## LOG#040. Relativity: Examples(IV).

Example 1. Compton effect. Let us define as  “a” a photon of frequency . Then, it hits an electron “b” at rest, changing its frequency into , we denote “c” this new photon, and the electron then moves after the … Continue reading

## LOG#039. Relativity: Examples(III).

Example 1. Absorption of a photon by an atom. In this process, we have from momenergy conservation: If the atom is the rest frame, before absorption we get Description: an atom “a” at rest with mass absorbs a photon “b” … Continue reading

## LOG#038. Relativity: Examples(II).

Example 1. Completely inelastic collision of 2 particles . We will calculate the mass and velocity after the collision, when a cluster is formed. From the consevation of momentum in the collision, we get Then, Squaring both sides: In the … Continue reading

## LOG#037. Relativity: Examples(I)

Problem 1. In the S-frame, 2 events are happening simultaneously at 3 lyrs of distance. In the S’-frame those events happen at 3.5 lyrs. Answer to the following questions: i) What is the relative speed between frames? ii) What is … Continue reading

## LOG#035. Doppler effect and SR.

The Doppler effect is a very important phenomenon both in classical wave motion and relativistic physics. For instance, nowadays it is used to the detect exoplanets and it has lots of applications in Astrophysics and Cosmology. Firstly, we remember the … Continue reading

## LOG#034. Stellar aberration.

In this entry, we are going to study a relativistic effect known as “stellar aberration”. From the known Lorentz transformations of velocities (inverse case), we get:             The classical result (galilean addition of velocities) is … Continue reading

## LOG#033. Electromagnetism in SR.

The Maxwell’s equations and the electromagnetism phenomena are one of the highest achievements and discoveries of the human kind. Thanks to it, we had radio waves, microwaves, electricity, the telephone, the telegraph, TV, electronics, computers, cell-phones, and internet. Electromagnetic waves … Continue reading

## LOG#032. Invariance and relativity.

Invariance, symmetry and invariant quantities are in the essence, heart and core of Physmatics. Let me begin this post with classical physics. Newton’s fundamental law reads:     Suppose two different frames obtained by a pure translation in space:   … Continue reading

## LOG#029. Interstellar trips in SR.

My final article dedicated to the memory of Neil Armstrong. The idea is to study quantitatively the relativistic rocket motion with numbers, after all we have deduced the important formulae, and we will explain what is happening in the two … Continue reading

## LOG#028. Rockets and relativity.

The second post in this special thread of 3 devoted to Neil Armstrong memory has to do with rocketry. Firstly, for completion, we are going to study the motion of a rocket in “vacuum” according to classical physics. Then, we … Continue reading