Relativity Theory

By Simone Malacrida

The following basic physics topics are presented in this book:
Galilean relativity
crisis of classical physics
theory of special relativity
theory of general relativity
relativistic astrophysics and cosmology
attempts at unification and open questions

• Language: English
• Publisher: Simone Malacrida
• Release date: Dec 23, 2022
• ISBN: 9798215668665

Simone Malacrida

Simone Malacrida (1977) Ha lavorato nel settore della ricerca (ottica e nanotecnologie) e, in seguito, in quello industriale-impiantistico, in particolare nel Power, nell'Oil&Gas e nelle infrastrutture. E' interessato a problematiche finanziarie ed energetiche. Ha pubblicato un primo ciclo di 21 libri principali (10 divulgativi e didattici e 11 romanzi) + 91 manuali didattici derivati. Un secondo ciclo, sempre di 21 libri, è in corso di elaborazione e sviluppo.

Book preview

The following basic physics topics are presented in this book:

Galilean relativity

crisis of classical physics

theory of special relativity

theory of general relativity

relativistic astrophysics and cosmology

attempts at unification and open questions

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Simone Malacrida (1977)

Engineer and writer, has worked on research, finance, energy policy and industrial plants.

ANALYTICAL INDEX

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INTRODUCTION

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I - GALILEIAN RELATIVITY

The concept of relativity according to Galileo

Newton's vision

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II -PROBLEMS OF CLASSICAL PHYSICS

Introduction

astronomical observations

The invariant transformations of electromagnetism

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III -SPECIAL RELATIVITY

Einstein's solution

Revisitation of classical mechanics

Space-time

Aftermath

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IV - GENERAL RELATIVITY

Introduction

Tensor mathematics

General Theory of Relativity

Experimental confirmations

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V - ASTROPHYSICS AND RELATIVIST COSMOLOGY

Solutions of Einstein's equations

Singularities and black holes

Relativistic cosmology

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VI - ATTEMPTS AT UNIFICATION AND OPEN QUESTIONS

Introduction

Attempts at unification

From GUT to The Theory of Everything

INTRODUCTION

In this book the entire theory of relativity is presented, as it has been presented throughout the history of science.

First, space is given to the theory of relativity according to Galileo and according to classical physics.

After having exposed the problems of classical mechanics, a detailed overview of the special theory of relativity is given.

Tensor mathematics introduces the understanding of the theory of general relativity, the consequences of which are highlighted both at an astrophysical and cosmological level.

Finally, attempts at unification between quantum field theory and general relativity are proposed, with the problems still open.

What is set out in this manual is only partially addressed at university level, unless one chooses a course of study strictly related to astrophysics and cosmology.

Knowledge of advanced mathematical analysis is required to understand the manual, at least from the theory of general relativity onwards.

I

GALILEIAN RELATIVITY

The concept of relativity according to Galileo

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Galileo was the first to scientifically ask himself the question of the validity of physical laws, especially of mechanics, and of the role of different observers in different reference systems.

Galileo started from the hypothesis that the laws of mechanics are always the same for inertial reference systems, ie reference systems that satisfy the principle of inertia.

Simply put, such frames of reference are not accelerated.

These reference systems can be expressed through the formalism of the Cartesian axes in three dimensions (with Cartesian coordinates) and by adopting the rules of Euclidean geometry.

The observer present in the reference system is integral with the reference system, therefore it does not have its own motion, but only that of the system.

The first point that Galileo highlighted is that of the simultaneity of the experiment.

Two observers placed in different inertial frames of reference must perform the same experiment at the same instant in order to have an identical result.

Therefore they will have to exchange information to synchronize this experiment.

Galileo tried to measure the speed of light and deduced that it was so high compared to daily practice, as to make the time necessary for the exchange of information irrelevant.

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The first conclusion of Galilean relativity was that time remained the same in the passage from one inertial system to another.

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Since the two reference systems have different speeds, Galileo posed the problem of how to carry out a transformation of the speeds, passing from one system to another.

By applying Euclidean geometry together with Cartesian coordinates, he vectorically composed the velocities according to the well-known law of the parallelogram.

This law, already known by Leonardo, now found an explanation in the Galilean theory of relativity.

Ultimately, given two inertial systems, the passage of space-time coordinates from one system to another according