What is Cosmology: Definition and 921 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. 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...
  2. 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...
  3. 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
  4. bcrowell

    Up to date cosmology textbook, >Linder, <Weinberg?

    Is there any cosmology book out there that is up to date, more substantial than Linder, but less so than Weinberg? I own Linder and have read it, and it's fine, but it only goes so far. I have a pretty firm grasp of GR, but if I bought Weinberg I think the chances I'd wade through it are slim...
  5. S

    Masters project in cosmology or theoretical particle physics ?

    Hey I didnt know where to put this so the masters projects we can do for next year came out .. but I am not really interested in any of them However we can propose projects So i was thinking if anyone could lead me in the right direction Im want something in either COSMOLOGY or...
  6. S

    Project in cosmology or theoretical particle physics ?

    Hey I didnt know where to put this so the masters projects we can do for next year came out .. but I am not really interested in any of them However we can propose projects So i was thinking if anyone could lead me in the right direction Im want something in either COSMOLOGY or THEORETICAL...
  7. L

    Understanding Statistical Homogeneity in Cosmology

    For a random field, f, the two point correlator is defined as \xi(x,y)=\langle f(x) f(y) \rangle = \int \mathcal{D}f \text{Pr}[f] f(x) f(y) where \text{Pr}[f] is the probability of realising some field configuration. Statistical homogeneity means that \text{Pr}[f(x)]=Pr[f(x-a)]...
  8. N

    What is the best book for learning general relativity and cosmology/

    Hi, I have basic understanding of calculus and geometry.Can you please suggest some book on cosmology and space time with some mathematical component to it.
  9. A

    Cosmology With Sunyaev-zeldovich Effect

    constraining dark matter and dark energy with sunyaev-zeldovich effect. need help on this topic
  10. J

    Calculating Luminosity Distance in an Empty Cosmology

    If had empty cosmology? What would happen if we had no matter or radiation or dark energyand only had curvature? How would this effect luminosity distance? From the friedman equations I get that H2=-k/R2. Is this right?
  11. marcus

    Latest Penrose video on Conformal Cyclic Cosmology

    http://pirsa.org/11040063/ Big Perimeter audience, appreciative interest, long question period after. He undercuts his critics (who said the concentric circles could have appeared by chance) by criticising their methods and makes at least one valid point. I would say that the critics still...
  12. D

    Planck Mission and M-Theory Cosmology

    A ways back, I seem to remember reading on the Planck Mission page that it's observations of the CMB could help foster support for M-theory cosmology and weaken support for Inflation, or vice-versa. I thought it had something to do with detection of Non-Gaussianity in the CMB. I could not...
  13. T

    The Incredible Advances in Cosmology of the Last Decade

    What advances is theoretical or observational cosmology in the last decade have for you been the most impressive? This is open to all, but especially to the pros!
  14. T

    Cosmology - Friedman Equation Problem

    I am doing question A1/16 part (i) at the top of page 13 here: http://www.maths.cam.ac.uk/undergrad/pastpapers/2001/Part_2/list_II.pdf I am stuck on the last part where we're given the equation of state P=\sigma\rho c^2 and we have to find a(t) and SHOW a(0)=0. I will work through to where...
  15. B

    My conversion with someone regarding cosmology, conclusion included

    I think this conversion is so valuable, I decide to share it with you all. We come up with two models, one is playing cards. one is lottery. they both work. "To deal with such paradoxes we shall adopt an approach that we call model-dependent realism...
  16. marcus

    Probability of Inflation in Loop Quantum Cosmology (new Ashtekar Sloan paper)

    http://arxiv.org/abs/1103.2475 Probability of Inflation in Loop Quantum Cosmology Abhay Ashtekar, David Sloan 34 pages, 3 figures (Submitted on 12 Mar 2011) "Inflationary models of the early universe provide a natural mechanism for the formation of large scale structure. This success brings...
  17. marcus

    What caused the shift of interest in quantum cosmology?

    This raises an interesting physics question. What physics reason could there be for the shift of researcher interest in quantum cosmology which this Inspire search illustrates? Here is the Inspire top ten quantum cosmo list for 1996-1998...
  18. G

    Book about Measurements in Astronomy and Cosmology

    Hello! I am a physicist. Although I think I understand quite well the laws of Newtonian physics and general relativity that explain the observable universe, I am a complete dummy in what concerns doing measurements in the universe. For instance, I have no idea how to measure the distance to a...
  19. A

    Justifying investment in Cosmology

    How is the large investment spent on say... space missions or large telescopes justified when the country is in a recession? Can you guys think of any examples of large investments into cosmology that were fruitful/failed?
  20. P

    Shockwave cosmology and white holes

    Now I’ve been trying to read up on this Shockwave cosmology model and wanted to see if I have the correct view since most of the math is over my head. Now from what I understand in this model is that there is a white hole singularity that explodes and instantly disappears and it produces a...
  21. B

    Physics Classes and Programs to take in high school for a Astrophysics and Cosmology

    I'm currently a high school freshman in NYC and was wondering what classes I should focus on in school and what programs are available in astrophysics, cosmology, and or relating to it for someone my age? Thanks so much.
  22. M

    Exploring MSc Particles, Strings & Cosmology at Durham

    Hi folks, I'm a 3rd year student doing a BSc in Mathematics and Physics (in Scotland) and I was wondering if anyone could share with me their experiences of the MSc particles, strings and cosmology at Durham (previously MSc elementary particle theory) or any of the other similar courses at...
  23. A

    Exploring Filaments in Cosmology: The Role of Dark Matter

    Hi, http://www.msnbc.msn.com/id/3077693/ns/technology_and_science-space/ http://thefutureofthings.com/news/5497/dark-matter-filament-detected-near-the-milky-way.html What are these filaments in space? Are they made of pure plasma or is dark matter involved too? How could dark...
  24. marcus

    Interested in Spinfoam Cosmology? Check out Francesca Vidotto's Online Talk!

    Spinfoam cosmology is a fast-growing field, since it represents the application of the full LQG theory to the BB and expanding universe. In the early years loop cosmology addressed a restricted model with just a small number of degrees of freedom. Going from oldfashioned LQC loop cosmology to...
  25. TrickyDicky

    Relativity of simultaneity and cosmology

    According to SR relativity of simultaneity, the temporal order of events depends on the frame of reference from which the observer watches the events and different observers with a spacelike separation between them or at relativistic speeds won't agree in the order of events. Now , in...
  26. A

    How Is Redshift Calculated in Changing Epochs?

    Homework Statement The redshift of a galaxy is measured at the present epoch t0 and again at the infnitesimal future epoch t0 + δt0. Show that the rate of change of z with t0 is given by \frac{dz}{dt_{o}}=(1+z)H_{o}-H(z) Homework Equations Hint - Start From: \frac{\delta z}{\delta...
  27. H

    Studying Topics to be covered before studying cosmology

    I would like to ask what topics one should study before studying cosmology. I have begun self-learning physics since last summer, and my goal is to build a foundation solid enough to learn cosmology in great depth. I seem to be just touching on different topics: relativity, the uncertainty...
  28. K

    PhD in Cosmology: Best UK Universities

    Could anyone suggest good universities in the UK for studying cosmology at a PhD level? Thank you!
  29. G

    What Is the Age of the Universe According to Different Models of Cosmology?

    Homework Statement From CMB measurements, we know the total density of the Universe matches the critical density to 2 percent. From observations of Supernova it seems that 70 percent of that is in the form of dark energy. But the supernova observations are not as solid as the CMB result...
  30. G

    Programs Which UK Universities Offer the Best PhD Programs in Cosmology?

    Hi, I graduate university this summer with a physics degree, (4 year masters, specialising in astrophysics and particle physics), and I'm very keen to do a PhD in cosmology. Does anyone know which departments are the best to work in, for this field? I'd love a project on QSOs as a probe of...
  31. S

    Is a Cosmology PhD a Dead End or a Gateway to Diverse Career Opportunities?

    I've asked a similar question earlier already, but I want to be more specific now. I'm contemplating doing a PhD in cosmology (mainly numerical analysis of galaxy observations). It's a good group with a good international standing. I'm just a bit worried about the time after my PhD. How...
  32. T

    Is the future of Cosmology limitless or are we bound by fundamental questions?

    I have some general, fundermental questions about Cosmology and the future of Cosmology: 1. Is there a resource or management initative of some kind, which is keeping track of all the theories, sub theories, completely different theories and competing theories related to cosmology? If so is...
  33. B

    Question from Weinberg's cosmology text

    I am trying to learn gauge issues in cosmology from Weinberg's "Cosmology". However, I am completely stumped at how he gets 5.3.4 from 5.3.3. I was doing great until that point and now I'm going crazy. Any help would be highly appreciated!
  34. bcrowell

    More on Penrose's Conformal Cyclic Cosmology

    We had a discussion of Penrose's conformal cyclic cosmology last month: https://www.physicsforums.com/showthread.php?t=427567 His popular-level book Cycles of Time was published first in the UK, but is now available in the US. I got a copy and have read it, so I can report on a few of the...
  35. A

    [Cosmology] Fundamental Plane to find distance

    I have been given data for the Coma and S639 clusters, including their velocity distances. For part a I calibrated the fundamental plane using the Coma data, and got: log(Re) = 1.24log(\sigma) - .82log<I> - .259 I am now supposed to use the S639 data along with the above fit to get a distance...
  36. P

    Physics Is Pursuing a Career in Astrophysics and Cosmology Still Considered Risky in 2010?

    Hello Its 2010 now and I am not really up to date with careers. Is it still an extremely risky to go into astrophysics and/or cosmology? Can you guys tell me how things are going for scientists of all branches if you know? Thanks
  37. marcus

    Bounce derived in spinfoam cosmology

    http://arxiv.org/abs/1010.1258 Big Bounce in Dipole Cosmology Marco Valerio Battisti, Antonino Marciano 5 pages (Submitted on 6 Oct 2010) "We derive the cosmological Big Bounce scenario from the dipole approximation of Loop Quantum Gravity. We show that a non-singular evolution takes place for...
  38. K

    Superstring Cosmology: Compactifying 7 Dimensions

    In Superstring Cosmology and Superstring Gas Cosmology they try to address the question as to how compactification occurs. Is it believed that possibly cosmic strings wrapped themselves around 7 dimensions and collapsed due to their tension? This isn't a personal theory just a curiosity as to...
  39. S

    Exploring Loop Quantum Cosmology with the Planck Satellite

    Will the results from the PLanck satellite shed any light on Loop Quantum Cosmology or any other form of matter bounce?
  40. R

    Cosmology Questions That Have Perplexed Me Over the Years

    Hi all, it's my first post here, and I'm glad to have found it. I'm a software engineer by trade, but I've always been immensely fascinated by cosmology, and I think it's my true passion (when I went to school, I was concerned that pursuing cosmology would not pay the bills, so the pragmatist in...
  41. marcus

    Cycles of time-Penrose says his cyclic cosmology obeys thermodynamics.

    Cycles of time--Penrose says his cyclic cosmology obeys thermodynamics. Roger Penrose has devised a cyclic cosmology which he sees as not violating the second law of thermodynamics. There are several online videos of him lecturing about it. I'll get some links. I'm curious to know if others...
  42. P

    Schools What are the top universities for Cosmology?

    What are the top undergrad universities for a major in Cosmology minus Ivy?
  43. C

    Is Our Understanding of the Universe Shaped by Archetypal Concepts?

    Hello, I've been thinking recently about the truths and realities that are found in the Universe and I just wanted to share a bit of what I have been thinking about. I'm 16 years old right now and I have a drive to understand the way nature displays itself to conscious beings. I'd like to...
  44. marcus

    Chalnoth case against Loop Quantum Cosmology

    Loop Quantum Cosmology could be interesting to discuss because 1) it has been radically transformed since 2007 (with what Ashtekar calls "improved dynamics") 2) it has begun a phase of rapid growth (new crop of researchers , publication rate more than doubled since 2006) 3) it now includes...
  45. S

    Pre Big Bang Cosmology: Is There a Consensus?

    Is there a consesnsus as to whether the big bang represent an ultimate beginning ? it seems to me that the answer to that question is no. The reason for this is that we need a quantum theoy of gravity to describe the moment of the big bang and all current attempts at this eg LQG, Hoyava...
  46. MathematicalPhysicist

    Arithmetic quantum gravity and cosmology

    So basically I am about to embark on my Msc in the pure maths department. Now I wish to conduct research on the subject of arithmetic quantum chaos and its applications in number theory and in gravity and cosmology. In my university I found someone who is an expert in its applications to...
  47. S

    Can Conformal Weyl Gravity be a Viable Cosmology?

    Can Conformal Weyl Gravity be considered a viable cosmological theory?
  48. D

    Need career guidance in cosmology

    Hi All, I am a computer science engineering graduate , currently working in software company. I am very much interested in cosmology since my childhood. I tried putting off my urge to choose cosmology as my career for a very long time. But I can't do that anymore. So can anyone suggest me...
  49. M

    Programs PhD in Cosmology with a 2nd Class Degree

    I am just going into my fourth year of a 4 year MSci course and have got my results from my third year. It's not as good as I had hoped and my average is a 2.1. I know that Cosmology is very difficult to get into and PhD's are over subscribed. I was also hoping to work at one of the...
  50. B

    Is the standard model of cosmology flawed?

    What exactly is going on in physics and with the standard model of cosmology? We had a model that seemed to describe in absolute perfection the workings of the universe, but over the last few decades observations have been made that explicitly counter what's expected from general relativity...
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