Hobbies
The Möbius Function
The Möbius function is denoted by , where is the Greek letter mu. Depending on the factorisation of , the function takes the values . The last says that if is even, then and if [more…]
Science
Engineering
Making A Ruby Laser – Part Five
Melting a hole through steel: The above image needs a little explanation! The Doc messed up his camera settings and under exposed the image. So I loaded it into Gimp and played with the curves [more…]
Engineering
Making A Ruby Laser – Part Four
The Doc’s ruby laser focused onto a lighter flint. The flint has been glued to the end of a match stick. The ‘explosion’ measures approximately 4 inches diameter. Interesting things to note are the ‘candy [more…]
Engineering
Making A Ruby Laser – Part Three
More information on laser speckle can be found here: Speckle pattern A Mirror Alignment Tool The most important part of constructing a ruby laser (or any laser with external mirrors) are getting the mirrors alligned [more…]
Hobbies
The Fields Medal
“Rise above oneself and grasp the world” These are awarded every four years for advancement in the field of mathematics. There is an age limit of 40 on the recipients. It is a recognition of [more…]
Hobbies
Euler’s Totient Function
Euler’s totient function counts the number of positive integers up to that are relatively prime to , where is considered to be relatively prime to all . These numbers are called the totatives of . [more…]
Engineering
Making A Ruby Laser – Part Two
(a ruby rod lit by two bright blue LEDs. Due to the IR filter in my camera the pink colour is actually red. What you are seeing is the absorption of the blue light and the [more…]
Engineering
Making A Ruby Laser – Part One
Introduction For many years the Doc has had the desire to attempt the construction of a ruby laser. After six months of hard work, disappointment, late nights, lots of booze and a drained bank account [more…]
Arts
Shunting Review
Some of you who have stumbled upon this wonderful site in recent weeks and months may be wondering what various references to shunting and occasional photos of a railway scene are all about. You may [more…]