Wednesday 7 November 2018

Physics in the Early 20th Century


Modern ideas

What do you know about the following?
Radiation         Relativity         Quantum mechanics 


The vastness of the universe

Few people realize how much our picture of the universe has changed in 100 years. At the end of the 19th century, the universe was thought to contain only hundreds of thousands of stars arranged in no particularly interesting patterns. The most distance stars were thought to be about 100,000 light years away (meaning that it would take light 100,000 years to travel from Earth to such distant stars; 1 light-year is about 10 trillion kilometres or 6 trillion miles). Today, astronomers have observed objects that are about 10,000,000,000 [= ten billion] light years away. Furthermore, they have discovered that the universe contains many interesting structures. Amazingly, it was not until the 1920's that it was realized that galaxies exist. Galaxies are vast collections of stars grouped together in a relatively localized region of the universe. A typical galaxy contains 100,000,000,000 [=one hundred billion] stars and is 100,000 light years in size.

Some important physicists

What do you know about the following scientists? 
Neils Bohr       Werner Heisenberg    Erwin Schrodinger      Frederic Joliot-Curie
Enrico Fermi   H.G. Wells                   Leo Szilard                   Vannevar Bush
Thomas Kuhn


National Socialism and the scientists – two sides to every story

At the peak of atomic and nuclear physics, there was a rise in National Socialism. The Nazis drove out many German scientists, including Albert Einstein, Otto Hahn, Lise Meitner, and Fritz Strassmann due to “anti-intellectualism” according to McGee. This led to certain German and Jewish intellectuals fleeing into the arms of German enemies, bringing nuclear research to other countries such as the United States. Ultimately, these escaped researchers contributed to the development and research of atomic ware fare under the code name—the Manhattan Project.   

Breakthroughs 1912-1947

1915 – relativity          1916 – wormhole        1917 – cosmological constant           
1919 – proton discovered       1922 – primeval soup 1925- size of universe contended      
1926- uncertainty principle    1927- universe is expanding   1928-antimatter exists
1929 – galaxies moving away                        1932 – electrons / splitting the atom 
1934 – dark matter     1939 – nuclear fission

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