Theoretical Foundation for Black Holes and the Supermassive compact object at the Galactic Centre - by The Nobel Committee for Physics - Article review

This document contains a review of the article: "Theoretical Foundation for Black Holes and the Supermassive compact object at the Galactic Centre - by The Nobel Committee for Physics" by The Nobel Committee for Physics
To order to read the article select:https://www.nobelprize.org/uploads/2020/10/advanced-physicsprize2020.pdf

Contents

Reflection

1. Introduction

2. The early history

Page 2

3. The Schwarzschild metric

4. The period 1939-1964

5. The first observational hints for supermassive black holes

Page 3

However, it soon became clear that any such giant star would be extremely unstable and short-lived, and therefore could not explain the quasar observations.
In principle this is a physical issue which describes the evolution of a star, 'slowly' swallowing individual stars over a long period of time. During this process the density can slowly increase (step wise), avoiding any singularity issue

6. The singularity theorem

See the document: https://arxiv.org/pdf/1410.5226.pdf
What is a sigularity? Read par 4.1 of this document.
Schmidt’s discovery prompted Wheeler to reconsider the physics of gravitational collapse and he discussed this with Penrose, who began to think about the problem in late 1964
Wheeler should reconsider the physical behaviour of the evolution leading to extremely massif objects, including an intern collapse.
Oppenheimer and Snyder had described the spherically symmetric case where an astronomical body contracts to within its Schwarzschild radius, forming a singularity of infinite density.
this should be: creating an object with a very large density. See also above
However, it was far from clear that this could happen in the real world and whether the assumption of spherical symmetry was a prerequisite for gravitational collapse.
The only way to demonstrate that objects with very large density exist, is by means of the work performed by Ghez and Genzel. There work does not demonstrate that these objects have to be symmetric.
Penrose set out to analyse the situation without the assumption of spherical symmetry, assuming only that the collapsing matter had a positive energy density.
The concept of positive energy density is a whole different ball game. This resembles the "dark energy" concept, which introduces the same conflicts.

7. Supermassive black holes become the leading model to explain quasars

8. Early tests of the hypothesis of supermassive black holes in galactic nuclei

9. The centre of the Milky Way as a laboratory for fundamental physics

10. Focused observational programs led by Ghez and Genzel

11. Detection of stellar motions in the Galactic centre

12. The era of adaptive optics: tracing individual star orbits

13. The discovery of a compact object in the Galactic centre

14. Recent updates on Galactic centre results

The best fit of the orbit including special and general relativistic effects is shown as a solid line in the plots.
More detailed information is required to understand what the SR and GR effects are.
Furthermore, the team was able to detect the relativistic precession of the orbit—a truly remarkable experimental achievement addressing fundamental physics.
More information is required to understand this.

15. Detection of motion of heated matter near the innermost stable orbit

These observations provide additional strong support for the hypothesis that the compact object at the Galactic centre is a supermassive black hole, as predicted by the theory of general relativity.
The question to answer is: What is the difference between a compact object versus a supermassive black hole.

16.

Reflection 1 - General interpretations or questions.

The theoretical work by Roger Penrose and the observations made by the teams led by Reinhard Genzel and Andrea Ghez are of unprecedented importance.
The comments in this document are mainly based on the interpretations of the these results with the purpose to put down my own thoughts in writing and to remember for future reference.

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Created: 11 Oktober 2020

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