Assignment #3 - Universal Gravitation and Discovery Disputes

Isaac Newton was an English scientist, mathematician, and philosopher who lived from 1642-1727. He is highly regarded as one of the most influential scientists due to his many contributions to the field. Newton is most known for his three laws of motion, which serves as the foundation for classical mechanics. He derived these three laws of motion from Johannes Kepler’s three laws of planetary motion and his own concept of gravity. ¹

Figure 1 - Sir Isaac Newton

Figure 2 - Johannes Kepler

Newton’s first law of motion is that an object will continue to move at a constant velocity as long as there are no forces acting on it. For example, bowling alley lanes have near frictionless surface; therefore if it were an infinite lane, the bowling ball would never stop rolling (never reach a resting point). His second law of motion is that a force is equivalent to its mass times acceleration and that gravitational acceleration on Earth is equivalent for all objects. For example, if you drop a pen and a ball from the same height, it would experience the same acceleration. Newton’s third law is that for every acting force, there is a reacting force. For example, if one pushes on a wall with a force, the wall pushes back at the same amount of force.

Newton then applied his laws to planetary objects by claiming that the force of gravity between two objects is proportional to the product of the two masses divided by the square the distance between the two objects. He used this to explain the motion of planetary objects and it helped support the idea of a heliocentric model. This was a breakthrough because in combination with Kepler’s three laws of planetary motion it helped to affirm the fact the planets have an elliptical orbit. It also helped Newton believe that the Earth is a spherical object.

Figure 3 - Newton's Law of Universal Gravitation

A main reason for Newton’s many scientific disputes is his tendency to publish papers only after someone published something similar. Three scientists, Christopher Wren, Robert Hooke, and Edmond Halley disagreed over Newton’s idea of elliptical orbits due to the gravitational force of the Sun, which varied planet-to-planet. Hooke was one who argued with Newton over who discovered the inverse square law and elliptical orbits first; the dispute only ended due to Hooke’s death in 1703. ²

As much as Newton did for the field of science, he also contributed to the mathematical field with his development of calculus. However, Gottfried Leibniz claimed to have developed his theory of calculus first because it was published first, though Newton claimed he developed it first but kept it to himself as he so often does. Though Leibniz published his work almost ten years before Newton did, at the time Newton’s work was published it was the more accepted due to the bias toward Newton. Although in present day, it is Leibniz’s notation and his way of writing calculus that is widely used. In my opinion, it is Leibniz that deserves most of the praise because it is the notation that is widely used in present day. In the situation of a person who first made a discovery but kept it secret, or the one who made it later and announced it first, I believe the one who announced it first should be acknowledged as the real discoverer because he or she is the only one that has distinct proof that it was their theory that was developed first. ⁴  

References:

¹ http://www.universetoday.com/38643/what-did-isaac-newton-discover/

² http://space.about.com/cs/astronomyhistory/a/isaacnewtonbio_2.htm

³ http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/KeplersLaws.htm
⁴ http://www.storyofmathematics.com/17th_leibniz.html

Images From:
Figure 1: http://www.crystalinks.com/newton.html
Figure 2: http://kepler.nasa.gov/Mission/JohannesKepler/
Figure 3: https://www.learner.org/courses/physics/visual/visual.html?shortname=figure6