Chronology Protection in <i>f</i>(<i>T</i>) Gravity: The Case of Gott’s Pair of Moving Cosmic Strings
As a consequence of the spacetime structure, defined by the tetrad field instead of the metric tensor alone, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>(</mo><...
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| Format: | Article |
| Language: | English |
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MDPI AG
2024-01-01
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| Series: | Universe |
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| Online Access: | https://www.mdpi.com/2218-1997/10/1/52 |
| _version_ | 1797342432051855360 |
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| author | Franco Fiorini |
| author_facet | Franco Fiorini |
| author_sort | Franco Fiorini |
| collection | DOAJ |
| description | As a consequence of the spacetime structure, defined by the tetrad field instead of the metric tensor alone, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>(</mo><mi>T</mi><mo>)</mo></mrow></semantics></math></inline-formula> gravity seems to harbor its own chronology protection agency. When Gott’s pair of moving cosmic strings is considered, it is shown that the requirement of having a global parallelization—i.e., a global smooth field of tetrads– drastically restricts the form of the tetrads on the junction surface between the two strings. The junction conditions on the tetrad field are satisfied only if the corresponding boosts needed to put the strings in motion are null on the matching surface. This seems to throw overboard Gott’s construction from the outset without the need for analyzing the divergence of the expectation value of the energy–momentum tensor on the Cauchy horizon, evading in this way bothersome quarrels concerning the choice of vacuum. |
| first_indexed | 2024-03-08T10:33:12Z |
| format | Article |
| id | doaj.art-2b43b47a7ab04c27961afd990e71c124 |
| institution | Directory Open Access Journal |
| issn | 2218-1997 |
| language | English |
| last_indexed | 2024-03-08T10:33:12Z |
| publishDate | 2024-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Universe |
| spelling | doaj.art-2b43b47a7ab04c27961afd990e71c1242024-01-26T18:43:09ZengMDPI AGUniverse2218-19972024-01-011015210.3390/universe10010052Chronology Protection in <i>f</i>(<i>T</i>) Gravity: The Case of Gott’s Pair of Moving Cosmic StringsFranco Fiorini0Departamento de Ingeniería en Telecomunicaciones, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) and Instituto Balseiro (UNCUYO), Centro Atómico Bariloche, Av. Ezequiel Bustillo 9500, San Carlos de Bariloche 8400, ArgentinaAs a consequence of the spacetime structure, defined by the tetrad field instead of the metric tensor alone, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi>f</mi><mo>(</mo><mi>T</mi><mo>)</mo></mrow></semantics></math></inline-formula> gravity seems to harbor its own chronology protection agency. When Gott’s pair of moving cosmic strings is considered, it is shown that the requirement of having a global parallelization—i.e., a global smooth field of tetrads– drastically restricts the form of the tetrads on the junction surface between the two strings. The junction conditions on the tetrad field are satisfied only if the corresponding boosts needed to put the strings in motion are null on the matching surface. This seems to throw overboard Gott’s construction from the outset without the need for analyzing the divergence of the expectation value of the energy–momentum tensor on the Cauchy horizon, evading in this way bothersome quarrels concerning the choice of vacuum.https://www.mdpi.com/2218-1997/10/1/52cosmic strings<i>f</i>(<i>T</i>) gravityGott’s space |
| spellingShingle | Franco Fiorini Chronology Protection in <i>f</i>(<i>T</i>) Gravity: The Case of Gott’s Pair of Moving Cosmic Strings Universe cosmic strings <i>f</i>(<i>T</i>) gravity Gott’s space |
| title | Chronology Protection in <i>f</i>(<i>T</i>) Gravity: The Case of Gott’s Pair of Moving Cosmic Strings |
| title_full | Chronology Protection in <i>f</i>(<i>T</i>) Gravity: The Case of Gott’s Pair of Moving Cosmic Strings |
| title_fullStr | Chronology Protection in <i>f</i>(<i>T</i>) Gravity: The Case of Gott’s Pair of Moving Cosmic Strings |
| title_full_unstemmed | Chronology Protection in <i>f</i>(<i>T</i>) Gravity: The Case of Gott’s Pair of Moving Cosmic Strings |
| title_short | Chronology Protection in <i>f</i>(<i>T</i>) Gravity: The Case of Gott’s Pair of Moving Cosmic Strings |
| title_sort | chronology protection in i f i i t i gravity the case of gott s pair of moving cosmic strings |
| topic | cosmic strings <i>f</i>(<i>T</i>) gravity Gott’s space |
| url | https://www.mdpi.com/2218-1997/10/1/52 |
| work_keys_str_mv | AT francofiorini chronologyprotectioninifiitigravitythecaseofgottspairofmovingcosmicstrings |