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CVSP 204 : Lecture September 4 2016
Title: Twentieth Century advances in Physics
Brief outline:
The main conceptual changes in understanding the physical world that were discovered in the twentieth
century are presented. Starting with the introduction of the quantum of light by Planck in 1900 and
ending with the standard models for cosmology and particle structure as we understand them now.
A brief discussion of the consequences of the special relativity for the structure of space and time
introduced by Einstein in 1905 is presented, to be followed by Einstein’s interpretation of the force of
gravity as simply a curvature in this space time. This general theory of relativity then leads to a
cosmological model of an expanding universe that finds its origin in a “big bang” that took place some
thirteen billion years ago and a structure full of such esoteric objects such black holes , dark matter and
dark energy. The recent discovery of gravitational waves conform the interaction between such black
holes.
Quantum Mechanics was introduced by Heisenberg and Schrodinger in 1925-26 and made relativistic by
Dirac in 1926. These formulations led to the deep understanding of the quantum behavior of nature at
very short distances in atoms and nuclei, and the prediction of the existence of antimatter. The creation
of matter from radiation and the annihilation of matter with anti-matter producing radiation provides
an explanation of the development of the universe from its original big bang to the present. The
quantum nature of physics at very small distances led also to the study of “elementary particles” and
their interactions culminating in the current understanding of the fundamental blocks of nature (quarks)
and their various interactions.
K. Bitar
Sept.1 2016.