Saturday 11 April 2009

Introduction to Particle Physics Particle Physics is a branch of physics that studies the fundamental constitutes of matter and energy. The fundamental constitutes of our universe (as far as we know) are 12 particles that can't be broken down any further. These particles and the four fundamental forces, come together to create what we call "The Standard Model." Before we look at the Standard Model however, I should explain in greater depth what the fundamental particles are. They consist of 6 so-called leptons and 6 so-called quarks. But to explain these, I must explain how the atom is structured. An atom consists of a nucleus which in it has electrically charged protons and neutral neutrons. Both these sub-atomic particles are made of up and down quarks.Then there are electrons that orbit the nucleus. These leptons are tiny compared with quarks. Then there are the four fundamental forces. These are Gravity (one you probably already know about), Electromagnetism (which affects the electrically charged subatomic particles), Strong Force (which acts like an elastic band upon the protons and the neutrons), and Weak Force (which is responsible for radioactivity.) The Standard Model shows the fundamental particles and which forces affect them (Look Right) As you can see, the Weak Force affects all the particles, the Strong Force affects all the quarks and Electromagnetism affects half of the Leptons (including the Electron) and all the quarks. It is because of the strong force affecting the quarks that we have a nucleus in our atoms. So this concludes my introduction to Particle Physics. Soon, I will be following this up with a "Particle Physics continued" post.

Friday 10 April 2009

A Brief Bio of Niels Bohr By Cameron Webb He was born the son of a University professor, won the Nobel Prize in Physics, worked with Einstein and had a son who would also go on to win the Nobel Prize - his name was Niels Bohr. In 1885, Niels Bohr was born to a professor named Christian Bohr in Copenhagen. It was his father that would go on to nourish his interest in Physics. From an early age, Bohr loved Physics. In 1909, he gained a masters degree in Physics and two years latter he earned his Ph.D. Ten years later, after becoming a professor at the Copenhagen, he was allowed to set up the Institute of Theoretical Physics with the assistance of the Danish Government. It was this and his research in "...the investigation of the structure of atoms and of the radiation emanating from them," that earned him his Nobel prize in 1922. During his time at the Uni of Copenhagen, he became best friends with Albert Einstein. They both wanted to solve the mystery of the Universe and were constantly giving each other "problems" to solve. These became known as the "Bohr-Einstein Debates." It was these debates that led to Bohr publishing the "Copenhagen Interpretation of Quantum Mechanics," that explained things like wave functions (see my article on Parallel Universes.) Even in the Manhattan Project (the project that developed the first atomic bomb) Einstein and Bohr were working together. Einstein had been sent in to exile at the start of Hitler's reign. He then moved to America and told the Americans that Germany were developing an atomic bomb. It was his warning that allowed Winston Churchill to make an informed decision during the operation that prevented the Nazi's from finishing their atomic bomb and that pointed out how essential it was to develop the bomb first. During the project both Einstein and Bohr were directly involved in the production. As well as these incredible contributions, he also was the father of another Nobel Prize winner - Aage Niels Bohr. If this wasn't enough, he spent the final years of his life towards research in molecular biology.

The Periodic Table By Cameron Webb The Periodic Table is simply a way of displaying chemical elements. One of the special things about the periodic table is how it is arraged, elements are listed in order of the increasing atomic number, like the number of protons in the atoms nucleus. Also rows of elements are arranged so that the elements with similar properties fall into the same columns (groups or families). For example group 1 is Alkali metals, Group 2 are the Alkali Earth Metals, Group 7 are the Halogins, Group 8 are the Nobal Gases and the big group in the middle are the Transition Metals. In 1869, a Russian chemist named Dmitri Mendeleev came up with a way of organizing the elements-this was obviously the "Periodic Table" He set them out in order of the weight of the atom, and then grouped them into rows and columns based on their chemical and physical properties. One of the things which made it even more incredible is that he was able to place these elements in the periodic table with out the aid of any modern equipment, but what I find quite amusing is that he played a sort of game to place these elements. What he did was he wrote the elements on a piece of card and played a sorting game with them ( thier size, how much electrons it had, stuff like that.) This then led to the shape of the periodic table.

Wednesday 8 April 2009

A Brief Bio of Sir Isaac Newton By Saul McNally-Summers You may have only heard of Isaac Newton when your science teacher was talking about gravity. Although this is an achievement on its own, Sir Isaac Newton contribution to Science was far greater. He was born in 1643 in Lincolnshire. Then, after his schooling years, he was encouraged to become a farmer-however, he hated it. Afterwards however, Trinity College saw his potential and accepted him so that he could study philosophers such as Galileo. Even at university, he began to develop a mathematical theory. Throughout his career, Sir Isaac Newton developed calculus, explained the visible spectrum, explained gravity but, probably his biggest contribution to science was his three laws of motion. His three laws of motion were published in his book Philosophiae Naturalis Principia Mathematica. These laws stated that(in simple English:) 1. (The Law of Inertia) An object at rest or an object moving at a constant speed will stay on its current course unless affected by an external force. 2. This law basically explains how mass and acceleration are directly linked. He basically said that if the mass of an object increases its acceleration decrease and vice versa. 3. His third law is his most famous. It states that if a force goes one way, an equally powerful force must go the other - hence recoil on a gun. I hope now you understand just what an influential man Sir Isaac Newton was in the history of mankind.

Tuesday 7 April 2009

The Doppler Effect, Red Shift, Blue Shift and Frequency For all most a century people have been witnessing something very strange. Ever since the Industrial revolution transport started, i.e. trains, and as soon as an object become fast enough it produced a noise, they noticed that the further away the object is the quieter the sound is, but the closer the noise the louder the sound but as soon as it moves away from us it suddenly becomes quiet again. This interested an Austrian physicist called Christen Doppler who proposed this in 1842 and named it after him, "The Doppler Effect" What he said confirmed that the sound's pitch was higher than the emitted frequency when the sound source approached him, and lower than the emitted frequency when the sound source was further away from him. (Notice on the diagram how the wavelength (period) is shorter than the low frequency wavelength this shows that the high frequency graph has a higher pitch than the low frequency graph) this graph can show you what it would look like if a car drove past you, the high frequency graph would be when the car is closer to you when the low frequency graph would be when the car is further away from you. This also can lead us to new topic which is Red Shift, Blue Shift and Frequency but both are very similar. I have mentioned some bits about frequency but there are very important bits that I have missed out which might make the Doppler Effect make more sense. Frequency has a spectrum but with most things there is a problem and in this topic there is no exceptions, the problem is light and sound. Lets take a car as an example, the car emits light and sound these are represented by circles. This shows that the car is stationary, but look at the circles when the car is moving to the right, but when an object is moving to the right there is less space between the lines than the left. This causes a frequency change, as the lines on the right are closer together causing a higher frequency when the lines on the left are further apart causing a lower frequency. If we look at the frequency spectrum on the right the colour is mainly red, we call this Red Shift, and if we look at the frequency spectrum on the right the colours are mainly blue, we call this Blue Shift. So as you can see it all adds together in just one article. Hope this has helped. By Cameron Webb

The Theory behind Parallel Universes By Saul McNally Summers Parallel Universes You have probably only heard the term “parallel universe,” in Sci-Fi films such as Doctor Who and Star Trek. But what exactly is a “parallel universe” and who thought of the concept in the first place. For centuries physicists had been working out the laws of the world (e.g. Newton’s three laws of Motion.) But in 1900, a physicist named Max Planck, found during his study of radiation some things that disagreed with these laws. This suggested to him that there were maybe other forces in the universe that operated on a lower level than the ones he already knew about. Then, other scientists began to find that single particles could “shape-shift.” After years of study, Niels Bohr put forward the Copenhagen Interpretation of Quantum Mechanics. This stated that all things could take the form of all possible states of matter at once. The amount of possible states a quantum object could be in is called its wave function. The apparent state of an object IN all its possible states, we say is called its superposition. Bohr also stated that when we look at a quantum object, we affect its behaviour. Therefore, when we look at an object (e.g. a photon) we make it CHOOSE what state of matter from its wave function it wants to be from its wave function! This explains why different physicists have taken different readings from the same Quantum Object as it chose what state to be. However, another physicist disagreed with Bohr’s statement that the object chooses its state. Instead, he believed that when an object is looked upon, the world divides – in one, it chooses a state and in the other, it chooses another to accommodate both possible outcomes. This is what is known as the “Many Worlds Theory.” One modern day example of this happening is when you are born. In one universe you are born as an attractive, clever, polite girl but in another (to accommodate both possible outcomes) you are a rebellious, unattractive female. As a last example, let’s look at Zimbabwe and America. In a parallel universe, Zimbabwe is a rich, democratized country whereas America is corrupt and poor. It’s hard to believe but if parallel universes really did exist, that is what the world would be like. Related topics: - Quantum Mechanics - Many Worlds Theory - Wavefunction

Bouancy What is Bouyancy? In physics the term "Bouyancy" means upwards force that keeps things afloat. Who thought up of Bouyancy? People have been aware of objects floating on water (or sinking) since before recorded history. But it was not until Archimedes of Syracuse that the theory of flotation and the buoyancy principle was discovered. How does it work? The force (for example gravity) that is applied on the object is equal to the weight of the fluid. The two main parts that buoyancy depends on are the object's volume (boat), and the weight of the neighbouring fluid (water). But if the object heavier than the fluid it would sink for example a rock dropped into a pond, the rock mass is larger than the mass of the water, also the rocks area has to match the area of water and the area of the rock is heavier than the area of the water. By Cameron Webb