The world is complicated; it’s made up of so many different materials. People collected, categorized and analyzed them to find a pattern that would simplify the complexity. They gathered more than 80 elements which were arranged in the famous table by Dimitri Mendeleev.
Each of the elements had a different behavior and was considered to be made of indivisible units called atoms.
In Cambridge, 1896, was the first experiment with Thomson’s apparatus, where particle could be accelerated, and the bending voltage could be measured. Thus the mass of the particle could be deduced. The hydrogen was the lightest particle known at that time. The first particle: the electron was discovered.
In Manchester, Rutheford used the decay of radioactive elements as a projectile of beam and fired them into a thing gold foil. They were alpha particles, and 1/8000 bounced back. That suggested a model of the atom structure similar to the solar system.
Through Quantum Mechanics, today, we know that we can’t know the exact locations of the electrons, but we can predict their respective shells around the nucleus which is composed of protons and neutrons.
In the early 20th century, cosmic rays were discovered and new particles appeared that couldn’t be explained by the fundamental three particles.
Since cosmic rays were hard to detect, scientists rushed to create cosmic rays in the laboratories and by 1960 over 80 new particles was found and named like gamma, delta, and lambda etc..
Murray Gell-Mann organized those particles based on approximate symmetries, and through that classification, properties of particles were predicted. He concluded that each of those 80 particles is formed by three other particles called quarks.
In 1968 the biggest scientific instrument of its time confirmed that the quark idea was correct. They used the electron beam to take an electron micrograph of the proton and they found that it was made of three objects with the correct charges
12 fundamental particles are arranged into a table like Mendeleev’s table and assigned in three families. The first consist of 4 important: the protons, neutrons, the electron and the electron neutrino.
The other two families are identical in every way to the first except that they are heavier. To understand we are going to recreate the conditions that were present at the start of the universe, less than a billionth of a second after the Big Bang.
The Large Hadron Collider, 27 kilometers in circumference and filled with over 2000 superconducting magnets each at 1.9 Kelvin, that means there are colder than the space between the stars. Inside, we accelerate protons to 99.999999 % the speed of light before bringing them into collision and detectors take pictures of the collisions 600 million times a second.
Forces cause the sun to shine, they make the ice melt in your drink, and they make a plant emerge from seeds. Forces are the agents of change in the universe. We understand the world today in terms of 4 major forces: the strong and weak nuclear forces, electromagnetism, and gravity.
2000 years after the Greeks, we thought that electricity and magnetism are different phenomena, until Faraday came and found out that if you take a coil of wire and you move a magnet inside it, you will create a current of electricity, so he showed that both electricity and magnetism were closely related.
Maxwell saw the true connection between the two disciplines, and he produced a revolution in the physics that Einstein described as the most profound and fruitful physics have experienced since the time of Newton. He unified Electricity and magnetism and found a relation between electromagnetism and light itself.
There has to be another force present in the nucleus that prevent the charge particles to repel each other, this force is called the Strong force. It’s responsible for 98 % of the mass of the particle.
Positrons are emitted from the nucleus in radioactive decay; it is an anti matter electrons, identical in every way except that they have opposite charge. In 1934, Fermi proposed the existence of weak nuclear forces that can convert protons into neutrons, or neutrons into protons, at the same emitting positrons, electrons or neutrinos from the nucleus. In 1960, Scientists were able to bring together the electromagnetic force and the weak nuclear force into a single force called: Electroweak force.
Is it possible to unify all those 3 forces into one single super force? The theory of everything.
Imagine a world where things can pop into existence seemingly out of nothing, and disappear as quickly. Imagine where you can be everywhere in the universe at the same time, and yet nobody can know precisely where you are. According to the standard model of particle physics, this is exactly how the world behave, because at its heart, lies the beautiful theory of quantum mechanics.
The photoelectric effect, in 1905, forced us to discover quantum mechanics. It’s a gold leaf electroscope, and it’s charged up, and causes the gold leaf to rise. When we shine a light on the plate, the plate will be discharged and the leaf falls down again.
What is interesting is that the electron that comes out of the plate depends not on the brightness of the light, but only on the color. That is impossible to understand if you think about light as a wave motion. It took Einstein to explain this phenomenon by assigning photons, the particles of light. In 1940’s the quantum electrodynamics theory started to emerge to explain the dual nature of light.
Quantum electrodynamics explains forces from a new perspective, in terms of particles. Imagine two electrons approaching each other; we know that they will repel each other.
The new perspective states that they will repel each other because a photon of light is being transferred between the two electrons. So the photon is the particle that carries the electromagnetic force.
In the 1970’s, it appeared mathematically that the strong forces required 8 exchange particles, we call them gluons. The weak forces required 3 exchange particles; we call them w+, w-, and z. To see those we need the huge particle accelerator in Geneva.
The secret to create new particles is, E=mc^2. They speed particles up, and smash them together, the energy of the collisions turns into new particles. In 1979, the particle detector called PETRA, revealed the first spectacular carrying particle other than the photon, the gluon. The W and Z particles took a little bit longer to be revealed because they are massive, and we need to produce more energy to see them. They did it. So why W and Z are massive while the photon and gluons are massless?
In the 1960’s Higgs came up with a way of generating masses for the particles avoiding the mathematical difficulties of the above question. The concept of Higgs on the acquired mass can be explained with the following analogy.
Imagine a group of students sitting in a hall, a highly educated professor crosses the hall way, many students interrupt him to ask him questions, so he is slowed, and he acquires knowledge , mass, just like the W and Z. However if a normal student crosses the hall way, he won’t be interrupted, and he will be faster, just like the photon particle.
The Higgs mechanism appears to be the way to understand the mass of the W and Z acquiring particles. The Higgs field exists everywhere in the space with a non-zero value.
Therefore it is the source of all the mass. Some people call it God’s particle; others call it the Particle of everything. So after predicting the other particles, and observing them, the Higgs particle remains the center of attention, & research of physics.