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General relativity, also known as the general theory of relativity and Einstein's theory of gravity, is the geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics.
- Why Is General Relativity Important?
- General Relativity in A Nutshell: A Quick Overview
- The Underlying Postulates of General Relativity
- The Mathematics of General Relativity Explained Intuitively
- Metric Tensor: The “Fundamental tensor” of General Relativity
- Christoffel Symbols & Their Geometric Meaning
- Curvature Tensors & How They Relate to Gravity in General Relativity
- The Energy-Momentum Tensor
- Geodesics & How Objects Move in Curved Spacetime
- Tidal Forces in General Relativity
Before we get started on what general relativity actually is, there is an important aspect to be discussed: why should you even care about this topic? Sure, you’ve clicked on this article, so you’re probably interested to learn more, but still; what makes general relativity an important theory? Here is a list of a few of the most important applicat...
Here, I will present a quick overview of the whole theory of general relativity, which will lay down the most important ideas and help you see the big picture. After that, we will look into each of these things in much more detail. Now, you may have heard the phrase “gravity is the curvature of spacetime” at some point. This phrasing can, however, ...
Every theory is always based on a few underlying principles or postulates, which pretty much lead to the specifics and the results of the theory. General relativity is no different. Really there are two main postulates that general relativity is based on, which are the following: 1. The principle of general covariance: this is mainly a mathematical...
In this section, we’ll go over the important mathematical tools used in general relativity, such as themetric tensor and the Christoffel symbols. We’ll also explore the physical and geometric interpretationsof these. It’s important, however, to realize that the focus of this article is not necessarily in the math, but rather what the math actually ...
Arguably the most important tensor in general relativity is the metric tensor, which I did mention earlier already. But what is the metric tensor actually and what is it used for? In short, the metric tensor is used to define lengths and other geometric properties of spacetime in general relativity. The metric generalizes these properties to any cu...
The next important concept we’ll look at are the Christoffel symbols, which come up in the geodesic equation and in describing spacetime curvature (both which we will talk about in more detail later). Christoffel symbols are mathematical objects that describe how basis vectors change in a coordinate system. In general relativity, Christoffel symbol...
By now, it should be clear that gravity is described by spacetime curvature in general relativity. The point of this section is to explain how spacetime curvature is actually described mathematically, which is by using different curvature tensors. To give some insight into why the different curvature tensors have the form they have, it is important...
As you may know by now, gravity is described by spacetime curvature. But according to Newtonian physics, gravity is caused by mass, such as the mass of a planet. So far, we have not talked about what actually causes gravity or the curvature of spacetime in general relativity. The answer is a bit more complicated in general relativity than just mass...
We are now ready to actually get to the interesting physics concepts of general relativity. The key idea is the notion of geodesics, which are in their most simple sense, just trajectories through spacetime. Fundamentally, a geodesic is just a straight line. If you happen to be in a curved spacetime, however, straight lines will naturally follow th...
The effects of tidal forces can be seen as the rise of sea levels caused by the Moon’s gravity. However, tidal forces are always present when an object is in a gravitational field and these may cause the object to get deformed. Newtonian gravity explains this by the fact that different parts of an object experience a different gravitational force a...
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May 2, 2024 · General relativity, part of the wide-ranging physical theory of relativity formed by the German-born physicist Albert Einstein. It was conceived by Einstein in 1916. General relativity is concerned with gravity, one of the fundamental forces in the universe. Gravity defines macroscopic behaviour,
- The Editors of Encyclopaedia Britannica
Black holes and the expanding universe are two concepts that have their roots in general relativity. Even GPS satellites must account for general relativistic effects to deliver accurate position measurements to people on Earth.
May 14, 2023 · General relativity is physicist Albert Einstein's understanding of how gravity affects the fabric of space-time. The theory, which Einstein published in 1915, expanded the...
- Scott Dutfield
For 100 years, the general theory of relativity has been a pillar of modern physics. The basic idea is so elegant that you don’t need superpowers to understand it. Begin with Isaac Newton’s first law of motion: An object remains in uniform motion unless acted on by a force.
Summary. Geodesics Equation. According to general theory of relativity, gravitation is not a force but a property of spacetime geometry. A test particle and light move in response to the geometry of the spacetime. Actually, curved spacetimes of general relativity are explored by reviewing the nature of the motion of freely falling particles and ...
