Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Concept Videos

Nuclear Stability03:18

Nuclear Stability

23.4K
Protons and neutrons, collectively called nucleons, are packed together tightly in a nucleus. With a radius of about 10−15 meters, a nucleus is quite small compared to the radius of the entire atom, which is about 10−10 meters. Nuclei are extremely dense compared to bulk matter, averaging 1.8 × 1014 grams per cubic centimeter. If the earth’s density were equal to the average nuclear density, the earth’s radius would be only about 200 meters.
To hold positively charged protons together...
23.4K
RNA Stability01:53

RNA Stability

35.8K
Intact DNA strands can be found in fossils, while scientists sometimes struggle to keep RNA intact under laboratory conditions. The structural variations between RNA and DNA underlie the differences in their stability and longevity. Because DNA is double-stranded, it is inherently more stable. The single-stranded structure of RNA is less stable but also more flexible and can form weak internal bonds. Additionally, most RNAs in the cell are relatively short, while DNA can be up to 250 million...
35.8K
Velocity of an Object01:18

Velocity of an Object

213
Understanding how an object moves along a path requires distinguishing between motion over a time span and motion at a precise moment. A useful example is a vehicle traveling along a straight and level path, where its position at any given time is known. The initial step in analyzing this motion is to measure how far the vehicle travels over a fixed time period. This measurement, called average velocity, is computed by dividing the total change in position by the duration over which the change...
213
Stability01:28

Stability

426
The time response of a linear time-invariant (LTI) system can be divided into transient and steady-state responses. The transient response represents the system's initial reaction to a change in input and diminishes to zero over time. In contrast, the steady-state response is the behavior that persists after the transient effects have faded.
The stability of an LTI system is determined by the roots of its characteristic equation, known as poles. A system is stable if it produces a bounded...
426
Potential Due to a Polarized Object01:29

Potential Due to a Polarized Object

814
A neutral atom consists of a positively charged nucleus surrounded by a negatively charged electron cloud. When placed in an external electric field, the external electric force pulls the electrons and nucleus apart, opposite to the intrinsic attraction between the nucleus and the electrons. The opposing forces balance each other with a slight shift between the center of masses of the nucleus and the electron cloud, resulting in a polarized atom. On the other hand, a few molecules, like water,...
814
Potential Due to a Magnetized Object01:24

Potential Due to a Magnetized Object

829
Magnetic dipoles in magnetic materials are aligned when placed under an external magnetic field. For paramagnets and ferromagnets, dipole alignment occurs in the direction of the magnetic field. However, the dipoles align opposite to the field in the case of diamagnets. This state of magnetic polarization due to the external field is called magnetization. Magnetization is defined as the dipole moment per unit volume. It plays a similar role to polarization in electrostatics.
The vector...
829

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Primordial-Black-Hole-Based Pathways to Little Red Dots.

Physical review letters·2026
Same author

Black Hole Quasinormal Mode Resonances.

Physical review letters·2025
Same author

Two-Step Procedure to Detect Cosmological Gravitational Wave Backgrounds with Next-Generation Terrestrial Gravitational-Wave Detectors.

Physical review letters·2025
Same author

Unstable Chords and Destructive Resonant Excitation of Black Hole Quasinormal Modes.

Physical review letters·2025
Same author

Next-generation chemotherapy treatments based on black hole algorithms: From cancer remission to chronic disease management.

Computers in biology and medicine·2024
Same author

Universe-inspired algorithms for control engineering: A review.

Heliyon·2024

Related Experiment Video

Updated: Feb 16, 2026

Using Multiple Light Scattering to Examine the Stability of Phyllanthus emblica L. Extracts Obtained with Different Extraction Methods
06:12

Using Multiple Light Scattering to Examine the Stability of Phyllanthus emblica L. Extracts Obtained with Different Extraction Methods

Published on: April 14, 2023

1.0K

Light-Ring Stability for Ultracompact Objects.

Pedro V P Cunha1,2, Emanuele Berti2,3, Carlos A R Herdeiro1

  • 1Departamento de Física da Universidade de Aveiro and CIDMA, Campus de Santiago, 3810-183 Aveiro, Portugal.

Physical Review Letters
|January 6, 2018
PubMed
Summary

Gravitational collapse solutions with a light ring must have at least two, one stable. This implies ultracompact objects may cause spacetime instabilities, challenging their role as black hole alternatives.

More Related Videos

Author Spotlight: Advancing Knowledge in Far-From-Equilibrium Materials Through Light-Sheet Microscopy
08:32

Author Spotlight: Advancing Knowledge in Far-From-Equilibrium Materials Through Light-Sheet Microscopy

Published on: January 26, 2024

3.4K
Creating Objects and Object Categories for Studying Perception and Perceptual Learning
14:38

Creating Objects and Object Categories for Studying Perception and Perceptual Learning

Published on: November 2, 2012

12.3K

Related Experiment Videos

Last Updated: Feb 16, 2026

Using Multiple Light Scattering to Examine the Stability of Phyllanthus emblica L. Extracts Obtained with Different Extraction Methods
06:12

Using Multiple Light Scattering to Examine the Stability of Phyllanthus emblica L. Extracts Obtained with Different Extraction Methods

Published on: April 14, 2023

1.0K
Author Spotlight: Advancing Knowledge in Far-From-Equilibrium Materials Through Light-Sheet Microscopy
08:32

Author Spotlight: Advancing Knowledge in Far-From-Equilibrium Materials Through Light-Sheet Microscopy

Published on: January 26, 2024

3.4K
Creating Objects and Object Categories for Studying Perception and Perceptual Learning
14:38

Creating Objects and Object Categories for Studying Perception and Perceptual Learning

Published on: November 2, 2012

12.3K

Area of Science:

  • General Relativity
  • Theoretical Astrophysics
  • Mathematical Physics

Background:

  • Axisymmetric, stationary solutions to Einstein's field equations are crucial for understanding gravitational collapse.
  • Ultracompact objects with light rings are theoretical constructs that may mimic black holes.
  • The existence and stability of light rings are key to spacetime dynamics and potential instabilities.

Purpose of the Study:

  • To investigate the properties of light rings in smooth, ultracompact objects formed from gravitational collapse.
  • To determine the number and stability of light rings under the null energy condition.
  • To assess the viability of ultracompact objects as observational alternatives to black holes.

Main Methods:

  • A topological argument using the Brouwer degree of a continuous map to show light rings appear in pairs.
  • Analysis of an effective potential to characterize the nature of paired light rings.
  • Application of Einstein's field equations and the null energy condition to determine stability.

Main Results:

  • Axisymmetric, stationary, smooth, ultracompact solutions with a light ring must possess at least two light rings.
  • These light rings form a pair: one saddle point and one local extremum of an effective potential.
  • Under the null energy condition, the extremum corresponds to a stable light ring.

Conclusions:

  • The existence of a stable light ring in ultracompact objects implies potential nonlinear spacetime instabilities.
  • These instabilities may render ultracompact objects dynamically unreasonable as black hole alternatives.
  • The pairing of light rings is a general feature applicable to various metric gravity theories.