This work outlined a heliocentric universe that broke away from the Ptolemaic geocentric model and offered new insights into planetary and retrograde motion of celestial matter. Although the book contained new answers to some formerly unexplainable observed planetary phenomena, it lacked the ability to explain earthly physical observations. As a result, the Aristotelian model was still preferred. However, this was the first major alternative to the geocentric theory and would begin what became known as the Copernican Revolution.
Using one of the largest sextons ever created, Tycho Brahe created the most comprehensive and accurate collections of observations ever assembled up to this point. He was believed to be accurate to within 1 arcminute (1/60 of a degree). Using these observations and his knowledge of the Copernican model, he creates his own cosmology. This new geoheliocentric system had the Sun revolving around the Earth while everything else revolved around the sun. He does not fully support Copernicus’ theory because he believes the Earth must be still based on the lack of stellar parallax he has observed over his years.
Johannes Kepler was a student of Tycho Brahe and inherited all of Brahe’s observations. Using these observational records, he is able to mathematically create three new laws:
1.) Planets move in an elliptical orbit with the sun as one of its foci
2.) Planets move more quickly when they are closer to the sun and slower when they are farther away
3.) (Distance)3 / (Time)2 = k(constant)
This is an important development because all of the laws are based on accurate observations and mathematical formulas, thereby adding a new level of certainty and validity to a developing heliocentric theory. His third law would be especially influential in shaping Newton’s idea of the sun exerting some kind of force on the planets.
Galileo becomes the first human being to ever see a magnified view of the sky in the winter of 1609. He observes the surface of the moon and sees it covered in mountains, craters, and valleys. He will go on to observe the moons of Jupiter, the different phases of Venus, and sunspots. All of these observations undermine Aristotelian physics and the Ptolemaic cosmological model. As a result, a new physics and cosmology becomes necessary to explain all of these new phenomena.
Descartes believed Galileo failed to show the dynamics of his new system by not explaining why bodies are moving but rather focused solely on the kinematic descriptions of motion. In an effort to succeed where Galileo had failed he published this discourse in 1637 that, along with his Principles of Philosophy in 1644, laid out his four methodological principles that he believes will provide the qualitative foundation needed for proofs regarding motion. They include Cartesian skepticism, analysis, synthesis, and inquiry. This became the foundation for Cartesian mechanics and epistemology.
Through several experiments, Galileo concludes a body’s rate of fall is independent of its weight and everything has the same uniform acceleration in a vacuum free-fall. This is a completely anti-Aristotelian conclusion and claimed the ancient concept of size does not affect the acceleration of falling bodies as people once thought it did. Although Galileo’s concepts of falling bodies, inertia, and projectile motion (published in his Discourses and Mathematical Demonstrations Relating to the Two new Sciences) failed to fully replace Aristotelian physics, it had successfully shown holes in the ancient system and set the conditions for much of Newton’s work.
Newton created this experiment to demonstrate his concepts of absolute space and time. The experiment itself involves a bucket filled with water suspended in the air by a piece of rope. The bucket is then twisted and released until it eventually comes back to a state of rest. If motion were relative, the bucket moving while the water was still and the water moving while the bucket was still would have to be identical. However, because there is an observable difference, the affects must be a result of accelerated motion in respect to absolute space. This concept of relativity would be revisited and reanalyzed by Einstein later.
Newton wrote this book in an attempt to make mechanics as certain as Euclid’s geometry by using mathematics and a systematic format. By the end of the book, he had set forth three laws of motion and a new theory of universal gravitation that could now be applied to all objects in motion throughout the universe. His first law was the law of inertia in which an object continues in a state of rest or uniform motion in a straight line unless otherwise compelled by other forces. His second law was the force law (F=MA) and his third law involved the idea that for every force there is an equal or opposite force. The final law was very important because it describes action at a distance. This book was the height of the scientific revolution and combined much of the previous work done by Galileo, Kepler, and others. It offered a new and complete way to think about the universe and provided a clear understanding to how forces of our world operate.
This was one of the many important discoveries found within Newton’s Principia. This law states every body is attracted to every other body with a force that is directly proportional to the product of masses of the bodies and inversely proportional to the square of the distance between the two bodies. (F = G[M1 x M2 / r2]) This law is relevant to both celestial and terrestrial bodies. This law solidifies Galileo’s observations regarding the planets orbits, the moon’s rotation, and centripetal force observed on Earth. This formula is also crucial because it allowed many new predictions to be made regarding the planets and other celestial matter.
In 1659, Robert Boyle built his first air pump with the assistance of Robert Hooke. He is now able to perform several hypothetical experiments that until this time have only been speculated upon by such people as Aristotle, Galileo, and others. After many tedious experiments, Boyle proves a vacuum or void can exist within his air pump. Eventually he is able to develop what becomes known as Boyle’s Law, which states the pressure and volume of a gas are inversely proportional. His experiments and publications are considered to be the first real emergence of modern chemistry.
In 1667 Becher published Physical Education and in it outlined the beginnings of the Phlogiston theory. Phlogiston was thought to be a tasteless, colorless, odorless, massless element that was contained within anything that could burn. It was a widely accepted principle for a long time because it was able to explain many of the observed results seen in many combustion processes. Lavoisier would eventually put an end to the theory through his ice calorimeter experiment.
In 1774 Priestly made a brand new discovery by isolating “air”. He would go on to further explain this discovery in a paper entitled An Account of Further Discoveries in Air, which he presented to the Royal Society in 1775. He called the new substance dephlogisticated air, what today we know of as oxygen gas. This was a pivotal point in the developments of chemistry and heat. This discovery would eventually help lead to the end of the phlogiston theory.
Lavoisier and Laplace performed a series of experiments involving coal, a guinea pig, and an ice calorimeter they had created. By the end of the experiment they had proven the combustion that takes place when the coal is burning and the respiration that takes place while the guinea pig is breathing is in fact the same process. This idea of respiration as a slow form of combustion suggested a mechanical model for living things and put an end to the phlogiston theory.
Lavoisier wrote this book to be a textbook. It is kept to the most simplistic manner possible and attempts to set the foundations for the rising scientific field of chemistry. The book is broken up into three parts: proofs and ideas, nomenclature and neutral salts, and operations of chemistry. This book solidified Lavoisier as the “father of modern chemistry” and set the format for all future work done in the field of chemistry.
This law is named after the French chemist Joseph Louis Gay-Lussac. In 1802 Gay-Lussac formulated a law stating that if the mass and pressure of a gas are held constant then the gas volume will increase linearly with an increase in temperature (V=kT). This was an important chemical discovery and is the basis for ideal gas laws still used today.
Joseph Black was a Scottish scientist who observed that the application of heat to boiling water does not increase the temperature of the water but instead increases the amount of steam. This leads him to develop some of the earliest concepts of latent heat, which will go on to become the foundation for thermodynamics. Black also went on to contribute to the idea that different substances have different specific heats. Both concepts would go one to fuel the creation and development of the modern steam engine.
Sadi Carnot was a French physicist who developed the Carnot Cycle, which described the process of an ideal heat engine. It was split into four steps by which the engine would convert heat into work in the most efficient manner possible. This cycle is contingent not on the working substances but rather the temperature range under which the work is done. This theory would become the foundation for what became known as the second law of thermodynamics and solidified Carnot’s reputation as the “Father of Thermodynamics.”
Thomson, also known as Lord Kelvin, was a mathematical physicist and engineer. Although he had several noteworthy accomplishments throughout the scientific fields, the paper he wrote in 1851 outlined his critiques of Carnot’s “death of heat” and maintained heat may be lost but not absolutely lost. This would become a critical component of that would eventually, along with the works of Carnot and others, form the second law of thermodynamics.
Named after William Thomson, or Lord Kelvin, the Kelvin scale is a thermodynamic temperature scale that uses absolute zero as the null mark. This value scale is important because it defines absolute zero as the point where entropy has reached a minimum and molecules lack any motion. This is an important concept on both a thermodynamic and quantum level. This set limit to the degree of cold would now become the theoretical benchmark for atomic and thermo concepts going forward.
In 1704 Newton published Opticks, a book that summarized his work and theories regarding the optics and refraction of light. In it, Newton discusses his two-prism experiment where he shines white light through a hole and into a prism, thereby creating a dispersion of colors across the spectrum. He then goes on to pass the rays of light through a second prism. This time, no further dispersions were observed. This leads Newton to believe the Cartesian modification theory of light is incorrect and the colors of light in fact arise independently.
Up until this point light was believed to be a particle such as the ones described by Newton in his Opticks. Young was very heavily influenced by Newton’s idea of corpuscles and cited him extensively when developing his wave theory. This new theory involved light traveling through weightless ether. This new wave theory is accentuated in Young’s double slit experiment and re-sparks the debate over what light is and how it works.
This experiment became the major arguing point for the wave theory of light started by Thomas Young. In the experiment, a light source is passed through two slits and projected at a further surface. In a corpuscular or particle theory of light, one would expect to see two points of light on the far side with a few very slight points surrounding it from where some of the particles intersected the edge of the slit. However, when Young performed the experiment he observed several distinct points of light on the far side. This leads Young to the conclusion that light must have wave-like qualities that create a ripple effect after passing through the two slits. This was not only a very important experiment for the wave theory of light but would also be revisited later upon the development of quantum mechanics.
This experiment was first performed by Albert Michelson and Edward Morley and was meant to detect he absolute motion of the Earth through space. Essentially the experiment involves a beam of light refracting off a sliver sheet, hitting mirrors, and returning to one spot. If the ether exists, an interference of some kind should and must occur in the measurement of the light. However, when Michelson and Morley perform the experiment they end up having both beams of light coming back at the same time. Therefore the ether must not exist. Initially, they are unable to explain the outcome of their own experiment, but this marks the death and end of the ether theory of light.
Dalton was one of the first scientists to begin developing the modern atomic theory. In this book he discussed elements, chemical combinations, and atoms. Dalton described atoms as the smallest possible unit of matter and believed each element was made up of its own unique atoms. These unique atoms are what give different elements and compounds their different characteristics. This was a very important work within development of the atomic theory and the periodic table.
The law, developed by Amedeo Avogadro, states that any two given samples of an ideal gas, at the same temperature, pressure, and volume, contain the same number of molecules. In other words, the number of molecules or atoms in any specific volume of a gas will be independent of size. This is a combination of the gas laws formulated by Dalton and Gay-Lussac. This, along with Avogadro’s diatomic theory, was a major development in the atomic theory.
Several scientists had made various kinds of atomic tables and categories by this point in history. However, in 1869 Mendeleev presented a talk to the Russian Chemical Society called The Dependence Between the Properties of the Atomic Weights of the Elements. In this talk he describes, categorizes, and lists the known elements according to their atomic weight and valence. This setup recognized the periodic properties of the elements’ atomic weights, grouped them according to common properties, and predicted where new elements should be found and appear. This was a very important structure that would go on to unify chemistry and elemental research among scientists and become the basis for the modern periodic table still used today.
Boltzmann was a very influential character in the development of the atomic theory. The Maxwell-Boltzmann distribution for the molecular speeds in gas was one of his most crowning achievements and would go on to become the foundation for classical statistical mechanics. This idea maintained it was impossible to know the exact position and speed of a single molecule due to the insignificant size and given amounts. As a result, one must rely on statistics to make predictions. This idea of uncertainty and probability would be influential in the development of the kinetic and atomic theories.
Thomson was a British physicist credited with discovering the electron. His most well-known and influential work was done using cathode ray tubes. In these experiments, Thomson would send a very low, controlled beam of light through a glass tube. When a magnet was placed near the tube, the current would bend toward the positive end of the magnet. This leads Thomson to think these particles must contain very small components within the atom itself. The atom itself must also contain both positive and negatively charged components. This is a major step in the atomic theory and development of the atomic structure of atoms.
This experiment involved shooting an alpha particle at an incredibly thin piece of gold foil and seeing what, if any, deflection takes place. They believed they would only find a very slight degree of deflection. However, when they perform the experiment they find the alpha particles go flying off in every direction. This meant J.J. Thomson’s plum pudding model was no longer viable. Instead, Rutherford suspected the alpha particle was highly compacted in the middle of the atom with the negatively charged electrons hovering it and taking up most of the space. This was the first time an atomic nucleus was demonstrated and was very important to the development of the atomic model as a whole.
Poisson is mostly known for his works in applied mathematics and mathematical physics. He developed several equations using the work of many famous past and present scientists. One of his most notable contributions came in his work on electricity and magnetism. He proposed electricity may be two kinds of liquids, the opposite ones attract while the similar ones repel thereby bringing everything into balance. This would be the beginning of the eventual connection between electricity and magnetism.
In 1820 the Danish physicist Hans Oersted developed the relationship between electricity and magnetism and called it electromagnetism. He deduces through experiments involving a copper wire carrying a change near a compass. He notices the needle of the compass will move depending on where they place a magnet near it at any given point. Because the magnet never touches the compass there must be field acting on the compass, an action at a distance. In other words, there is a magnetic field created by the electrical current. This circular force was very anti-Newtonian and did not initially fit into the mechanical idea of nature at the time. However, this would be a stepping-stone for Faraday and further development in the field of electromagnetism.
Faraday is credited with finding the electromagnetic field described by Oersted. Through a series of experiments involving magnets, metals, and electricity, Faraday was able to discover that by changing a magnetic field he was able to produce an electric current and motion. This proved the electromagnetic connection supposed by many past physicists. This final discovery led to a further understanding of the relationship between electricity, magnetism, and light.
Named after the Scottish physicist and mathematician James Maxwell, this equation mathematically explains and defines the relationship between electricity, magnetism, and the speed of light by combining several different equations and constants found in each individual phenomenon. Essentially, he provides the math needed to prove and interpret Michael Faraday’s electromagnetic wave theory.
After several years of refining his theory and eventually applying Boltzmann’s statistical mechanics, Max Planck developed a mathematical law to explain black bodies. A black body is a physical body that absorbs all kinds of radiation, including light. When heated, they also emit all kinds of radiation. This work on black bodies help further the understanding of quantum mechanics and would help once again bring back the idea that light may in fact be a kind of particle.
Special relativity is outlined in Einstein’s On the Electrodynamics of Moving Bodies. This would be the first point in a major shift in quantum mechanics in which the Newtonian concept of space and time would be challenged and shaken. First, Einstein describes the principle of relativity in which the physical description of any event appears the same in all inertial frames of reference. Einstein also maintains the speed of light is constant and independent of the source of motion. This theory has many implications, one of which being the idea that position and time are interconnected. This special theory of relativity would lead Einstein to develop a general theory and expand upon these new ideas of force, motion, and time.
1905 has been called Einstein’s miracle year because in this very short period of time this completely unknown amateur scientist would publish four papers that would go on to make him one of the greatest physicists of the era and possible one of the greatest scientists of all time. The first paper was called On a Heuristic Viewpoint Concerning the Production and Transformation of Light and it described the photoelectric effect. The second paper, On the Motion of Small Particles Suspended in a Stationary Liquid, as Required by the Molecular Kinetic Theory of Heat, explained Brownian motion, the erratic motion of tiny particles. The third paper was called On the Electrodynamics of Moving Bodies and described what would become known as the special theory of relativity. The final paper, entitled Does the Inertia of a Body Depend Upon Its Energy Content?, outlines the equivalency of the inter-convertibility of mass and energy, which is commonly expressed in the famous equation E = MC2.
This was a continuation and adaptation of Einstein’s special theory of relativity published a decade earlier. The theory states the gravitational field is curvature in space-time. This idea extended the relativity principle from constantly accelerating frames of motion to now being applicable to all physical frames of reference. This theory also gave way to the idea of red shift and a constantly expanding universe. Einstein’s general theory of relativity universalized his new conception of space-time and created an entirely new quantum view of the universe we live in.
This is the name given to the interpretation of quantum mechanics developed by several prominent scientists within Copenhagen, including Niels Bohr, Werner Heisenberg, and others. It involved such concepts as the Heisenberg uncertainty principle and Bohr’s duality. There is no agreed upon text of any kind because it is simply a combination of several theories. However, it became the main interpretation of the time and was very successful in connecting classic physics with new quantum theories and explaining it in natural and understandable language.
Heisenberg’s principle maintains one will never be capable of knowing both the speed and position of any quantum matter simultaneously. In other words, complete determinism will never be possible. The reason for this is, particles at the atomic level are so small that even observing them interferes with the system as a whole. Therefore, the system one observes will be entirely different from the one that formerly existed. This principle proves the quantum theory must be governed by probability and statistical mechanics rather than classical determinism.
Another major part of the Copenhagen Interpretation was Niels Bohr’s wave-particle duality principle. This is the idea that all particles have a wave nature and vice-versa. This is the foundation for the complementarity principle that asserts a phenomenon may be viewed in one way or the other, but not both simultaneously. This duality concept would aid in bringing an end to the debate between physicists regarding whether light was a wave or a particle.
The “Great War” broke out in 1914 and consumed a majority of the world for four years. This was obviously a crucial period of history for mankind as a whole, but also involved several historically scientific implications. The division among countries severed the vast majority of intellectual interaction among rivaling nations, many scientists were ostracized and driven from their homelands and initial areas of study, and perhaps most importantly World War I was the beginning of modern science’s infusion into the military realm.
World War II affected the scientific community in many of the same ways World War I had. This time it was arguably far worse. Scholastic communications were even harder, controlled countries were very hostile, and scientific knowledge, specifically in the emerging area of fission, was highly exploited by every government in an attempt to swing the outcome of the war in their favor. This would raise many new moral questions for individuals and nations. The role of science in the military and government would drastically change and become very intertwined.
The Manhattan Project was a highly secretive and classified research project that took place in the United States during World War II. It assembled some of the top scientists of the day to create an atomic bomb using fission within Uranium and Plutonium. The eventual success of this project resulted in two bombs being dropped on Japanese cities. This weapon did bring about an end to the war, but the collaboration of science and military force would bring about modern warfare as we know it today and forever reshape the political and scientific communities that exist currently.