arXiv subjects
Publications and source records attributed to Tilman Sauer.
The first comprehensive overview of the final version of the general theory of relativity was published by Einstein in 1916 after several expositions of preliminary versions and latest revisions of the theory in November 1915. A historical account of this review paper is given, of its prehistory, including a discussion of Einstein's collaboration with Marcel Grossmann, and of its immediate reception.
Path integral Monte Carlo (PIMC) simulations have become an important tool for the investigation of the statistical mechanics of quantum systems. I discuss some of the history of applying the Monte Carlo method to non-relativistic quantum systems in path-integral representation. The principle feasibility of the method was well established by the early eighties, a number of algorithmic improvements have been introduced in the last two decades.
Hilbert's paper on ``The Foundations of Physics (First Communication),'' is now primarily known for its parallel publication of essentially the same gravitational field equations of general relativity which Einstein published in a note on ``The Field Equations of Gravitation,'' five days later, on November 25, 1915. An intense correspondence between Hilbert and Einstein in the crucial month of November 1915, furthermore, confronts the historian with a case of parallel research and with the associated problem of reconstructing the interaction between Hilbert and Einstein at that time. Previous assessments of these issues have recently been challenged by Leo Corry, Jürgen Renn, and John Stachel who draw attention to a hitherto unnoticed first set of proofs for Hilbert's note. These proofs bear a printer's stamp of December 6 and display substantial differences to the published version. By focussing on the consequences of these findings for the reconstruction of Einstein's path towards general relativity, a number of questions about Hilbert's role in the episode, however, are left open. To what extent did Hilbert react to Einstein? What were Hilbert's research concerns in his note, and how did they come to overlap with Einstein's to some extent in the fall of 1915? How did Hilbert and Einstein regard each other and their concurrent activities at the time? What did Hilbert hope to achieve, and what, after all, did he achieve? With these questions in mind I discuss in this paper Hilbert's first note on the ``Foundations of Physics,'' its prehistory and characteristic features, and, for heuristic purposes, I do so largely from Hilbert's perspective.
We investigate the properties of two standard energy estimators used in path-integral Monte Carlo simulations. By disentangling the variance of the estimators and their autocorrelation times we analyse the dependence of the performance on the update algorithm and present a detailed comparison of refined update schemes such as multigrid and staging techniques. We show that a proper combination of the two estimators leads to a further reduction of the statistical error of the estimated energy with respect to the better of the two without extra cost.
We report recent progress in computer simulations of quantum systems described in the path-integral formulation. For the example of the $ϕ^4$ quantum chain we show that the accuracy of the simulation may greatly be enhanced by a combination of multigrid update techniques with a refined discretization scheme. This allows us to assess the accuracy of a variational approximation.
We present a comparison of the performance of two non-local update algorithms for path integral Monte Carlo (PIMC) simulations, the multigrid Monte Carlo method and the staging algorithm. Looking at autocorrelation times for the internal energy we show that both refined algorithms beat the slowing down which is encountered for standard local update schemes in the continuum limit. We investigate the conditions under which the staging algorithm performs optimally and give a brief discussion of the mutual merits of the two algorithms.
We discuss the recently proposed multicanonical multigrid Monte Carlo method and apply it to the scalar $ϕ^4$-model on a square lattice. To investigate the performance of the new algorithm at the field-driven first-order phase transitions between the two ordered phases we carefully analyze the autocorrelations of the Monte Carlo process. Compared with standard multicanonical simulations a real-time improvement of about one order of magnitude is established. The interface tension between the two ordered phases is extracted from high-statistics histograms of the magnetization applying histogram reweighting techniques.
We report results of a Monte Carlo simulation of the $ϕ^4$ quantum field theory using multigrid simulation techniques and a refined discretization scheme. The resulting accuracy of our data allows for a significant test of an analytical approximation based on a variational ansatz. While the variational approximation is well reproduced for a large range of parameters we find significant deviations for low temperatures and large couplings.
We report results of a Monte Carlo simulation of the $ϕ^4$ quantum chain. In order to enhance the efficiency of the simulation we combine multigrid simulation techniques with a refined discretization scheme. The resulting accuracy of our data allows for a significant test of an analytical approximation based on a variational ansatz. While the variational approximation is well reproduced for a large range of parameters we find significant deviations for low temperatures and large couplings.