Black Holes: Signal Escape Probability

In courses (2)

Description

This lecture delves into the scenario of a spacecraft near a black hole with a malfunctioning system that sends signals in random directions, exploring the probability of these signals escaping the black hole. The exercise involves analyzing light signals' trajectories, finding conditions for signal escape, and calculating the probability of signal escape. Additionally, the lecture covers properties of eternal circular orbits near black holes, equations of motion in the Schwarzschild metric, and the impact of space-time dimensions on gravity, particularly in two plus one dimensions. A final exercise addresses signal transmission to a constantly accelerated observer, requiring the application of previously learned formulas.

Official source

https://mediaspace.epfl.ch/media/0_pz2hnu5r

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Related concepts (17)

Gravity

In physics, gravity () is a fundamental interaction which causes mutual attraction between all things that have mass. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the strong interaction, 1036 times weaker than the electromagnetic force and 1029 times weaker than the weak interaction. As a result, it has no significant influence at the level of subatomic particles.

Black hole

A black hole is a region of spacetime where gravity is so strong that nothing, including light or other electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. The boundary of no escape is called the event horizon. Although it has a great effect on the fate and circumstances of an object crossing it, it has no locally detectable features according to general relativity.

Quantum gravity

Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics. It deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the vicinity of black holes or similar compact astrophysical objects, such as neutron stars as well as in the early stages of the universe moments after the Big Bang Three of the four fundamental forces of nature are described within the framework of quantum mechanics and quantum field theory: the electromagnetic interaction, the strong force, and the weak force; this leaves gravity as the only interaction that has not been fully accommodated.

Supermassive black hole

A supermassive black hole (SMBH or sometimes SBH) is the largest type of black hole, with its mass being on the order of hundreds of thousands, or millions to billions of times the mass of the Sun (). Black holes are a class of astronomical objects that have undergone gravitational collapse, leaving behind spheroidal regions of space from which nothing can escape, not even light. Observational evidence indicates that almost every large galaxy has a supermassive black hole at its center.

Micro black hole

Micro black holes, also called mini black holes or quantum mechanical black holes, are hypothetical tiny (