GRAVITY (Really Weak)
A natural phenomenon by which all things with mass are brought towards one another. Since energy and mass are equal all forms of energy create gravity and are effected by gravity. Though weak, the force has a very very long range.
The waves don't rely on the presence of material to transport their energy as mechanical waves do. Light is an example of this. These waves are created from the vibrations of electric charges. When the waves make contact with a material the wave causes the atom in the material to vibrate allowing for a wave of the same frequency to be recreated on the other side.
The Weak Force (Very Strong)
Even though this interaction is referred to as weak it is almost the complete opposite it is a very strong force but has a very very small range. Without the weak force, elements like Plutonium and Uranium could be handled without protection and the sun would no exist. The excess of this fusion process happening on the sun is what we know as the heat let off by the sun.
Strong Force (The Strongest)
With such great strength, short range comes with it. This strongest force is responsible for keeping the Protons in the Nucleus despite the repulsion they give off. The strong force is also responsible for connecting the quarks to create Protons and Neutrons.
In 1905 Einstein determined that the speed of light in a vacuum was independent of the motion of all the observers. This became known as the special relativity. He spent ten years trying to add acceleration into the equation, in doing so he determined that massive objects create a distortion in space and time which is known to us as gravity.
This is the theory of natural things at a small, atomic level. Classical physics are derived from the study of these atomic levels just put onto a larger scale. Although, quantum mechanics do differ from classical mechanics with the fact that energy, momentum, and other quantities are often restricted.
Remember those four fundamental forces? Unification interacts with the standard model which define the electromagnetic, weak, and strong interactions or forces, are merged into one single force. The behavior of these forces only combine at a very high energy state. after the unification point the symmetry in which the forces act break and they act differently.
A guitar string that has been tuned by stretching the string under tension across the guitar, depending on how the string is plucked and how much tension is in the string, different musical notes will be created by the string. These musical notes could be said to be excited of the guitar string under tension. In a similar manner, in string theory, the elementary particles we observe in particle accelerators could be thought of as the musical notes or excited state of strings.