THE FOUR FUNDAMENTAL FORCES
Gravity: Gravity, or Gravitation, is the natural process in which all objects with a mass are brought together. Forms of energy, including light and mass are usually the main cause for gravitation, and are under the influence of it. The founder of the "Law of Universal Gravitation" is Isaac Newton. He discovered this by watching an apple fall from a tree, which stated that a particle attracts another particle using the force of gravity, that is related to both objects masses, and the square distance between them. Gravity is essential to keep us sticking to the ground, and not floating up into the air.
Weak Nuclear Force: The Fundamental Weak Force is the main cause for radioactivity and supports the decay of unstable subatomic particles. It also initiates the nuclear fusion reaction that fuels the sun. In radioactive decays, the strength of a weak force is about 100,000 times less the strength of a electromagnetic force.
Strong Nuclear Force: As its name implies, the Strong Nuclear Force is the strongest force out of all Four Fundamental Forces. Its main job is to hold together the subatomic particles (protons and neutrons) in the nucleus. However, this force has the shortest range, meaning particles have to be extremely close in order for its effects to be felt.
Electromagnetic Force: The Electromagnetic force is the force that affects everything in the universe because of its infinite range. It has the ability to attract and repel charges meaning, the electrostatic force acting between the charged particles at rest, and the combination of electric and magnetic forces, creates charged particles to move relative to each other.
EINSTEIN'S THEORY OF RELATIVITY
In 1905, Albert Einstein determined that the laws of physics are the same for all non-accelerating observers. He also found that the speed of light in a vacuum was "independent of motion." The theory was officially made clear after 10 years, in 1915. The law stated that massive objects cause a distortion in space-time (gravity). A great example of this theory is Black Holes. Black Holes are a place in space where gravity pulls so intensely, not even light can get out. Gravity is so strong during this phase because matter is squeezed tightly into a confined space.
Quantum Mechanics is the science that deals with the behavior of matter and light not only in an atomic, but subatomic scale as well. It describes the properties of molecules as well as protons, neutrons, and electrons. The properties include their relations with one another as well as with electromagnetic radiation. This branch of mechanics deals with mathematical descriptions of motion while incorporating the concepts of quantization of energy and wave particle duality.
The final theory, ultimate theory, or master theory was the goal Einstein worked long and hard to achieve until the day he died. Unification is the law that describes everything in the universe. It is often said that this can be solved using the String Theory. While studying the unsolved answers of Unification, physicists had many questions, and believing that the theory was overall incorrect. Although in the year 1984, a match of the number 496 was found on both sides of the equations, proving Unification correct. Although the theory as a whole has still yet to be proven, considering the four forces are now said to be surrounded and encompassed.
THE STRING THEORY
The String Theory is the idea that the particles in physics are replaced by one dimensional objects said to be strings. All objects in our universe are said to be composed of small vibrating fragments. It is said that this theory believes several unobservable dimensions must exist among the universe. The strings come in two forms, closed and open. An open string has two ends that do not touch each other, while the closed string is a basic loop with no end. It was found that this "Type 1" string group can undergo five steps of interactions.