[hep-th/0008164] Survey of Two-Time Physics

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This may play a role in displaying the symmetries and constructing the dynamics of little understood systems, such as M-theory. 2T physics describes various 1T dynamical systems as different d-dimensional ``holographic'' views of the same 2T system in $d+2$ dimensions. The ``holography'' is due to gauge symmetries that tend to reduce the number of effective dimensions. Different 1T evolutions (i.e. different Hamiltonians) emerge from the same 2T theory when gauge fixing is done with different embeddings of d dimensions inside d+2 dimensions. Thus, in the 2T setting, the distinguished 1T which we call ``time'' is a gauge dependent concept. The 2T action has also a global SO(d,2) symmetry in flat spacetime, or a more general d+2 symmetry in curved spacetime, under which all dimensions are on an equal footing. This symmetry is observable in many 1T systems, but it remained unknown until discovered in the 2T formalism. 2T physics has mainly been developed in the context of particles, including spin and supersymmetry, but some advances have also been made with strings and p-branes, and insights for M-theory have already emerged. In the case of particles, there exists a general worldline formulation with background fields, as well as a field theory formulation, both described in terms of fields that depend on d+2 coordinates. The Standard Model of particle physics can be regarded as a gauge fixed form of a 2T theory in 4+2 dimensions. These facts already provide evidence for a new type of higher dimensional unification."/> <meta name="twitter:site" content="@arxiv"/> <meta name="twitter:card" content="summary"/> <meta name="twitter:title" content="Survey of Two-Time Physics"/> <meta name="twitter:description" content="Two-time physics (2T) is a general reformulation of one-time physics (1T) that displays previously unnoticed hidden symmetries in 1T dynamical systems and establishes previously unknown duality..."/> <meta name="twitter:image" content="https://static.arxiv.org/icons/twitter/arxiv-logo-twitter-square.png"/> <meta name="twitter:image:alt" content="arXiv logo"/> <link rel="stylesheet" media="screen" type="text/css" href="/static/browse/0.3.4/css/tooltip.css"/><link rel="stylesheet" media="screen" type="text/css" href="https://static.arxiv.org/js/bibex-dev/bibex.css?20200709"/> <script src="/static/browse/0.3.4/js/mathjaxToggle.min.js" type="text/javascript"></script> <script src="//code.jquery.com/jquery-latest.min.js" type="text/javascript"></script> <script src="//cdn.jsdelivr.net/npm/js-cookie@2/src/js.cookie.min.js" type="text/javascript"></script> <script src="//cdn.jsdelivr.net/npm/dompurify@2.3.5/dist/purify.min.js"></script> <script src="/static/browse/0.3.4/js/toggle-labs.js?20241022" type="text/javascript"></script> <script src="/static/browse/0.3.4/js/cite.js" type="text/javascript"></script><meta name="citation_title" content="Survey of Two-Time Physics" /><meta name="citation_author" content="Bars, Itzhak" /><meta name="citation_doi" content="10.1088/0264-9381/18/16/303" /><meta name="citation_date" content="2000/08/22" /><meta name="citation_online_date" content="2000/08/22" /><meta name="citation_pdf_url" content="http://arxiv.org/pdf/hep-th/0008164" /><meta name="citation_arxiv_id" content="hep-th/0008164" /><meta name="citation_abstract" content=" Two-time physics (2T) is a general reformulation of one-time physics (1T) that displays previously unnoticed hidden symmetries in 1T dynamical systems and establishes previously unknown duality type relations among them. This may play a role in displaying the symmetries and constructing the dynamics of little understood systems, such as M-theory. 2T physics describes various 1T dynamical systems as different d-dimensional ``holographic'' views of the same 2T system in $d+2$ dimensions. The ``holography'' is due to gauge symmetries that tend to reduce the number of effective dimensions. Different 1T evolutions (i.e. different Hamiltonians) emerge from the same 2T theory when gauge fixing is done with different embeddings of d dimensions inside d+2 dimensions. Thus, in the 2T setting, the distinguished 1T which we call ``time'' is a gauge dependent concept. The 2T action has also a global SO(d,2) symmetry in flat spacetime, or a more general d+2 symmetry in curved spacetime, under which all dimensions are on an equal footing. This symmetry is observable in many 1T systems, but it remained unknown until discovered in the 2T formalism. 2T physics has mainly been developed in the context of particles, including spin and supersymmetry, but some advances have also been made with strings and p-branes, and insights for M-theory have already emerged. In the case of particles, there exists a general worldline formulation with background fields, as well as a field theory formulation, both described in terms of fields that depend on d+2 coordinates. The Standard Model of particle physics can be regarded as a gauge fixed form of a 2T theory in 4+2 dimensions. 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paper titled Survey of Two-Time Physics, by Itzhak Bars</div> <a class="mobile-submission-download" href="/pdf/hep-th/0008164">View PDF</a> <blockquote class="abstract mathjax"> <span class="descriptor">Abstract:</span> Two-time physics (2T) is a general reformulation of one-time physics (1T) that displays previously unnoticed hidden symmetries in 1T dynamical systems and establishes previously unknown duality type relations among them. This may play a role in displaying the symmetries and constructing the dynamics of little understood systems, such as M-theory. 2T physics describes various 1T dynamical systems as different d-dimensional ``holographic'' views of the same 2T system in $d+2$ dimensions. The ``holography'' is due to gauge symmetries that tend to reduce the number of effective dimensions. Different 1T evolutions (i.e. different Hamiltonians) emerge from the same 2T theory when gauge fixing is done with different embeddings of d dimensions inside d+2 dimensions. Thus, in the 2T setting, the distinguished 1T which we call ``time'' is a gauge dependent concept. The 2T action has also a global SO(d,2) symmetry in flat spacetime, or a more general d+2 symmetry in curved spacetime, under which all dimensions are on an equal footing. This symmetry is observable in many 1T systems, but it remained unknown until discovered in the 2T formalism. 2T physics has mainly been developed in the context of particles, including spin and supersymmetry, but some advances have also been made with strings and p-branes, and insights for M-theory have already emerged. In the case of particles, there exists a general worldline formulation with background fields, as well as a field theory formulation, both described in terms of fields that depend on d+2 coordinates. The Standard Model of particle physics can be regarded as a gauge fixed form of a 2T theory in 4+2 dimensions. These facts already provide evidence for a new type of higher dimensional unification. </blockquote>  <div class="metatable"> <table summary="Additional metadata"> <tr> <td class="tablecell label">Comments:</td> <td class="tablecell comments mathjax">Latex, 22 pages, 1 figure</td> </tr> <tr> <td class="tablecell label">Subjects:</td> <td class="tablecell subjects"> <span class="primary-subject">High Energy Physics - Theory (hep-th)</span></td> </tr> <tr> <td class="tablecell label">Report number:</td> <td class="tablecell jref">CITUSC/00-048</td> </tr> <tr> <td class="tablecell label">Cite as:</td> <td class="tablecell arxivid"><span class="arxivid"><a href="https://arxiv.org/abs/hep-th/0008164">arXiv:hep-th/0008164</a></span></td> </tr> <tr> <td class="tablecell label"> </td> <td class="tablecell arxividv">(or <span class="arxivid"> <a href="https://arxiv.org/abs/hep-th/0008164v1">arXiv:hep-th/0008164v1</a></span> for this version) </td> </tr> <tr> <td class="tablecell label"> </td> <td class="tablecell arxivdoi"> <a href="https://doi.org/10.48550/arXiv.hep-th/0008164" id="arxiv-doi-link">https://doi.org/10.48550/arXiv.hep-th/0008164</a><div class="button-and-tooltip"> <button class="more-info" aria-describedby="more-info-desc-1"> <svg height="15" role="presentation" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path fill="currentColor" d="M256 8C119.043 8 8 119.083 8 256c0 136.997 111.043 248 248 248s248-111.003 248-248C504 119.083 392.957 8 256 8zm0 110c23.196 0 42 18.804 42 42s-18.804 42-42 42-42-18.804-42-42 18.804-42 42-42zm56 254c0 6.627-5.373 12-12 12h-88c-6.627 0-12-5.373-12-12v-24c0-6.627 5.373-12 12-12h12v-64h-12c-6.627 0-12-5.373-12-12v-24c0-6.627 5.373-12 12-12h64c6.627 0 12 5.373 12 12v100h12c6.627 0 12 5.373 12 12v24z" class=""></path></svg> <span class="visually-hidden">Focus to learn more</span> </button>  <div role="tooltip" id="more-info-desc-1"> <span class="left-corner"></span> arXiv-issued DOI via DataCite</div> </div> </td> </tr> <tr> <td class="tablecell label">Journal reference:</td> <td class="tablecell jref">Class.Quant.Grav. 18 (2001) 3113-3130</td> </tr> <tr> <td class="tablecell label"> <abbr title="Digital Object Identifier">Related DOI</abbr>: </td> <td class="tablecell doi"><a href="https://doi.org/10.1088/0264-9381/18/16/303" data-doi="10.1088/0264-9381/18/16/303" class="link-https link-external" rel="external noopener nofollow">https://doi.org/10.1088/0264-9381/18/16/303</a>  <div class="button-and-tooltip"> <button class="more-info" aria-describedby="more-info-desc-1"> <svg height="15" role="presentation" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 512 512"><path fill="currentColor" d="M256 8C119.043 8 8 119.083 8 256c0 136.997 111.043 248 248 248s248-111.003 248-248C504 119.083 392.957 8 256 8zm0 110c23.196 0 42 18.804 42 42s-18.804 42-42 42-42-18.804-42-42 18.804-42 42-42zm56 254c0 6.627-5.373 12-12 12h-88c-6.627 0-12-5.373-12-12v-24c0-6.627 5.373-12 12-12h12v-64h-12c-6.627 0-12-5.373-12-12v-24c0-6.627 5.373-12 12-12h64c6.627 0 12 5.373 12 12v100h12c6.627 0 12 5.373 12 12v24z" class=""></path></svg> <span class="visually-hidden">Focus to learn more</span> </button>  <div role="tooltip" id="more-info-desc-1"> <span class="left-corner"></span> DOI(s) linking to related resources </div> </div> </td> </tr> </table> </div> </div> </div> <div class="submission-history"> <h2>Submission history</h2> From: Itzhak Bars [<a href="/show-email/d9650010/hep-th/0008164" rel="nofollow">view email</a>] <br/> <strong>[v1]</strong> Tue, 22 Aug 2000 05:41:40 UTC (106 KB)<br/> </div> </div>  <div class="extra-services"> <div class="full-text"> <a name="other"></a> <span class="descriptor">Full-text links:</span> <h2>Access Paper:</h2> <ul> <div id="download-button-info" hidden> View a PDF of the paper titled Survey of Two-Time Physics, by Itzhak Bars</div><li><a href="/pdf/hep-th/0008164" aria-describedby="download-button-info" accesskey="f" class="abs-button 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[hep-th/0008164] Survey of Two-Time Physics