1897: Electron

Posted on by Dan
An atom showing its protons, neutrons, and electrons.
Nuclear Structure of the Atom

The atomic theory of the atom was proposed by John Dalton in the early 19th century. Dalton claimed that all atoms of the same element are identical, but that atoms of different elements vary in size and in mass. His theory suggested that atoms were indivisible particles, making them the smallest building blocks of matter. However by the middle of the 19th century, a growing body of experiment evidence began to challenge this notion. As the century drew to a close some scientists that speculated that atoms may be composed of additional fundamental units, and by the late 19th century convincing evidence began to emerge from experimental research to support this hypothesis.   The discovery of the electron was the first of a series of discovery’s, spanning a few decades, that identified the major subatomic particles of the atom.

J. J. Thompson’s Experiments

This experimental evidence came during the years 1894-1899 when J. J. Thomson conducted research with cathode ray tubes, the same technology that also played a critical role in the discovery of X-rays and on work which led to the discovery of radioactivity.  Cathode rays are the currents of electricity observed inside a high vacuum tube.  When two electrodes are connected to each end of the tube and voltage is supplied, a beam of particles flows from the negatively charged electrode (the cathode) the positively charged electrode (the anode).  In a lecture to the Royal Institution on April 30, 1897, J. J. Thomson suggested that these beams of particles were smaller, more fundamental units of the atom.  He termed them ‘corpuscles’ but the name never stuck, and they were eventually given name we are familiar with today: electrons. 

J. J. Thomson's cathode ray tube used to discover the electron
J. J. Thomson’s cathode ray tube used to discover the electron
(Credit: Donald Gillies)

J.J. Thomson performed several experiments whose conclusions supported his hypothesis.  Firstly, in 1894 Thomson established that cathode rays were not a form of electromagnetic radiation, the assumption at that time, by showing that they much move slower than the speed of light. Soon after he conducted experiments deflecting the rays from negatively charged electric plates to positively charged plates where he was able to show that the beams were streams of negatively charged particles.  In another experiment he used magnets to deflect the beams which allowed him to determine their mass-to-charge ration.  He approximated their mass at 1/2000th of a hydrogen atom indicating that they must be only a part of an atom.  This is an incredibly small mass and is the smallest measured mass of any particle that has mass.  Lastly, he showed that these particles are present in different types of atoms.

Diagram of a cathode ray tube
Diagram of a cathode ray tube

The revelation that atoms are made of smaller constituent units revolutionized how scientists viewed the atom world and spurred research on nuclear particles.  Soon after the atomic nucleus was discovered, and the field of nuclear physics was born.  Thomson went on to create one of the first models of the atom, which was called the plum pudding model.  He knew that atoms had an overall neutral charge.  Therefore, his model depicted the negatively charged electrons floating in a “soup” of positively charged protons.  It was a good first attempt at designing a model of the atom but was soon discarded for Ernest Rutherford’s nuclear model of the atom based on the results of his gold foil experiment.  

Impact and Legacy

The discovery of the electron had profound effects on both theoretical and applied science.

The discovery of the electron helped to usher in the era of atomic physics and help to give birth to the completely new and foreign field of quantum mechanics.   Both of these fields are closely related and describe the behavior of particles at the atomic and subatomic level.  Both fields rely on an understanding of atomic structure, of which electrons are a key component.

The discovery of the electron also had a fundamental impact on applied science as it laid the foundation for the development of electronics, a technology that would revolutionize our world.  Electrons, being charge carries, are the fundamental working units of electronic components such as capacitors, diodes, resistors, and transistors.  They are used in all of the familiar electronic devices such as televisions, smartphones, and computers and have made possible the digital transformation of our civilization. In addition to electronics, electrons are involved in atomic spectroscopy, which is the study of the interaction between light and matter. By studying energy levels and transitions of electrons, atomic physicists can identify elements, determine their properties, and study their behavior in various conditions. Spectroscopy is the method used by astronomers to determine the temperature, chemical composition, luminosity, and other characteristics of distant stars across the universe.

Continue reading more about the exciting history of science!

Joseph John Thomson

Posted on by Dan

Joseph John Thomson (1856 – 1940) was an English Nobel Laureate who made key contributions to the field of physics.  Most notably he is credited with discovering the electron.

The Life of J. J. Thomson

Joseph John Thomson
J. J. Thomson

J.J. Thomson was born in Cheetham Hill near Manchester in England.  His father planned for him to be an engineer, but when an apprenticeship couldn’t be found he was sent to Owens College at the young age of fourteen.  There he obtained a small scholarship to attend Trinity College, Cambridge where he obtained his Fellowship, received his Master of Arts degree, culminating in the Cavendish Professor of Physics at the University of Cambridge.

While at the University of Cambridge, Thomson did important research to advance our understanding of the atom.  Most important he was one of the first to suggest that the atom may be composed smaller, more fundamental units.  He carried out research with cathode rays, which are beams of light the follow from electrical discharge in a vacuum tube, that led to the discovery of the electron.  From his experiments, he was able to at which these rays were deflected by a magnetic field and to calculate the ration of the electrical charge to the mass of the particles.  What he discovered was that this ratio was always to same no matter what gases were used, and thus he determined that the particles making up the various elemental gases must be the same.

Along with discovering the electron Thomson was the first to determine that each hydrogen atom has only one electron.  He was pivotal in inventing the mass spectrometer which assisted in chemical analyses.  Thomson received various awards for his scientific achievements throughout his life including a Nobel Prize in physics in 1906.  He was knighted in 1908.  JJ Thomson died in 1940 at the age of 83 and was buried in Westminster Abbey with many other scientific greats.

Continue reading more about other impactful scientists!

John Dalton

Posted on by Dan
John Dalton portrait
John Dalton

John Dalton (1766 – 1844) was an Englishman born into a relatively poor Quaker family but due to his high intelligence and persistent curiosity he grew to make many important contributions to science in meteorology, chemistry, and physics.  He is remembered most for integrating atomic theory with chemistry.

Dalton embodied the Quaker way of life, living a humble life, never marring and never having any children.  He was content with teaching, lecturing, and doing his research.  In 1794 he wrote his first scientific paper on color blindness, concluding that color blindness was hereditary.  Both he and his brother were color-blind.  Although the specifics of his theory turned out to be incorrect, color blindness was termed Daltonism as a result of his work.

In the early 1800s Dalton formulated his atomic theory, although how he developed his ideas are not fully known.  But he did have a lifelong interest in meteorology and recorded over 200,000 observations in his diary.  He realized that evaporated water was independent or air, that they were each made of discrete particles, and that they mixed and occupied the same space.  Through that he conducted various other experiments on the other known elements of the time – hydrogen, carbon, sulfur, and more – in an attempt to  determine their relative sizes and weights.  He was thus able to formulate a complete atomic theory, although naturally some of his ideas turned out to be incorrect.

Dalton’s atomic theory states that elements are made of vanishingly small, fundamental particles called atoms.  These particles contain the same properties for each element but are different for different elements.  Chemical reactions occur when atoms from different elements are combined or separated.

In 1822 the Royal Society elected him as a member; eleven years later the French Academy of Sciences elected his as a foreign member.  Eleven years after that, in 1844 Dalton died of paralysis.  His ideas lived on laying the framework of atomic theory for future scientists to improve upon and thrust the atomic idea to the forefront of the physical sciences.

1730: The Marine Chronometer

Posted on by Dan
Marine Chronometer
A Marine Chronometer

Amazing that it may seem to people living in the 21st century, finding reliable longitudinal position at sea was not possible until 1730 when John Harrison invented the marine chronometer, a timepiece c

Maritime travel and trade was rapidly expanding in the time leading up to the 18th century.  The discovery of the North and South American continents by European explorers resulted in transoceanic voyages being made for the first time.  This meant a majority of time spent at sea spent out of sight of any landmass, making it trickier to accurately navigate the voyage.

The principle unresolved problem in these transoceanic voyages was finding reliable a longitudinal position while at sea.  This was not possible until 1730 when John Harrison invented the marine chronometer, a timepiece capable of keeping accurate time of a known, fixed location.  

The Longitude Problem

To determine a location one needs to know both the latitude and longitude of the location.  Latitude could easily be measured by using the sun or the stars.  Longitude was more difficult in that it could be calculated by comparing two accurate times – one of a known longitude (a Prime Meridian) and the other at any other location.  A little math works out the rest.  The Earth makes one full rotation per day (360º of longitude) and therefore turns one degree of longitude in 1/360th of a day, or every four minutes.  Work out the time distance from your location to the Prime Meridian, and you know your degree of longitude from the Prime Meridian.

Therefore the trick to determining longitude at sea then required an accurate timekeeping device that had to work on a ship.  However the only known accurate timekeeping devices of the time used a pendulum, which swayed as the boat rocked at sea.

Early methods of measuring longitude proved to be inaccurate, sometimes with deadly consequences.  The most common technique was called dead reckoning.  Beginning with a know starting location, the longitude was simply estimated by the captain based on a number of factors such as current and wind speed, direction of travel, and other factors.  The result was at best a close approximation with compounding errors decreasing the accuracy over time and distance.

A series of naval disasters, most notably a 1707 wreck of four British war ships that saw a loss of over 1500 lives, prompted the British government into action.  The Longitude Act of 1714 provided an incentive to solve this problem by offering a longitude prize ranging from £10,000 to £20,000 to anyone who could provide a simple and practical method to accurately determine a ship’s longitude at sea within one half of a degree.  Four years later the Academie de Paris offered a similar prize.  The race was on to solve the problem. 

John Harrison and the Marine Chronometer

Born in Yorkshire and a carpenter by profession, John Harrison invented a mechanized timekeeping machine that solved this problem which he called a chronometer.  This device was, in a sense, the worlds first global positioning device.  In 1730 he began working on his first prototype which he called H1.  The project took him over five years to complete and he presented his device to the Board of Longitude in 1736.  He was granted a sea trial – the first given by the board – and the device performed well.  He was award small grant for further development and Harrison set to work on his H2 device.

A series of Marine Chronometer devices made by John Harrison - H1 to H4
A series of Marine Chronometer devices made by John Harrison – H1 to H4

Over several years Harrison further refined his sea clock in the form of his H2 and H3 devices, but came to realize the device was fundamentally flawed.  He shifted gears and went from making a sea clock to a sea watch.  He realized that some watches would keep time as accurate as his larger sea clocks and were much more practical for sailing.  This lead to his most famous device the H4, which kept nearly perfect time, was around five inches in diameter.  

Harrison’s H4 watch essentially was a large pocket watch that was wound daily.  It possessed a 30-hour power supply. The main technological breakthrough of all his devices was a spring driven mechanism that replaced the pendulum.  The smaller watch allowed for a higher frequency of the balance, making it more accurate than his clocks. Various combinations of metals were used in the watch to overcome the deleterious effects of humidity and temperature change.  The watch took six years to construct, was completed in 1759 and tested in 1761.  The watch passed the test with remarkable accuracy.  It lost a mere five seconds on an 81 day voyage to the West Indies and back.  After some wrangling Harrison was able to receive his prize from the British government for the design. 

Continue reading more about the exciting history of science!

James Watt

Posted on by Dan

James Watt (1736 – 1819) vastly improved the Newcomen engine with a new steam engine of his own in 1781.  Watt’s improvements on the Newcomen’s engine provide one of the first significant examples of the application of cutting edge scientific research towards a technology that benefits society.

James Watt portrait
James Watt

Watt was born in Scotland, was the son of a shipwright, ship owner, and merchant and he never attended university because he was intended to take over the family shipping business when he grew older.  However when the family shipping business failed Watt traveled to London to learn instrument repair and returned to Scotland a year later where he eventually ended up working at Glasglow University as an instrument maker.   It was here that Watt began to experiment with steam power, and in 1763 Watt asked to repair a Newcomen engine from the university.

While fixing the Newcomen engine, which had been in use and remained largely unchanged in its design for over half a century, Watt noticed the huge inefficiency required to fully heat and then fully cool the entire massive cylinder at every stroke of the piston.  His insight was to create two chambers – one which was kept hot all of the time and one which was kept cool all of the time – that was connected by a valve that allowed steam to flow from the hot to the cool cylinder, where once it condensed would create the vacuum required to create the atmospheric pressure necessary to power the engine.  This change dramatically improved the efficiency and cost-effectiveness of the steam engine.  He also added subsequent improvements to his engine based on further experiments such as his double acting engine, which was a true steam engine as opposed to an atmospheric engine.

In 1769 Watt was able to patent his engine designs and he went on to have a successful commercial partnership with Matthew Boulton, an English manufacturer.   The Boulton & Watt steam engines were state of the art at the time and helped to advance the Industrial Revolution through their usage in factories and mills.  His legacy as a scientist and inventor is immortalized in the SI unit of power, the watt, being named after him.

Nicolaus Copernicus

Posted on by Dan
Nicolaus Copernicus portrait
Nicolaus Copernicus

Nicolaus Copernicus (1473 – 1543) can be equated with the person who’s work began the Scientific Revolution in Europe in the sixteenth century.  Although people think of Copernicus as a scientist he was really more of an intermediary between the ancient philosophers and modern scientists.  He did not carry out experiments or make any meaningful observations of the heavens.  Instead he had an idea for a model of the universe that he believed was better than any previous idea, and it happened to turn out to be correct.

Copernicus was born in Torun, a Polish town, and was the son of a wealthy merchant.  He eventually moved to Italy where he studied in universities there and was influenced by the humanist movement occurring at the time.  It was there he read a book by a German mathematician known as Regiomontanus called Epitome of the Almagest, where inconsistencies of the Ptolemaic model were pointed out.  This created doubt in Copernicus’ mind about the accuracy of Earth centered Ptolemaic model of the universe and he began to formulate an outline of a heliocentric model when he had mostly complete by 1510.

Copernicus’ model was much simpler than the Ptolemaic model in that it eliminated the need for the many cumbersome equants, epicycles, and deferrents needed to make the model work.  Despite its elegance, Copernicus delayed in publishing his work until the year that he died in 1543 when he published On the Revolution of the Celestial Spheres.  His delay in publishing was probably due to fear of criticism.  While it did provide a workable model of the universe it also raised many questions (both theological and physical) that Copernicus would have had no way of answering.  It was because of these questions that the Copernican model took almost a century to become widely accepted when the invention of the telescope proved inconclusively that his model was correct.

1712: The Newcomen Engine

Posted on by Dan

In 1712 Thomas Newcomen unknowingly ushered the world into the industrial revolution when he built an “atmospheric” engine to pump up water from a coal mine near Dudley Castle in England.  The Newcomen engine, as it came to be known, can thus be considered one of the most influential inventions in all of history.

A Novel Solution to a New Industrial Problem

The Newcomen Engine
The Newcomen Engine

The demand for coal was steadily increasing in the early 18th century and coal miners were having to dig deeper and deeper into to ground to gather it. Flooding of these ever deeper coal mines was becoming a problem to the point that manual and horse powered pumping was becoming an inadequate solution. At the dawn of the industrial revolution, and industrial machine was needed to solve the problem.

An ironmonger named Thomas Newcomen by combining ideas of various precursor engines. About a decade earlier an English inventor named Thomas Savery patented a steam powered pump which was not technically an engine because it had no moving parts. At around the same time the French physicist Denis Papin was conducting experiments using steam cylinders and pistons. Newcomen combined these ideas to eventually solve the problem by inventing the world’s first practical fuel-burning engine in 1712.

The Newcomen engine was a large, lumbering, and inefficient engine that did its work not by the power of steam but by the force of atmospheric pressure.  The discovery of the vacuum in the prior century showed the power of atmospheric pressure and this principle was utilized in the Newcomen engine. This engine was a very complex device despite being predicated on rather simple principles. Its basic method of operation goes as follows. A boiler created the steam that was pumped into a cylinder where the steam was then condensed by cold water. This process of heating and then cooling created a vacuum inside the cylinder.  The resulting atmospheric pressure created inside the cylinder forced a piston downward, pulling the pump upward and thus removing the water out of the mine.  The boiler created more steam pushing the piston upward where more cold water was introduced into the cylinder and the cycle was repeated around twelve times per minute.

Searching for Improvements in Energy Efficiency

What the Newcomen engine possessed in revolutionary status it lacked in efficiency.  The engine was highly inefficient and originally only used in coal mines where a power source was abundant and nearby.  However despite the engineering drawbacks its usefulness proved quite valuable – over 75 were built during Thomas Newcomen’s lifetime and over 1000 were in use by the end of the century.  They quickly spread across most of Europe and to America. The problem with the engine continued to be in its lack of efficiency. It was becoming difficult to operate in area’s where coal was expensive or in low supply.

Still, the Newcomen engine remained largely unchanged and in wide use for most of the 18th century. These engines saw an efficiency improvement later in the century by James Watt. In 1764 Watt was repairing a Newcomen engine when he became fixated on the amount of coal needed to operate the engine because it wasted so much heat. After mulling over a solution for some time he realized that much of the inefficiency had to deal with the heating and the cooling of the steam in the cylinder. He concluded that it would be much more efficient to keep the cylinder heated about boiling points at all times and to have a separate condenser for cooling. In 1769 he acquired a patent for his new device and soon after entered into a partnership with Matthew Boulton. The Boulton & Watt steam engines quickly became the best in the world. Later on Watt designed a double acting steam engine by allowing steam to enter the cylinder at both ends providing for both up and down power strokes. This was now a true steam engine.

Impact of the Newcomen Engine

The invention of the Newcomen engine marked the beginning of the Industrial Revolution. Prior to the Newcomen engine most power was supplied by natural sources such as wind, water, and human and animal muscle. The newcomen engine and the subsequent improvements made by James Watt paved the way for steam powered transportation in the form of boats and railroads. Electricity and the internal combustion engine would eventually replace powering engines for transportation in the 20th century, but even to day we still most of our electricity from steam powered turbines.

Continue reading more about the exciting history of science!

1735: Systema Naturae

Posted on by Dan

Systema Naturae was the manuscript published by Carl Linnaeus that marked the beginning of the modern system of species classification by establishing a hierarchical naming system for organisms.  This manuscript was originally published in 1735 and began as a small twelve page book.  Over the decades subsequent editions were published, twelve in all, with the last one being published in three volumes and consisting of over 2,400 pages.

Earlier Attempts at a Classification System of Life

The Greek philosopher Aristotle was the first to attempt to classify life in his History of Animals.  He chose to classify life according to its similarities in the form of a ladder-like hierarchy.  He regarded species as fixed and unchanged.  Medieval scholars, guided by Aristotle and the Bible, built on this idea creating The Great Chain of Being.  This classification system arranged the universe according to its natural order as decreed by God.  Those of the simplest order such as minerals were placed at the bottom, and that of the highest order which was God is seated at the top.  Consequently, this scale of natural order was borrowed by medieval rulers to justify slavery while helping to create and maintain a socially rigid hierarchy consisting of kings, nobles, vassals, peasants, and slaves. 

During the Renaissance scientists began experimenting on different classification systems. The discovery of new species of plants and animals in the New World, Africa, and Asia prompted excitement from scientists who were eager to place them into existing classification systems. But this also lead to a reanimation of the existing systems and encourages exploring with new and different systems.

Carl Linnaeus and the Classification of Species

Systema Naturae
Systema Naturae

Carl Linnaeus, later known as Carl von Linne, was born in southern Sweden to into a modest family where he became interested in plants form an early age. He was unique among scientists in this age in that his name went from a Latinized form to one of the vernacular, and this probably speaks to the high opinion of himself that he held throughout his life. After completing his medical studies he became intrigued by the idea that plants reproduce sexually through male and female parts corresponding to those of animals, although it seems he never fully understood the role of insects in pollination.

While on an expedition to the Netherlands in 1735 and still a student he published his ideas on taxonomy called Systema Naturae. This work went through many subsequent editions and quickly grew in volume. This first edition only included plants, his later editions included both plants and animals.

The tenth edition, published in 1758, is widely considered as the starting point for modern zoological nomenclature.  Throughout this edition Linnaeus used binomial nomenclature for all species – both plants and animals whereas in previous editions he had only used binomial nomenclature for plants. He was not the first person to use binomial nomenclature for life, Aristotle used it in his classification system but did not do so methodically.

The data accumulated throughout his various publications was immense. He provided names and descriptions for over 4400 species of animals and 7700 species of plants, mostly all of the species known by Europeans at the time. Everything in the living world was placed in a hierarchy of relationships. The hierarchy began with broad categories such as Kingdom and Class and moved down the ranks to the Genus and Species. Linnaeus took the bold step of placing man into his system of biological classification system with the Primates, a controversial move at the time. Despite this move Linnaeus still very clearly a religious man who considered man to be a special creation of God.

The Impact of Systema Naturae

It is had to overstate the influence of this book and its author.  Linnaeus’s system immediately proved useful and was soon quickly adopted by others. One of its main benefits was that it was straightforward and clear. Prior to Linnaeus taxonomy was burdened by cumbersome and inconsistent names.  Systema Naturae created a global system of naming and ranking organisms – a naming system that supersedes languages – that we continue to use to this day, with only some exceptions to the Linnaeus’ ranking system. 

With this rise of evolutionary thought a century later classification became a tool to explain genealogical relationships. Charles Darwin’s Theory of Evolution rendered the old idea of Aristotelian natural order behind Linnaeus’s system invalid. He showed that evolution could produce a hierarchy of similarity based on common decent.

Continue reading more about the exciting history of science!

Carl Linnaeus

Posted on by Dan

Carl Linnaeus (1707 – 1778) is famous for his work on species classification and his system for classification based on ranking and naming species is still in wide use today.  Linnaeus is often regarded as the father of modern taxonomy.

Early Life

Carl Linnaeus portrait
Carl Linnaeus

Linnaeus was born in Rashult, a town in southern Sweden. He was the oldest of five children and his father, Nils Linnaeus, was an avid gardener. This seems to help explain why it seems that from a very early age Linnaeus developed an affection for nature, in particular plants.  As a boy he would spend hours in his fathers garden exploring the growing plants. He education began at home, both in the garden and from his father who taught him the basics of reading and writing.

Carl’s father sensed his passion for botany and convinced a local doctor and botanist, Johan Rothman, to tutor him in medicine and botany. In 1727, at the age of 21, he enrolled to study at Lund University and the following year he transferred to Uppsala University, the most prestigious school in Sweden. There he was able to study both medicine and botany before embarking on a few expeditions around Sweden where he created and then refined his species classification system.

Scientific Career

The cornerstone of Linnaeus’s scientific career was the development of a hierarchical system of classification for all living organisms. In 1735 Linnaeus published one of his most famous works, Systema Naturae, which by the tenth edition can be considered the beginning of zoological nomenclature as it’s the first edition to use binomial nomenclature throughout.  By this time the work had grown from a twelve page manuscript to once classifying over 4,400 plant species and 7,700 animal species.

Along with his scientific work in taxonomy Linnaeus tried to apply science to bureaucratic practices with the goal of mobilizing resources to the improvement of the population and the strengthening of the state.  He was a founder of the Royal Swedish Academy of Science.  By the time of his death he was one of the most influential scientists of his time thanks to his enormous capacity for work and high ambition.

Continue reading more about impactful scientists!

Edmond Halley

Posted on by Dan
Edmond Halley portrait
Edmond Halley

Edmond Halley (1656 – 1742) was a prominent astronomer and mathematician who is best known today as the calculator of the orbit of Halley’s Comet. He made a lesser known but more significant contribution to science when he helped to arrange and the finance the publication of Isaac Newton’s Principia. 

Like many scientists of his day Halley was born into a wealthy family, where he was able to obtain a private home tutor before he entered school.  He ending up enrolling in Queens College at Oxford where he came under the tutelage of John Flamsteed, The United Kingdom’s first Astronomer Royal.  Roughly 45 years later Halley would succeed Flamsteed to become the UK’s second Astronomer Royal.

Halley earned his scientific reputation early in life by cataloging and publishing a star catalog of the Southern Hemisphere, earning him election to the Royal Society at the age of 22.  His personal wealthy and reputation allowed him to travel often where he would make many observations a variety topics such as winds, comets, planets, and magnetism.