Monday, October 3, 2011

History of Bacteria Discovery

Anton van Leeuwenhoek, the Dutchman first observed bacteria through his single-lens microscope in 1674. He made his own simple lenses to try to satisfy his curiosity about living things.

He observed the bacteria in suspension of white material he obtained from his teeth – dental plaque.

Later, Louis Pasteur demonstrated that the fermentation process was caused by the growth of microorganisms or bacteria.

Pasteur discovered the process of pasteurization – killing bacteria by heating – and invented a number of vaccines including one against rabies.

This was followed by Robert Koch’s experiments on bacteria as a source of disease, specifically the anthrax bacillus, for which he won the Nobel Prize in 1905. Robert Koch, a German Doctor showed the first time in 1876 that bacteria can cause disease.

The German medical scientist Paul Ehrlich (1854-1915) developed the first theory concerning how bacteria cause diseases and how the immune system fights these micro-organisms.

During the years from 1878 to 1884 Burrill, in Illinois , working on the well-known fire blight of apples and pears discovered that it was caused by bacteria.

Wakker a young Dutch pathologist, working on the so-called yellow disease of hyacinth, proved it to be caused by bacteria. He published his result from 1883-89.

In early 1900s, Russian immunologist Dr. Eli Metchnikoff, suggested that a synergistic interaction exists between bacteria and their host. He proposed that a link existed between better health and longer life after noted the longevity of Bulgarian peasants who ate a lot of yoghurt.
History of Bacteria Discovery

Sunday, October 2, 2011

Heliocentrism theory

The long-held belief of geocentric theory was challenged by Nicolas Copernicus (1473-1543) and mathematically confirmed by Johannes Kepler (1571-1630).

Their theory was called heliocentric, meaning that the sun was the center of solar system, and Earth and the other planets revolved around it.

The first person who put forward the heliocentric hypothesis was Aristarchus of Samos (310-230 BC). He was known as ‘the mathematician’ and his theoretical contributions to geography. He elaborated the heliocentric theory of the universe.

Aristarchus perhaps influenced by the work of Heraclides of Pontus suggested that a simple world system would result if the sun were put at the center of the universe and of the moon, the earth, and the five then-known planets revolved around the sun in orbits of different sizes and speeds.

Mathematician Pythagoras, in the sixth century before our era also proposed the same ideas. After him Philolaus, had suggested the movement of the earth and planets about a central fire but its definitive formulation appears to be Aristarchus work.

However, Copernicus worked out his system in full mathematician detail. Nicolaus Copernicus read the ideas of ancient Greek astronomers and mathematicians.

In 1512, Copernicus published a description of his ‘heliocentric’ model of the solar system. In this model, the sun was the center of the solar system.

Galileo Galilei (1564-1642) an Italian mathematician and scientist later proved the heliocentric theory.

His telescope also showed that the moon had peaks and valleys, crags and carters and that the sun had spots that appeared and disappeared, disapproving the Aristotelian-Christian belief of pristine heavens.
Heliocentrism theory
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