Chaos Regained: On the Possibility of a New Era of Orbital Dynamics

In this paper I explore how the nature, scope, and limits of the knowledge obtained in orbital dynamics—the science concerned with the motions of bodies in the solar system—has changed in recent years. Innovations in the design of spacecraft trajectories, as well as in astronomy, have led to a new hybrid of theory and experiment, and suggest that the kind of knowledge achieved in orbital dynamics today is dramatically different from the knowledge achieved prior to those innovations. Thus, orbital dynamics may have entered a new era

Visualizing Chaos

An important piece of information when dealing with a polynomial in the complex plane is its roots, the value or values of x for a given function f such that f(x)=0. Iterative root finding methods, such as Newton’s method, are utilized to discover an approximate value when these values cannot be explicitly solved. This process can be graphically represented for complex-valued functions and has been achieved with relative ease on a 2-Dimensional plane. However, this process can also be embodied on a sphere through the method of stereographic projection, which has not been attempted. In this research, I worked with iterative root finding methods, such as Newton’s and other higher order methods, on the complex plane. Upon mapping out their iterations on the 2-D plane, I wrote a program to stereographically project them upon a sphere in order to be able to analyze their complete dynamics

The six days and the deluge: some ideas on earth history in the Royal Society of London 1660-1775

The influence of the biblical story of Creation and the Deluge on ideas of earth history during the period 1660-1775 is examined with particular reference to papers on the subject published in the Philosophical Transactions of the Royal Society of London. Topics examined in more detail include the controversies over the origin of marine fossils and bones of prehistoric animals, ideas on natural causes of the Deluge and its role in shaping landforms, and the age of the earth. Despite the inhibiting effect of the Genesis account, there was considerable flexibility in interpretation of both the Creation and Deluge stories in terms of current scientific knowledge. The later papers display a good deal of uniformitarian thinking within the framework of a catastrophic deluge hypothesis

Candidates for historical supernovae and their comparison against known Chinese records

In this MSc thesis, possible/probable supernova remnants associated with possible/probable historical supernovae are discussed and advancements in knowledge surrounding possible remnants associated with historical supernovae older than about a thousand years are presented. Supernovas in 1006, 1054, 1181, 1572 and 1604 are all discussed for completeness, although these supernovae have been extensively researched and there is little reason to doubt previous work. The historical supernovae of 185, 386, 393 and 837 are all discussed in more detail. In the opinion of the author, supernova of 185 is linked with the remnant 315.3-2.3 in the light of recent research. The supernova of 386 is linked with G11.2-0.3 and a possible record linking G11.2-0.3 with a supernova in 45BC is dismissed. An association of a remnant supernova of 393 remains unsatisfactorily resolved, with CTB37A and CTB37B remaining candidates, and the author has suggested the remnants G343.1-0.7 and G351.7+0.8 as alternatives given a new I-D relation. The age and suitability of GRO/RX J0852 for historical association is discussed, and political reasons for the lack of historical records for an apparent supernova in -1200AD suggested. G292.0+1.8 is discussed as a candidate for a historical supernova and dismissed due to its invisibility in China. The supernova of 837AD is discussed and the link between this and the remnant IC443 remains unconfirmed due to conflicting astrophysical evidence

An investigation of some contemporary problems in astronomy and astrophysics by way of early astronomical records

Early astronomical records of comets, supernovae, novae, sunspots and aurorae from Far Eastern dynastic histories together with records from Babylonians cuneiform tablets are compiled and analysed. The present investigation gives new insight into the three following topics in current astronomy and astrophysics.(1) Halley's Comet Past orbits of Halley's Comet since 240 BC are studied in detail using mainly early Chinese observations. The date of perihelion passages are deduced for each return. The only gap in the Chinese records, for the return of 164 BC, is now filled by the discovery of two records on Babylonian tablets. This discovery improves the date of perihelion, which is established as within one week of Nov 16 in 164 BC. We are now confident that every return of Halley's Comet from 240 BC onwards has been recorded.(2) Supernovae and Novae A catalogue of historical supernovae and novae is compiled. Descriptions regarding the position of the eight well known supemovae SN 185, 386, 393, 1006, 1054, 1181, 1572 and 1604 are re-evaluated in term of recent studies. The spurious supernova SN 1408 is discussed in detail and found that there is insufficient evidence supporting a supernova interpretation. The positions of 26 well recorded historical novae are discussed in depth and their coordinates are deduced. (3) Solar Variability Catalogues of naked-eye sunspots and aurorae are compiled from Far Eastern sources. Analysis of these records suggests an average period of about 10 years for the basic solar cycle. Observational factors such as variation with the phases of the Moon are also discussed. A comparison of these data with other proxy indicators like (^14)C and (^10)Beshows a similar trend in the behaviour of the Sun over the last two thousand years

Fertility of populations as a function of the attained level of life expectancy in the course of human evolution

Der Beitrag befasst sich mit dem Problem 'alternder Gesellschaften' mit zunehmender Lebenserwartung der Durchschnittsbevölkerung. Von den meisten Demographen wird heutzutage allerdings bezweifelt, dass alternde Gesellschaften eine notwendige Konsequenz aus dem Rückgang der Mortalitätsrate und einer erhöhten Lebenserwartung sind, sondern der wesentliche Grund wird in der geringeren Fruchtbarkeitsrate gesehen. Somit kann gefolgert werden, dass Variationen in der Fruchtbarkeit einer Gesellschaft mehr Signifikanz für die Altersstruktur besitzen als Variationen in der Sterblichkeit. Diese, auf dem Neo-Malthusianismus beruhende These wird hier untersucht. Auf der Basis von Coale und Demenys Tabellen der 'stabilen Bevölkerung' werden Schlussfolgerungen aus der historischen Interpretation von grundlegenden Annahmen über stabile Populationen vorgetragen, ergänzt durch relevante Ergebnisse der historischen Demographie. Auf der Grundlage von Weltbevölkerungsstatistiken wird außerdem ein Modell der absoluten Fruchtbarkeitsraten für alle Stufen der Lebenserwartung für die zweite Hälfte des 20. Jahrhunderts entwickelt. Die Untersuchungen zeigen, dass der Stand der Fruchtbarkeit einer bestimmten Population funktional abhängig ist von dem Grad der Lebenserwartung. (ICH)''Aging societies' with increasing life expectancies of the average of all their members are facts in modern history that are disputed by nobody. What is disputed by the most renowned names in demography, however, is that aging populations are a consequence of the fall in mortality and thus the increase in life expectancy. It is claimed that the principle reason for 'aging' is to be found in a drop in fertility. In this sense today's demographers regard as a standard result: 'Variations in fertility are of more significance for the age structure of populations than variations in mortality.' In the following paper this thesis, which is based on a neo-Malthusian interpretation of the role of fertility in the demographic process, will be questioned.' (author's abstract

The Deluge of Spurious Correlations in Big Data

International audienceVery large databases are a ma jor opp ortunity for science and data analytics is a remarkable new field of investigation in computer science. The effectiveness of these toolsis used to support a “philosophy” against the scientific method as developed throughout history. According to this view, computer-discovered correlations should replace understanding and guide prediction and action. Consequently, there will be no need to givescientific meaning to phenomena, by proposing, say, causal relations, since regularities in very large databases are enough: “with enough data, the numbers speak for themselves”. The “end of science” is proclaimed. Using classical results from ergodic theory, Ramsey theory and algorithmic information theory, we show that this “philosophy” is wrong. For example, we prove that very large databases have to contain arbitrary correlations. These correlations appear only due to the size, not the nature, of data. They can be found in “randomly” generated, large enough databases, which - as we will prove - implies that most correlations are spurious. Too much information tends to behave like very little information. The scientific method can be enriched by computer mining in immense databases, but not replaced by it