DOCSLIB.ORG

Determination of the Ppn Parameter with the Hipparcos Data

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Determination of the Ppn Parameter with the Hipparcos Data 49 DETERMINATION OF THE PPN PARAMETER WITH THE HIPPARCOS DATA 1 1 2 M. Frschl e , F. Mignard , F. Arenou 1 Observatoire de la C^ote d'Azur, CERGA, UMR CNRS 6527, Avenue Cop ernic, F06130 Grasse, France 2 Observatoire de Paris-Meudon, DASGAL, URA CNRS 335, F92195 Meudon Principal Cedex, France ABSTRACT Assuming that the de ection for all stars is of the form: 1 + mas 4 In the pro cessing of the Hipparcos data, relativistic 2 e ects in the propagation of light, like the ab erra- tion and the b ending of light rays, were intro duced could be known to b etter than 0.001. Unfortu- at an early level in the mo delling. Thanks to the nately, the correlation between the global parallax accumulation of very accurate measurements of star zero p oint and is very large 0:92 and increases p ositions at various elongations from the Sun, it was the exp ected formal error of by an estimated factor p ossible to assess byhowmuch the PPN parameter of ab out 2.5, so that it b ecomes 0.003. However, such deviates from its General Relativityvalue. A series a result would rank among the b est determinations of tests has b een implemented to determine this pa- obtained byvarious means. rameter and evaluate the magnitude of the p ossible sources of errors. From the results we can conclude A fairly large number of determinations of have that the co ecient is within 0.3 p er cent of unity, app eared in the past twentyyears Will 1981, 1984, with =0:997 0:003. This value is not signi cantly 1987 involving b oth the b ending of light, the Shapiro di erent from unity, as predicted by General Relativ- time delay in the solar system or the motion of the ity. Mo on. Concerning the measurement of the b ending in the visible from the Hipparcos data, it is simply a rep- Keywords: Astrometry, General Relativity. etition at large angles of the celebrated 1919 ex- p editions to Brazil and to Princip e Island Dyson et al. 1920, which to ok advantage of a solar eclipse to observe stars with resp ect to each other in the solar 1. INTRODUCTION neighb ourho o d. This was followed by a subsequent comparison to the same stellar eld without the Sun. Since then, a total of nine solar eclipses have b een The accuracy of the Hipparcos measurements implied used for light de ection measurements. In this kind that the relativistic e ect in the light propagation of exp eriment, the error is very large and generally had to b e included in the mo delling of the data reduc- exceeds 10 p er cent. In addition to the intrinsic di- tion. This concerned the second order light ab erra- culty in observing at small distances from the Sun, in tion which is of the order of 1 mas 1 mas=0.001 arc- the adverse conditions of an eclipse, the main source sec and the light de ection whose magnitude is of uncertainty is the astrometry over two indep en- 4.07 mas at right angles to the solar direction for dent exp osures of the same eld with two di erent an observer at one astronomical unit from the Sun. techniques, involving a delicate calibration of scaling After a careful calibration of the instrument parame- factors. ters, each abscissa on a reference great-circle RGC had a typical precision of 3 mas for a star of 8{9 The adventofvery{long{base interferometry at radio mag. Each consortium has generated for the full wavelengths has pro duced greatly improved determi- mission ab out 3.5 million abscissae. Thus, ideally, nations of , thanks to the capability of measuring if the reduction is without systematic errors and by the distance b etween radio{sources as they pass very neglecting all kind of correlations, an unknown an- close to the Sun. Somewhat akin to Hipparcos in gular parameter in the abscissa mo delling common its principle, a recent global pro cessing of the VLBI to all stars could b e determined with a precision as data used to monitor the Earth's rotation includes go o d as: the determination of from observations carried out 3 over almost the entire celestial sphere. This yields p =0:0016 mas 6 Rob ertson & Carter 1984, Rob ertson et al. 1991: 3:5 10 1 + Based on observations made with the ESA Hipparcos =1:000 0:001 satellite. 2 50 In all these observations, the refraction of the radio 133 degrees. At rst glance, this is a drawback, waves in the solar corona, which b ends the ray more but it allows a b etter randomisation of the sys- strongly than in the visible, limits the accuracy as tematic errors thanks to the large coverage in one must mo del this additional b ending to correct elongation; the data. The Hipparcos data retains the b est of the This is the rst optical measurement of p er- twoabove metho ds: the optical wavelength where no formed without need for solar eclipses; corona e ect is to b e feared and the accuracy and full sky coverage of the VLBI technique. All observations treated have b een made with the same instrument, well calibrated all over the In addition to its b ending, a light signal takes a longer sky and over a p erio d of 37 months. time to travel a given distance in a gravitational eld than in the vacuum and the magnitude of this `time delay' Shapiro 1964 dep ends also on . The analysis by Reasenb erg et al. 1979 of the radar time-delay 2. THE LIGHT DEFLECTION MODEL using Mariner 9 and the Viking landers and orbiters has resulted in: The general derivation of the equation of light-rays 1 + in the PPN formalism is given in So el 1989 and =1:000 0:001 yields the measurable angle b etween two sources in 2 a gravitational eld as a function of the co ordinates. Despite the use of a dual-frequency at 2.3 and 8.4 Let us de ne the co ordinate de ection as the an- 1 GHz, the propagation in the solar corona remains gle between the unp erturb ed and p erturb ed paths, the ma jor factor limiting the accuracy. by: A global evaluation of the PPN parameters by 1 + sin 2GM 1 = 1 Hellings 1984 has allowed the use of a large data 2 rc 2 1 cos sample of solar system observations: meridian tran- sits of planets and the Mo on, lunar laser ranging mea- where G is the gravitational constant, M the solar surements, radar range measurements on Mercury, mass, r the distance between the satellite and the Venus and Mars. The dynamics of all these ob jects center of the Sun and c the sp eed of light. The angle and the observations were mo delled in the PPN for- is the angular distance between the star and the malism and the b est t yielded: Sun. 1 + The e ect of the light de ection on the RGC abscissa =0:9994 0:0008 is given by: 2 ' = cos 1 1 However the great heterogeneity of the observational and material makes the assessment of the true uncertainty dicult. 2GM 1 + cos " sin ' = 1 2 rc 2 1 cos " cos From the measurementof the rate of change of the 2 fringe delays of radiosources during a solar o cculta- tion, Lebach et al. 1995 have obtained: where " is the latitude of the Sun with resp ect to the RGC and the abscissa di erence on the RGC b e- 1 + tween the star and the Sun as shown in Figure 1. In =0:9998 0:0008 the Hipparcos data pro cessing a value of = 1 has 2 b een used consistently, so that the true unknown to where the quoted error includes the standard error b e used in the analysis of the residuals is 1. The of the t and accounts for systematic errors brought geometry of the light de ection and that of the par- ab out by the source structure and the propagation allactic e ect are very similar, di ering in direction e ects. and in their dep endence in , with = sin for 2 the parallactic e ect and the expression of Equation 1 Very recently Williams et al. 1996 have made sev- for the de ection. This di erence proves essential in eral determinations of PPN parameters from lunar separating the two e ects in the observation equa- laser ranging. The test of geo detic precession based tions. However the separation is not p erfect, despite on the rotation of the lunar orbit can b e taken as a the go o d coverage in elongation, and the two e ects 1 p er cent test of . In addition, a careful discussion remain largely correlated. of the di erent terms in the lunar motion yields even- tually =1:000 0:005 as the present LLR result. 3. OBSERVATION EQUATIONS With the Hipparcos data, the information related to the is unique in several resp ects: We have used all the star abscissa residuals result- ing from the FAST and NDAC solutions, expressed The measurements are carried out in the visible in the Hipparcos catalogue system. For each mea- and are then free from the large b ending of ra- surement the calibrated standard errors and the cor- dio waves by the solar corona, which limits the relation between the two nearly simultaneous mea- accuracy of the astrometry by VLBI; surements are available in the Hipparcos and Tycho Catalogues ESA 1997, Volume 1, Section 2.8.
Load more

Recommended publications
  • Download This Article (Pdf)
    244 Trimble, JAAVSO Volume 43, 2015 As International as They Would Let Us Be Virginia Trimble Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575; [email protected] Received July 15, 2015; accepted August 28, 2015 Abstract Astronomy has always crossed borders, continents, and oceans. AAVSO itself has roughly half its membership residing outside the USA. In this excessively long paper, I look briefly at ancient and medieval beginnings and more extensively at the 18th and 19th centuries, plunge into the tragedies associated with World War I, and then try to say something relatively cheerful about subsequent events. Most of the people mentioned here you will have heard of before (Eratosthenes, Copernicus, Kepler, Olbers, Lockyer, Eddington…), others, just as important, perhaps not (von Zach, Gould, Argelander, Freundlich…). Division into heroes and villains is neither necessary nor possible, though some of the stories are tragic. In the end, all one can really say about astronomers’ efforts to keep open channels of communication that others wanted to choke off is, “the best we can do is the best we can do.” 1. Introduction astronomy (though some of the practitioners were actually Christian and Jewish) coincided with the largest extents of Astronomy has always been among the most international of regions governed by caliphates and other Moslem empire-like sciences. Some of the reasons are obvious. You cannot observe structures. In addition, Arabic astronomy also drew on earlier the whole sky continuously from any one place. Attempts to Greek, Persian, and Indian writings. measure geocentric parallax and to observe solar eclipses have In contrast, the Europe of the 16th century, across which required going to the ends (or anyhow the middles) of the earth.
    [Show full text]
  • Einstein, Eddington, and the Eclipse: Travel Impressions
    EINSTEIN, EDDINGTON, AND THE ECLIPSE: TRAVEL IMPRESSIONS ESSAY 195 INTRODUCTION The total solar eclipse that occurred on 29 May 1919—perhaps considered the most famous solar eclipse ever—was exceptional for a variety of scientific, political, social, and even religious reasons. At just over five minutes of totality (more precisely, 302 seconds), it was a long eclipse. Behind the sun appeared the Taurus constellation, which included the Hyades, the brightest star cluster in the ecliptic. The preparations of the British teams that observed it, and which are the subject of this essay, took place in the middle of the Great War, during a period of international instability. The observation locations selected by these specialists were in the tropics, in distant regions unknown to most astronomers, and thus required extensive preparations. These places included the city of Sobral, in the north-eastern state of Ceará in Brazil, and the equatorial island of Príncipe, then part of the Portuguese empire, and today part of the Republic of São Tomé and Príncipe. Located in the Gulf of Guinea on the West African coast, Príncipe was then known as one of the world’s largest cocoa producers, and was under international suspicion for practicing slave labour. Additionally, among the teams of expeditionary astronomers from various countries—including the United Kingdom, the United States, and Brazil—there was not just one, but two British teams. This was an uncommon choice given the material, as well as the scientific and financial effort involved, accentuated by the unfavourable context of the war. The expedition that observed at Príncipe included Arthur Stanley Eddington (1882– 1944), the astrophysicist and young director of the Cambridge Observatory, as well as the clockmaker and calculator Edwin Turner Cottingham (1869–1940); the expedition that visited Brazil included Andrew Claude de la Cherois Crommelin (1865–1939), and Charles Rundle Davidson (1875–1970), both experienced astronomers at the Greenwich Observatory (see pp.
    [Show full text]
  • Hubble Sees Light Bending Around Nearby Star : Nature News
    NATURE | NEWS Hubble sees light bending around nearby star Rare astronomical observation shows effects of relativity. Alexandra Witze 07 June 2017 STSI Stein 2051 B is a white-dwarf star in the constellation Camelopardalis. The Hubble Space Telescope has spotted light bending because of the gravity of a nearby white dwarf star — the first time astronomers have seen this type of distortion around a star other than the Sun. The finding once again confirms Einstein’s general theory of relativity. A team led by Kailash Sahu, an astronomer at the Space Telescope Science Institute in Baltimore, Maryland, watched the position of a distant star jiggle slightly, as its light bent around a white dwarf in the line of sight of observers on Earth. The amount of distortion allowed the researchers to directly calculate the white dwarf’s mass — 67% that of the Sun. “It’s a very difficult observation with a really nice result,” says Pier-Emmanuel Tremblay, an astrophysicist at the University of Warwick in Coventry, UK, who was not involved in the discovery. The findings were published in Science 1 and presented at a meeting of the American Astronomical Society in Austin, Texas, on 7 June. White dwarfs are the remains of stars that have finished burning their nuclear fuel. The Sun will eventually become one. Sahu’s team studied a white dwarf known as Stein 2051 B, in the constellation Camelopardalis. At 5 parsecs (17 light years) from Earth, it is the sixth-nearest white dwarf. Because it is so close, it appears to move quickly across the sky compared with more-distant stars.
    [Show full text]
  • Smart Optics for ESA Space Science Missions
    Smart Optics for ESA Space Science Missions • Gaia, JWST, Darwin • Scientific objectives • Payload description • Optical technology developments Dr. Ph. Gondoin (ESA) ESA’s IR and visible astronomy missions DARWIN GAIA Herschel Planck Eddington JWST 1 GAIA Science Objectives Understanding the structure and evolution of the Galaxy, i.e.: – census of the content of a large part of the Galaxy – quantification of the present spatial structure from distance (3-D map) – knowledge of the 3-D space motions Æ Complementary astrometry, photometry and radial velocities: – Astrometry: distance and tranverse kinematics – Photometry: extinction, intrinsic luminosity, abundances, ages, – Radial velocities: 3-D kinematics, gravitational forces, mass distribution, stellar orbits GAIA (compared with Hipparcos) Hipparcos GAIA Magnitude limit 12 20-21 mag Completeness 7.3 – 9.0 ~20 mag Bright limit ~0 ~3-7 mag Number of objects 120 000 26 million to V = 15 250 million to V = 18 1000 million to V = 20 Effective distance limit 1 kpc 1 Mpc Quasars None ~5 ×105 Galaxies None 106 - 107 Accuracy ~1 milliarcsec 4 µarcsec at V = 10 10 µarcsec at V = 15 200 µarcsec at V = 20 Broad band 2-colour (B and V) 4-colour to V = 20 Mediumphotometry band None 11-colour to V = 20 Radialphotometry velocity None 1-10 km/s to V = 16-17 Observing programme Pre-selected On-board and unbiased 2 PayloadGAIA payload • 2 astrometric telescopes: • Separated by 106o • SiC mirrors (1.4 m × 0.5 m) • Large focal plane (TDI operating CCDs) • 1 additional telescope equipped with: • Medium-band photometer • Radial-velocity spectrometer Optical technology for GAIA • CCD’s and focal plane technology: (ASTRIUM.GB+E2V under ESA TRP contract) – Astrometry: 3 side buttable, small pixel (9 µm), high perf.
    [Show full text]
  • The Atmospheric Remote-Sensing Infrared Exoplanet Large-Survey
    ariel The Atmospheric Remote-Sensing Infrared Exoplanet Large-survey Towards an H-R Diagram for Planets A Candidate for the ESA M4 Mission TABLE OF CONTENTS 1 Executive Summary ....................................................................................................... 1 2 Science Case ................................................................................................................ 3 2.1 The ARIEL Mission as Part of Cosmic Vision .................................................................... 3 2.1.1 Background: highlights & limits of current knowledge of planets ....................................... 3 2.1.2 The way forward: the chemical composition of a large sample of planets .............................. 4 2.1.3 Current observations of exo-atmospheres: strengths & pitfalls .......................................... 4 2.1.4 The way forward: ARIEL ....................................................................................... 5 2.2 Key Science Questions Addressed by Ariel ....................................................................... 6 2.3 Key Q&A about Ariel ................................................................................................. 6 2.4 Assumptions Needed to Achieve the Science Objectives ..................................................... 10 2.4.1 How do we observe exo-atmospheres? ..................................................................... 10 2.4.2 Targets available for ARIEL ..................................................................................
    [Show full text]
  • Stellar Structure and Habitable Planet Finding
    SP-538 January 2004 Second Eddington Workshop Stellar Structure and Habitable Planet Finding 9-11 April 2003 Palermo, Italy SUB Gottingen 7 212 196 901 Organised by European Space Agency and INAF — Osservatorio Astronomico di Palermo European Spate Agenty Agente spatiale europeenne CONTENTS Preface ix Oral Papers The Eddington baseline mission, F. Favata 3 Models of stellar structure for asteroseismology, F. D'Antona, J. Montalban, I. Mazz- itelli 13 Eddington and the internal constitution of the stars, I. W. Roxburgh 23 Science requirements and their translation into instrumental design, C. Catala, A. Aricha, 0. Boulade, E. Diaz, G. Epstein, F. Favata, K. Home, H. Kjeldsen, D. Lumb, M. Mas-Hesse, 1. Roxburgh 39 CCD selection for Eddington, D. Lumb 47 Laboratory tests of Eddington photometry, D. M. Walton, G. Ramsay, A. Smith 51 The Eddington CCD data simulator, T. Arentoft, H. Kjeldsen, J. De Ridder, D. Stello 59 The Eddington light curve simulator, J. De Ridder, H. Kjeldsen, T. Arentoft, A. Claret 67 Choosing the proper transit detection algorithm for Eddington, B. Tingley 71 The nature of OGLE transiting planet candidates, J. Eisloffel, M. Kiirster, A. P. Hatzes, E. Guenther 81 Asteroseismology and extrasolar planets of K Giants, A. P. Hatzes, J. Setiawan, L. Pasquini, L. da Silva 87 The Sun as a reference for Eddington, S. Turck-Chieze 95 Pulsating pre-main sequence stars as possible Eddington targets, K. Zwintz, W. W. Weiss 105 Mode extraction from time series: from the challenges of COROT to those of Edding- ton,T. Appourchaux, O. Moreira, G. Berthomieu, T. Toutain 109 Colour information in asteroseismology, R.
    [Show full text]
  • 1.7 News & Views MH
    news and views lifetimes. In the longer run, the experience 1. Claverie, A., Isaak, G. R., McLeod, C. P., van der Raay, H. B. & that cancers with different EGFR mutations gained with MOST on the nature of stellar Roca Cortes, T. Nature 282, 591–594 (1979). may respond differently to inhibitors7. 2. Grec, G., Fossat, E. & Pomerantz, M. Nature 288, 541–544 pulsations, as well as on optimal techniques (1980). Finally, in cancers that initially respond and for space-based photometry,will be of crucial 3. Matthews, J. M. et al. Nature 430, 51–53 (2004). subsequently recur,the EGFR gene will be the importance to coming asteroseismic missions 4. Goldreich, P. & Keeley, D. A. Astrophys. J. 212, 243–251 (1977). first place to look for additional mutations — such as the French-based COROT mission 5. Christensen-Dalsgaard, J. & Frandsen, S. Solar Phys. 82, that have conferred drug resistance. 469–486 (1983). and, one may hope, the far more ambitious 6. Kjeldsen, H. & Bedding, T. R. Astron. Astrophys. 293, 87–106 How will these observations be translated Eddington mission originally selected for (1995). into clinical practice? EGFR mutations are (but currently not included in) the pro- 7. Brown, T. M., Gilliland, R. L., Noyes, R. W. & Ramsey, L. W. more common in women who have never ■ Astrophys. J. 368, 599–609 (1991). gramme of the European Space Agency. 8. Martic, M., Lebrun, J.-C., Appourchaux, T. & Korzennik, S. G. smoked. Overall, however, fewer than 10% of Jørgen Christensen-Dalsgaard and Hans Kjeldsen Astron. Astrophys. 418, 295–303 (2004). lung adenocarcinomas in patients in the are in the Department of Physics and Astronomy, 9.
    [Show full text]
  • Advanced Technologies for Future Space Telescopes and Instruments
    Advanced Technologies for Future Space Telescopes and Instruments - A sample of upcoming astronomy missions - Interferometry in space (Darwin) - Very large telescopes in orbit (XEUS) - Future space telescope concepts (TPF) Dr. Ph. Gondoin (ESA) IR and visible astronomy missions (ESA Cosmic Vision – NASA Origin programs) DARWIN TPF GAIA SIM Herschel SIRTF Planck Eddington Kepler JWST Corot 1 GAIA Science Objective: Understanding the structure and evolution of the Galaxy PayloadGAIA payload • 2 astrometric telescopes: • Separated by 106o • SiC mirrors (1.4 m × 0.5 m) • Large focal plane (TDI operating CCDs) • 1 additional telescope equipped with: • Medium-band photometer • Radial-velocity spectrometer 2 Technology requirements for GAIA (applicable to many future space missions) • Large focal plane assemblies: – 250 CCDs per astrometry field, 3 side buttable, small pixel (9 µm), high perf. CCDs ( large CTE, low-noise, wide size, high QE), TDI operation • Ultra-stable telescope structure and optical bench: • Light weight mirror elements: – SiC mirrors (highly aspherized for good off-axis performance) Large SiC mirror for space telescopes (Boostec) ESA Herschell telescope: 1.35 m prototype 3.5 m brazed flight model (12 petals) 3 James Webb Space Telescope (JWST) Mirror Actuators Beryllium Mirrors Mirror System AMSD SBMD Wavefront Sensing and Control, Mirror Phasing Secondary mirror uses six actuators In a hexapod configuration Primary mirror segments attached to backplane using actuators in a three-point kinematic mount NIRSpec: a Multi-object
    [Show full text]
  • Lynx X-Ray Observatory 2018 Interim Report
    2018 INTERIM REPORT LYNX X-RAY OBSERVATORY 2020 Astrophysics Decadal Mission Concept Studies Lynx Interim Report August 2018 Science and Technology Definition Team (STDT) Chairs: Dr. Feryal Özel University of Arizona Dr. Alexey Vikhlinin Smithsonian Astrophysical Observatory Submitted on behalf of the Lynx Team B. EXECUTIVE SUMMARY Lynx is the X-ray observatory with radical leaps in capability that will uncover the otherwise invisible Universe • to see the dawn of black holes • reveal what drives galaxy formation and evolution • unveil the energetic side of stellar evolution and stellar ecosystems One of the exciting challenges of human discovery is understanding the complexities of the Universe in which we live. NASA Astrophysics is driven by three defining questions: How did we get here? How does the universe work? Are we alone? In the 2020’s and beyond, a multi-wavelength and multi-messenger approach will be required to address these questions. X-ray observations are essential to this quest. The great power of X-ray measurements stems from the well-established fact that much of the baryonic matter, as well as the settings for some of the most active energy releases in the Universe, are primarily visible in the X-ray band. X-ray observations with a next-generation observatory are mandatory to gain a true understanding of the origins and underlying physics of the cosmos. The following on-going or near-future developments make such an observatory especially timely: 9 • Very massive, ~10 M⊙, black holes are being discovered at ever higher redshifts, currently reaching z ≈ 7.5. The birth and early evolution of such supermassive black holes are a remarkable, yet poorly understood phenomenon, with strong impacts on the evolution of the first galaxies.
    [Show full text]
  • The Legacy of Einstein's Eclipse, Gravitational Lensing
    The Legacy of Einstein’s Eclipse, Gravitational Lensing Jorge L. Cervantes-Cota 1, Salvador Galindo-Uribarri 1 and George F. Smoot 2,3,4,* 1 Department of Physics, National Institute for Nuclear Research, Km 36.5 Carretera Mexico-Toluca, Ocoyoacac, C.P.52750 Mexico State, Mexico; [email protected] (J.L.C.-C.); [email protected] (S.G.-U.) 2 IAS TT & WF Chao Foundation Professor, Institute for Advanced Study, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong 3 Université Sorbonne Paris Cité, Laboratoire APC-PCCP, Université Paris Diderot, 10 rue Alice Domon et Leonie Duquet, CEDEX 13, 75205 Paris, France 4 Department of Physics and LBNL, University of California, MS Bldg 50-5505 LBNL, 1 Cyclotron Road, Berkeley, CA 94720, USA * Correspondence: [email protected]; Tel.: +1-510-486-5505 Abstract: A hundred years ago, two British expeditions measured the deflection of starlight by the Sun’s gravitational field, confirming the prediction made by Einstein’s General Theory of Relativity. One hundred years later many physicists around the world are involved in studying the consequences and use as a research tool, of the deflection of light by gravitational fields, a discipline that today receives the generic name of Gravitational Lensing. The present review aims to commemorate the centenary of Einstein’s Eclipse expeditions by presenting a historical perspective of the development and milestones on gravitational light bending, covering from early XIX century speculations, to its current use as an important research tool in astronomy and cosmology. Keywords: gravitational lensing; history of science PACS: 01.65.+g; 98.62.Sb 1.
    [Show full text]
  • Planckplanck
    PlanckPlanck Planned achievements: most detailed observations to date of Cosmic Microwave Background Launch date: planned for February 2007 (with Herschel) Mission end: after 15 months of observations Launch vehicle/site: Ariane-5 from Kourou, French Guiana Launch mass: about 1430 kg (445 kg science payload) Orbit: planned Lissajous orbit around L2 Lagrangian point, 1.5 million km from Earth in anti-Sun direction. 4-month transfer from Earth Principal contractors: Alcatel Space Industries (prime, Payload Module, AIV), Alenia Spazio (Service Module). Phase-B April 2001 - June 2002; Phase-C/D July 2002 - September 2006, CDR November 2003 Planck is designed to help answer key these clots are detected as very slight questions: how did the Universe come differences – sometimes as small as to be and how will it evolve? To do one in a million – in the apparent this, it will map with the highest temperature of the CMB. All of the accuracy yet the first light that filled valuable information lies in the the Universe after the Big Bang. Its precise shape and intensity of these telescope will focus radiation from the temperature variations. In 1992, sky onto two arrays of highly NASA’s COBE satellite made the first sensitive radio detectors. Together, blurry maps of these anisotropies in they will measure the temperature of the CMB. Planck will map these the Cosmic Microwave Background features as fully and accurately as (CMB) radiation over the whole sky, possible. searching for regions slightly warmer or colder than the average 2.73 K. The anisotropies hold the answers to many key questions in cosmology.
    [Show full text]
  • Sir Arthur Eddington and the Foundations of Modern Physics
    Sir Arthur Eddington and the Foundations of Modern Physics Ian T. Durham Submitted for the degree of PhD 1 December 2004 University of St. Andrews School of Mathematics & Statistics St. Andrews, Fife, Scotland 1 Dedicated to Alyson Nate & Sadie for living through it all and loving me for being you Mom & Dad my heroes Larry & Alice Sharon for constant love and support for everything said and unsaid Maggie for making 13 a lucky number Gram D. Gram S. for always being interested for strength and good food Steve & Alice for making Texas worth visiting 2 Contents Preface … 4 Eddington’s Life and Worldview … 10 A Philosophical Analysis of Eddington’s Work … 23 The Roaring Twenties: Dawn of the New Quantum Theory … 52 Probability Leads to Uncertainty … 85 Filling in the Gaps … 116 Uniqueness … 151 Exclusion … 185 Numerical Considerations and Applications … 211 Clarity of Perception … 232 Appendix A: The Zoo Puzzle … 268 Appendix B: The Burying Ground at St. Giles … 274 Appendix C: A Dialogue Concerning the Nature of Exclusion and its Relation to Force … 278 References … 283 3 I Preface Albert Einstein’s theory of general relativity is perhaps the most significant development in the history of modern cosmology. It turned the entire field of cosmology into a quantitative science. In it, Einstein described gravity as being a consequence of the geometry of the universe. Though this precise point is still unsettled, it is undeniable that dimensionality plays a role in modern physics and in gravity itself. Following quickly on the heels of Einstein’s discovery, physicists attempted to link gravity to the only other fundamental force of nature known at that time: electromagnetism.
    [Show full text]