Category: Physics
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Swampland conjectures (Part 1)
This is the first post in a series of posts about the Swampland conjectures. In each post, I will discuss one Swampland conjecture. The basics of General Relativity and QFT are assumed for the readers of this series. In this first post, we will discuss a conjecture called the “No global symmetries conjecture”. The statement…
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All three laws of motion matter
In this post, I will try to explain why all three laws of motion are independent and why the first and third laws of motion aren’t special cases of the second law. Newton’s first law of motion says that “An object continues its state of motion until an external force is applied on it”. However,…
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What are conformal field theories? (Part 1)
In this series of posts, I will explain what conformal field theories (CFTs) are. Basic familiarity with Quantum Field Theories (QFTs) is assumed. In usual relativistic QFTs have some spacetime symmetries. These symmetries are rotations (one about every space direction), boosts (one along every space direction) and translations (one along every spacetime direction). The set…
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My 10 years in Physics
Today (20th October 2024) completes my 10 years as a university student (studying Physics). I took my first class as a Physics undergraduate on 20th October 2014 at the University of the Punjab, and in these 10 years, so much happened. There have been a lot of ups and downs that I have gone through…
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What are RG flows?
In this post, I will explain what Renormalization Group (RG) flow is. I will assume the knowledge of the basics of QFT for this post. The idea of an RG flow is intimately related to the idea of effective field theories (EFTs). An EFT is a theory that makes predictions upto some energy scale (called…
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How to derive the Schwarzchild metric?
In this post, we will go through the reasoning that gives us the Schwarzchild solution of Einstein field equations. Prerequisites for this post include familiarity with Einstein field equations. We start with the Einstein field equation (EFE) and convert it to a form that is used to solve this equation. This form is called the…
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How to deduce Schrodinger equation?
In this post, I will give arguments to motivate why Schrodinger equation has the form that it has. An understanding of classical mechanics, eigenvalues and eigenfunctions is required for following this post. In conventional formulation of quantum mechanics, there are some postulates. Among them, three postulates are as follows. The “operators” mentioned above operate on…
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How to derive Einstein’s field equation?
This post summarizes the reasoning that goes in deriving Einstein’s field equation. There are more than one ways to derive this field equation but I will focus on the most conventional path to derive it. Basic understanding of tensor analysis and special realtivity is assumed to understand this post. What we need is an equation…
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Barbour-Bertotti best matching
This post is first in a series about some of my recent work. It tries to implement a procedure called Barbour-Bertotti best matching principle (explained below) using an approach called Entropic Dynamics (explained in a future post). Suppose you see three stars in the sky and take a picture of them at a given time.…
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Getting realistic vaccua from string theory (A summary)
This is a small post on how to try to get realistic four-dimensional spacetimes from type IIA and type IIB string theories. I will try to explain the technical points as much as I can. I will assume the knowledge of metric, Ricci, and Riemann tensors and very basic QFT. Let me know if some…
Hassaan Saleem 