## Special Relativity

## General Relativity

## Recent Articles

How Are Photons Affected By Gravity If They Have No Mass? The Physics Explained

We know that photons have no mass and we like to think that gravity only affects things that have a mass. However, photons still get deflected by the Sun and can even orbit around a black hole. How...

In my opinion, if there is one area of mathematics you should really get good at, it would be vector calculus. Learning vector calculus will build a strong basis for understanding any area of...

Einstein Field Equations: A Step-By-Step Derivation (Two Ways)

In this article, we'll derive the Einstein field equations with all calculations done in a step-by-step manner. The Einstein field equations can be derived from the Bianchi identity by postulating...

Why Do Moving Charges Create a Magnetic Field? The Physics Explained

When I first learned electromagnetism, I was taught that magnetic fields are always created by moving charges, but it was never quite clear to me why moving charged particles specifically create a...

Constraints In Lagrangian Mechanics: A Complete Guide With Examples

In Lagrangian mechanics, while constraints are often not necessary, they may sometimes be useful. However, what do we actually mean by constraints in Lagrangian mechanics? In Lagrangian mechanics,...

Generalized Coordinates: Everything You Need To Know (with examples)

Generalized coordinates are one of the key reasons why other formulations of classical mechanics, such as Lagrangian mechanics, are so useful. However, it's often not exactly clear what generalized...