19th and 20th Century Scientific Advances

19th and 20th Century Scientific Progress

• Science became intimately linked to progress at the turn of the 20th century, with cutting-edge research driving crucial shifts in fundamental ideas.
• Discoveries abounded, and rules were rewritten at both subatomic and cosmological levels.

Wilhelm Conrad Röntgen

• German physicist Wilhelm Conrad Röntgen made a pivotal discovery: X-rays.
• This discovery occurred in 1895.
• X-rays were produced through electrically charged vacuum tubes, glowing fluorescent screens, and exposing photographic plates.
• The discovery impacted medicine and physics significantly.
• Röntgen won the first Nobel Prize in Physics in 1901, but he donated the prize money to research.
• He also contributed significantly to mechanics, thermodynamics, and electricity.

Ivan Pavlov

• Russian-born Ivan Pavlov, initially pursuing a religious career, switched to a scientific path.
• He specialized in physiology and became a professor in 1890 at the Military Medical Academy in St. Petersburg.
• Pavlov conducted research on the digestive secretions of dogs.
• Key discovery: dogs' learned to associate food with a bell.
• Dogs subsequently salivated to the bell, though no food was presented. This led to Pavlov's discovery of classical/Pavlovian conditioning.
• Pavlov received the Nobel Prize in Physiology or Medicine in 1904 for his work.

Kitasato Shibasaburo

• Japanese physician and bacteriologist Kitasato Shibasaburo studied in Tokyo and Berlin.
• Developed serum therapy to combat tetanus and diphtheria.
• In 1890, he isolated a serum containing antitoxin.
• This antitoxin was extracted from animals exposed to tetanus and provided immunity to the serum recipient.

Jules Henri Poincaré

• French mathematical physicist Jules Henri Poincaré.
• Noted for efforts to determine if the solar system is stable.
• Observing that tiny alterations in initial conditions can lead to significant, unpredictable changes in outcomes.
• His findings, including chaotic behavior, became an important underpinning for chaos theory in later decades.
• Key insights about the complex nature of systems.

J.J. Thomson

• English physicist J.J. Thomson was instrumental in describing atomic structure.
• Thomson identified "corpuscles" – later called electrons – through cathode ray tube experiments.
• These corpuscles carried a negative electric charge, far smaller than a hydrogen atom.
• Proposed the "plum pudding" model of the atom: positive charge dispersed throughout the atom, with electrons embedded within it like plums.
• Thomson also confirmed the existence of isotopes: chemically similar elements but with differing atomic weights.

Svante Arrhenius

• Svante Arrhenius studied physics at the University of Uppsala in Sweden.
• Eventually became a professor of physics at Uppsala.
• Studying the nature of elements and their chemical properties.