Time travel

2018 ◽  
Author(s):  
Paul Horwich
Keyword(s):  
Special Theory ◽  
Time Travel ◽  
Theory Of Relativity ◽  
Philosophical Debate ◽  
Kurt Gödel ◽  
Dilation Effect ◽  
Global Curvature ◽  
General Relativistic ◽  
The Subject ◽  
Considerable Discussion

The prospect of a machine in which one could be transported through time is no longer mere fantasy, having become in this century the subject of serious scientific and philosophical debate. From Einstein’s special theory of relativity we have learned that a form of time travel into the future may be accomplished by moving quickly, and therefore ageing slowly (exploiting the time dilation effect). And in 1949 Kurt Gödel announced his discovery of (general relativistic) spacetimes whose global curvature allows voyages into the past as well. Since then the study of time travel has had three main strands. First, there has been research by theoretical physicists into the character and plausibility of structures, beyond those found by Gödel, that could engender closed timelike lines and closed causal chains. These phenomena include rotating universes, black holes, traversable wormholes and infinite cosmic strings (Earman 1995). Second, there has been concern with the semantic issue of whether the terms ‘cause’, ‘time’ and ‘travel’ are applicable, strictly speaking, to such bizarre models, given how different they are from the contexts in which those terms are normally employed (Yourgrau 1993). However, one may be sceptical about the significance of this issue, since the questions of primary interest – focused on the nature and reality of the Gödel-style models – seem independent of whether their description requires a shift in the meanings of those words. And, third, there has been considerable discussion within both physics and philosophy of various alleged paradoxes of time travel, and of their power to preclude the spacetime models in which time travel could occur.

Poincare's Silence and Einstein's Relativity: The Role of Theory and Experiment in Poincaré's Physics

1970 ◽  
Vol 5 (1) ◽  
pp. 73-84 ◽  
Author(s):  
Stanley Goldberg
Keyword(s):  
Special Theory ◽  
Theoretical Physics ◽  
Theory Of Relativity ◽  
Special Theory Of Relativity ◽  
Henri Poincaré ◽  
Home Town ◽  
Académie Des Sciences ◽  
The Subject ◽  
Theory And Experiment

It is a matter of record that Henri Poincaré never responded publicly to Einstein's Special Theory of Relativity (RT). Since almost no private papers of Poincaré are available, his attitude toward Einstein's work and his silence on that score become somewhat of a mystery. It is almost certain that Poincaré knew of Einstein's work in RT. First, he was fluent in German, having learned it as a young man when the Germans occupied his home town of Nancy in 1870. Second, he often reported to the members of the Académie des Sciences on current work in electrodynamics in Germany. It is highly improbable that he would have missed the abstract of Einstein's first paper on RT or the subsequent articles by Einstein on the subject, especially those which were translated into French, since they were in areas directly related to his own interests in theoretical physics.

scholarly journals Mössbauer experiments in a rotating system and physical interpretation of their results

2021 ◽  
pp. 34-43
Author(s):  
Alexander L. Kholmetskii ◽  
Tolga Yarman ◽  
Ozan Yarman ◽  
Metin Arik
Keyword(s):  
Energy Shift ◽  
Special Theory ◽  
Relativistic Energy ◽  
Theory Of Relativity ◽  
Rotating System ◽  
Rotating Systems ◽  
Extra Energy ◽  
Quantum Mechanical Description ◽  
Dilation Effect ◽  
The Moment

We discuss the results of modern Mössbauer experiments in a rotating system, which show the presence of an extra energy shift between the emitted and absorbed resonant radiation in addition to the relativistic energy shift of the resonant lines due to the time dilation effect in the co-rotating source and absorber with different radial coordinates. We analyse the available attempts to explain the origin of the extra energy shift, which include some extensions of special theory of relativity with hypothesis about the existence of limited acceleration in nature, with hypothesis about a so-called «time-dependent Doppler effect», as well as in the framework of the general theory of relativity under re-analysis of the metric effects in the rotating system, which is focused to the problem of correct synchronisation of clocks in a rotating system with a laboratory clock. We show that all such attempts remain unsuccessful until the moment, and we indicate possible ways of solving this problem, which should combine metric effects in rotating systems with quantum mechanical description of resonant nuclei confined in crystal cells.

scholarly journals Design, analysis and reformulation of a didactic sequence for teaching the special theory of relativity in high school

2015 ◽  
Vol 37 (3) ◽  
pp. 3401-1-3401-10 ◽  
Author(s):  
María Rita Otero ◽  
Marcelo Arlego ◽  
Fabiana Prodanoff
Keyword(s):  
High School ◽  
Special Relativity ◽  
Special Theory ◽  
Careful Analysis ◽  
Point Of View ◽  
Relativity Theory ◽  
Theory Of Relativity ◽  
Galilean Relativity ◽  
Firm Basis ◽  
The Subject

In this work, we design, implement and analyze a didactic sequence for the teaching of the basic topics of special relativity theory in high school. The sequence proposes a series of situations, specially designed to allow the emergence of the central aspects of special relativity. The conceptualization process is investigated from the point of view of the theory of conceptual fields of Vergnaud. By means of a careful analysis of classroom student productions we detect the key theorems-in-action they use, evidencing that most of conceptual errors are of pre-relativistic nature. This leads us to a reformulation of the sequence, which promotes the conceptualization of Galilean relativity and the principles of the special relativity. This previous step aims at bringing to students a firm basis to address the more complex aspects of the subject.

General introduction

1979 ◽  
Vol 368 (1732) ◽  
pp. 3-4
Keyword(s):  
Initial Period ◽  
Space Time ◽  
Relativistic Astrophysics ◽  
Theory Of Relativity ◽  
Kerr Geometry ◽  
Time Singularities ◽  
General Relativistic ◽  
The Subject ◽  
Insight Into ◽  
Theoretical Side

It is now over 60 years since Einstein first put forward his General theory of Relativity, providing what was, at that time, a daring new view of the geometry of the world and an extraordinary insight into the nature of the gravitational field - perhaps the single most strikingly original contribution to the scientific thought of recent times. But despite an initial period of active development both in the observational and theoretical sides of the subject, there followed a long period of comparative quiescence during which the subject had seemed to have little contact with the rest of physics and even less with feasible observations or experiments. In recent years, however, this situation has changed dramatically. On the theoretical side, for example, there has been much clarification of the nature of gravitational waves and of the fact that these waves carry positive mass-energy. Much more is known concerning exact solutions of Einstein’s equations. The space-time singularities that had been previously suspected as being features only of special symmetrical solutions are now known to be inevitable for wide classes of space-times. The theory of black holes has arisen and has led to a remarkably complete picture with a detailed and well-understood space-time geometry (the Kerr geometry). The relation to quantum theory, while still enigmatic, has made significant advances (e.g. Hawking radiation). The subject of General-Relativistic astrophysics has been born and has flourished.

3. Philosophical implications of relativity

2021 ◽  
pp. 46-63
Author(s):  
Jenann Ismael
Keyword(s):  
Special Theory ◽  
Time Travel ◽  
Time Dilation ◽  
Theory Of Relativity ◽  
Special Theory Of Relativity ◽  
Length Contraction ◽  
Temporal Intervals

‘Philosophical implications of relativity’ looks at the counterintuitive implications of the special theory of relativity. It begins with time dilation and length contraction, wherein the measurements of spatial distances and temporal intervals appear to vary with the motion of the observer. The question of whether relativity allows for the possibility of time travel is raised and the so-called paradoxes of time travel are explored.

scholarly journals Coordinate systems in the general relativistic framework

1986 ◽  
Vol 114 ◽  
pp. 145-168 ◽  
Author(s):  
T. Fukushima ◽  
M.-K Fujimoto ◽  
H. Kinoshita ◽  
S. Aoki
Keyword(s):  
Coordinate System ◽  
Reference Frame ◽  
Reference Frames ◽  
Special Theory ◽  
Newtonian Mechanics ◽  
Theory Of Relativity ◽  
Coordinate Systems ◽  
Relativistic Extension ◽  
General Relativistic ◽  
Relativistic Framework

The treatment of the coordinate systems is briefly reviewed in the Newtonian mechanics, in the special theory of relativity, and in the general relativistic theory, respectively. Some reference frames and coordinate systems proposed within the general relativistic framework are introduced. With use of the ideas on which these coordinate systems are based, the proper reference frame comoving with a system of mass-points is defined as a general relativistic extension of the relative coordinate system in the Newtonian mechanics. The coordinate transformation connecting this and the background coordinate systems is presented explicitly in the post-Newtonian formalism. The conversion formulas of some physical quantities caused by this coordirate transformation are discussed. The concept of the rotating coordinate system is reexamined within the relativistic framework. A modification of the introduced proper reference frame is proposed as the basic coordinate system in the astrometry. The relation between the solar system barycentric coordinate system and the terrestrial coordinate system is given explicitly.

The Special Theory of Relativity

1980 ◽  
Vol 33 (2) ◽  
pp. 155-166
Author(s):  
Hermann Bondi
Keyword(s):  
Special Theory ◽  
The Other ◽  
Theory Of Relativity ◽  
Special Theory Of Relativity ◽  
Great Pleasure ◽  
Other Hand ◽  
The Subject

It does indeed give me great pleasure to have been honoured by the request to give this lecture. And it is with a little trepidation that I have chosen my subject, the very title of which could frighten off many people, and I am very glad to see that your Institute consists of people made of sterner stuff. On the other hand, I did feel that the subject in question met the nature of this lecture. It was generally cultural and it relates to navigation. And so let me start on this subject which has a reputation for being difficult. And let me assure you that Einstein's work on relativity is not at all difficult. It is very simple. But it rests on the extremely difficult, abstract theories that we owe to Galileo and to Newton.

2. From space and time to spacetime: the era of Einstein

2021 ◽  
pp. 17-45
Author(s):  
Jenann Ismael
Keyword(s):  
General Theory ◽  
20Th Century ◽  
Special Theory ◽  
Dimensional Structure ◽  
Early 20Th Century ◽  
Theory Of Relativity ◽  
Speed Of Light ◽  
Philosophical Debate ◽  
Space And Time ◽  
Theory Of Motion

Isaac Newton’s theory of motion was superseded by Albert Einstein’s theories of relativity. By the early 20th century, it was clear that there was something wrong with Newton’s theory. Newton’s theory together with Maxwell’s newly proposed equations of electromagnetism predicted that the speed of light should depend on the motion of the observer, but experiments found that the velocity of light is independent of the motion of the observer. Einstein proposed the special theory of relativity in 1905 which merged space and time into a four-dimensional structure known as spacetime. Ten years later he proposed the general theory which extended the special theory to include gravity. With Einstein’s theories, an ancient philosophical debate between Heraclitus and Parmenides on change as the fundamental character of time was revived.

scholarly journals Philosophy in science – a case study of the reception of the Special and the General Theory of Relativity in Kraków and Lwów before 1925

2016 ◽  
Vol 15 ◽  
pp. 245-273 ◽  
Author(s):  
Paweł Polak ◽  
Keyword(s):  
General Theory ◽  
Special Theory ◽  
Scientific Activity ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Special Theory Of Relativity ◽  
Philosophical Debate ◽  
Science Philosophy ◽  
The Impact

A centenary of Einstein’s General Theory of Relativity brings forward some questions with regard to the impact of Einstein’s theory on philosophy. This theory, and the chronologically earlier Special Theory of Relativity, have had many important philosophical implications. In Poland they provoked interesting philosophical discussions before WWII. The history of those discussions reveals numerous noteworthy facts concerning the relationships between mathematics, physics and philosophy. A case study of the reception of the Special and General Theory of Relativity in Kraków and Lwów before 1925 focuses on the peculiar specificity of exact sciences and philosophy in Polish Galicia. The concept of “philosophy in science” coined by Michael Heller is particularly suitable for describing this specificity. The article begins with a short overview of the early reception of the Special Theory of Relativity in Kraków. Next, it shows how the discussions during the 10th and 11th Congresses of Polish Physicians and Natural Scientists (Lwów 1907, Kraków 1911) influenced the reception of the STR. What is also discussed are the roots of the specificity of the reception in Lwów, i.e. the influence of the considerations about the foundations of mechanics and a public philosophical debate around Einstein’s theories. In order to demonstrate how different the reception of these theories was in Kraków, a description is provided of a methodological debate between S. Zaremba and T. Banachiewicz. Some notes are also added about the concurrent styles of philosophy of science (philosophy of nature). The article ends with conclusions about the specificity of Kraków’s and Lwów’s styles of philosophy in science. This study reveals that in this period Einstein’s theories significantly stimulated philosophical considerations in Poland. These considerations have become an important supplement to the scientific activity in Kraków and Lwów.

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