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658 BCE
Eratosthenes
Eratosthenes made several remarkable discoveries and inventions. He was the first person to calculate the circumference of the Earth (with remarkable accuracy), and he invented a system of latitude and longitude. He calculated the tilt of the earth's axis (again with remarkable accuracy); he may also have accurately calculated the distance from the earth to the sun and invented the leap day.[3] He created a map of the world based on the available geographical knowledge of the era. -
150 BCE
Ptolemy
Ptolemy was an astronomer and mathematician. He believed that the Earth was the center of the Universe. . Even starting with this incorrect theory, he was able to combine what he saw of the stars' movements with mathematics, especially geometry, to predict the movements of the planets. His famous work was called the Almagesti. In order to make his predictions true, he worked out that the planets must move in epicycles, smaller circles, and the Earth itself moved along an equant. -
1543
Copernicus
n his work, "De Revolutionibus Orbium Caelestium," published in 1543, Copernicus explained his new heliocentric, or sun centered, model. He believed that the motion of the earth around the sun explained the motion of the planets better than Ptolemy's epicycle theory. Copernicus also introduced the idea that day and night are the result of the rotation of the Earth on its axis and that Mercury and Venus are closer to the Sun than the Earth is. -
Tycho Brahe
He decided to dedicate his life and considerable resources to recording planetary positions ten times more accurately than the best previous work. He achieved his goal of measuring to one minute of arc. This was a tremendous feat before the invention of the telescope. His aim was to confirm his own picture of the universe, which was that the Earth was at rest, the sun went around the Earth and the planets all went around the sun - an intermediate picture between Ptolemy and Copernicus. -
Johannes Kepler
He reluctantly concluded that his geometric scheme was wrong. In its place, he found his three laws of planetary motion:
I The planets move in elliptical orbits with the sun at a focus.
II In their orbits around the sun, the planets sweep out equal areas in equal times.
III The squares of the times to complete one orbit are proportional to the cubes of the average distances from the sun. -
Issac Newton
Among his many accomplishments, Newton formulated the basic laws of motion that are the basis of mechanics. Newton's three revolutionary laws are:
an object at rest stays at rest, or an object in constant motion stays in constant motion, until it is acted upon by a force
the change in speed of an object is proportional to the force acting upon it
when an object 1 exerts a force on object 2, object 2 exerts a force on object 1 equal and opposite to the original force -
Albert Einstein
Albert Einstein was a German-born theoretical physicist who developed the theory of relativity, one of the two pillars of modern physics. He is best known to the general public for his mass–energy equivalence formula E = mc², which has been dubbed "the world's most famous equation". He received the 1921 Nobel Prize in Physics "for his services to theoretical physics, and especially for his discovery of the law of the photoelectric effect", a pivotal step in the development of quantum theory.