Archives for Cosmology
Perfect Gas with Dipole Moments – what can it model?
Can a Perfect Gas of Dipolar Molecules Model Stars or Planets? Short answer: No — a “perfect gas with N molecules each having a dipole moment p” is not…
Universal Expansion Clock: Why the Big Bang Was Infinitely Long Ago
Milne’s Expansion Clock: Why the Big Bang Is “Infinitely Long Ago” This explains how, in Milne’s kinematic relativity, using the rate of expansion (or its integral) as the universal clock…
How the Arrow of Time Emerges from the Big Bang
How the Arrow of Time Emerges from the Big Bang Why do we experience time flowing in one direction — from past to future — when the laws of physics…
Why Entropy Increases After the Big Bang
Why Entropy Increases After the Big Bang The universe began in a very special, low-entropy state — a smooth, nearly homogeneous high-energy configuration. But why does entropy increase from there?…
The Big Bang — Pencil on its Tip
The Big Bang — Pencil on its Tip Was the Big Bang more like a pendulum or like a pencil balanced on its tip? Many physicists believe that the early…
Understanding Rindler Space
Understanding Rindler Space 1. What is Rindler Space? Rindler space describes the spacetime experienced by an observer undergoing constant acceleration in special relativity. It is useful for understanding: Uniformly accelerated…
Understanding the Event Horizon
Understanding the Event Horizon 1. The Event Horizon as a Global Concept The event horizon is not a physical surface but a mathematical boundary beyond which nothing can escape. Its…
Neutron Stars and Pulsars – Mathematical Differences
Mathematical Difference: Neutron Star vs Pulsar Neutron Star A neutron star is a highly dense remnant of a massive star after a supernova explosion. It is characterized by: Mass: \(…
Non Stationary Spacetime Metric and redshift
Redshift from a Non-Stationary Metric 1. Understanding Redshift from a Non-Stationary Metric The redshift arises because the wavelength of light is stretched as it propagates through a dynamically changing…
Hawking Radiation, How black holes evaporate
Stephen Hawking's seminal paper on black hole radiation, often referred to as **Hawking Radiation**, explains how black holes, previously thought to only absorb matter and energy, can actually emit radiation…