<!DOCTYPE html><HTML lang="en"> <head><meta charset="utf-8"> <title>Kutach (Douglas N.) - Time Travel and Consistency Constraints (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_20/PaperSummary_20915.htm">Time Travel and Consistency Constraints</A></th></tr> <tr><th><A HREF = "../../Authors/K/Author_Kutach (Douglas N.).htm">Kutach (Douglas N.)</a></th></tr> <tr><th>Source: Philosophy of Science, Vol. 70, No. 5, (December 2003), pp. 1098-1113</th></tr> <tr><th>Paper - Abstract</th></tr> </TABLE> </CENTER> <P><CENTER><TABLE class = "Bridge" WIDTH=600><tr><td><A HREF = "../../PaperSummaries/PaperSummary_20/PaperSummary_20915.htm">Paper Summary</A></td><td><A HREF = "../../PaperSummaries/PaperSummary_20/PaperCitings_20915.htm">Books / Papers 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"><li>The possibility of <a name="1"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time travel</A><SUP>1</SUP>, as permitted in General Relativity, is responsible for constraining physical fields beyond what laws of nature would otherwise require. </li><li>In the special case where <a name="2"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">time travel</A><SUP>2</SUP> is limited to a single object returning to the past and interacting with itself, consistency constraints can be avoided if the dynamics is continuous and the object s state space satisfies a certain topological requirement: that all null-homotopic mappings from the state-space to itself have some fixed point. </li><li>Where consistency constraints do exist, no new physics is needed to enforce them. One needs only to accept certain global topological constraints as laws, something that is reasonable in any case. </li></ol> </FONT> <BR><U>Sections</U><FONT COLOR = "800080"><ol type="1"><li>Introduction</li><li>Preliminary Distinctions</li><li>What s the Problem with <a name="3"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">Time Travel</A><SUP>3</SUP>?</li><li>Topological Constraints on <a name="4"></a><A HREF="../../Notes/Notes_11/Notes_1133.htm">Time Travel</A><SUP>4</SUP></li><li>Are Consistency Constraints Laws of Nature? </li></ol> </FONT><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="2018-08-02T09:28" pubdate>02/08/2018 09:28:11</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>