 and σ=0.19 Homework Equations Definition of the density parameter: Where p0 is the current density and pc is the critical density. The Attempt at a Solution I feel like I don't...
  19. H

    Calculating the scale factor (cosmology) for a universe starting at the Big Bang

    Homework Statement Show that by using the Friedmann-equation you can determine the scale factor for a Universe in it's early stages (starting with the Big Bang) to: Homework Equations The equation for the scale factor: Where r(t) is the distance from us to a given galaxy to the time t...
  20. N

    No Inflation in Brane Cosmology: Is Dark Energy the Driver?

    In brane cosmology how can there be no such thing as inflation. I was watching a lecture with Neil Turok and he said he made a bet with Hawking that says that the new Planck satellite will give us information that could prove against inflation. So, my question being, instead of inflation in the...
  21. D

    Cosmology - given omega_m and a static universe, find the range of values of q_0

    Hi there, the full question is as follows: Suppose omega_m = 0.2. If we observe cosmic acceleration at z=0, what is the possible range of values of q_0? What is the minimum value of lambda? What is omega_total? so I'm having trouble with the relationship between q_{0}, \Omega_{m,0}, \lambda...
  22. marcus

    Recent papers relevant to cosmology that seemed extra interesting

    The recent report from the South Pole Telescope seemed to several of us to be exceptionally interesting making one think we might have a thread that just lists recent papers, as they come out, which seem as if they might be important to cosmology. Here are a few. http://arxiv.org/abs/1210.7231 A...
  23. marcus

    Fundamental Cosmology conference (Stockholm, November 2012)

    There's an interesting conference taking place this month at the NORDITA institute for theoretical physics in Stockholm. It brings together, from a number of different areas, researchers working on various models of what was happening around the start of expansion--replacing the "singularity"...
  24. tom.stoer

    Invariant mass and spin in deSitter cosmology

    A friend of mine was reading Penrose's new book on CCC; I do not want to discuss this story here but a rather interesting detail which could be relevant w/o the whole CCC stuff. SR and GR rely on (global and local) Lorentz invariance. From these symmetries one can derive invariant mass M² and...
  25. J

    Simple argument for a linear cosmology

    Starting with the Robertson-Walker metric \large ds^2 = -dt^2 + a^2(t) [ \frac{dr^2}{1-kr^2} + r^2(d\theta^2+\sin^2\theta d\phi^2] Consider a light ray emitted at the Big Bang traveling radially outwards from our position. Therefore we have: ds = 0 d\theta = d\phi = 0 Substituting...
  26. wolram

    When talking cosmology what exactly is a manifold, is there any

    When talking cosmology what exactly is a manifold, is there any observational evidence that we live in one ?
  27. Faradave

    What is the Latest Measurement of the Hubble Constant Using Infrared Light?

    I’m a layman new to the Cosmology Forum and just finished reading through the very helpful, “Effort to get us all on the same page (balloon analogy anyone?)” by Marcus et. al. followed by “Look 88 billion years…”. [If you’re in a hurry see the nice summary by Mark M at cosmo.pdf.] Along the...
  28. B

    Total Energy in Newtonian Cosmology

    Homework Statement "Consider a perfectly homogeneous and isotropic universe filled with dust of uniform density ρ(t). Let universe expand, dust is carried radially outward from origin. Conservation of total energy E. E = K(t) + U(t) K(t) = (1/2)*mv^2(t) and U(t) = -GMm/r(t) where M =...
  29. F

    Cosmology: What math/physics background?

    Hi. I'm an undergraduate student interested in cosmology. Initially, it was astrophysics, and I know it's a large field and I'm generalizing, but I felt a lot of the work was statistical analysis and letting the computer crunch images and letting it do things for you. I know a lot of...
  30. phinds

    Skepticism: Is Carmelian Cosmology Meaningful?

    In a serious thread, a newbie brought up Carmelian cosmology and clearly thinks it's meaningful but in the brief look I gave it, it looks like nonsense, which is why I put this post in Skepticism & Debunking. Any thoughts? Thanks EDIT: Never mind. I spent a few more minutes looking at it...
  31. 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...
  32. 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...
  33. 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
  34. 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.
  35. 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...
  36. 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...
  37. 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...
  38. 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...
  39. 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... :-(
  40. L

    What is the difference between Astronomy, Astrophyics and Cosmology?

    What is the difference between Astronomy, Astrophyics and Cosmology?
  41. 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...
  42. 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?
  43. 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...
  44. 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...
  45. 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
  46. 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...
  47. 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".
  48. 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 ±...
  49. T

    What are some recommended Cosmology books?

    Hello, Has anyone read any good or interesting Cosmology books lately? Thanks
  50. 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...
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