1,721,007 research outputs found
Weyl's principle, cosmic time and quantum fundamentalism
Get PDFWe examine the necessary physical underpinnings for setting up the cosmological standard model with a global cosmic time parameter. In particular, we discuss the role of Weyl's principle which asserts that cosmic matter moves according to certain regularity requirements. After a brief historical introduction to Weyl's principle we argue that although the principle is often not explicitly mentioned in modern standard texts on cosmology, it is implicitly assumed and is, in fact, necessary for a physically well-defined notion of cosmic time. We finally point out that Weyl's principle might be in conflict with the wide-spread idea that the universe at some very early stage can be described exclusively in terms of quantum theory
Collision of Traditions. The Emergence of Logical Empiricism Between the Riemannian and Helmholtzian Traditions
Get PDFThis paper attempts to explain the emergence of the logical empiricist
philosophy of space and time as a collision of mathematical traditions.
The historical development of the ``Riemannian'' and ``Helmholtzian''
traditions in 19th century mathematics is investigated. Whereas Helmholtz's
insistence on rigid bodies in geometry was developed group theoretically
by Lie and philosophically by Poincaré, Riemann's Habilitationsvotrag
triggered Christoffel's and Lipschitz's work on quadratic differential
forms, paving the way to Ricci's absolute differential calculus.
The transition from special to general relativity is briefly sketched
as a process of escaping from the Helmholtzian tradition and entering
the Riemannian one. Early logical empiricist conventionalism,
it is argued, emerges as the failed attempt to interpret Einstein's
reflections on rods and clocks in general relativity through the conceptual
resources of the Helmholtzian tradition. Einstein's epistemology
of geometry should, in spite of his rhetorical appeal to Helmholtz and
Poincaré, be understood in the wake the Riemannian tradition
and of its aftermath in the work of Levi-Civita, Weyl, Eddington, and
others
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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