Wim Raven | Philipps University Marburg (original) (raw)
Papers by Wim Raven
Ibn Dawud al-Isfahani in EI3, 2017
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
State Formation and State Decline in the Near and Middle East, 2016
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
This is a pre-print of an article published in Acta Applicandae Mathematicae.
Kindlers Literatur Lexikon (KLL), 2020
We point out that current textbooks of modern physics are a century out-of-date in their treatmen... more We point out that current textbooks of modern physics are a century out-of-date in their treatment of blackbody radiation within classical physics. Relativistic classical electrodynamics including classical electromagnetic zero-point radiation gives the Planck spectrum with zero-point radiation as the blackbody radiation spectrum. In contrast, nonrelativistic mechanics cannot support the idea of zero-point energy; therefore if nonrelativistic classical statistical mechanics or nonrelativistic mechanical scatterers are invoked for radiation equilibrium, one arrives at only the low-frequency Rayleigh-Jeans part of the spectrum which involves no zero-point energy, and does not include the high-frequency part of the spectrum involving relativistically-invariant classical zero-point radiation. Here we first discuss the correct understanding of blackbody radiation within relativistic classical physics, and then we review the historical treatment. Finally, we point out how the presence of Lorentz-invariant classical zero-point radiation and the use of relativistic particle interactions transform the previous historical arguments so as now to give the Planck spectrum including classical zero-point radiation. Within relativistic classical electromagnetic theory, Planck's constant appears as the scale of source-free zero-point radiation.
Developing countries have limitations in almost every area of modernization. These limitations ar... more Developing countries have limitations in almost every area of modernization. These limitations are not limited to only education and the classroom in which teachers and learners exercise their duties but also other aspects of human endeavors. Scholarly approaches embraced by educators in the quest to evolve knowledge, especially those whose basis arises from Science and Mathematics, have generated considerable improvement over the years. These approaches beget a pattern aimed at preparing emerging learners with up to date knowledge on how best to solve challenges required of complex yet everyday human life. The goal of education and, by extension, science is to equip citizens with the requisite skills to embrace challenges and solve everyday human problems. This article exposes the trend in STEM, STEAM, and STREAM approaches, as well as the rationale for each of the appendage components of the evolution. The global application of robots in areas with a shortage of manpower is a trend in the global economy and governance. Africa's classroom integration and limitation of technology in classroom learning can potentially be resolved with solutions from robotics. A measure of the grounds covered in the developing countries and the gap expected to be covered were extensively explored. The limitation in knowledge, expertise, and resources to cope with these emerging trends for purposeful and meaningful classroom integration in Africa were investigated.
We have conducted wide-field H i mapping of a ∼ 5.5 • × 5.5 • region surrounding the NGC 3783 gal... more We have conducted wide-field H i mapping of a ∼ 5.5 • × 5.5 • region surrounding the NGC 3783 galaxy group, to an H i mass limit of ∼ 4 × 10 8 M ⊙. The observations were made using the multibeam system on the Parkes 64-m radiotelescope, as part of the Galaxy Evolution Multiwavelength Study (GEMS). We find twelve H i detections in our Parkes data, four more than catalogued in HIPASS. We find two new group members, and discover an isolated region of H i gas with an H i mass of ∼ 4 × 10 8 M ⊙ , without a visible corresponding optical counterpart. We discuss the likelihood of this H i region being a low surface brightness galaxy, primordial gas, or a remnant of tidal debris. For the NGC 3783 group we derive a mean recession velocity of 2903±26 km s −1 , and a velocity dispersion of 190±24 km s −1. The galaxy NGC 3783 is the nearest galaxy to the luminosity weighted centre of the group, and is at the group mean velocity. From the X-ray and dynamical state of this galaxy group, this group appears to be in the early stages of its evolution.
Ibn Dawud al-Isfahani in EI3, 2017
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
State Formation and State Decline in the Near and Middle East, 2016
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
Kindlers Literatur Lexikon (KLL), 2020
This is a pre-print of an article published in Acta Applicandae Mathematicae.
Kindlers Literatur Lexikon (KLL), 2020
We point out that current textbooks of modern physics are a century out-of-date in their treatmen... more We point out that current textbooks of modern physics are a century out-of-date in their treatment of blackbody radiation within classical physics. Relativistic classical electrodynamics including classical electromagnetic zero-point radiation gives the Planck spectrum with zero-point radiation as the blackbody radiation spectrum. In contrast, nonrelativistic mechanics cannot support the idea of zero-point energy; therefore if nonrelativistic classical statistical mechanics or nonrelativistic mechanical scatterers are invoked for radiation equilibrium, one arrives at only the low-frequency Rayleigh-Jeans part of the spectrum which involves no zero-point energy, and does not include the high-frequency part of the spectrum involving relativistically-invariant classical zero-point radiation. Here we first discuss the correct understanding of blackbody radiation within relativistic classical physics, and then we review the historical treatment. Finally, we point out how the presence of Lorentz-invariant classical zero-point radiation and the use of relativistic particle interactions transform the previous historical arguments so as now to give the Planck spectrum including classical zero-point radiation. Within relativistic classical electromagnetic theory, Planck's constant appears as the scale of source-free zero-point radiation.
Developing countries have limitations in almost every area of modernization. These limitations ar... more Developing countries have limitations in almost every area of modernization. These limitations are not limited to only education and the classroom in which teachers and learners exercise their duties but also other aspects of human endeavors. Scholarly approaches embraced by educators in the quest to evolve knowledge, especially those whose basis arises from Science and Mathematics, have generated considerable improvement over the years. These approaches beget a pattern aimed at preparing emerging learners with up to date knowledge on how best to solve challenges required of complex yet everyday human life. The goal of education and, by extension, science is to equip citizens with the requisite skills to embrace challenges and solve everyday human problems. This article exposes the trend in STEM, STEAM, and STREAM approaches, as well as the rationale for each of the appendage components of the evolution. The global application of robots in areas with a shortage of manpower is a trend in the global economy and governance. Africa's classroom integration and limitation of technology in classroom learning can potentially be resolved with solutions from robotics. A measure of the grounds covered in the developing countries and the gap expected to be covered were extensively explored. The limitation in knowledge, expertise, and resources to cope with these emerging trends for purposeful and meaningful classroom integration in Africa were investigated.
We have conducted wide-field H i mapping of a ∼ 5.5 • × 5.5 • region surrounding the NGC 3783 gal... more We have conducted wide-field H i mapping of a ∼ 5.5 • × 5.5 • region surrounding the NGC 3783 galaxy group, to an H i mass limit of ∼ 4 × 10 8 M ⊙. The observations were made using the multibeam system on the Parkes 64-m radiotelescope, as part of the Galaxy Evolution Multiwavelength Study (GEMS). We find twelve H i detections in our Parkes data, four more than catalogued in HIPASS. We find two new group members, and discover an isolated region of H i gas with an H i mass of ∼ 4 × 10 8 M ⊙ , without a visible corresponding optical counterpart. We discuss the likelihood of this H i region being a low surface brightness galaxy, primordial gas, or a remnant of tidal debris. For the NGC 3783 group we derive a mean recession velocity of 2903±26 km s −1 , and a velocity dispersion of 190±24 km s −1. The galaxy NGC 3783 is the nearest galaxy to the luminosity weighted centre of the group, and is at the group mean velocity. From the X-ray and dynamical state of this galaxy group, this group appears to be in the early stages of its evolution.