{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,27]],"date-time":"2026-03-27T14:45:32Z","timestamp":1774622732019,"version":"3.50.1"},"reference-count":98,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2024,8,7]],"date-time":"2024-08-07T00:00:00Z","timestamp":1722988800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>It has been proven that in standard Einstein gravity, exotic matter (i.e., matter violating the pointwise and averaged Weak and Null Energy Conditions) is required to stabilize traversable wormholes. Quantum field theory permits these violations due to the quantum coherent effects found in any quantum field. Even reasonable classical scalar fields violate the energy conditions. In the case of the Casimir effect and squeezed vacuum states, these violations have been experimentally proven. It is advantageous to investigate methods to minimize the use of exotic matter. One such area of interest is extended theories of Einstein gravity. It has been claimed that in some extended theories, stable traversable wormholes solutions can be found without the use of exotic matter. There are many extended theories of gravity, and in this review paper, we first explore\u00a0f(R)\u00a0theories and then explore some wormhole solutions in\u00a0f(R)\u00a0theories, including Lovelock gravity and Einstein Dilaton Gauss\u2013Bonnet (EdGB) gravity. For completeness, we have also reviewed \u2018Other wormholes\u2019 such as Casimir wormholes, dark matter halo wormholes, thin-shell wormholes, and Nonlocal Gravity (NLG) wormholes, where alternative techniques are used to either avoid or reduce the amount of exotic matter that is required.<\/jats:p>","DOI":"10.3390\/sym16081007","type":"journal-article","created":{"date-parts":[[2024,8,8]],"date-time":"2024-08-08T07:01:25Z","timestamp":1723100485000},"page":"1007","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["A Review of Stable, Traversable Wormholes in f(R) Gravity Theories"],"prefix":"10.3390","volume":"16","author":[{"ORCID":"https:\/\/orcid.org\/0009-0008-6059-605X","authenticated-orcid":false,"given":"Ramesh","family":"Radhakrishnan","sequence":"first","affiliation":[{"name":"Early Universe, Cosmology, and Strings (EUCOS) Group, Center for Astrophysics, Space Physics, and Engineering Research (CASPER), Waco, TX 76798, USA"},{"name":"Department of Physics, Baylor University, Waco, TX 76798, USA"}]},{"given":"Patrick","family":"Brown","sequence":"additional","affiliation":[{"name":"Early Universe, Cosmology, and Strings (EUCOS) Group, Center for Astrophysics, Space Physics, and Engineering Research (CASPER), Waco, TX 76798, USA"},{"name":"Department of Physics, Baylor University, Waco, TX 76798, USA"}]},{"ORCID":"https:\/\/orcid.org\/0009-0003-5758-7279","authenticated-orcid":false,"given":"Jacob","family":"Matulevich","sequence":"additional","affiliation":[{"name":"Early Universe, Cosmology, and Strings (EUCOS) Group, Center for Astrophysics, Space Physics, and Engineering Research (CASPER), Waco, TX 76798, USA"},{"name":"Department of Physics, Baylor University, Waco, TX 76798, USA"}]},{"given":"Eric","family":"Davis","sequence":"additional","affiliation":[{"name":"Early Universe, Cosmology, and Strings (EUCOS) Group, Center for Astrophysics, Space Physics, and Engineering Research (CASPER), Waco, TX 76798, USA"},{"name":"Department of Physics, Baylor University, Waco, TX 76798, USA"}]},{"given":"Delaram","family":"Mirfendereski","sequence":"additional","affiliation":[{"name":"Early Universe, Cosmology, and Strings (EUCOS) Group, Center for Astrophysics, Space Physics, and Engineering Research (CASPER), Waco, TX 76798, USA"},{"name":"Department of Physics and Astronomy, The University of Texas Rio Grande Valley (UTRGV), Edinburg, TX 78539, USA"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8528-285X","authenticated-orcid":false,"given":"Gerald","family":"Cleaver","sequence":"additional","affiliation":[{"name":"Early Universe, Cosmology, and Strings (EUCOS) Group, Center for Astrophysics, Space Physics, and Engineering Research (CASPER), Waco, TX 76798, USA"},{"name":"Department of Physics, Baylor University, Waco, TX 76798, USA"}]}],"member":"1968","published-online":{"date-parts":[[2024,8,7]]},"reference":[{"key":"ref_1","first-page":"448","article-title":"Beitr\u00e4ge zur Einsteinschen Gravitationstheorie","volume":"17","author":"Flamm","year":"1916","journal-title":"Phys. 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