scholarly journals Astronomical Units and Constants in a Relativistic Framework

1995 ◽  
Vol 10 ◽  
pp. 201-201
Author(s):  
N. Capitaine ◽  
B. Guinot

In 1991, IAU Resolution A4 introduced General Relativity as the theoretical background for defining celestial space-time reference sytems. It is now essential that units and constants used in dynamical astronomy be defined in the same framework, at least in a manner which is compatible with the minimum degree of approximation of the metrics given in Resolution A4.This resolution states that astronomical constants and quantities should be expressed in SI units, but does not consider the use of astronomical units. We should first evaluate the usefulness of maintaining the system of astronomical units. If this system is kept, it must be defined in the spirit of Resolution A4. According to Huang T.-Y., Han C.-H., Yi Z.-H., Xu B.-X. (What is the astronomical unit of length?, to be published in Asttron. Astrophys.), the astronomical units for time and length are units for proper quantities and are therefore proper quantities. We fully concur with this point of view. Astronomical units are used to establish the system of graduation of coordinates which appear in ephemerides: the graduation units are not, properly speaking astronomical units. Astronomical constants, expressed in SI or astronomical units, are also proper quantities.

1998 ◽  
Vol 11 (1) ◽  
pp. 194-199
Author(s):  
V.A. Brumberg ◽  
P. Bretagnon ◽  
N. Capitaine ◽  
T. Damour ◽  
T.M. Eubanks ◽  
...  

RCMA SWG was appointed by the IAU WGAS (Working Group on Astronomical Standards) in accordance with IAU Resolution C6 (1994) with the aim ‘to provide definitions of the astronomical units, of the quantities linking these astronomical units to the units of the International System (SI), and of other astronomical quantities, compatible with the theory of General Relativity’. It is evident that the relativistic aspects of units of measurement cannot be isolated from the more general problem of astronomical constants and fundamental astronomy concepts in the relativistic framework. Therefore, along with the problem of units the main topics of discussion of RCMA SWG concerned also the IAU (1991) Resolutions on References Systems (RSs) and Time Scales (TSs) and their interpretation in IERS Standards (1992) and IERS Conventions (1996). In what follows we tried to summarize the results of these discussions.


1999 ◽  
Vol 172 ◽  
pp. 435-436
Author(s):  
Sergei A. Klioner ◽  
Michael Soffel

There are several important reasons to consider relativistic effects in rotational motion of celestial bodies. General Relativity is now recommended by the International Astronomical Union and International Union of Geodesy and Geophysics as a theoretical framework for modeling of high-precision observational data. On the other hand, various geodynamical observations provide data which are widely used for testing General Relativity itself.In Newtonian mechanics it is well known how to describe rotational motion of an extended body. In General Relativity this is a rather subtle issue. The concept of a precessing extended rigid body in general relativity encounters fundamental difficulties and cannot be introduced even in the first post-Newtonian approximation. From a practical point of view, however, the rotational motion of the Earth even at the Newtonian level is defined operationally through the time-dependence of geocentric quasi-inertial coordinates of observing sites. An analogous operational definition can be applied in general relativity. To this end, we need a set of physically adequate reference systems.


2015 ◽  
Vol 52 (2) ◽  
pp. 221-232
Author(s):  
Pál Dömösi ◽  
Géza Horváth

In this paper we introduce a novel block cipher based on the composition of abstract finite automata and Latin cubes. For information encryption and decryption the apparatus uses the same secret keys, which consist of key-automata based on composition of abstract finite automata such that the transition matrices of the component automata form Latin cubes. The aim of the paper is to show the essence of our algorithms not only for specialists working in compositions of abstract automata but also for all researchers interested in cryptosystems. Therefore, automata theoretical background of our results is not emphasized. The introduced cryptosystem is important also from a theoretical point of view, because it is the first fully functioning block cipher based on automata network.


1965 ◽  
Vol 21 ◽  
pp. 153-175
Author(s):  
D. O. Muhleman

This paper is devoted to an exact discussion of the determination of the astronomical unit with radar and to an extensive error analysis of the technique. Theoretical relationships between the constants are used to construct a consistent set of numerical values of constants based on these results.


2004 ◽  
Vol 17 (1-2) ◽  
pp. 165-197 ◽  
Author(s):  
Erhard Scholz

Hermann Weyl (1885–1955) was one of the early contributors to the mathematics of general relativity. This article argues that in 1929, for the formulation of a general relativistic framework of the Dirac equation, he both abolished and preserved in modified form the conceptual perspective that he had developed earlier in his “analysis of the problem of space.” The ideas of infinitesimal congruence from the early 1920s were aufgehoben (in all senses of the German word) in the general relativistic framework for the Dirac equation. He preserved the central idea of gauge as a “purely infinitesimal” aspect of (internal) symmetries in a group extension schema. With respect to methodology, however, Weyl gave up his earlier preferences for relatively a-priori arguments and tried to incorporate as much empiricism as he could. This signified a clearly expressed empirical turn for him. Moreover, in this step he emphasized that the mathematical objects used for the representation of matter structures stood at the center of the construction, rather than interaction fields which, in the early 1920s, he had considered as more or less derivable from geometrico-philosophical considerations.


2016 ◽  
Vol 7 (2) ◽  
pp. 150-166 ◽  
Author(s):  
Péter Ván

Abstract The experimental basis and theoretical background of non-Fourier heat conduction is shortly reviewed from the point of view of non-equilibrium thermodynamics. The performance of different theories is compared in case of heat pulse experiments.


2018 ◽  
Vol 27 (14) ◽  
pp. 1830009
Author(s):  
Virginia Trimble

A large majority of the physics and astronomy communities are now sure that gravitational waves exist, can be looked for, and can be studied via their effects on laboratory apparatus as well as on astronomical objects. So far, everything found out has agreed with the predictions of general relativity, but hopes are high for new information about the universe and its contents and perhaps for hints of a better theory of gravity than general relativity (which even Einstein expected to come eventually). This is one version of the story, from 1905 to the present, told from an unusual point of view, because the author was, for 28.5 years, married to Joseph Weber, who built the first detectors starting in the early 1960s and operated one or more until his death on 30 September 2000.


2021 ◽  
Vol 11 (2) ◽  
pp. 83-101
Author(s):  
Mária T. Patakyová

Abstract Digitalisation is a challenge from the regulatory point of view. Competition law, as a special type of regulation, is no exception to this. The article explores the risks of digitalisation, especially the ones related to the enhanced use of pricing algorithms. In theory, pricing algorithms are not easily assessed from the perspective of competition law, let alone its application in practice. The prohibition of anticompetitive agreements (pursuant to Article 101 of the Treaty on Functioning of the European Union (TFEU)) is applied with certain difficulty to agreements created by using pricing algorithms. This is an unfortunate situation, as horizontal agreements represent one of the worst infringements of EU competition law, including price cartels or bid rigging. Apart from presenting a theoretical background, the article dives into the practice of the Antimonopoly Office of the Slovak Republic (AMO) in order to assess which practical issues the AMO might face when applying the theoretical concepts. In sum, the article asks from a theoretical perspective which issues of competition law have been introduced (or deepened) by the enhanced digitalisation, looking in particular to pricing algorithms. On top of that, the article explores the issues which may be encountered in practice, taking the Slovak jurisdiction as the example. The willingness and feasibility of the AMO to enforce digital issues such as pricing algorithms is assessed based on the previous acts of the AMO as well as the new Act on Protection of Competition, adopted by the Slovak parliament on 11 May 2021.


2019 ◽  
Vol 16 (16) ◽  
pp. 158-169
Author(s):  
Olena Stanishevska

Introduction. In scientific literature dedicated to J. Brahms, much attention has been paid to a song genre. The researches note that J. Brahms’s songs can be regarded as a continuation of genre-specific features of Austro-German Lied, which retains the purity of the generic semantics in the composer’s works, without involving typically operatic means of vocal intoning, or approaching the so-called “poem with music”. J. Brahms’s songs do not allow the singer to demonstrate the full range of his/her voice, to reveal his/her artistic temperament, to show the technical skill. Absorption in a special emotional aura of J. Brahms’s songs requires a variety of timbre-intonational resources of a singer, his/her ability not to lose the sense of the whole while detailing the melodious overture. Of particular interest is the issue of music and words correlation in J. Brahms’s songs. As a rule, the composer is considered to be the immediate successor of F. Schubert rather than R. Schuman in his orientation to musical embodiment of a generalized poetic image. At the same time, this issue requires more detailed study, since the composer was very sensitive to the poetic text, in particular, from the point of view of coordinating the intonation-phonetic features of German language and vocal intonation. Theoretical Background. Recent research and publications analysis. Opus 49 by J. Brahms seems to be in the shadow of musicological thought and performing practice. It should be noted that a very famous opus part is “Lullaby”, which is mentioned in the monographs of K. Tsareva (1986), M. Druskin (1959), and K. Geiringer (1965). In the literature being considered the abovementioned opus is not completely covered, thus determining the relevance of our article. There are references to individual songs in different sources, but incidentally, in the context of different issues. Objective is to study J. Brahms’s opus 49 in the aspect of the interaction of poetic word and music, verbal and musical intoning. Methods: 1) historical method, allowing to comprehend the selected material in the perspective of the development of Austro-German song of the XIX century; 2) intonational method, which involves the study of vocal melody in terms of phonetic-tonic links; 3) genre method, caused by the features of chamber vocal lyrics; 4) stylistic method, corresponding to a specific opus consideration in the general context of the composer’s creative work. Results and Discussion. The composer did not have any tendency to the songs cyclization, however, the vocal miniatures, assembled in one opus, appear to be lyrical notes, self-contained but united by poetic motives and nature of the author’s expression. Many researchers see a cyclic organization of his particular vocal opuses. For example, I. Mykhailov (1987: 19) proves the existence of cyclic principles at different compositional levels in composer’s songs: separate “melodious pairs”, a number of songs with the texts by one poet inside the opus, a whole vocal opus with the texts by different authors. According to I. Mikhailov, the cyclic connection of songs is emphasized by several compositional techniques: thematic one, i.e. the unity of the musical material; the continuity of songs alternation, which is sometimes manifested in the absence of a piano introduction of the next song. In opus 49, the author chooses different poetic sources – poems by P. Heyse, L. Hölty, A. F. Schack, and J. Wenzig. The composer refers to one of the samples of the famous collection by Joachim von Arnim and Clemens Brentano “The Magic Horn of a Boy”. Given the anthological principle of poetic texts selection, no transparent storyline in opus 49, such as “A Beautiful Miller” by F. Schubert or “Poet’s Love” by R. Schumann, there is no reason to regard it as a cycle. However, the opus’ songs are arranged in a certain semantic sequence. Owing to the fact that three songs (“Sunday Morning”, “To a Violet”, “Longing for the Sweetheart”) are united by homogeneous poetic motifs, one can regard them as forming a microcycle within the whole. The second micro-cycle of the opus is represented by No. 4 and No. 5 (“Lullaby” and “Twilight”). In interpreting the poetic text, J. Brahms adheres to the principle of emotional and musical generality, once detailing the text, if at all. Here, he succeeds F. Schubert. However, he uses the technique of keywords, distinguishing them in two ways: rhythmically (with syncope) and through intrinsic chants; the composer also uses different types of intoning. Following the tradition of the 19th-century Austro-German song, the composer regards the genre as an alliance of two full members: the vocalist and the pianist, with the part being an instrumental generalization. The intonational image of the whole in vocal music arises at the crossing of two texts – poetic and musical. German has intonation difficulties owing to a large number of consonants. Problems, encountered by the singers in intoning German language, are compensated by the consonants and vowels, which are most favorable for correct sound formation, allowing to achieve the required quality. The soft consonants and vowels should be regarded as the ideal vocal sound, that is, a model for other phonemes in musical-poetic text. While creating vocal melodies of Opus 49 songs, J. Brahms cares the phonetics of a German text in the singing to be comfortable for the performer. Conclusions. J. Brahms uses such principles and techniques of literary original musical embodiment as preservation of the holistic image, created by the author of the poems, on the one hand, and its detailing on the other. In the second case, the composer resorts to all means of musical expression: motive-thematic, texture-register, rhythmic, harmonious, texture ones. The prospects of the research lie in studying the interaction of verbal and musical intonation in other vocal works of J. Brahms, as well as in chamber-vocal music of late romantics.


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