Category: Impactful Scientists

Ernest Rutherford

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Ernest Rutherford
Ernest Rutherford

Ernest Rutherford (1871 – 1937) was a prominent physicist from New Zealand who made significant contributions to field of nuclear physics during the early 20th century. He greatest contribution to physics was his discovery of the atomic nucleus in 1911.

Rutherford came from a humble background. He began his education at a local school where he excelled in mathematics and science. Following his undergraduate studies he was awarded a scholarship to further his education at the prestigious Cavendish Laboratory at the University of Cambridge in England. Under the guidance of J.J. Thomson, he conducted research on the electrical conductivity of bases and earned his Ph.D. in 1898. After finishing his doctorate he joined the faculty of McGill University in Canada, where he conducted groundbreaking research on radioactivity, which laid the groundwork for his future discoveries.

Rutherford’s Gold Foil Experiment

Rutherford’s most famous discovery was the discovery of the atomic nucleus. In 1909 he conducted his famous Gold Foil Experiment, where he bombarded a thing sheet of gold foil with alpha particles. Surprisingly to Rutherford and his team, some of the particles were deflected at large angles while most others easily passed through. His interpretation of these results led to his proposal of a new atomic model, which challenged the “plum pudding” model proposed by his mentor J.J. Thomson.

Based on the Gold Foil Experiment, Rutherford hypothesized that atoms have small, dense, and positively charged nucleus at their center, surrounded by mostly empty space in which negatively charged particles orbit. This model eventually gained acceptance and revolutionized the field of nuclear physics. This discovery paved the way for future advancements in nuclear physics, such as the discovery of isotopes and the concept of radioactive decay, both processes that involve the atomic nucleus. His work still remains a cornerstone in nuclear physics to this day.

Carl Sagan

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Carl Sagan (1934 – 1996) was an American astronomer, influential popularize of science, and author. His scientific achievements and contributions are vast. He published over 600 scientific papers, authored over 20 books, and co-wrote the popular 1980 television series Cosmos.

Early Life

Carl Sagan
Carl Sagan
(Credit: NASA)

Carl Sagan was born in 1934 in Brooklyn, New York. As he recalls in his books, he acquired an interest in science at a young age. One influential experience was a visit to the 1939 New York World Fair at the age of four. After that experience he frequently read books on astronomy from his local library. Sagan attended the University of Chicago where he was associated with or taught by many notable scientists and Nobel Laureates. He completed his B.S. in 1955, M.S. in physics in 1955, and in 1960 was awarded his Doctorate in astronomy and astrophysics.

Scientific Career

Carl Sagan had a distinguished career. He first worked as a fellow at the University of Berkley, California for two years before being offered a lecture position at Harvard University. After working at Harvard for a few years he was surprisingly denied tenure. He quickly moved on to Cornell University where he became their director of Laboratory for Planetary Studies. He later was promoted to associate director of the Center for Radiophysics and Space Research. In 1977, he was named the David Duncan Professor of Astronomy and Space Science, a position he held for the rest of his life.

He worked with NASA several of their space missions. He helped determine possible landing sites on Mars for the Viking Program. He was instrumental in sending out the first physical messages sent into space in the form of the Pioneer Plaque and the more famous Voyager Golden Record.

Carl Sagan Standing Next to a Model of a Viking Lander
Carl Sagan Standing Next to a Model of a Viking Lander
(Credit: Wikimedia Commons)

While he was always a respected scientists among his colleagues, but it was the highly successful Mariner missions to Mars launched Sagan’s public career. People wanted to know more about Mars and Sagan became a sort of spokesperson about the topic. He was selected to appear in several educational films and his exceptional style and clear delivery quickly earned him notoriety. His expertise was in high demand and he soon began appearing on television talk shows. Carl Sagan had become a celebrity scientist.

Bringing Science to the People

Carl Sagan had a burning passion to share his love of science with everyone. He was a prolific author and who made reading about science enjoyable. In 1978 he won a Pulitzer Prize for The Dragons of Eden. The following year he co-wrote the popular PBS televisions series Cosmos. The series was a smashing success and more than 600 million people have viewed the series before the century was over. Sagan died of pneumonia in 1996 at the age of 62.

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Richard Dawkins

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Richard Dawkins (1941 – present) is an evolutionary biologist known for emphasizing the role of the gene in biological evolution.  His 1976 book The Selfish Gene popularized this gene-centered view of evolution.

Richard Dawkins
Richard Dawkins

Richard Dawkins was born in Kenya to two parents very much interested in the natural sciences who cultivated his curiosity in the natural world.  At the age of eight his family moved to England where he attended public school before enrolling at Balliol College, Oxford – a constituent college of Oxford University.  He was raised in a traditional Anglican upbringing, but by this point in his life he had abandoned Christianity in favor of the scientific worldview.

After a brief teaching job at UC Berkley in the USA, Dawkins returned to the UK in 1970 to be a lecturer at the University of Oxford.  In 1976 he published his book The Selfish Gene, a wildly popular book that was effective at both explaining the gene-centered view of evolution to laypeople as well as persuasively convincing other scientists the validity of the idea.  Not since Charles Darwin’s revolutionary book On The Origin of Species has a scientific literature been so successful at achieving both of those important ends.  Interestingly, Dawkins coined the now famous term meme in this book, a term that has become an icon of internet culture.

Dawkins has gone on to author countless other best-selling science books while working as a professor at the University of Oxford.  Since 1970 he has been a fellow of New College, Oxford.  In 1995 he was appointed as chair to The Simonyi Professorship for the Public Understanding of Science, a position endowed by Charles Simonyi with the instructions that Richard Dawkins be the first to hold the position.  In 2006 he founded the Richard Dawkins Foundation for Reason and Science – a nonprofit science education organization.

More recently, Dawkins has become an outspoken critic of religion, especially of creationism.  In 2006 he published his most popular book The God Delusion where he debunks the notion of an intervening God in our universe and where he masterfully illustrates religious faith as a delusion.  The book has proven to be provocative to some, yet it has sold over 1 million copies while becoming an international best seller.  In public he has been a leading figure in promoting the virtues of atheism while lambasting vices of religion.  As of May 2019 Dawkins is currently authoring another book titled Outgrowing God: A Beginner’s Guide to Atheism. It is expected out in September 2019.

Max Planck

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Max Planck picture
Max Planck

Max Planck (1858 – 1947) was a German physicist whose revolutionary research led to the foundation quantum mechanics and quantum theory.  Quantum theory was an entirely new type of physics that replaced classic physics on the atomic scale.

Max Planck was born in Kiel, Germany in 1858.  As a youth his family moved to Munich where he enrolled in the Maximilian Gymnasium school where he was introduced to mathematics, astronomy, and mechanics. He graduated at the age of 17 and made the decision to pursue a career in physics.  He promptly enrolled in the University of Munich but after a year he transferred to Friedrich Wilhelms University, where he attended lectures by two of Germany’s most eminent physicists – Hermann von Helmholtz and Gustav Kirchhoff.  He was intrigued by the concept of thermodynamics and began to read over papers written by Rudolf Clausius, one of the pioneers of thermodynamics.  Planck graduated and began teaching physics, first at the University of Munich, then at the University of Kiel, and finally at Friedrich Wilhelms University in Berlin, where he became a full professor in 1892.  It was in this position where he conducted some of his most important research.

In 1894 Planck turned his attention to the problem of black-body radiation.  In 1859 Kirchoff had identified a black-body as a perfect absorber and emitter of radiation at all wavelengths.  Physicists could create a black-body curve by displaying how much radiant energy is emitted at different frequencies for a given temperature of the black-body.  Classical theory was having difficulty in having their predictions match up with the observations.  In order to solve this problem, Planck made a radical proposal.  He proposed that energy could only be emitted in certain, discrete amounts called quanta, whereas classical theory allowed for all possible values of energy. He was able to derive a formula that accurately predicted the energy radiated by a black body – E=hv, where h is Planck’s constant and v is the frequency of radiation. This was the beginning of quantum mechanics and for this work he won the 1918 Nobel Prize in Physics.

Unlike many German scientists of his day, Planck stayed in Germany his entire life and lived through World War 2.  His home in Berlin was destroyed by an Allied air raid where he lost all of his scientific papers.  He died shortly after the war ended in 1947.  The following year the Kaiser Wilhelm Society was renamed the Max Planck Society in his honor.

Marie Curie

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Marie Curie
Marie Curie

Marie Curie (1867 – 1934) was a Polish physicist and chemist who overcame a gender discrimination in the sciences to conduct groundbreaking work on radioactivity. Her incredible scientific career awarded her two Nobel Prizes in two different fields and earned her the distinction of being the first woman to win the award.

Marie Curie was born in Warsaw to the parents of two teachers who were very interested in science.  She was the top student in her high school, passionate about science, and wanted to peruse a higher education however there were obstacles in her way.  She was unable to enroll in traditional higher education institutions because she was a woman and her family had little money to support her.  To earn money for herself and to help support her sister’s studies she worked as a tutor.  In her free time she read books on physics, chemistry and mathematics.  In 1891 she departed Poland for Paris, France to join in studies with her sister.  There she studies physics, chemistry, and mathematics, and once again was the top student in her class.  She earned her Ph.D. in physics and in 1985 she married Pierre Curie.  That same year Wilhelm Roentgen discovered x-rays.  The following year Henri Becquerel discovered a new type of ray, resembling that of x-rays yet different, emitting from Uranium.

Curie decided to study these new rays emitting from Uranium and made a handful of remarkable discoveries.  Her husband became interested in her work and joined her.  Their joint work resulted in the discovery of new two elements – Polonium, named for Curie’s home country Poland, and Radium, named for the word ray.  They discovered that Radium would continuously produce heat without any chemical reactions occurring that it emitted rays in far greater quantity than Uranium.  They term they coined for this phenomenon they were observing was radioactivity.  The term stuck.

In December 1903 Marie Curie was the first woman ever to be awarded a Nobel Prize.  Along with her husband Pierre, Marie won the prize in physics for her work in the field of radiation.  The award brought recognition and money for the two scientists, however they would not be able to enjoy it for long.  Pierre was killed in a tragic accident in 1906 when he was hit by a horse-drawn carriage while crossing the street.  Marie Curie continued her scientific work after her husband passed away and was awarded a second Nobel Prize in 1911, this time in the field of chemistry.  By now she had cemented her reputation as one of the elite scientists alive.

Curie continued to work up until her death in 1934 when she died from a rare bone marrow disease.  The disease was likely cause by her long-term exposure to radiation without proper protection.  Her legacy was that of one of the greatest scientists of the time and her work broke barriers for other woman to pursue work in the scientific fields of their choosing.

Niels Bohr

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Niels Bohr (1885 – 1962) was a Danish physicist who significantly improved our understanding of the structure of the atom.  His improved model of the atom solved the problems associated with classical physics and was based on the newer quantum mechanic physics.

Early Life and Education

Niels Bohr was born on October 7th, 1885 in Copenhagen, the capital of Denmark.  He was born into an intellectual and supportive family, and his upbringing consisted of a rich educational environment. His father, Christian Bohr, was a professor of physiology at the University of Copenhagen. His mother, Ellen Bohr, came from a prominent Jewish-Danish banking family with influence in parliamentary circles. The combination of his fathers scientific work and his mothers cultural pedigree together created a home environment that nurtured curiosity and scholarly pursuit. It is no surprise that young Niels Bohr grew up strong in mathematics and was naturally attracted to science at a young age. 

In 1903 he enrolled as an undergraduate at the University of Copenhagen, where he received his master’s and doctorate in physics by 1911.  That same year he traveled to England to work in the Cavendish Laboratory where he met J.J. Thomson. The two scientists didn’t work well together at first, but Bohr soon met another scientist at a different laboratory whom he worked better with. In March 1912 Bohr traveled to Manchester to work with Ernest Rutherford, who had recently won a Nobel Prize in Chemistry for his work on radioactivity.

Scientific Career

Niels Bohr
Niels Bohr

Bohr returned to Denmark in 1912 after having secured a teaching position at the University of Copenhagen.  He brought with him new ideas about the structure of the atom.  It was becoming clear that Rutherford’s model of the atom, based on classical physics, was unstable.  According to classical physics, the electrons moving around the nucleus of an atom in orbit would emit electromagnetic radiation, causing the electron to lose energy and eventually spiral into the nucleus.  The form of electromagnetic radiation being emitted came to be called photons, with each photon having its own precise wavelength and amount of energy.  Quantum physics states that objects emit photons in discrete packets rather than in continuous streams. Using quantum physics, Bohr proposed that electrons are confined to fixed orbits, each with their own distinct energy level.  They only suddenly jump to lower or higher orbits as a precise amount of energy is emitted or absorbed in the atom.  For example to move an electron to a lower energy level it emits a photon of the precise amount of energy that is the difference between the two orbits.  Using Plank’s constant, the frequency of photons, and some information about the electrons mass and charge, Bohr was able to obtain an accurate mathematical formula for the hydrogen atom.  In 1922, Niels Bohr was awarded Nobel Prize in Physics for this work.

Bohr continued to work on quantum physics for the remainder of his life.  He founded the Niels Bohr Institute at the University of Copenhagen.  Later in life he was a part of the Manhattan Project during the Second World War, working with many other great physicists.  He died in Copenhagen at the age of 77.

Albert Einstein

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Albert Einstein portrait
Albert Einstein

The scientific career of German-born physicist Albert Einstein (1879 – 1955) was one of the most impactful ever in the history of science.  His work led to significant and meaningful changes in our understanding of several fundamental laws of nature including gravity, light, and time.

Albert Einstein was born on March 14, 1879 in Ulm, Germany.  He became interested in nature and mathematics at an early age.  There were two key moments in his childhood that inspired a wonder of curiosity in him.  The first moment was when he was sick at the age of five.  His father brought him a compass and this device stirred his curiosity and sparked his intellect.  At age twelve he stumbled upon a book of geometry that has much the same effect on him as the compass.

In 1896 Einstein enrolled for a science degree at the Swiss Federal Institute of Technology in Zurich.  He graduated in 1900 with his teachers being largely unimpressed with him.  Two years later he would obtain a post of an examiner in the Swiss Federal patent office where he would go on to make some of his greatest discoveries.

The year 1905 was called the year of miracles for Einstein.  He published four scientific papers each with immense importance for science.  His papers topics were on the photoelectric effect, Brownian motion, the Theory of Special Relativity, and the equivalence of mass and energy.  These four papers gained him international respectability and propelled his academic career.  He won the Nobel Prize for Physics in 1921 for his work on the photoelectric effect.

As Einstein began teaching physics at various institutions he began formulating his General Theory of Relativity, which he finally published in 1915. This theory shows how gravity works as a geometric feature of space and time and how its curvature is directly related to the energy and momentum of the present mass and radiation.

As Einstein aged he still worked in science but became more involved in politics.  He emigrated to the United States in 1933 due to the rise of Nazi power in Germany.  During World War 2 he would work on the Manhattan Project which developed the atomic bomb.  This was a difficult moral decision for him since he was a pacifist, but he was uneasy that Germany would develop the bomb first and ultimately decided to help the US develop it before Germany.  Einstein died in 1955 with the legacy of being one of the most impactful scientists in all of history.

Dmitri Mendeleev

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Dmitri Mendeleev picture
Dmitri Mendeleev

Dmitri Mendeleev (1834 – 1907) was a Russian chemist who is most famous for publishing his periodic table of elements.  The period table is one of the most recognizable symbols in science.

Mendeleev was born in the Russian province of Siberia in 1834, the youngest of seventeen siblings.  At the age of sixteen Mendeleev moved  with his family to the the Russian capitol of St. Petersburg and enrolled in his father’s old school, St Petersburg’s Main Pedagogical Institute.  At age 21 he got a teaching job in the Crimea but soon returned to St. Petersburg to study for a master’s degree in chemistry from the University of St. Petersburg which he obtained in 1856.

Mendeleev was becoming more passionate about science and more concerned that Russia was falling behind Germany in the field.  He believed improving Russian educational textbooks was one way to close the gap.  In 1861 he published the 500-page textbook Organic Chemistry which won him the Demidov Prize of the Petersburg Academy of Sciences.  He continued to be a a teacher of chemistry and write additional textbooks over the next few decades.

During his time teaching and writing textbooks Mendeleev began to notice patterns and relationships among the known elements.  He found many similar properties in groups of elements such as the halogens and the alkaline earth metals.  He noticed the atomic weight’s of the elements could be used to arrange elements within groups, and also to arrange groups themselves. In 1869 he published publish The Relation between the Properties and Atomic Weights of the Elements, revealing his periodic table to the world.

Mendeleev’s periodic table was impactful for its predictive power.  Due to its ordering, it predicted that some of the atomic weights of known elements may be wrong.  It also predicted the existence of unknown elements and it predicted what properties these elements would possess.  Both of these predictions ended up being true.

Mendeleev received substantial fame and recognition for his periodic table.  In 1905, the British Royal Society awarded him its highest honor, the Copley Medal.  The same year he was elected to the Royal Swedish Academy of Sciences.  He died just after the turn of the century in 1907 from the influenza virus.  Element number 101 is named Mendelevium in his honor.

Alessandro Volta

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Alessandro Volta portrait
Alessandro Volta

Alessandro Volta (1745 – 1827) was an Italian physicist and chemist who was a pioneer in electricity.  He is best known for inventing the battery, which was the first artificial source of continuous electrical current.

Volta was born in Como, Italy, was educated first at home and then at a Jesuit school.  He became interested in electricity at an early age and began publishing papers on the topic in his early twenties.  By 1774 he had  became a professor of physics at the Royal School in Como. One of his first major accomplishments was the discovery and isolation of methane gas. 

In 1791 his friend Luigi Galvani published his views of animal electricity, a form of electricity Galvani believed to be generated in the bodies of animals which would flow through the nerves, causing muscles to move.  Galvani experiments showed that when two different metals came into contact with a dead frog, the frogs muscles would twitch.  Volta disagreed with Galvani on his animal electricity hypothesis as he believed that it was the through the contact of two dissimilar metals that caused the electric current to flow.  In an attempt to prove this Volta built what he called the Voltaic pile, the first ever electric battery. 

The Voltaic pile provided a powerful too for other scientists to made additional observations and discoveries in the field of electricity.  It was easy enough for anyone to make.  Within weeks it was used to dissolve water into hydrogen and oxygen and within a few years newer and more powerful batteries were being created and used to isolate new chemical substances.

In 1791 Volta was already deemed an expert in electricity and he was elected to be a Fellow of the Royal Society.  Impressed by his battery and work on electricity, Napoleon Bonaparte made him a Count in 1809.  Volta died in 1827 but his legacy would live on.  In 1881 in recognition of his fantastic contributions to electrical science the term volt would be the official SI unit of electric potential.

Luigi Galvani

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Luigi Galvani portrait
Luigi Galvani

Luigi Galvani (1737 – 1798) was a pioneer of bioelectricity who made important contributions in physics, chemistry, and biology.  He was the first person to demonstrate the electrical basis for nerve impulses when he made a dead frogs muscle move when he jolted it with electricity.

Galvani was born in Bologna, Italy and obtained a degree in medicine at the University of Bologna in 1759.  After graduation he applied for a position at the university and became a lecturer of anatomist of the university.  In the 1770s Galvani had started to become interested in the relationship between electricity and life.

During experiments he conducted, Galvani realized that he could use electricity to make the dissected legs of a frog contract.  For example, when Galvani used a scalpel made of steel to cut through the leg of a frog hanging from a brass hook, the leg visibly twitched.  Based on his observations Galvani concluded that the body contained a type of electrical fluid which he dubbed animal electricity.  He knew that his conclusions would be controversial and he delayed publishing his work until 1791 when he published Commentary on the Effect of Electricity on Muscular Motion.

Some of his scientific colleagues accepted his views, but he received opposition from the Italian physicist Alessandro Volta.  Volta believed that it was through the contact of two dissimilar metals, such as the steel in the scalpel and the brass of the hook, that caused the electric current to flow.  In response to Galvani Volta invented the Voltaic Pile, the first battery.  He realized that the frog’s leg served as a conductor of electricity (electrolyte) and he replaced the leg with brine-soaked paper placed in between to pieces of metal.  Volta’s conclusion ultimately proved correct however Galvani was still correct in attributing the muscular contractions to the electrical stimuli.  Where Galvani was wrong was in the idea of an inherent animal electricity operating within the body.

Galvani continued to investigate animal electricity until the end of his life.  It is his work that inspired Mary Shelly to write her famous work Frankenstein in 1818.  Galvani died at his brothers home in December 1798.