<!DOCTYPE html><HTML lang="en"> <head><meta charset="utf-8"> <title>Earman (John) & Wuthrich (Christian) - Time Machines (Theo Todman's Book Collection - Paper Abstracts) </title> <link href="../../TheosStyle.css" rel="stylesheet" type="text/css"><link rel="shortcut icon" href="../../TT_ICO.png" /></head> <BODY> <CENTER> <div id="header"><HR><h1>Theo Todman's Web Page - Paper Abstracts</h1><HR></div><A name="Top"></A> <TABLE class = "Bridge" WIDTH=950> <tr><th><A HREF = "../../PaperSummaries/PaperSummary_17/PaperSummary_17912.htm">Time Machines</A></th></tr> <tr><th><A HREF = "../../Authors/E/Author_Earman (John).htm">Earman (John)</a> & <A HREF = "../../Authors/W/Author_Wuthrich (Christian).htm">Wuthrich (Christian)</a></th></tr> <tr><th>Source: Stanford Encyclopaedia of Philosophy, 2004-10</th></tr> <tr><th>Paper - Abstract</th></tr> </TABLE> </CENTER> <P><CENTER><TABLE class = "Bridge" WIDTH=800><tr><td><A HREF = "../../PaperSummaries/PaperSummary_17/PaperSummary_17912.htm">Paper Summary</A></td><td><A HREF = "../../PaperSummaries/PaperSummary_17/PaperCitings_17912.htm">Books / Papers Citing this Paper</A></td><td><A HREF = "../../PaperSummaries/PaperSummary_17/PapersToNotes_17912.htm">Notes Citing this Paper</A></td><td><A HREF="#ColourConventions">Text Colour-Conventions</a></td></tr></TABLE></CENTER></P> <hr><P><FONT COLOR = "0000FF"><U>Author s Abstract</U><FONT COLOR = "800080"><ol type="1">Recent years have seen a growing consensus in the philosophical community that the grandfather paradox and similar logical puzzles do not preclude the possibility of <a name="1"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time travel</A><SUP>1</SUP> scenarios that utilize spacetimes containing closed timelike curves. At the same time, physicists, who for half a century acknowledged that the general theory of relativity is compatible with such spacetimes, have intensely studied the question whether the operation of a <a name="2"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machine</A><SUP>2</SUP> would be admissible in the context of the same theory and of its quantum cousins. A <a name="3"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machine</A><SUP>3</SUP> is a device which brings about closed timelike curves and thus enables <a name="4"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time travel</A><SUP>4</SUP>  where none would have existed otherwise. The physics literature contains various no-go theorems for <a name="5"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machines</A><SUP>5</SUP>, i.e., theorems which purport to establish that, under physically plausible assumptions, the operation of a <a name="6"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machine</A><SUP>6</SUP> is impossible. We conclude that for the time being there exists no conclusive no-go theorem against <a name="7"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machines</A><SUP>7</SUP>. The character of the material covered in this article makes it inevitable that its content is of a rather technical nature. We contend, however, that philosophers should nevertheless be interested in this literature for at least two reasons. First, the topic of <a name="8"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machines</A><SUP>8</SUP> leads to a number of interesting foundations issues in classical and quantum theories of gravity; and second, philosophers can contribute to the topic by clarifying what it means for a device to count as a <a name="9"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machine</A><SUP>9</SUP>, by relating the debate to other concerns such as Penrose's cosmic censorship conjecture and the fate of determinism in general relativity theory, and by eliminating a number of confusions regarding the status of the paradoxes of <a name="10"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time travel</A><SUP>10</SUP>. The present article addresses these ambitions in as non-technical a manner as possible, and the reader is referred to the relevant physics literature for details. </ol> </FONT><BR><U>Contents</U><FONT COLOR = "800080"><ol type="1"><li>Introduction: <a name="11"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time travel</A><SUP>11</SUP> vs. <a name="12"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machines</A><SUP>12</SUP></li><li>What is a (Thornian) <a name="13"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machine</A><SUP>13</SUP>? Preliminaries</li><li>When can a would-be <a name="14"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machine</A><SUP>14</SUP> be held responsible for the emergence of CTCs?</li><li>No-go results for (Thornian) <a name="15"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time machines</A><SUP>15</SUP> in classical general relativity theory</li><li>No-go results in quantum gravity</li><li>Conclusion</li><li>Bibliography<BR>Other Internet Resources<BR>Related Entries </li></ol> </FONT><hr><FONT COLOR = "0000FF"><B>Comment: </B><BR><BR>Recommended by <a name="16"></a>"<A HREF = "../../Abstracts/Abstract_19/Abstract_19191.htm">Richmond (Alasdair) - Time Travel and Philosophy</A>". First published Thu Nov 25, 2004; substantive revision Thu Oct 7, 2010. For the full text, see <a name="W915W"></a><A HREF = "https://plato.stanford.edu/archives/win2010/entries/time-machine/" TARGET = "_top">Link</A>.<BR><FONT COLOR = "0000FF"><HR></P><a name="ColourConventions"></a><p><b>Text Colour Conventions (see <A HREF="../../Notes/Notes_10/Notes_1025.htm">disclaimer</a>)</b></p><OL TYPE="1"><LI><FONT COLOR = "0000FF">Blue</FONT>: Text by me; &copy; Theo Todman, 2018</li><LI><FONT COLOR = "800080">Mauve</FONT>: Text by correspondent(s) or other author(s); &copy; the author(s)</li></OL> <BR><HR><BR><CENTER> <TABLE class = "Bridge" WIDTH=950> <TR><TD WIDTH="30%">&copy; Theo Todman, June 2007 - August 2018.</TD> <TD WIDTH="40%">Please address any comments on this page to <A HREF="mailto:theo@theotodman.com">theo@theotodman.com</A>.</TD> <TD WIDTH="30%">File output: <time datetime="2018-08-02T08:48" pubdate>02/08/2018 08:48:38</time> <br><A HREF="../../Notes/Notes_10/Notes_1010.htm">Website Maintenance Dashboard</A></TD></TR> <TD WIDTH="30%"><A HREF="#Top">Return to Top of this Page</A></TD> <TD WIDTH="40%"><A HREF="../../Notes/Notes_11/Notes_1140.htm">Return to Theo Todman's Philosophy Page</A></TD> <TD WIDTH="30%"><A HREF="../../index.htm">Return to Theo Todman's Home Page</A></TD> </TR></TABLE></CENTER><HR> </BODY> </HTML>