Black Holes From Sagittarius A* to Wormholes: Singularity, Gravitational Waves and the Quantum Mystery

Black Holes From Sagittarius A* to Wormholes

This video from New Scientist exploration of black holes covers what they are, how we detect them, and the big mysteries they pose from the center of the Milky Way to cosmic-scale phenomena.

Overview

The video provides a guided tour of black holes, explaining what they are, how we recognize them, and why they challenge our current physics. It outlines the three defining quantities of a black hole and then dives into the main categories of black holes, from stellar mass to supermassive objects at galactic centers, and even the speculative forms that could resolve fundamental puzzles.

Defining Black Holes

Black holes are described by mass, rotation, and electric charge. The event horizon marks the boundary where light cannot escape, and behind it lies the singularity in many theories. The concept dates to Schwarzschild and has since been supported by observations that include stellar orbits around Sgr A* and the first direct detections of gravitational waves by LIGO. The first image of a black hole, captured by the Event Horizon Telescope, confirmed a long standing prediction and opened new avenues for testing gravity in extreme regimes.

Types and Growth

Stellar mass black holes form from dying stars and are common across galaxies. Supermassive black holes, millions to billions of solar masses, reside in galaxy centers and may grow through accretion and mergers. Intermediate mass black holes, 1 to 300 solar masses, are the missing link and are hypothesized to form in dense star clusters or via repeated mergers. Primordial black holes could have formed in the early universe with a wide range of masses and are candidates for dark matter components. The video connects these categories to questions about galaxy formation and cosmic evolution.

Frontier Concepts

To address the paradoxes at a black hole’s core, theorists have proposed regular black holes that avoid singularities and preserve information. Fuzz balls from string theory propose a quantum structure that mimics a black hole at a distance but differs at the horizon. Gravastars rely on a bubble of vacuum energy to stave off collapse, while knee stars imagine a nested arrangement of gravistars. Wormholes offer a speculative doorway to other universes or white holes, though maintaining stability requires exotic matter. NASA and research communities remain cautious about these ideas while recognizing their value for guiding theory and observation.

Future Prospects

Advances like space based detectors and upgrades to the Event Horizon Telescope could illuminate photon rings and spacetime structure with unprecedented detail. The potential space based Black Hole Explorer mission, planned for the 2030s, points toward sharper tests of general relativity and the quantum nature of gravity. The video ends by highlighting the enduring mysteries and the possibility of breakthroughs that could redefine our understanding of the cosmos.