Analysis of Brief History of Time by Stephen Hawking

Brief History of time is a book written by Stephen Hawking. In it he discusses the origin, structure and the eventual progression of the Universe. He also converses on time and space and the basic building blocks of the universe like quarks, the Big Bang phenomena and Black holes. He also discusses the theory of general relativity and quantum mechanics.
In earlier days it was the conception that the earth rotated around the sun. Copernicus and Galileo disproved this concept and proved that it was the earth that was rotating around the sun. Kepler also proved that the earth had an elliptical orbit. Newton with proved this with his complex mathematical equations. The origin of the Universe was a subject of contemplation. The religious view was that it was created at a particular point of time. Edwin Hubble in 1929 discovered that galaxies were moving away from each other. Today scientists use the general theory of relativity and quantum mechanics to explain the workings of the universe.
Next the analysis goes on to explain space and time. Newton discovered the laws of motion to explain the working of movements in the universe. Newton believed that time was an independent concept of space. However this does not work for objects near the speed of light. Scientists used ether to explain the speed of light. But that was not an adequate explanation. Events can be explained using light cones. The top of the cone tells us where light from the event will travel. The bottom tells us where light was in the past.
In this section Hawking talks about the expanding universe. He uses the Doppler shift to explain the idea. There are two types of happenings in Doppler shift, red and blue shift. Red shift is happening when something is moving away from us. This is caused by the wave-length of visible light reaching us and the frequency decreasing. Blue shift happens when something is moving towards us. Hawkins uses the Doppler shift to explain that the universe is getting bigger.
Here Hawking discusses the Uncertainty Principle. Uncertainty principle states that the speed and position of particle cannot be determined simultaneously. The uncertainty principle disproved the idea that the universe was deterministic. Quantum physics states that light acts as waves and particles. Light waves have crests and troughs. The highest point is the crest and the lowest point is the trough. Sometimes they overlap and that is when colors occur.
In this chapter Hawking explains elementary particles of the Universe. The universe consists of Quarks and anti-quarks. There are six types of Quarks: they are: up quark, down quark, strange quark, charmed quark, bottom quark and top quark. Quarks are the building blocks of matter. All quarks have something called the spin. For example a particle of the spin 0 looks the same in every direction. A particle of spin 1 looks different from every direction. Strong nuclear forces are that keep the protons and neutrons together.
Here Hawking discusses about Black Holes. Black holes are stars that have collapsed. Black holes devour things into their center because of their strong gravity. Black holes can be shaped differently. Black holes will be spherical if they do not rotate and will bulge in the middle if they rotate. Black holes are difficult to find as they do not emit light. Disorder known as entropy is related to black holes. The scientific law dealing with entropy is the second law of thermodynamics.
Here Hawking discusses the origin and fate of the universe. The universe originated with a Big Bang. When the Universe started to become bigger, things started to cool in the universe.
Here Hawking proposes a unified theory of physics. In 1984 there developed the string theory among scientists where objects are not particles but two dimensional strings. The universe could be multi-dimensional. However unified theory of physics is still in the offing.