Hegel's Criticism of Newton's Physics: A Reconsideration"

The persisting conception of Hegel's criticism of Newton's physics as an irrational or at least hopelessly exaggerated one partly has its roots mainly in Hegel's terminology and in his style. This does not mean that a mere translation of Hegel's arguments into any contemporary philosophical language be sufficient to immediately convince every Newtonian scientist. However, a non-Hegelian way of rephrasing the core of Hegel's anti-Newtonian philosophy of nature can help to understand to which extent the latter does satisfy any scientist's criteria for a rational and self-consistent theory. To demonstrate this is the central aim of my talk, which is structured as follows: In the first part, I'm trying to highlight basic features of Hegel's criticism of Newton's optics and celestial mechanics, eventually focussing on his concept of a "sense of nature". This part has the character of a review. Second -­ and that is supposed to be the "reconsideration" part of my paper -­ I'll try to highlight the fundamental difference between Newton's and Hegel's ideas of natural laws and of the relation between mathematics and physics. Third, the metaphysical background of this difference will be analyzed. It is by the analysis of this metaphysical background that I hope to render Hegel's criticism of Newton's scientific revolution more understandable

Optical constants of refractory oxides at high temperatures

Many cosmic dust species, among them refractory oxides, form at temperatures higher than 300 K. Nevertheless, most astrophysical studies are based on the room-temperature optical constants of solids, such as corundum and spinel. A more realistic approach is needed for these materials, especially in the context of modeling late-type stars. We aimed at deriving sets of optical constants of selected, astrophysically relevant oxide dust species with high melting points. A high-temperature-high-pressure-cell and a Fourier-transform spectrometer were used to measure reflectance spectra of polished samples. For corundum (alpha-Al$_2$O$_3$), spinel (MgAl$_2$O$_4$), and alpha-quartz (SiO$_2$), temperature-dependent optical constants were measured from 300 K up to more than 900 K. Small particle spectra were also calculated from these data. All three examined oxides show a significant temperature dependence of their mid-IR bands. For the case of corundum, we find that the 13$\mu$m emission feature - seen in the IR spectra of many AGB stars - can very well be assigned to this mineral species. The best fit of the feature is achieved with oblate corundum grains at mean temperatures around 550 K. Spinel remains a viable carrier of the 13$\mu$m feature as well, but only for T < 300 K and nearly spherical grain shapes. Under such circumstances, spinel grains may also account for the 31.8$\mu$m band that is frequently seen in sources of the 13$\mu$m feature and which has not yet been identified with certainty.Comment: Astronomy & Astrophysics, accepted, 26 February 2013. Article with 18 pages and 15 figure

Reconsidering the origin of the 21 micron feature: Oxides in carbon-rich PPNe?

The origin of the so-called "21 micron" feature which is especially prominent in the spectra of some carbon-rich protoplanetary nebulae (PPNe}) is the matter of a lively debate. A large number of potential band carriers have been presented and discarded within the past decade. The present paper gives an overview of the problems related to the hitherto proposed feature identifications, including the recently suggested candidate carrier silicon carbide. We also discuss the case for spectroscopically promising oxides. SiC is shown to produce a strong resonance band at 20-21 micron if coated by a layer of silicon dioxide. At low temperatures, core-mantle particles composed of SiC and amorphous SiO$_2$ indeed have their strongest spectral signature at a position of 20.1 micron, which coincides with the position of the "21 micron" emission band. The optical constants of another candidate carrier that has been relatively neglected so far -- iron monoxide -- are proven to permit a fairly accurate reproduction of the "21 micron" feature profile as well, especially when low-temperature measurements of the infrared properties of FeO are taken into account. As candidate carrier of the "21 micron" emission band, FeO has the advantage of being stable against further oxidation and reduction only in a narrow range of chemical and physical conditions, coinciding with the fact that the feature, too, is detected in a small group of objects only. However, it is unclear how FeO should form or survive particularly in carbon-rich PPNe.Comment: 28 pages, 15 figures, accepted for publication in ApJ (December

Adaptive Survival Trials

Mid-study design modifications are becoming increasingly accepted in confirmatory clinical trials, so long as appropriate methods are applied such that error rates are controlled. It is therefore unfortunate that the important case of time-to-event endpoints is not easily handled by the standard theory. We analyze current methods that allow design modifications to be based on the full interim data, i.e., not only the observed event times but also secondary endpoint and safety data from patients who are yet to have an event. We show that the final test statistic may ignore a substantial subset of the observed event times. Since it is the data corresponding to the earliest recruited patients that is ignored, this neglect becomes egregious when there is specific interest in learning about long-term survival. An alternative test incorporating all event times is proposed, where a conservative assumption is made in order to guarantee type I error control. We examine the properties of our proposed approach using the example of a clinical trial comparing two cancer therapies.Comment: 22 pages, 7 figure

Recent Results of Solid-State Spectroscopy

Solid state spectroscopy continues to be an important source of information on the mineralogical composition and physical properties of dust grains both in space and on planetary surfaces. With only a few exceptions, artificially produced or natural terrestrial analog materials, rather than 'real' cosmic dust grains, are the subject of solid state astrophysics. The Jena laboratory has provided a large number of data sets characterizing the UV, optical and infrared properties of such cosmic dust analogs. The present paper highlights recent developments and results achieved in this context, focussing on 'non-standard conditions' such as very low temperatures, very high temperatures and very long wavelengths.Comment: 15 pages, 10 figures. Contribution to an IAU Conference "The Molecular Universe" held in Toledo in June 201