Introducing a general time machine solution and analysis of a vacuum spacetime generating closed timelike curves

2021 ◽  
Vol 137 (1) ◽  
Author(s):  
Bidyut Bikash Hazarika
Author(s):  
Faizuddin Ahmed

We present a cyclic symmetry type II vacuum spacetime admitting closed timelike curves (CTCs) which appear after a certain instant of time, i.e., a time-machine spacetime. The various authors in past have considered the 2D and 4D flat generalization of Misner space, but in the present work, we have considered the curved spacetime generalzations of 4D Misner space, and is asymptotically flat radially


1994 ◽  
Vol 03 (01) ◽  
pp. 277-280 ◽  
Author(s):  
ALAN R. STEIF

Multiparticle solutions for sources moving at the speed of light and corresponding to superpositions of single-particle plane-wave solutions are constructed in 2+1 gravity. It is shown that the two-particle spacetimes admit closed timelike curves provided the center-of-momentum energy exceeds a certain critical value. This occurs, however, at the cost of unphysical boundary conditions which are analogous to those affecting Gott’s time machine. As the energy exceeds the critical value, the closed timelike curves first occur at spatial infinity, then migrate inward as the energy is further increased. The total mass of the system also becomes imaginary for particle energies greater than the critical value.


2003 ◽  
Vol 18 (23) ◽  
pp. 4169-4200 ◽  
Author(s):  
G. M. Shore

The existence of time machines, understood as space–time constructions exhibiting physically realised closed timelike curves (CTC's), would raise fundamental problems with causality and challenge our current understanding of classical and quantum theories of gravity. In this paper, we investigate three proposals for time machines which share some common features: cosmic strings in relative motion, where the conical space–time appears to allow CTC's; colliding gravitational shock waves, which in Aichelburg–Sexl coordinates imply discontinuous geodesics; and the superluminal propagation of light in gravitational radiation metrics in a modified electrodynamics featuring violations of the strong equivalence principle. While we show that ultimately none of these constructions creates a working time machine, their study illustrates the subtle levels at which causal self-consistency imposes itself, and we consider what intuition can be drawn from these examples for future theories.


2001 ◽  
Vol 16 (02) ◽  
pp. 99-102
Author(s):  
P. VALTANCOLI

We build the (2+1)-AdS gravity generalization of the Gott time machine using a first-order formalism for solving the scattering of point sources. The two-body dynamics is solved by two invariant masses, whose difference is simply related to the total angular momentum of the system. We show how to build a time machine when at least one of the two invariant masses is no more real but acquires an imaginary part.


The article is devoted to reengineering of technological processes - a method of their qualitative transformation on an innovative basis, which in turn assumes the availability of tools that make it possible to establish the economic efficiency and technical capability of such transformations of construction production, to identify the effect of their implementation. In this regard, the problem of forming a parametric model of reengineering of construction technological processes, which involves four enlarged groups of indicators that reflect the quantitative and qualitative characteristics of the processes: materials used, working time, machine time, spatial organization, is considered. It is established that parameters can have either an absolute (physical, cost) or relative (point, percentage) expression and also make their own decomposition. The practical significance of the provisions given in the article is determined by the development of methods of technical rationing, which leads to a reduction in the cost and duration of construction.


CounterText ◽  
2015 ◽  
Vol 1 (2) ◽  
pp. 232-269 ◽  
Author(s):  
Ivan Callus

In this essay Ivan Callus provides some reflections on literature in the present. He considers the tenability of the post-literary label and looks at works that might be posited as having some degree of countertextual affinity. The essay, while not setting itself up as a creative piece, deliberately structures itself unconventionally. It frames its argument within twenty-one sections that are self-contained but that also echo each other in their attempt to develop an overarching argument which draws out some of the challenges that lie before the countertextual and the post-literary. Punctuating the essay and contributing to its unconventional take on the practice of literary criticism is a series of exercises for the reader to complete, if so wished; the essay makes no attempt, however, to suggest that a countertextual criticism ought to make a routine of such devices. The separate sections contain reflections on a number of texts and writers, among them, and in order of appearance, Hamlet, Anthony Trollope, Jacques Derrida, The Time Machine, Don Quixote, Mark Z. Danielewski, Mark B. N. Hansen, Gunter Kress, Scott's Reliquiae Trotcosienses, W. B. Yeats, Kate Tempest, David Jones, Anne Michaels, Bernice Eisenstein, Paul Auster, J. M. Coetzee, Billy Collins, Deidre Shauna Lynch, Tim Parks, Tom McCarthy – and Hamlet again. The essay's length fulfils a performative function but also facilitates as extensive a catalogue of aspects of the countertextual in literature and elsewhere as is feasible or as might be dared at this stage.


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