3.33 Sspd_chapter 1_part 13_ constituent particles of solid state  (Page 3/14)

In 19 ^th Century and 20 ^th Century as Sciences of rocks , fossils and celestial bodies developed, the Creationist Theory was questioned.

Through radio-active dating it was confirmed that rocks are much older than what is supposed by the Creationists.

Second jolt was given by Wegner’s plate tectonic theory which propounded that the outer crust of Earth is divided into 13 plates which are floating around on the semi-molten upper basaltic mantle. Therefore the distribution of the continents were not always as they are distributed now. The distribution is ever changing.

The final jolt was given to the creationists by Expanding Universe Theory discovered in 1920.

In the Mount Wilson Observatory, Los Angeles, California, two scientists Hubble and Humason discovered that all distant galaxies seem to be receding from us. Further the recession velocity was directly proportional to the distance of the galaxy and the constant of proportionality was called H ( Hubble constant). This theory of Expanding Universe gave birth to the concept of The BIG BANG THEORY.

1.13.1. THE BIG BANG THEORY.

In 1940 George Gamow propounded the theory of Big Bang. According to this at a singularity a big bang occurred in the remote past. This event occurred 13.7 billion years before the present. From that point onward space started expanding and time started ticking. At the time of Big bang, there was infinite temperature and infinite density at the point of singularity. We do not know what the form of matter was at that time. As space expanded and time passed , temperature came down and density reduced.

Till 10 ^-43 seconds after the instant of Big Bang, quantum gravitation theory was applicable. This state is known as Super Symmetry. At this point all the four forces merge as one force as shown in Fig.(1.73).

The four forces present in nature are: Gravitational force, Electromagnetic force, Strong force and Weak force.

In Table(1.27) , a quantative description of the four forces are given. The radius of the sphere of influence and its magnitude at one Fermi distance (10 ^-15 m) is enumerated in the Chart. The radius of the nucleus is Seven Fermi Unit but was measured as 30 Fermi Unit by Rutherford Experiment.

Table 1.27 A comparative study of the four forces. [ Table 13.1 from Chapter 13,‘Elementary Particles’, Concepts of Modern Physics, by Arthur Beiser, TMH, 6 th Edition, 2003]