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Falling Objects: discovered that both heavy and
light objects fall toward Earth with the same acceleration if the effect of air resistance is eliminated. Galileo's Experiments Projectiles: An object falling straight down reaches the ground in the same amount of time as the one that also has lateral motion -
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1st and 2nd laws of planetary motion
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3rd law of planetary motion
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Support for Copernicus' heliocentric theory
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Newton proposed the three laws of motion in which objects moved because they were being pulled or pushed by FORCES. This lay the foundation for the Industrial Revolution: steam engines - locomotives and ships, bridges, dams skyscrapers. He then applied his theory of forces to the universe itself by proposing the new theory of gravity - he compared the falling of an apple with the falling of the moon. http://www.youtube.com/watch?v=BXnhEDMUJt8
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law of elasticity and springs
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writes about wave theory of light
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-Two decades later, all of London was terrified and amazed by a brilliant comet that was lighting up the night sky.
-Newton carefully tracked the motion of the comet with a reflecting telescope one of his inventions) and found that its motion fit his equations perfectly if it was assumed to be in free fall and acted on by gravity.
- With the amateur astronomer Edmund Halley, he could predict precisely when the comet later known as Halley's comet) would return - the first prediction of its kind. -
According to Newton, the gravitational forces act INSTANTANEOUSLY, For example, if the sun were to suddenly disappear, the earth would be instantly thrown out of its orbit and would freeze up in deep space. Thus, it's possible to synchronize all watches so they beat uniformly anywhere in the universe. 1s on earth is the same length of time as 1s on Mars and Jupiter. SImilarly, 1m on Earth is the same length as 1m on Mars and Jupiter.
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Newton's Law of Universal Gravitation
inverse square law and mass dependence of gravity -
publishes corpuscular theory of light and colour
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noticed that three previous comets are the same and predicts its return in 1758
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theory of electricity and lightning
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measured the gravitational constant, G with a torsion balance
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interference and wave description of light
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force on an electric current in a magnetic field
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an electric current deflects a magnetised needle
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a moving magnet induces an electric current
magnetic lines of force
the electric dynamo
the electric transformer
laws of electrolysis -
Law of electromagnetic forces
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theory of Doppler Effect for sound and light
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Kirchoff's laws of electrical networks
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James Clerk Maxwell based on Michael Faraday's discovery of electricity and magnestism, developed a theory of light, not based on Newtonian forces, but on a new concept called "Fields". He demonstrated the field lines by sprinkling iron filings on a magnet on a sheet of paper - they rearranged themselves in a web like pattern. He explained the electric field lines in the same way - our hair stands on end when we touch a source of static electricity.
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He know from Faraday's and others' work that a moving magnetic field can create an electric field, and vice versa. He combined the two together to create cyclical motion - with electric and magnetic fields continually feeding off each other and turning into each other - an electromagnetic wave. He measured the speed of this wave and it was the speed of light! He claimed that this WAS light. Unlike Newton's forces, which were instantaneous, these waves traveled at a definite speed: 'c'
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Embarrasingly, any attempts to merge Newtonian mechanics with Maxwell's theory failed. Maxweel's theory confirmed that light was a wave and can travel through vacuum nothing) but this left open the question, what is waving? Newtonian physicits tried to answer this question by postulating that light consisted of waves vibrating in an invisible "aether", a stationary gas that filled up the universe.
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Albert Michelson and Edward Morley performed an experiment to test the "aether" theory. They reasoned that the earth moves within the sea of aether, creating an "aether wind," and hence the speed of light should change, depending on the direction the earth took. In their experiment, a single beam of light is split into two distinct beams, each shot in diffreent directions at right angles to each other. They found that the speed of light was identical for all light beams, i.e no aether!
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Marie Curie, a chemist, with the work of others on radioactivity, found that even a few ounces of radium could somehow light up a darkened room. She also showed that seemingly unlimited quantities of energy could come from an unknown source deep inside the atom., in defiance of the law of conservation of energy, which states that energy cannot be created or destroyed.
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In 1900, Max Planck explains that energy is released by matter in discrete packets, which he calls quanta. The quantum theory explains why a heated object emits only light of specific colors, and this sets the stage for new theories about the structure of the atom.
Planck discovers the quantum nature of energyhttp://www.pbs.org/wgbh/aso/databank/entries/dp00qu.html -
Einstein publishes the special theory of relativityIn 1905, Albert Einstein shakes up the Newtonian view of the world when he publishes his special theory of relativity.
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Rutherford's Model of the AtomIn 1911, Ernest Rutherford describes an atom as a nucleus, containing positively charged particles called protons, surrounded by a cloud of negatively charged electrons.
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Bohr Model of the AtomIn 1913, Niels Bohr states that electrons circle the nucleus at specific quantum levels, providing further explanation of Planck's theory.
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Hubble identifies a new galaxy
In 1924, Edwin Hubble finds a Cepheid in the Andromeda Nebula, allowing him to measure the distance to the nebula. He finds it to be so far from earth that in fact Andromeda is a separate galaxy, and our Milky Way is only one small part of the universe. -
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Big bang theory is introduced
That same year, 1927, Georges LeMaitre develops a theory of the origins of the universe, which becomes knows as the "big bang." -
Hubble finds proof that the universe is expandingIn 1929, Edwin Hubble finds that very distant stars appear to be moving away from earth at a speed proportional to their distance.
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Lawrence invents the cyclotron In 1931, Ernest Lawrence invents the cyclotron, which allows physicists to study the behavior of atomic particles accelerated at very high speeds. This inaugurates an age of "big science."
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Chadwick discovers the neutron In 1932, James Chadwick discovers that the nucleus of an atom is composed of protons and neutrally charged particles he calls neutrons.
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Fermi creates controlled nuclear reaction In 1942, as part of the Manhattan Project working to develop an atomic bomb, Enrico Fermi creates the first controlled nuclear reaction by bombarding an atom of uranium with an accelerated neutron.
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The first atomic bomb is detonated In 1945, an atomic bomb is first exploded in New Mexico and another is soon dropped on Japan.
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In 1964, Murray Gell-Mann proposes that subatomic particles such as protons and neutrons are composed of even smaller particles, which he calls "quarks." The existence of quarks is proven ten years later.
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Penzias and Wilson discover cosmic microwave radiation In 1965, Arno Penzias and Robert Wilson hear an annoying hiss in their satellite antenna, which they identify as cosmic microwave radiation left over from the big bang.
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Bell and Hewish discover pulsars On the Edge: Little Green Men In 1967, Jocelyn Bell finds a message from a distant star, the first identified pulsar in the universe
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In 1967, Steven Weinberg continues the search to replace the laws of Newton with new explanations that explain the behavior of all forces, including those at the subatomic level.
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In 1976, Thomas Kibble suggests that the uneven distribution of matter in the universe can be explained by the existence of cosmic strings formed shortly after the big bang.
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With the aid of radio telescopes and the Hubble Space Telescope, launched in 1990, astronomers can now see the birth of galaxies, find planets orbiting distant stars, and probe 15 billion light years to the edge of the known (and expanding) universe. We have identified and continue to study numerous cosmic phenomena such as pulsars, quasars, black holes, and dark matter. At the other extreme, a "zoo" of subatomic particles has been studied, and much of their behavior is understood. But no
