| Related sites for http://www.astro.ucla.edu/~wright/cosmolog.htm |
| Supernova_Cosmology_Project This Berkeley labs site is based on observation of red shift in stars going supernova. | | Tufts_Institute_of_Cosmology The Cosmology group at Tufts University with links to other cosmology sites | | The_Big_Bang_(One_More_Time) A new model of the universe says it repeats itself in an endless cycle. Article from Christian Science Monitor. (May 9, 2002) | | Turning_On_the_Universe Astronomers say the Universe's expansion has been accelerating recently. A new model for repulsive 'dark energy' may help explain the acceleration in a more natural way than other models. From Physica | | Review_of_Mistake_of_Einstein Cosmologists have used recent data to constrain the type of 'dark energy' that may fill all of space. (July 30, 1999) | | Coalition_for_Plasma_Science A group of institutions, organizations, and companies joining forces to increase awareness and understanding of plasma science and its many applications and benefits for society. | | Helicon_Plasma_Thesis PhD thesis on helicon wave plasmas by Darryn Schneider. | | MATLAB_Instruction_Modules_for_Introductory_Plasma_Physics Modules to teach single particle motion, dispersion relation, particle simulation and ray-tracing. | | NRL_Plasma_Formulary Revised Edition. The NRL Plasma Formulary has been the handbook of plasma physicists for the past 20 years. It is available in PostScript, PDF, and TeX formats. | | Plasma_Dictionary All terms and definitions presented in alphabetical order. | | Plasma_Everywhere Introduction on plasmas from NASA. Plasmosphere surrounding our world. | | Plasma_on_the_Internet Plasma-gate. Lists of Plasma Physics servers on the internet. (From WIS Institute). | | Plasma_Physics_and_Nuclear_Fusion_Experiments List of web sites describing experiments world-wide to study the physics of nuclear fusion by magnetic confinement. | | Plasma_Physics_Research_Center Plasma Physics Research Center Tehran-Iran | | Plasma_Simulation_Projects Projects on numerical plasma simulation, including HPEM code, Monte Carlo Module, and Feature Profile Model, developed at the Computational Optical and Discharge Physics Group, University of Illinois. | | Plasma_TV_Science Guide to plasma science used within the plasma television technology. Includes educational resources and links to related information. | | Theoretical_Principles_of_Plasma_Physics_and_Atomic_Physics Essential facts and formulae. | | Who_is_Who_in_Atomic_and_Plasma_Physics_(WWAPP) Database from Plasma Laboratory at Weizmann Institute of Science, Israel. | | AP_Statistics_at_the_College_Board The College Board's official AP Statistics page. Course description, sample exam questions, teacher resources and contact information. | | Business_Statistics Covers averages, normal distribution, best curve fit and skewness. Includes resource links. | | Center_for_Statistics_Education The American Statistical Association sponsors educational resources for K-12 and above. ASA's LearnStat program provides continuing education for professional statisticians and educators. | | Computer-Assisted_Statistics_Teaching_(CAST) A complete web-based course in introductory statistics. Registration required. | | Curve_Fit Beginner's guide to nonlinear regression. Emphasizes how to interpret results. | | The_Data_and_Story_Library Online library of datafiles and stories that illustrate the use of basic statistics methods. The goal is to provide data from a wide variety of topics so that statistics teachers can find interesting, | | DISCUS Discovering Important Statistical Concepts Using Spreadsheets. Uses Excel spreadsheets to investigate statistical concepts. | | Intro_Stat__EPR_Approach This site contains information about the Entity-Property-Relationship (EPR) approach to the introductory statistics course by Donald Macnaughton. | | Introduction_to_Mathematical_Statistics Lecture notes from a year-long course in mathematical statistics. | | Introductory_Statistics___Concepts,_Models,_and_Applications_by_David_Stockburger An online, searchable introductory statistics text. By David Stockburger of Southwest Missouri State University. | | Intuitive_Biostatistics Harvey Motulsky, OUP (1995). Site for the book, with online extracts (PDF). | | K-12_Statistics_Education Resources in statistics including lessons and useful data sets. | | Number_Watch Monitors the media in search of misleading numbers in news, politics and science. | | Numeracy_in_the_News Features sections on data collection and sampling, creating graphs, probability and inference. Also, includes special topic articles and teacher spreadsheet programs. | | Primer_in_Statistics Covers mean, mode, median, standard deviation, area approximation, charts and testing for normality. | | Resources_in_Statistics,_Quantitative_Methods_and_Experimental_Design Statistics-related exercises and humour, for courses from high school to graduate level. | | Rice_Virtual_Lab_in_Statistics This resource for teaching statistics includes java simulations, case studies, an online text, and an analysis lab. | | SAS_JMP Tutorials for SAS's JMP Statistical Analysis Software. | | Seeing_Statistics Tutorial using graphs to illustrate concepts. Includes glossary of terms. Online purchase. | | StatiBot An on-line expert system for finding statistical tests appropriate to a dataset. | | Statistica Book, with worked examples and courses are specially designed for the non-mathematicians. Includes excerpts and ordering information. | | Statistical_Data_Analysis Tutorial describes time series analysis, popular distributions, and other topics. |
|
Ned Wright's Cosmology TutorialWelcome to Ned Wright's Cosmology Tutorial News of the UniverseFrequently Asked QuestionsEnter the tutorial or the Italian version  or the French version  Cosmological fads and fallacies Cosmology and artCosmology, Religion & KansasSend me your commentsNew on the tutorial: A discussion of the history of the CMB dipole discovery.A history of COBE,the COsmic Background Explorer, in pictures.A cool rollover page that blinksbetween a color image contructed from 3 WMAP bandsand the WMAP ILC reduced galaxy mapA calculator that takes light travel timeand computes the redshift.There is also an advanced versionof my Cosmology Calculator.Cosmology is the study of the origin, current state, and future of ourUniverse. This field has been revolutionized by many discoveries madeduring the past century. My cosmology tutorial is an attempt tosummarize these discoveries. It will be "under construction" for theforeseeable future as new discoveries are made. I will attempt to keepthese pages up-to-date as a resource for the cosmology courses I teachat UCLA. The tutorial is completely non-commercial, buttax deductible donations to UCLA are always welcome.Astronomy and cosmology are very much mathematical sciences, but I haveattempted to avoid higher math in these pages. I do use high schoolalgebra and geometry - courses required for admission to UCLA -but I have also included some animations [1, 2,3, 4,5,6,7],some Java applets [1,2],and many illustrations in the tutorials,the ABC's of Distances,and the answers to some of the Frequently Asked Questions.In addition to the cosmology tutorial,there is also a relativity tutorial andextensive discussions on the age,density andsize of the Universe.There is also a bibliography of books at arange of levels, and a Javascriptcalculator of themany distances involved in cosmology.Slides for recent talks:Slidesfor the 105th Faculty Research Lecture at UCLA, 28 Oct 2008.Colloquiumat the Geneva Observatory, 10 Nov 2006.Public talk at the 20 Oct2006 meeting of the Ventura County AstronomicalSociety27 Sep 2006 colloquiumat the Arizona State University School of Earth and Space Exploration.24 Sep 2006 Talk at the Mt. Wilson Observatory AssociationInvited talkat Einstein's Legacy: Relativistic Astrophysics and Cosmology,7-11 Nov 2005.Presentationat the International Symposium on Particle Physics, Astrophysics and CosmologyLectures at the International Summer Institute on Particle physics, Astrophysics and Cosmology, Hangzhou China, 2005 August 15,16,18."Fact and Fiction inCosmology", a public lecture at the Cal State Northridge planetarium.13 March 2005 AFHU EinsteinSymposium Talk3 March 2005 Director'sDistinguished Lecture at LLNL27 May 2004 Ohio StateColloquium11 Oct 2003 UCLA Extension CourseSeptember, 2003 NATO ASI in Cargese lectures(1,2,3)lectures at the July, 2003 winter school in Argentina"Are We Likely to Be Alone" at the4 April 2003 CSEOL SymposiumAstrophysics Fact SheetThe course notes(130 pages, 398 equations, 51 figures)for the upper division undergraduate Stellar Systems and Cosmology course,Astronomy 140, that I last taught in spring 2008 are available on the Web.And for a much more technical discussion of cosmologysee my graduate course Astro 275lecture notes (116 pages, 364 equations, 40 figures).This course was last taught in the spring of 2007.If this course Web site gets closed, you can use a backup Postscriptcopy of the A275 notes.Use Ghostscript to view this file or save it to disk and send it toa Postscript printer.News of the UniverseDark Flow Detected - Not!24 Sep 2008 - Kashlinsky et al. (2008) have claimed a detection of abulk flow in the motion of many distant X-ray emitting clusters of galaxies.Unfortunately this paper and thecompanion paperhave several errors so their conclusions cannot be trusted.A technical discussion of these errors can be foundhere.Meet the Fermi Gamma-ray Space Telescope 26 Aug 2008 -NASAreleased an all sky mapin gamma raysfrom the satellite formerly known as GLAST, newly renamed asthe Fermi Gamma-ray Space Telescope or FGST.Enrico Fermi discovered the Fermi-Dirac statistics followed by particles known as fermions, such as electrons and protons,emigrated to America to escape fascism, and built the firstnuclear reactor as part of the Manhattan Project.FGST will have greatly improved angular resolution and sensitivity forhigh energy gamma rays with E > 1 GeV at the short wavelengthend of the electromagnetic spectrum, and should discover thousands ofgamma ray sources at cosmological distances.Variable Constants? 20 Jun 2008 -Murphy, Flambaum, Muller & Henkel (2008) show that the ratio of the proton mass to the electron mass has varied by less than 1.8 parts per million (95% CL) since redshift z = 0.68466. They comparedthe radio inversion lines of ammonia to the pure rotation lines ofHCN and HCO+. All of these lines are measured very precisely usingradio astronomy techniques, and the redshifts are consistent. But theammonia lines are much more sensitive to the proton:electron mass ratioso this quantity has not varied in the past 6 billion years. Thisreport is an improvement over previous results using the same quasar absorption line cloud.Another Bullet Cluster17 Jun 2008 - Bradac et al. (2008) have found another bullet cluster where twoclusters of galaxies have collided, leaving the hot gas in betweenthe clumps of galaxies, but the source of gravity has passed right through the collision, staying with the galaxies. Since the hot gas is most of thenormal matter, this shows that the source of gravity is not the normalmatter, but rather dark matter. This is a problem for alternative modelsthat modify gravity to eliminate the need for dark matter.Supernova Initial Flash22 May 2008 - Soderberg etal. report an observation of a soft X-ray flare from a spotthat later turned out to be a Type Ibc supernova. The peak flux wasabout 7 x 10-10 erg/cm2/sec for about 400seconds. At the 27 Mpc distance of the host galaxy NGC 2770 this isabout 2 x 1046 ergs in X-rays produced when the shockwavebreaks out of the massive star whose core has collapsed. The UV peakeda day later, and the optical 20 days later as the remains of the starexpanded and cooled.This was quite an interesting result when it appeared three months agoon arxiv.org, but it was embargoed byNature until publication so I didn't post this news item until now.New High Redshift CMB Measurement13 May 2008 -Srianand et al. have announced a measurement of TCMB at a redshift of 2.418.Absorption lines from carbon monoxide (CO) molecules were seen inthe spectrum of a distant quasar, and showed rotational excitationin the CO ground vibrational state.The temperature seen is 9.15 +/- 0.7 K, while the Big Bang modelpredicts 9.315 K.So this observation is consistent with the Big Bang, butcontradicts the Steady State model.New Union Supernova Catalog 28 Apr 2008 -Kowalski et al. (2008)of the Supernova Cosmology Project present a union catalog of supernovae.The catalog contains 332 SNe that pass all cuts when the low redshift SNeare included. Click on the thumbnail at right for binned ΔDMvs. redshift tables and plots.ΔDM is the difference in the distance modulus between the data or model and an empty Universemodel. A higher distance modulus means the supernovae are fainterthan expected in an empty Universe.Tired Light is Still Dead24 Apr 2008 -Blondin et al. (2008)studied distant supernovaeusing spectra to judge the age of the objectduring each observation. They found an aging rate that varied withredshift z like1/(1+z)(0.97 +/- 0.10),compatible with the expected1/(1+z) for expanding Universes, but 9.7 standard deviationsaway from the constant aging rate expected in the tired light model.Dark Matter Detected?17 Apr 2008 - The DAMA/LIBRAexperiment announced a confirmation of their previously found annual modulation signal inthe count rate of a deep underground CsI detector. They see amodulation of +/-0.027 counts/kg/keV/day in the 2.5 to 3.5 keV band,but since the amplitude of modulation is supposed to be at most 7% ofthe dark matter signal this implies a dark matter generated event rateof 0.38 cts/kg/keV/day or more. The total rate in the experiment is1.24 cts/kg/keV/day in this 2.5-3.5 keV band, so the dark matter rateis at least 31% of the total. With such a large fraction of the totalrate coming from dark matter events in this 3 keV bump one would expectto see a corresponding bump in the total rate spectrum and it isactually present. But the CDMSexperiment in the Soudan minesaw no counts in 397.8kg-days of exposure, so the high DAMA/LIBRA rate seems unlikely -but not impossible given the differences in the detector materials andmethods. However, it is peculiar that the annual modulation techniqueis being used when the ratio of dark matter to background counts is thislarge.Naked Eye Visible Gamma Ray Burst Afterglow from z=1!19 Mar 2008 - The NASA satellite Swift has detected the most luminous explosion yet seen.Gamma Ray Burst GRB080219B got slightly brighter than opticalmagnitude 6, the limit of naked-eye visibility, and has a redshiftgreater than or probably equal to 0.937,the higher of two absorption line redshifts.The absolute magnitude is then -38!The press is catching up to this story: the New York Times, the Associated Press, and the Agence France Presse all have articles on this. Here is the NASA press release.WMAP 5 year Data Released  5 Mar 2008 - WMAP released its five year dataset today,with 7 papers and new maps and power spectra posted toLAMBDA.Highlights of the new results include: Definite evidence for light neutrinos. The presence of theneutrino background was necessary from Big BangNucleosynthesisresults, but now the CMB requires their presence at 99.5% confidence. The epoch of reionization is now more than 3 sigma earlier than theredshift z=6.2where the Gunn-Peterson effect blackens quasar spectra. The tensor:scalar ratio is now shown to be less than 0.2. More than 400 radio sources are seen by WMAP.The image at right is a new combined CMB power spectrum showing thata 6 parameter ΛCDM model still fits all the CMB data as well asthe Baryon Acoustic Oscillation signal and the supernova data. Click onthe image for a larger version.The NASA press release finally came out late on March 7. Coverage atScience Daily, the New Scientist, and the New York Times, quoting me.Supernova Progenitor Seen? - Probably Not15 Feb 2008 - Roelofs, Bassa, Voss & Nelemans (2008) comment on the claimeddetection by Voss & Nelemans (2008, Nature, 451, 802)of an X-ray binary progenitor at the position of the Type Iasupernova SN 2007on. They find that the X-ray source is probablystill present, although significantly fainter. Furthermore, with better astrometry the X-ray position is slightly offset fromthe position of the supernova, by 1.18+/-0.27 arc-seconds. Since a Type Ia supernova completelydisrupts the white dwarf that explodes, a surviving X-ray source is veryunlikely. So the putative progenitor was quite possibly a chance coincidence with a variable X-ray source.Highest Redshift Galaxy? but no lines12 Feb 2008 - The HST and the Spitzer Space Telescope have issued a press release claiming the detection of a galaxy at redshift z=7.6. However, NO lines havebeen observed. Based on previous z=10 galaxies, we should require two linesbefore believing any story like this. The NASA budget must be tight.Very Precise Distance to a Cepheid11 Feb 2008 - Kervella et al. report a distance to the Cepheid variable RS Puppis of 1992 +/- 28 parsecs. This distance was obtained geometrically using a light echotechnique. Cepheids are used to calibrate the Hubble constant that determinesthe age and size of the Universe. ESO has issued a press release. The paper will be published in Astronomy & Astrophysics.Quasi-Steady State Cosmology Fails Again18 Jan 2008 - Narlikar, Burbidgeand Vishwakarma (2007, J. Astr. & Ap., 28, 67) claim to fit the CMB anisotropy data with the QSSC model.Not surprisingly, this claim is false.Crafoord Prize to Sunyaev 17 Jan 2008 - the Crafoord Prizein Astronomy and Mathematics was split between Rashid Sunyaevand two string theorists. Sunyaev is famous for the Sunyaev-Zeldovich effect and other studies ofthe Cosmic Microwave Background.Born and raised in the Soviet Union, Sunyaev is now directorof the Max Planck Institute for Astrophysics in Garching near Munich.Not Much Evidence for Cosmic Texture07 Dec 07 - What is essentially a 1.4 standard deviation result is intoday's Science:Cruz et al.(2007, Science, 318,1612),a paper that explains the giant hole in space by an unwinding texture event. A textureis a topological defect like a cosmic string, and the model that cosmic structures were created by topological defects was ruled outby COBE.But it is always possible that a small fraction of cosmic structures arecreated by topological defects, and Cruz et al. consider a model wherethat small fraction is just one cosmic defect matched to the "cold spot"in the Cosmic Microwave Background (CMB)found by WMAP.They find a likelihood ratio of 2.5 to 1,which is normally considered to be exp(n2/2) where n is the number of standard deviations.Cruz et al. do not consider the giant voidfound in the direction of the cold spot. If both thecold spot and the void can be explained by texture their model would gainin credibility. This void has always been claimed to be evidenceof a bridge to another Universe, so it has certainlybeen a magnet for unusual theories.Giant Hole in Space?23 Aug 2007 - There is a widely picked up press releaseabout results by Rudnicket al. (2007, ApJ in press)on explaining a WMAP cold spotreported earlier.The original report on the WMAP cold spot was statistically weaksince the authors searched through roughly 100,000 combinationsof position and resolution, so finding an oddly cold spot wasnot too surprising. But the new result shows that the WMAP coldspot coincides with an anomalous spot in the radio survey NVSS.Rudnick et al.have interpreted this as a very large void in the distributionof matter in this direction, causing the cold spot via the late-integratedSachs-Wolfeeffect. However, they have no distance information on the sources in the spotso the interpretation is still uncertain. But the coincidence betweenthe WMAP cold spot and the NVSS low source count spot is intriguing.The timing of the press release is a bit unusual, since the paper wasreleased on the preprint server in April, and has not yet appeared inprint, so neither of the usual hooks for timing press releases was used.UPDATE: 19 May 2008 - Smith and Huterer find no evidence for the void in the NVSS.Big Bang Pioneer Passes12 Aug 2007 - Ralph Alpher who, along with his thesis adviser George Gamow and colleague Robert Herman developed the hot Big Bang model, died today. Alpher and Herman's paper (1949, Phys. Rev., 75, 1089-1095) gave two versions of thehot Big Bang, one with To = 1 Kand one with To = 5 K. Fred Hoyle ignored these resultswhen he used the T(CN) = 2.3 K observed by McKellar (1939)as evidence against the Big Bang in a 1950 book review. Redshift 10 Galaxies? 12 Jul 07 -Stark et al.claim to have detected Lyman alphaemission from 6 candidate objectswith redshiftsbetween 8.5 and 10.2. These are very faint sources which have been magnified by the gravitational lensingof a foreground clusterof galaxies, and even then barely detected with very long exposures on theKeck telescopes.The negative image at right shows a near infrared image taken withthe Hubble Space Telescope,and it is clear that whatever there is in thecenter of the circle is very faint. But when the light coming from thecenter of the circle is spread out into a spectrum using theNIRSPECinstrument built at UCLA there is an easilyvisible clump in the spectral image, shown at left. This is also anegative image, so the dark spot in the center of the circle is an emission line. This spectral line is at a wavelength of 1.355 microns,which is 11.1 times longer than the rest wavelength of Lyman alpha,so if it really is Lyman alpha, the redshift of this source is 10.1.Using my cosmology calculator, one findsthat the age of the Universe was 475 million years when this galaxyemitted the light that we see. That light took 13.190 billion years toreach us, and the galaxy is now 31.578 billion lightyears away from us due to the expansion of the Universe.One note of caution: a previous claimed redshift 10 galaxybased on the same kind of evidence was not confirmed.Variable Constants?21 Jun 2007 -A new study of ammonia and carbon monoxide lines in a distantquasar shows that the electron to proton mass ratio has remainedquite constant. Earlier work with ultraviolet lines ofmolecular hydrogen, redshifted into the optical, suggested asmall change in this ratio, but this new study uses radio astronomywhich allows much more precise measurements of line ratios.Underground Laboratory Cosmology 09 Jun 2007 -Today I visited the Soudan UndergroundLaboratory near Tower, MN. This is in an old iron mine in the MesabiIron Range, where hematite (70 percent iron by weight) was brought upfrom nearly 0.8 km underground. It is run as a state historical park,so you can tour the engine house and see the antique hoist, then hear theantique hoist crank up and lift the previous tourists out of the mine.Then you put on your hard hat, get in the 1.2 meter square cage and godown into the Earth. In the physics lab the lights and air handling system let you forgetyou are so deep underground, and you find the MINOS far detector.MINOS stands for Main Injector Neutrino Oscillation Search, and is anexperiment that generates a neutrino beam at Fermilab near Chicago, andsend the neutrinos through 800 km of rocks to the Soudan UndergroundLaboratory. There the 6000 ton MINOS far detector sees about 2 or 3 neutrinosper day. Everything you see in the physics laboratory had to go down inthe 1.2 meter square cage!The MINOS detector sees many cosmic ray muons and you can see the latest event on the Web.The MINOS experiment has confirmed the earlier results of the Super-Kamiokandeexperiment that used atmospheric neutrinos.It appears that muon neutrinos oscillate into tau neutrinosindicating a difference in mass squared of about 0.0025 eV2.While neutrino oscillation experiments only measure delta mass squaredvalues, this result indicates that neutrinos are probably not thecosmological dark matter, since if the tau neutrino has a mass of 0.05 eV,and the muon and electron neutrinos are much lighter, then neutrinosmake up only 0.1 percent of the critical density of the Universe,and the current model has 23 percent of the critical density in darkmatter.The other cosmological experiment in the Soudan lab is theCryogenic Dark Matter Search (CDMS).This experiment is searching for dark matter made up ofWIMPs.So far it only has measured upper limits.News of the Universe ArchiveOther Good LinksNed Wright's Home PageAccess Statistics and AwardsFAQ | Tutorial : Part 1 | Part 2 | Part 3 | Part 4 | Age | Distances | Bibliography | Relativity © 1996-2008 EdwardL. Wright. Last modified 30 Nov 2008 |
|
