Possible relationship between initial conditions for inflation and past geodesic incompleteness of the inflationary spacetime
According to the Borde-Guth-Vilenkin (BGV) theorem an expanding region of spacetime cannot be extended to the past beyond some boundary $\mathcal{B}$. Therefore, the inflationary universe must have had some kind of beginning. However, the BGW theorem says nothing about the boundary conditions on $\m...
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description | According to the Borde-Guth-Vilenkin (BGV) theorem an expanding region of
spacetime cannot be extended to the past beyond some boundary $\mathcal{B}$.
Therefore, the inflationary universe must have had some kind of beginning.
However, the BGW theorem says nothing about the boundary conditions on
$\mathcal{B}$, or even about its location. Here we present a single-scalar
field model of the Two-Measures Theory, where the non-Riemannian volume element
$\Upsilon d^4x$ is present in the action. As a result of the model dynamics, an
upper bound $\varphi_0$ of admissible values of the scalar field $\varphi$
appears, which sets the position of $\mathcal{B}$ in the form of a spacelike
hypersurface $\Upsilon(x)=0$ with a boundary condition: $\Upsilon\rightarrow
0^+$ as $\varphi\rightarrow\varphi_0^{\,\,\,-}$. A detailed study has
established that if the initial kinetic energy density $\rho_{kin}^{(in)}$
prevails over initial gradient energy density $\rho_{grad}^{(in)}$ then there
is an interval of initial values $\varphi_{in}^{(min)}\leq \varphi_{in} |
doi_str_mv | 10.48550/arxiv.2303.00249 |
format | Article |
fullrecord | <record><control><sourceid>arxiv_GOX</sourceid><recordid>TN_cdi_arxiv_primary_2303_00249</recordid><sourceformat>XML</sourceformat><sourcesystem>PC</sourcesystem><sourcerecordid>2303_00249</sourcerecordid><originalsourceid>FETCH-LOGICAL-a679-31ae54ba8dcc2bee7a7569855bea1fb0fdbb33f0f2ec1d94ad87bcdfdb208a803</originalsourceid><addsrcrecordid>eNpFULlOxDAQdUOBFj6AivmBBCdONkmJVlzSSmyxfTS2x-xIiR3FFkfBvxOySFQjvUvznhA3hcyrtq7lHc6f_J6XSqpcyrLqLsX3IcTIeiCYacDEwccTT6ApfRB5YM-JcQATvOWVBRfmBXZnMaC3MGFM8EbBUmSzcCaM00CJPMUIwUE60b8D5y-IExpKPNKVuHA4RLr-uxtxfHw47p6z_evTy-5-n-G26TJVINWVxtYaU2qiBpt62y2FNGHhtHRWa6WcdCWZwnYV2rbRxi5wKVtspdqI23Ps2r-fZh6XN_rfHfp1B_UDE1xd7Q</addsrcrecordid><sourcetype>Open Access Repository</sourcetype><iscdi>true</iscdi><recordtype>article</recordtype></control><display><type>article</type><title>Possible relationship between initial conditions for inflation and past geodesic incompleteness of the inflationary spacetime</title><source>arXiv.org</source><creator>Kaganovich, Alexander</creator><creatorcontrib>Kaganovich, Alexander</creatorcontrib><description>According to the Borde-Guth-Vilenkin (BGV) theorem an expanding region of
spacetime cannot be extended to the past beyond some boundary $\mathcal{B}$.
Therefore, the inflationary universe must have had some kind of beginning.
However, the BGW theorem says nothing about the boundary conditions on
$\mathcal{B}$, or even about its location. Here we present a single-scalar
field model of the Two-Measures Theory, where the non-Riemannian volume element
$\Upsilon d^4x$ is present in the action. As a result of the model dynamics, an
upper bound $\varphi_0$ of admissible values of the scalar field $\varphi$
appears, which sets the position of $\mathcal{B}$ in the form of a spacelike
hypersurface $\Upsilon(x)=0$ with a boundary condition: $\Upsilon\rightarrow
0^+$ as $\varphi\rightarrow\varphi_0^{\,\,\,-}$. A detailed study has
established that if the initial kinetic energy density $\rho_{kin}^{(in)}$
prevails over initial gradient energy density $\rho_{grad}^{(in)}$ then there
is an interval of initial values $\varphi_{in}^{(min)}\leq \varphi_{in}
<\varphi_0$, where $\rho_{kin}^{(in)}$ and $\rho_{grad}^{(in)}$ cannot exceed
the potential energy density and hence the initial conditions necessary for the
onset of inflation are satisfied. It is shown that under almost all possible
left-handed boundary conditions on $\mathcal{B}$, that is where
$\Upsilon\rightarrow 0^-$, the metric tensor in the Einstein frame has a jump
discontinuity on $\mathcal{B}$, so the Christoffel connection coefficients are
not defined on the spacelike hypersurface $\Upsilon=0$. Thus, if
$\varphi_{in}^{(min)}\leq \varphi_{in}<\varphi_0$ and
$\rho_{kin}^{(in)}>\rho_{grad}^{(in)}$, then there was an inflationary stage in
the history of our Universe and the congruence of timelike geodesics cannot be
extended to the past beyond the hypersurface $\Upsilon=0$.</description><identifier>DOI: 10.48550/arxiv.2303.00249</identifier><language>eng</language><subject>Physics - General Relativity and Quantum Cosmology ; Physics - High Energy Physics - Theory</subject><creationdate>2023-03</creationdate><rights>http://creativecommons.org/licenses/by/4.0</rights><oa>free_for_read</oa><woscitedreferencessubscribed>false</woscitedreferencessubscribed></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><link.rule.ids>228,230,780,885</link.rule.ids><linktorsrc>$$Uhttps://arxiv.org/abs/2303.00249$$EView_record_in_Cornell_University$$FView_record_in_$$GCornell_University$$Hfree_for_read</linktorsrc><backlink>$$Uhttps://doi.org/10.48550/arXiv.2303.00249$$DView paper in arXiv$$Hfree_for_read</backlink></links><search><creatorcontrib>Kaganovich, Alexander</creatorcontrib><title>Possible relationship between initial conditions for inflation and past geodesic incompleteness of the inflationary spacetime</title><description>According to the Borde-Guth-Vilenkin (BGV) theorem an expanding region of
spacetime cannot be extended to the past beyond some boundary $\mathcal{B}$.
Therefore, the inflationary universe must have had some kind of beginning.
However, the BGW theorem says nothing about the boundary conditions on
$\mathcal{B}$, or even about its location. Here we present a single-scalar
field model of the Two-Measures Theory, where the non-Riemannian volume element
$\Upsilon d^4x$ is present in the action. As a result of the model dynamics, an
upper bound $\varphi_0$ of admissible values of the scalar field $\varphi$
appears, which sets the position of $\mathcal{B}$ in the form of a spacelike
hypersurface $\Upsilon(x)=0$ with a boundary condition: $\Upsilon\rightarrow
0^+$ as $\varphi\rightarrow\varphi_0^{\,\,\,-}$. A detailed study has
established that if the initial kinetic energy density $\rho_{kin}^{(in)}$
prevails over initial gradient energy density $\rho_{grad}^{(in)}$ then there
is an interval of initial values $\varphi_{in}^{(min)}\leq \varphi_{in}
<\varphi_0$, where $\rho_{kin}^{(in)}$ and $\rho_{grad}^{(in)}$ cannot exceed
the potential energy density and hence the initial conditions necessary for the
onset of inflation are satisfied. It is shown that under almost all possible
left-handed boundary conditions on $\mathcal{B}$, that is where
$\Upsilon\rightarrow 0^-$, the metric tensor in the Einstein frame has a jump
discontinuity on $\mathcal{B}$, so the Christoffel connection coefficients are
not defined on the spacelike hypersurface $\Upsilon=0$. Thus, if
$\varphi_{in}^{(min)}\leq \varphi_{in}<\varphi_0$ and
$\rho_{kin}^{(in)}>\rho_{grad}^{(in)}$, then there was an inflationary stage in
the history of our Universe and the congruence of timelike geodesics cannot be
extended to the past beyond the hypersurface $\Upsilon=0$.</description><subject>Physics - General Relativity and Quantum Cosmology</subject><subject>Physics - High Energy Physics - Theory</subject><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2023</creationdate><recordtype>article</recordtype><sourceid>GOX</sourceid><recordid>eNpFULlOxDAQdUOBFj6AivmBBCdONkmJVlzSSmyxfTS2x-xIiR3FFkfBvxOySFQjvUvznhA3hcyrtq7lHc6f_J6XSqpcyrLqLsX3IcTIeiCYacDEwccTT6ApfRB5YM-JcQATvOWVBRfmBXZnMaC3MGFM8EbBUmSzcCaM00CJPMUIwUE60b8D5y-IExpKPNKVuHA4RLr-uxtxfHw47p6z_evTy-5-n-G26TJVINWVxtYaU2qiBpt62y2FNGHhtHRWa6WcdCWZwnYV2rbRxi5wKVtspdqI23Ps2r-fZh6XN_rfHfp1B_UDE1xd7Q</recordid><startdate>20230301</startdate><enddate>20230301</enddate><creator>Kaganovich, Alexander</creator><scope>GOX</scope></search><sort><creationdate>20230301</creationdate><title>Possible relationship between initial conditions for inflation and past geodesic incompleteness of the inflationary spacetime</title><author>Kaganovich, Alexander</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-a679-31ae54ba8dcc2bee7a7569855bea1fb0fdbb33f0f2ec1d94ad87bcdfdb208a803</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2023</creationdate><topic>Physics - General Relativity and Quantum Cosmology</topic><topic>Physics - High Energy Physics - Theory</topic><toplevel>online_resources</toplevel><creatorcontrib>Kaganovich, Alexander</creatorcontrib><collection>arXiv.org</collection></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext_linktorsrc</fulltext></delivery><addata><au>Kaganovich, Alexander</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>Possible relationship between initial conditions for inflation and past geodesic incompleteness of the inflationary spacetime</atitle><date>2023-03-01</date><risdate>2023</risdate><abstract>According to the Borde-Guth-Vilenkin (BGV) theorem an expanding region of
spacetime cannot be extended to the past beyond some boundary $\mathcal{B}$.
Therefore, the inflationary universe must have had some kind of beginning.
However, the BGW theorem says nothing about the boundary conditions on
$\mathcal{B}$, or even about its location. Here we present a single-scalar
field model of the Two-Measures Theory, where the non-Riemannian volume element
$\Upsilon d^4x$ is present in the action. As a result of the model dynamics, an
upper bound $\varphi_0$ of admissible values of the scalar field $\varphi$
appears, which sets the position of $\mathcal{B}$ in the form of a spacelike
hypersurface $\Upsilon(x)=0$ with a boundary condition: $\Upsilon\rightarrow
0^+$ as $\varphi\rightarrow\varphi_0^{\,\,\,-}$. A detailed study has
established that if the initial kinetic energy density $\rho_{kin}^{(in)}$
prevails over initial gradient energy density $\rho_{grad}^{(in)}$ then there
is an interval of initial values $\varphi_{in}^{(min)}\leq \varphi_{in}
<\varphi_0$, where $\rho_{kin}^{(in)}$ and $\rho_{grad}^{(in)}$ cannot exceed
the potential energy density and hence the initial conditions necessary for the
onset of inflation are satisfied. It is shown that under almost all possible
left-handed boundary conditions on $\mathcal{B}$, that is where
$\Upsilon\rightarrow 0^-$, the metric tensor in the Einstein frame has a jump
discontinuity on $\mathcal{B}$, so the Christoffel connection coefficients are
not defined on the spacelike hypersurface $\Upsilon=0$. Thus, if
$\varphi_{in}^{(min)}\leq \varphi_{in}<\varphi_0$ and
$\rho_{kin}^{(in)}>\rho_{grad}^{(in)}$, then there was an inflationary stage in
the history of our Universe and the congruence of timelike geodesics cannot be
extended to the past beyond the hypersurface $\Upsilon=0$.</abstract><doi>10.48550/arxiv.2303.00249</doi><oa>free_for_read</oa></addata></record> |
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subjects | Physics - General Relativity and Quantum Cosmology Physics - High Energy Physics - Theory |
title | Possible relationship between initial conditions for inflation and past geodesic incompleteness of the inflationary spacetime |
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