Modified Gravity: Exploring Black Holes, Compact Objects, Wormholes, and Beyond

Dear Colleagues,

We are pleased to announce a Special Issue titled “Modified Gravity: Exploring Black Holes, Compact Objects, Wormholes, and Beyond”, which will be published in the journal Symmetry (MDPI). This Special Issue will bring together original research articles and comprehensive reviews investigating the frontiers of theoretical physics, with a focus on the interplay between supersymmetry and gravity in its many modern forms.

In recent years, we have witnessed an accelerating interest in the investigation of extended and alternative theories of gravity as frameworks for addressing unsolved problems in cosmology and high-energy physics. The rapid growth of observational data from gravitational wave detectors, high-energy astrophysical observatories, and cosmological surveys has compelled theorists to improve or extend Einstein’s general relativity to incorporate new physical insights, for example, those from quantum gravity or supersymmetric theories. For this Special Issue, we welcome papers that advance physics from the fundamental level to phenomenological applications in astrophysics and cosmology.

One of the key themes of this Special Issue involves the Modified Theories of Gravity. These include generalizations of Einstein’s theory that can accommodate phenomena such as cosmic acceleration, dark matter effects, and early universe inflation without proposing exotic matter. Examples include f(R) gravity, Gauss–Bonnet and Lovelock gravities, scalar–tensor theories, Brans–Dicke theory, and teleparallel gravity formulations. These modified frameworks not only are mathematically rich but also offer testable predictions that diverge from standard general relativity. Investigations into exact/numerical solutions, cosmological dynamics, gravitational wave signatures, and weak-field limits within these frameworks are especially encouraged.

Black Holes represent a central testing ground for both classical and quantum gravity. In modified gravity theories, black hole solutions can exhibit novel properties, for example, non-trivial scalar hair, modified thermodynamics, or departures from the standard no-hair theorems. Quantum gravity also seeks to explain the microstructure of black holes and resolve puzzles such as the information loss paradox. This Special Issue will showcase works exploring black hole mechanics, quantum aspects such as Hawking radiation, entropy counting in string theory or loop quantum gravity, and black hole formation in the early universe. Studies involving higher-dimensional or rotating solutions, as well as those connected to observational phenomena, are particularly encouraged.

Compact objects, such as neutron stars, quark stars, and hypothetical exotic stars, serve as natural laboratories for probing the extreme regimes of gravity, matter, and quantum field theory. These dense astrophysical remnants offer crucial insights into the behavior of matter under ultra-high densities and strong gravitational fields, where both general relativity and nuclear physics reach their limits. Modified gravity theories often yield alternative mass–radius relations, stability criteria, and observational signatures for compact stars, distinguishing them from predictions of general relativity. In particular, quark stars, composed of deconfined up, down, and strange quarks, arise in several beyond-standard-model scenarios and may offer observational imprints through gravitational wave emissions or surface thermal spectra. Moreover, the inclusion of anisotropies, magnetic fields, and phase transitions in the modeling of such stars provides fertile ground for testing new theoretical ideas. Contributions exploring compact stars in the context of extended gravity theories, supersymmetric matter content, or quantum corrections are highly encouraged, especially in relation to their astrophysical detectability and stability.

Closely related are Wormholes, hypothetical tunnels connecting distant points in spacetime. While classically unstable in general relativity, wormholes can be stabilized in various extended theories of gravity or by exotic matter fields, such as phantom energy or non-minimal scalar couplings. They offer intriguing possibilities not only as theoretical constructs but also as potential probes of high-energy gravitational regimes. For this Special Issue, we invite articles exploring traversable wormholes, thin-shell constructions, stability analysis, and their compatibility with quantum field theory or energy conditions in extended theories. Additionally, potential astrophysical signatures of wormhole-like structures are of growing interest.

Together, these themes form a highly interconnected web of theoretical concepts and physical applications. The aim of this Special Issue is to foster a rich exchange between experts in high-energy theory, gravitation, and cosmology by presenting new results, synthesizing current aspects of understanding, and identifying future directions in this field.

We strongly encourage both theoretical and phenomenological contributions from researchers working at the forefront of these areas. Interdisciplinary approaches that draw connections between these domains, especially through the lens of supersymmetry and quantum gravity, are particularly welcome. Review articles that provide broad and pedagogical overviews of subtopics in these areas will also be considered for publication.

We look forward to receiving your submissions and hope that this Special Issue will represent a valuable resource for the community working on the theoretical foundations of gravity and fundamental physics.

Dr. Takol Tangphati
Dr. Daris Samart
Dr. Supakchai Ponglertsakul
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Symmetry is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

• modified theories of gravity
• black holes
• compact objects
• wormholes