Alfred Wegener and Marie Tharp

Alfred Wegener

• Meteorologist and Arctic explorer, first to propose theory of continental drift
• Proposed theory in 1912, published The Origin of Continents and Oceans in 1915
• Believed continents were once joined in a supercontinent called Pangaea
• Theory met opposition from geologists - they rejected his idea, citing lack of explanation for why or how continents moved
• Wegener's theory was supported by:
  • Fossil evidence: fossils of Cynognatus found in South America and Africa
  • Rock formations: similar formations along African and South American coasts
  • Mountain ranges: ancient mountain ranges, now split across continents
  • Glacial deposits: at the equator, supporting idea continents drifted
• Conducted four expeditions to Greenland, died in Greenland in 1930
• Theory later proven correct in 1950s-60s with discovery of tectonic plates

Marie Tharp

• Geologist and cartographer
• Created charts of the ocean floor, identified the Mid-Atlantic Ridge, providing evidence for continental drift
• Work provided significant evidence for continental drift
• Received limited recognition for discovery of the Mid-Atlantic Ridge

Continental Drift

• Proposed 250 million years ago, continents were once connected
• Coastlines of western Africa and eastern South America appear to fit together
• Wegener found similar species of fossils, rock formations, and mountain ranges on continents now separated
• Continental drift theory was not widely accepted until the discovery of tectonic plates in the 1950s-60s

Famous Scientists

• Wilhelm Conrad Röntgen (1845 – 1923)

  • German physicist, discovered X-rays in 1895
  • Studied mechanics, heat, and electricity.
  • His work led to advances in physics and medicine.

• Ivan Pavlov (1849 – 1936)

  • Russian-born physiologist, conducted research on digestive secretions in dogs
  • Discovered that dogs learned to associate the arrival of food with the sound of a bell, and eventually salivated just to the sound (classical conditioning).
  • Key contribution is the Conditioned Reflex.
  • He won the Nobel Prize in Physiology or Medicine for his work in 1904.

• Kitasato Shibasaburo (1853 – 1931)

  • Japanese Physician and bacteriologist
  • Developed serum therapy to protect against diphtheria and tetanus.

• Jules Henri Poincaré (1854 – 1912)

  • Mathematical physicist from France, pioneered the study of chaos theory
  • He focused on stability of the solar system, and discovered that tiny changes in initial conditions could lead to unpredictable changes.
  • His work informed Albert Einstein's theory of relativity

• J.J.Thomson (1856 – 1940)

  • English physicist, investigated the structure of the atom
  • Identified "corpuscles" (electrons) – particles negatively charged and lighter than a hydrogen atom
  • Proposed the "plum pudding" model of the atom – a positive charge spread across the atom, and electrons were embedded within it
  • Confirmed the existence of isotopes

• Svante Arrhenius (1859 – 1927)

  • Swedish chemist, conducted research on electrolytes
  • Developed the theory of electrolytic dissociation.

• Annie Jump Cannon (1863 – 1941)

  • American astronomer
  • Classified stars based on their spectral characteristics
  • Classified over 350,000 stars at Harvard College Observatory

• Henrietta Swan Leavitt (1868 – 1921)

  • American astronomer - worked at Harvard College Observatory
  • Discovered the period-luminosity relationship for Cepheid variable stars.
  • Discovered over 2,400 variable stars and four novae.

• Harriet Brooks (1876 – 1933)

  • Canadian nuclear physicist
  • First female nuclear physicist in Canada.
  • Discovered that one element can change into another through nuclear decay (radioactive decay)

• Srinivasa Ramanujan (1887 – 1920)

  • Indian mathematician, known for his work in mathematical analysis and number theory
  • Developed over 120 mathematical theorems, even though his education was limited.

• Erwin Schrödinger (1887 – 1961)

  • Austrian physicist known for his work in quantum mechanics
  • Developed the Schrödinger equation, which describes how the wave function of a quantum-mechanical system evolves in time.

• Ronald Fisher (1890 – 1962)

  • British statistician and geneticist
  • Pioneered the application of statistics to scientific experimentation.

• Harold Urey and Stanley Miller (1893 – 1981, 1930 – 2007)

  • American chemists, conducted experiments to simulate early Earth conditions.
  • Used hydrogen, methane, and ammonia to create simple, organic molecules in a closed system.