John Pierson: Physics & Chemistry from 1650 to 1950

The following is a timeline by John Pierson covering the historical and philosophical progression of physics and chemistry from 1650 to 1950. As a clarification,you may notice that the duration specified for each item on the graph is different. For the events, this is simply the year in which the event occurred. For the people, this duration should cover a fairly accurate ballpark of when they were most active in their primary field or field of interest to the historical progression portrayed here. You may have also noticed that the items are color coded. The colors specify the field of work these people or events were most significant to, though do keep in mind that the color does not necessarily mean that they were restricted to only that field. Orange Refers to - Heat/Thermodynamics Purple Refers to - Electromagnetism Blue Refers to- Mechanics Green Refers to - Chemistry


Robert Hooke

1650 - 1665

Robert Hooke began to take a closer look at the microscopic aspects of the universe. He created the wave theory of light after observing the phenomenon of refraction. Also, Hooke was the first to look at the manner in which matter expands when heat is introduced, and he usefully thought about air as a collection of tiny particles separated by large distances.


1654 - 1662

Robert Boyle is considered the first real chemist, or in other words, the first scientist whose work could be considered to be make the transition between what was then known as alchemy and what is now known as chemistry. Boyle was an excellent experimenter and observer, and amassed huge amounts of scientific information. Boyle also formulated “Boyle’s law” which asserted the inverse mathematical relationship between the pressure and the volume of a gas.


1661 - 1666

Becher wanted to formulate a new way of thinking about heat that was more useful to science than the existing framework provided by the alchemic four elements. His new introduced elements (3 kinds of earth) were significant to an understanding of combustion- he theorized that in the process of combustion one of these earth elements was released. This was a key precursor to phlogiston theory.


1670 - 1687

Newton’s Principia published in 1687 was and still is incredibly significant to the historical progression of Physics. His Principia included the phenomenon of universal gravitiation and presented the three laws of motion. These theories formed the basis for classical mechanics which would be disputed and improved upon for hundreds of years after the Principia’s publication. Some of the subjects within his theory which would be later disputed by the scientific community were;
1. His assumption of linear motion.

2. His assumption of the existence of gravity and the true nature of this gravitational force.

3. His assumption that a lumineforous aether, or invisible medium exisisted throughout the universe and was a material through which all things moved
4. His theories of optics, light, and color


1694 - 1716

Stahl coined the term phlogiston theory based on the ideas of Becher, that certain matter (Phlogiston) had to be released in combustion. Noting that the processes of burning and decaying give off heat, Stahl thought phlogiston theory was an adequate framework to describe these phenomena. However, throughout the development of phlogiston theory, one anamalous result was repeatedly observed; durng the calcination of metas, it was observed that the metal prior to calcination weighed less than the calcified metal. The assertion that combustion releases a physical substance thus came into question.

The Steam Engine


Largely due to the work of Thomas Newcomen, the invention of the steam engine became more commercially successful and accessible to science at this time. To put it simply, steam power harnessed heat in order to produce motion. This process was easily observable in the workings of a steam engine, but the exact workings of this phenomenon were not fully understood until much later. In particular, the steam engine would prove useful to Carnot’s work in thermodynamics.


1771 - 1783

Lavoisier was important both to the progression of chemistry and to the scientific community’s understanding of heat. With respect to heat and combustion, a more effective method of explanation than phlogiston theory was needed. Lavoisier argued that in combustion, it made more sense that matter was absorbed (oxygen) than released (phlogiston). He thought that a new nomenclature for these phenomena was immediately necessary as the term “phlogiston” betrayed our way of thinking about these processes. It was for this reason that Lavoisier introduced the term “caloric”, the new “fiery material” which was a mass-less but nonetheless physical substance that passed through solids and liquids. In chemstry Lavoisier discovered elements such as hyrogen and oxygen, and he attempted to classify what he thought were the smallest units of matter as well as made important distinctions between compounds and elements.


1777 - 1783

Priestley was the first person to isolate oxygen, at the time calling it dephlogisticated air, and he disputed the phenomena of calcination and combustion with Lavoisier. Though he continued to support phlogiston theory and disgareed with many of Lavoisier’s new proposed theories, his work with oxygen and combustion provided Lavoisier with much of the information he needed to construct his theories.


1793 - 1807

In the early 19th century, Thomas Young formed the wave theory of light to rival Newton’s work on optics, which had claimed that light was particulate. Since the effects of light were not easily observable, Young’s research was mostly theoretical and based on analogy, though he was able to construct some experiments to reflect his theories. Specifically, Young’s double-slit experiment resulted in interference patterns and thus visibly revealed light’s wave-like behavior. This experiment also brought aether up again as a topic of debate within the scientific community, since many believed that there had to be an invisible medium through which these waves could spread.


1800 - 1815

Sometimes referred to as the “Kepler of Chemistry”, Dalton similarly looked for mathematical order in phenomena that originally seemed chaotic or unknowable. Dalton believed that different pure substances had different, but distinct and measurable capacities. He thus searches for distinct things that cannot be broken down any further, and he attempts to discover their relative weights. Concretely, he finds that mercury and water, with different mean temperatures, expand accordinging to the same law; as he says, their quantity of expansion is the square of the temperature from their respective freezing points. This bears implications for sciences predictive power with respect to temperature and pressure.


1802 - 1821

Gay-Lussac made an important contribution to the study of gases by performing experiments on chemical reactions, focusing on the ratio of the volumes of the gasses involved. Gay-Lussac discovered that the relationship between masses of the same volume of different gasses corresponds to the relationship between their respective molecular weights. This would prove useful to Avogadro.


1811 - 1823

Avogadro improved on Dalton’s work as Dalton had relied on weights, rather than volumes in his understanding the different kinds of molecules and their respective compositions. He also rejects Dalton’s assumption that two atoms have to combine in a one to one ratio. Avogadro’s ability to rethink the ratios and different compositions of molecular matter was largely due to the data of Gay-Lussac. He was thus able to theorize that equal volumes of gas at equal temperature and pressure held equal numbers of molescules, and that equal volumes of a gas could be used to determine atomic weights.


1816 - 1824

Along with Oerstead laid the foundations for electromagnetism. He discovered that magnetic needles were affected by electric currents, and demonstrated an experiment in which parallel wires carrying electric currents repel or attract each other depending on the direction of flow of these currents. This experiment was incredibly important to the field of electromagnetism and was later built on by Faraday.


1820 - 1822

Began to observe the interaction between magnetism and electricity, and specifically asserted that electric currents could create magnetic fields. With electrically charged copper wire and a compass, Oestead showed that magnetic effects spread in all directions from this wire in a circular pattern. This both proved his theories on the relation of electricity and magnetism, and contradicting Newton’s ideas on linear motion. Oerstead also suggested that light and heat were related to this electromagnetic force.


1821 - 1833

An excellent observer and experimenter who further explored Oerstead’s work with electromagnetism and light. Faraday was not an excellent mathematician but he had an incredible talents. One was his ability to invent and improve practical (physical) scientific tools, and the other was his ability to understand complex scientific phenomena by visualizing them in his head. Faraday invented something similar to what we now know as a motor in 1831 by using electromagnetism to create circular motion. Circular motion was at the time an edgy subject, as it could be said to contradict the largely accepted Newtonian physics which assumed linear motion. Also, Faraday's work with interaction of electricity, magnetism, and motion, would be incredibly significant to science going forward.


1822 - 1824

Carnot was able to improve the scientific community’s understanding of heat by taking a closer look at the workings of the steam engine. This physical heat engine became a jumping point for Carnot’s idealized engine or cycle, which allowed Carnot to make exact mathematical calculations concerning the relation of heat and motion. Though his theory used caloric rather than entropy in decribing heat phenomena, his work set the stage for the second law of thermodynamics which would soon be explored.


1840 - 1850

Like Carnot, a brewer named James Prescott Joule looked closely at heat and its relation to mechanical work. Joules work led to the first law of thermodynamics and the idea of conservation of energy, which states that the total amount of energy within a closed system will remain constant over a period of time. The distinction here is in the term energy, not heat; much of Joule's discoveries contradicted the claims of the caloric theory of heat formed by Lavoisier.


1845 - 1860

A scientific all-star, William Thompson or Lord Kelvin was involved in many fields including geology, physics, elecricity, but is particularly important to us here for his work in thermodynamics. He was a key player in the formulation of the first and second laws of thermodynamics, and improved on the work of many other scientists such as Joule, and Carnot. He debated the legitimacy of caloric theory, and was skeptical that heat, or a specifically a physical heat substance like caloric could be converted into mechanical power.


1850 - 1865

Considered one of the founders of thermodynamics, Clausius finally made a clear distinction between an understanding of heat as a physical thing and an understanding of heat as a motion of other things. His work marked an important shift from the caloric theory of heat to the kinetic, which began to use the term “entropy” to describe heat. Within this Kinetic theory, temperature or heat actually becomes a measure of velocity or motion. Clausius was credited with formulating the second law of thermodynamics which stated that over time, a system experiencing differences in temperature, pressure, and potential will form equilibrium.


1853 - 1860

Improved the scientific progression of chemistry by pursuing a more pure explanation of of the scientific phenomena in question and searching for a more consistent use of terminology. He championed the work of Avogadro, whose work was not considered important for some time, and he was thus able to improve the scientific community’s understanding of chemistry.


1860 - 1865

Farraday lacked the mathematical expertise to prove some of his theories. Maxwell’s calculations described how these electric currents could act as sources for magnetic fields and explains the behavior of these currents and fields as they act within time varying environments. He finds that the interaction between these two is based on a constant which is the speed of light at 671 million miles per hour. However, Maxwell’s equations presupposed the existence of an aether and evidently the existence of a fixed speed of light. Maxwell also made significant contributions to the Kinetic theory along with Boltzmann.

The Periodic Table

1869 - 1870

Since Lavoisier in the late 18th century, chemists had been attempting to organize a more precise method of classification for the elements or smallest units of matter. Mendeleev and Meyer both published nearly identical tables in 1869 and 1870, which classified these elements based on their atomic weight and other knowable characteristics. This table was enormously important as it was a reliable template on which scientists could stand in making their observations and experimentation. Future discoveries would not only confirm the table's usefulness but also serve to explain more clearly why it's composition is so accurate.


1877 - 1900

Along with Clausius, Thomson, and Carnot, Boltzmann was very much involved in the developing field of thermodynamics. With a new kinetic theory of heat, it was difficult to predict the behavior of certain phenomena as the changes that occurred were many, small, and random. For this reason Boltzmann began to use statistical analysis to provide a more useful method of measurement. This method proved useful to thermodynamics and would be especially important later in the field of quantum mechanics.

Michelson - Morley Experiment


19th century science was predicated on the notion that an "aether" or invisible material had to exist for light and sound to move through. Michelson and Morley designed a hihgly sophisticated experiment that was supposed to determine the existence and the nature of this aether; where and how does it move? And does it move at all? The results ended up presenting a strong case against the existence of an aether, and accordingly presented some scientific problems. If objects move through nothingness, how does light, a mass-less wave exist and behave the way it does? This shattering discovery changed the course of science.


1901 - 1923

Is considered the founder of quantum theory which studies very small systems composed of waves and matter by mathematics. Planck disagreed that the Copenhagen interpretation of quantum mechanics by bohr and Heisenberg was the best explanation of the how the particle and wave-like properties of matter and energy behave. Planck thought that this would not be necessary once more could be known about how waves work.


1905 - 1933

Einstein incited a revolution in physics by undermining the classical mechanics of Newton with his special and general theories of relativity. Einstein’s special theory of relativity used Maxwell’s equations on electromagnetism and applied them to mechanics. Based on the idea that there was no aether in existence, the special theory claimed that perception of speed and time was relative to the observers frame of reference. Within this Einstein postulated a constant speed of light in a vacuum. Einstein also wanted to think about Newton’s gravity in a new way, and incorporated this with his general theory of relativity.


1907 - 1917

Introduced the idea of radioactive half life in 1908, asserting that elements can disintegrate and transmute into other elements. In 1911 he developed one of the first atomic models as the “Rutherford model” which theorized that atoms have a positive charge concentrated in a small nucleus.


1912 - 1933

In 1913 Bohr published a model of atomic structure which illustrated the idea that electrons travel in distinct orbitals around an atom’s nucleus. He noted that the chemical properties of elements are largely decided by the number of electrons present in their outer orbitals. Within this model, he theorized that electrons dropped from high-energy orbitals to lower-energy orbits, causing an emittance of energy or light. This idea became very important to quantum theory. Bohr also formulated a complimetary principle to Heisenberg’s uncertainty principle, theorizing that things can show wave-like and particle-like properties but not both at the same time.


1922 - 1935

Introduced the uncertainty principle to quantum mechanics, based on the notion that all of the values of a system cannot be known at the same time. When dealing with large amounts of incredibly small matter, one could not know the positions or speed of this matter. He notes that the system of interest contains objects so small that “turning on the lights” or using any sort of detector would actually change the system. His theories showed that observation has significant effects on how the universe works, denoting a necessity to interpret quantum mechanics making use of statistical analysis.


1926 - 1935

Is significant for the cat-thought experiment he created relating to quantum mechanics. His experiment was supposed to point out the problem of the Copenhagen interpretation of quantum mechanics explored by Bohr and Heisenberg, but what it ultimately did was present a scenario that illustrates how something happening on a quantum level could affect something happening on a larger, classical level. The cat experiment served to illustrate that probabilities are the true reality of the universe until observers interfere and collapse this reality. This understanding helps Schrodinger and others make further discovers about quantum mechanics, such as beginning to think of electrons in terms of probabilities rather than in specific locations and trajectories.