# Special Issue "Symmetry in Gravity Research"

A special issue of *Symmetry* (ISSN 2073-8994). This special issue belongs to the section "Physics".

Deadline for manuscript submissions: **closed (31 July 2023)** | Viewed by 13764

## Special Issue Editors

2. Center of Application and Research of Computational Physics, Shanghai University of Engineering Science, Shanghai 201620, China

3. Guangxi Key Laboratory for Relativistic Astrophysics, Guangxi University, Nanning 530004, China

**Interests:**statistical physics; observational data statistics and numerical simulation of celestial motions

2. School of Astronomy and Space Science, University of Chinese Academy of Sciences, Beijing 100049, China

**Interests:**gravitational wave astronomy

Special Issues, Collections and Topics in MDPI journals

## Special Issue Information

Dear Colleagues,

Due to objects with extremely large masses existing in our universe, gravity has not only become the dominant factor in the motion of celestial bodies but also the decisive factor in the structure and evolution of celestial bodies. Newton not only explained the law of planetary motion by using the law of gravitation but also successfully predicted and discovered Neptune. In 1905, Einstein put forward the special theory of relativity, which broke through the concept of absolute time and absolute space. General relativity is a theory that describes the gravitational interaction between matter. Its foundation was completed by Albert Einstein in 1915 and officially published in 1916. This theory represents the first time that the gravitational field was regarded as equivalent to the curvature of space–time. In 1916, Einstein predicted the existence of gravitational waves based on general relativity. The existence of gravitational waves is the result of Lorentz invariance of general relativity, because it introduces the concept of finite propagation velocity of interaction. Fortunately, gravitational waves have been detected. Recently, researchers have paid much attention to the calculation of black hole shadows. In addition, some observational results have forced scientists to generalize or modify the standard general relativity. Because of this, theories of gravity have received great attention. Therefore, gravitational theories and their applications are very important in astronomy and astrophysics.

Symmetry is a core concept in modern physics. It generally refers to gauge symmetry, local symmetry and global symmetry. It refers to the invariance of a theoretical Lagrangian or equation of motion under the change in some variables. If these variables change with time and space, this invariance is called local symmetry; otherwise, it is called global symmetry. The so-called symmetry refers to the invariance after a certain operation. In general, each symmetry corresponds to a conserved quantity: for example, space translation invariance corresponds to momentum conservation; time shift invariance corresponds to energy conservation; space rotation invariance corresponds to the conservation of angular momentum. Based on symmetry, the gravitational theories will become very simple. That is, symmetry is very important to gravitational physics because it corresponds to some physical properties such as conservation laws.

The aim of this Special Issue is to collect original and significant contributions dealing with symmetry in gravity research. This Special Issue may also serve as a platform for the exchange of ideas between scientists of different disciplines interested in gravity. It is devoted to discussing physical properties of various symmetric or nonsymmetric gravitational problems involving Newtonian gravity, general relativity and modified gravity theories. It includes, but is not limited to, the following fields: (1) symmetric black hole solutions; (2) symmetry and integrability of gravitational systems; (3) symmetric geometric integration algorithms of gravitational systems; (4) circular orbits, periodic orbits and chaotic orbits of photons or particles in symmetric gravitational systems; (5) gravitational waves in symmetric gravity systems; (6) black hole shadows in symmetric spacetimes; (7) planetary dynamics in symmetric gravity systems.

Prof. Dr. Xin Wu

Prof. Dr. Wenbiao Han*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.

## Keywords

- Newtonian theory of gravity
- general relativity
- modified theories of gravity
- black holes
- gravitational waves
- black hole shadows
- chaos
- geometric integration algorithms
- integrability
- periodic orbits
- planetary systems