Scientists and Their Contributions

8/9/2019 Scientists and Their Contributions

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SCIENTISTS

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Modern astronomy begins with Copernicus (1473-1543)declaring (1530) the Earth rotates on its axis once daily andtravels around the Sun once yearly. Next Tycho Brahe (1546-1601)made important contributions by devising instruments to observemotion of planets. In particular, Brahe compiled extensive data onthe planet Mars. However, Johannes Kepler made the monumentaldiscovery of the time. Brahe, fearing his bright assistant mighteclipse him as the premiere astronomer of the day, assignedKepler the perplexing orbit of the planet Mars (Mars has the mostelliptical orbit of all the planets). Ironically it was precisely the

Mars data that allowed Kepler to develop his three laws describingthe orbit of planets around the Sun. Kepler's Three Laws ofPlanetary Motion: 1. Planets revolve around the Sun in an ellipticalpath, with the Sun occupying one of the foci of the ellipse. 2.Straight line joining sun and planet sweeps out equal areas inequal intervals of time. 3. Squares of planets' orbital periods areproportional to the cubes of the semimajor axes of their orbits.

Johannes KeplerJohannes Kepler

(1571-1630)(1571-1630)


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Mathematician/astronomer/physicist who madenumerous contributions to modern science. Galileo was firstto use telescope to gather evidence proving the earthrevolves around the sun. His position represented such aradical departure from accepted thought that he was tried bythe Inquisition in Rome, ordered to recant, and forced tospend the last eight years of his life under house arrest. Butmost of Galileo's projects didn't conflict with the church'sinterests, falling bodies, magnets, floating objects, the tides,

compasses, arc of a cannonball, and rolling objects. Heinformally stated the principles later embodied in Newton'sfirst two laws of motion. He also invented the mechanicalpendulum clock, improved the telescope, and developed thefirst thermometer. Because of his pioneering work ingravitation/motion and in combining mathematical analysiswith experimentation, Galileo is credited with ushering in the

new age of science.

Galileo GalileiGalileo Galilei

(1563-1642)(1563-1642)


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There can be no outstanding scientist list without Sir IsaacNewton; he made revolutionary advances in mathematics, optics,physics, and astronomy. In 1687 Newton published thePhilosophiae naturalis principia mathematica. Principia, as it hasbecome known, is recognized as the greatest scientific book ever

written! Newton analyzed motion of bodies under the action ofcentripetal forces. The results were applied to orbiting bodies,projectiles, pendulums, and free-fall near the Earth. He furtherdemonstrated planets were attracted toward the Sun by a forcevarying as the inverse square of the distance and generalized thatall heavenly bodies mutually attract one another. In order toperform his calculations, Newton invented calculus. Newton alsoexplained a wide range of previously unrelated phenomena such

as eccentric orbits of comets, tides and their variation, precessionof the Earth's axis, and motion of Moon as perturbed by gravity ofSun. Newton was deeply interested in light and published optics in1704. Although he believed a wave theory more probable, herelied on a corpuscular theory to account for phenomena such asreflexion, refraction, colors, and diffraction. Newton's Three Lawsof Motion: 1. A body continues in a state of rest, or motion with aconstant velocity, unless compelled to change by an unbalancedforce. 2. The acceleration of an object is directly proportional tothe net force acting upon it and inversely proportional to its mass.

Sir Isaac NewtonSir Isaac Newton

(1643-1737)(1643-1737)


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Darwin studied medicine at Edinburgh University but wasrepelled by the sight of surgery performed without anesthesia andentered Cambridge University to become a clergyman. In 1831after receiving his degree, Darwin served as an unpaid naturaliston the H.M.S. Beagle for a five-year scientific expedition to thePacific coast of South America. The research resulting from thisvoyage formed the basis of Darwin's famous book, On the Originof Species by Means of Natrural Selection. Published in 1859,Darwin concluded: 1. Evolutionary change was gradual and

required thousands to millions of years. 2. Primary mechanism forevolution was process called natural selection. 3. Millions ofspecies alive today arose from single original life form throughbranching process called "specialization." Variation within speciesoccurs randomly and survival/extinction determined by organism'sability to adapt to its environment. Darwin's work had atremendous impact on society since the theory challenged beliefsabout the creation of life on earth. After publication of Origin ofSpecies, Darwin continued to write on botany, geology, andzoology until his death in 1882. He is buried in Westminster Abbey.

CharlesCharles

Darwin(1809-1882)Darwin(1809-1882)


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French chemist/biologist who made numerouscontributions to science including: 1. Separated mirrorimage molecules and studied effect of polarized light.

2. Demonstrated handedness of molecules from plantmold using one isomer of racemic acid. 3. Yeast is anorganism and does not require oxygen forfermentation. 4. Pasteurization (mild heating) afterfermentation kills microorganisms and preventssouring. 5. Identified parasite responsible for killing

silkworms and saved French silk industry. 6. Proposedgerm theory of disease urging doctors to use cleaninstruments, wash hands, and disinfect bandages inThe Germ Theory and its Application to Medicine andSurgery. 7. Developed treatment to prevent anthrax.Named technique "vaccination"' and applied it tochicken cholera and rabies.

Louis PasteurLouis Pasteur

(1822-1895)(1822-1895)


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Maxwell is considered the scientist of the 19th century whohad the greatest influence on 20th century physics. In 1931

Einstein described Maxwell's work as "the most profound and themost fruitful that physics has experienced since the time ofNewton." Maxwell calculated the speed of propagation of anelectromagnetic field as approximately that of the speed of light.He proposed the phenomenon of light is an electromagneticphenomenon. In 1873 Maxwell published his Treatise on Electricityand Magnetism which contains his famous Maxwell equations; thefour partial differential equations are one of the great

achievements of 19th-century mathematics. Maxwell alsoformulated, independently of Ludwig Boltzmann, the Maxwell-Boltzmann kinetic theory of gases. This theory showed thatmolecules at high temperature have only a high probability ofmoving toward those at low temperature. Maxwell's approach didnot reject the earlier studies of thermodynamics but used a bettertheory of the basis to explain the observations and experiments.

James ClerkJames Clerk

Maxwell (1831-Maxwell (1831-

1879)1879)


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No one made greater contributions to chemistry thanFisher. In his early years developed new dyes and identifiedthe active ingredients in tea/coffee/cocoa. Between 1882-

1906 Fisher performed perhaps the most outstanding workin the history of chemistry. He established structures for the16 stereoisomers of the aldohexoses (C6H12O6)glucosebeing the most prominent member. In the process hesynthesized glucose, fructose and mannose starting withglycerol. In other work he showed substances such asadenine, xanthine, caffeine, uric acid, and guanine all

belonged to the family he called purines. Fisher advancedour knowledge of protein by developing methods toseparate/identify individual amino acids. He alsosynthesized proteins and identified the peptide bondholding them together in chains. Fisher devised crossrepresentations (today called Fisher projections) andproposed the often used lock & key model to explain the fit

of a drug onto a receptor site.

Emil Fisher(1852-Emil Fisher(1852-

1919)1919)


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Einstein is probably the most famous

scientist of all time. He burst on the scene in1905 when he managed to solve three of theoutstanding problems of physics:photoelectric effect, Brownian motion, andspecial theory of relativity. These threepublications have become known as the"Einstein trilogy." Einstein's greatest workoccurred in 1915 when at the "advanced age"of 36, he published the general theory of

relativity showing that gravity andacceleration are the same.

Albert Einstein(1879-Albert Einstein(1879-

1955)1955)


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In 1924 Hubble measured the distance to theAndromeda nebula and showed it was about a hundredthousand times as far away as the nearest stars. It had to

be a separate galaxy, comparable in size to our own MilkyWay but much further away. Hubble began to classifygalaxies according to their content, distance, shape, andbrightness patterns. By observing redshifts in the lightwavelengths emitted, Hubble concluded that galaxies moveaway from each other at a rate dependent to the distancebetween them (Hubble's Law). The further away they were

the faster they receded. Hubble calculated the point wherethe expansion began and estimated the age of the universeat about 2 billion years (more recent estimates put it at 20billion years). No person had a greater impact indetermining the extent of our universe than Edwin Hubble.From proving that other galaxies existed to proving thatgalaxies move apart from one another, Hubble's work

defined our place in the cosmos. In honor of Hubble'sachievements, the Orbiting Space Telescope was named

Ediwin HubbleEdiwin Hubble

(1889-1953)(1889-1953)


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Considered the second outstanding scientist of the 20thcentury, Dirac was one of the pioneers of quantummechanics and developed the first theory of the

electron that took into account special relativity. Thetheory described many observed attributes of theelectron that previous theories had been unable toanticipate. But the most remarkable prediction of thetheory was that the electron should have an anti-particle associated with it, having the same mass, butwith a positive instead of negative charge. In 1932 this

particlelater called the positronwas discovered, andsince then many other anti-particles have beenpredicted and observed. Dirac developed a version ofthe Schrdinger Equation, known as the DiracEquation, which is relativistically correct. For his workon anti-particles and wave mechanics, he received theNobel Prize in physics in 1933. Dirac was Lucasian

Professor of Mathematics at Cambridge from 1932 to1969 and professor of physics at Florida State

Paul Dirac (1902-Paul Dirac (1902-

1984)1984)


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Stephen Hawking was born on January 8th 1942. He didhis undergraduate degree in physics at Oxford and thenwent on to graduate training in Cosmology at Cambridge. It

was during his later year at Oxford that he developedmedical problems and was subsequently diagnosed withMotor Neuron Disease. This however, did not prevent himfrom earning his PhD and subsequently embarking on avery successful research career.

Another major area that he worked on was the area ofquantum mechanics. One of the aims in physics was to finda unifying theory: one that would explain all matter in theuniverse. The problem was that physical laws that could beapplied to macroscopic structures no longer worked atsubatomic levels. However, through his research on theorigins of the earth, he started to develop links betweengravity and the behavior of atoms. This information thenallowed for the development of the Grand Unified Theory,which physicists use to explain all matter.

Stephen HawkingStephen Hawking

(1942)(1942)


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Scientists and Their Contributions