Ernest Rutherford: The Father of Nuclear Theory  

Yes, Rutherford discovered the nucleus with his gold foil experiment, but before that, he discovered that there are different kinds of radiation, found that materials can decay into other elements, found a new radioactive element, discovered that radioactivity decays with a half-life, and used these facts to discover that the earth was hundreds of millions of years older than it was expected to be!  And he did all this with handmade equipment made out of hand-blown glass and tin cans and cigar boxes.  Not bad for a poor kid from nowhere, New Zealand.  Ready for the crazy story of a charismatic, brilliant, loud, and ridiculously prolific scientist?  Let’s go.

Ernest Rutherford’s life changed when a Chemist named J. C. Maclaurin decided to get married in July of 1895.  Why did this change Rutherford’s life?  Well, Maclaurin had been granted a scholarship to study abroad, however, the wedding invalidated the scholarship so it went to the only other applicant, 24-year-old Rutherford.  Supposedly, when Rutherford got the news he was working at the family farm and threw down his shovel, exclaiming, “That’s the last potato I’ll ever dig[1]

Ernest Rutherford
Ernest Rutherford

Ernest Rutherford (Ern to family and friends) was born in New Zealand and was the 4th child out of 12 of a poor Scottish farmer and an English schoolteacher.   Ern always excelled at school, but also was a rough and tumble country boy who enjoyed rugby and fishing.[2]  His mother insisted that “all knowledge is power” although Rutherford put it as, “We didn’t have the money so we had to think.[3]”  With several scholarships, Rutherford got bachelor’s and master’s degrees in mathematics and science.  At the time New Zealand had a total of 126 engineers in the entire province (it wasn’t a country at the time), so Rutherford decided to become a schoolteacher, which was not a success.  A former student recalled, “He was entirely hopeless as a schoolmaster [and] disorder prevailed in his classes.”  When a student was sent out for misbehaving, they only had to, “stay out of the classroom long enough for Rutherford’s enormous mind to have bulged in some other direction, sneak back to his seat and he would inevitably not be noticed.[4]”  While in college, Ern stayed at a boardinghouse, where he eventually fell in love with the landlady’s daughter, Mary Newton.  In 1894, Ern asked Mary for her hand in marriage, but Mary refused as she didn’t want to “be a handicap” to his education, saying, it, “would be idiotic,” to get married.  However, she would wait for him, telling Rutherford, “I wouldn’t dream of marrying anyone else.”  “Free” from marriage, Rutherford “won” the scholarship I mentioned at the beginning of this video. 

Rutherford now had a bit of money to study anywhere in the world and he decided to sail to England as JJ Thomson, the head of the Cavendish laboratories in Cambridge, had just changed the rules to let “aliens”, or non-Cambridge graduates, go to graduate school there.  JJ Thomson immediately hired Rutherford and Rutherford found his new boss to be, “very pleasant” and “not fossilized at all”.  However, Rutherford found his fellow students to be another matter, writing Mary that they treated him and fellow Irish student John Townsend quite badly: “They snigger at us… I’d like to do a Maori war-dance on the chest of one and will do that in the future if things don’t mend.”  However, after a couple of months, Rutherford was asked to give a public talk.  Once again he wrote Mary, “My paper before the Physical Society was a heavy blow to their assumed superiority and now they all offer to help us in any way they can.”  Rutherford arrived in England at quite the opportune time.  Just months after his arrival, on January 5th of 1896, the papers carried a strange story that vacuum tubes called Crookes tubes could make powerful invisible rays named x-rays.  Soon, as Rutherford recalled later, “Every laboratory in the world took out its old Crookes tubes to produce x-rays, and the Cavendish Laboratory was no exception. [5]”  Rutherford had been working on transmitting signals with radio waves but was convinced by JJ Thomson to switch to the effects of x-rays on gasses.

Meanwhile, in France, a wealthy third-generation scientist named Henri Becquerel had found that uranium would spontaneously produce rays that, like x-rays, could go through the thick paper and develop film.  In 1897, a Polish immigrant to France named Marie Sklodowska Curie decided to study “Uranium rays” for her dissertation.  Curie found that Thorium also produced these rays and named this process “radio-activity”.  She also found that there must be some tiny amounts of new radioactive elements, Polonium, and Radium, hidden in ore.  When Rutherford heard about Curie’s results he decided that since he had been studying the effects of x-rays on gasses, he might also study the effects of radioactivity on gasses. 

Rutherford setup

Rutherford thus put a bit of uranium on a plate separated from another plate by air and measured the current that flowed between the plates as a measure of the radioactivity, a method he copied from Marie Curie.  However, Curie was studying the uranium, and Rutherford wanted to study the radioactivity.  Therefore, Rutherford added layers of thin metal foil in the way of the uranium rays to see what happened to the strength of the radiation.  The results were very strange.  At first, the thin layers of metal would quickly diminish the strength of the current.  But then, after a while, the amount seemed almost constant.  What was going on? On September 1, 1898, Rutherford published his conclusion: “uranium radiation is complex, and there are present at least two distinct types of radiation – one that is readily absorbed, which will be termed for convenience the alpha radiation, and the other of a more penetrative character, which will be termed the beta radiation.”[6]  The very next year a French physicist named Paul Villard was given some radium to study by the Curies and discovered a third, even more, powerful ray, that Rutherford eventually called gamma radiation (as alpha, beta, and gamma, are the first three letters of the Greek alphabet). 

At around the same time that Rutherford was discovering alpha and beta radiation, a Physics professor at McGill University in Montreal, Canada retired.  Naturally, the department head wrote JJ Thomson and asked his advice on whom to hire to replace him.  Thomson wrote back, “I have never had a student with more enthusiasm or ability for original research than Mr. Rutherford.[7]”  Rutherford was a little hesitant to leave Cambridge, but he felt the lingering prejudice against him as an outsider would keep him from getting a fellowship in England and he was excited about having, as he put it, “a swell lab[8]” so that he could “knock the shine out of the Yankees![9]”  Also, with this new position he finally earned enough money to get married writing Mary, “Rejoice with me, my dear girl, for matrimony is looming in the distance.[10]”  Still, it took another year and a half to arrange the finances for their long-awaited marriage.

Rutherford quickly attracted a crack group of young researchers.  Rutherford was young, brilliant, full of energy, and always, always gave credit to others for their contributions.  Many of his assistants and grad students ended up famous in their own right.  Rutherford was also one of the few male science professors who hired women.   Years later Rutherford wrote that women “contribute substantially to progress in the various branches of learning.”  And, “for this reason, no less than for those of elementary justice” he “welcome(s) the presence of women in [the] laboratory.[11]” In fact, one of his first acts at McGill was asking a woman named Harriet Brooks, who had just graduated from there with a degree in science, to be his first graduate student.  Brooks did important work with Rutherford, and I will talk about some of it in a bit, but she left Rutherford in 1904 to become a teacher at Barnard College where she got engaged to a local Physics teacher.  She was then told that if she married, she would be fired!  Eventually, she broke off the relationship but the stress caused her to leave Barnard too.  She then worked for Marie Curie and then got a scholarship to work with Rutherford again.  Then an old flame from McGill proposed to her and just two years after Brooks wrote that “a woman has a right to the practice of her profession and cannot be condemned to abandon it merely because she marries,” she quit Physics altogether to be married.  Sigh. 

Back in 1899, when Rutherford first arrived at McGill, he was approached by an electrical engineer named “Bobby” Owens for advice on what to do to fulfill the research portion of his scholarship.  Rutherford suggested examining the radiation from thorium oxide in the same way that Rutherford had studied uranium.   To their shock, “The radiation from thorium oxide was not constant but varied in a most capricious manner.[12]”  Rutherford took over the research and quickly found that “this inconstancy is due to slow currents of air produced in an open room.[13]”  But that was crazy; no radiation that they had ever found would blow hither and thither with the breeze!  Rutherford decided the thorium must have been emanating a gas that was being pushed by the air and this gas must be radioactive.  Rutherford then created an ingenious method of studying the radiation from this gas.  He put some thorium oxide in a long tube and blew filtered air over the thorium to blow the radioactive gas into an electroscope.  He then turned off the air and measured the intensity of the radioactivity of the gas as a function of time.  To his surprise, the gas lost radioactivity in a matter of minutes.  In fact, no matter how much gas they had, it always decreased by 2 over a set amount of time (around 1 minute).  This was the discovery of the “half-life” of radioactive materials!

I forgot to mention in my video about Marie Curie and the discovery of radium, but even before it was fully isolated, radium took over the scientific world by storm.  Even “low quality” radium would glow and heat (and burn fingers) endlessly without any input source.  In the early 1900s, most of the scientific world felt that “Without doubt, it is the most wonderful body known[14]”.   In 1901, a chemist named Friedrich Giesel used Marie Curie’s methods to prepare “pure” radium and sell it on the market.  Rutherford immediately bought 30 milligrams for 30 pounds (around $10,000 in today’s dollars, also his paycheck at the time was 500 pounds a year[15]).  Giesel then upped the prize twelve times, making himself a fortune, and also making radium out of the range for almost any laboratory[16].   As Radium salt was about 1 million times more radioactive than uranium or thorium this dramatically changed what Rutherford could study.  For example, the Curies had reported that radium would, like Thorium, produce a radioactive gas that would last for weeks instead of days.  However, Rutherford lamented that “the specimens of impure radium then in the possession of the author did not possess the power of emitting such an emanation[17]”.  Now, with “pure” radium, Harriet Brooks, Rutherford’s graduate student (remember her?), had emanations from radium to examine.  Brooks and Rutherford concluded that these emanations were not “a vapor of radium” but a new radioactive element with a different mass!  Now alchemists had been trying to change one element into another (usually gold) for thousands of years, but no one knew that radioactive materials were just naturally decaying into other elements all on their own!  It was a radical result.  However, at first, the Curies disagreed with the results and most other scientists merely ignored them.

Then, in March of 1901, Rutherford debated the existence of electrons against a young chemist named Fredrick Soddy[18].  Soddy not only lost the debate but also decided to devote himself to working with Rutherford.  Soddy started studying the chemical properties of the radioactive gas from Thorium.  In 1902, Soddy tried to get the gas to react to any other element, but it stubbornly refused, meaning that it had to be a noble gas.  Soddy then thought it must be Argon gas[19].  Soddy recalled, “I remember quite well standing there transfixed as though stunned by the colossal import of the thing and blurting out…’Rutherford, the Thorium is disintegrating and transmuting itself into an argon gas.’  Rutherford replied, “For Mike’s sake, Soddy, don’t call it transmutation.  They’ll have our heads off as alchemists… Make it a transformation.[20]”  These seemed like more conclusive results, the Curies were convinced, and soon most people believed in the “transformation” model of radioactivity.  By the way, it took until Fredrick Soddy realized the existence of isotopes years later that they realized that the emanation from Radium and the emanation from Thorium were both isotopes of the same gas, Radon. 

Rutherford then came up with an ingenious new use for the half-life of radioactive materials and their “transformation” from one element and isotope into another.  By examining how much radioactive material an object had, how much of the material it was decaying into it had and how quickly it was decaying from one to the other, Rutherford could determine how old the material was.  He tested it on a piece of pitchblende and found it was about 700 million years old![21]  This was totally shocking as at the time the Earth was thought to be only 100 million years old.  It took many years, but this technique, called radiometric dating, is what was used to determine the currently accepted age of the Earth (around 4.5 billion years old).

Rutherford was unbelievably successful at McGill but Rutherford still felt “rather out of things” in Canada, complaining to JJ Thomson that, “this feeling of isolation is the great drawback to colonial appointments.[22]”  Finally, in 1907, Rutherford was awarded a job at the University of Manchester and happily went back to the UK.   The very next year, Rutherford was quite shocked to be awarded the Nobel Prize in Chemistry for “investigations into the disintegration of the elements, and the chemistry of radioactive substances” (he was particularly surprised as he wasn’t a Chemist).  Unlike the Curies, however, Rutherford loved the fame and attention, and he wrote that he and his wife “had the time of our lives,” in Sweden.  Five years later, he was knighted and made Lord Rutherford of Nelson or as he told his 13-year-old daughter Eileen, “Henceforth, young lady, you may address me as ‘Sir Ernest’”. 

At the same time that Rutherford was awarded his Nobel Prize, he also was working on a new experiment with a German scientist named Hens Geiger that is often called the “gold foil experiment” where he studied how “his” alpha particles from radium would scatter when going through thin solids.  Although Rutherford was known to bellow, “Don’t let me catch anyone talking about the Universe in my department,” Rutherford was about to upend our understanding of reality and cause a lot of deep discussions about the universe.  For Rutherford was about to discover the nucleus and that story is next time on “The Lightning Tamers”.

Rutherford: “Never say, ‘I tried it once and it did not work’”

[1] according to Jorgensen, Timothy Strange Glow: The Story of Radiation p. 244

[2] according to Reeves, Richard A Force of Nature: The Frontier Genius of Ernest Rutherford p. 27

[3] The actual quote is in present tense i.e. “We don’t have the money so we have to think”  

[4] recalled by Gillespie, O and written in Reeves, Richard A Force of Nature: The Frontier Genius of Ernest Rutherford p. 29

[5] p 34 “Background to Modern Science” 1938 ‘Forty Years of Physics’ Rutheford

[6] Rutherford, Ernest, “Uranium Radiation and the Electrical Conduction Produced by It” Philosophical Magazine p. 116

[7] Thomson, JJ quoted in Eve, A. S. Rutherford p. 55

[8] Rutherford, Ernest to Newton, Mary Aug 11, 1895 quoted in Eve, A. S. Rutherford p. 56

[9] Rutherford, Ernest to Newton, Mary Aug 3, 1898 quoted in Eve, A. S. Rutherford p. 55

[10] Rutherford, Ernest to Newton, Mary Aug 3, 1898 quoted in Eve, A. S. Rutherford p. 55

[11] Rutherford, E quoted in Rayner-Canham, M. & G Harriet Brooks: Pioneer Nuclear Scientist p. 23

[12] Rutherford, E. Owens, R (1899) “Thorium and uranium radiation” Transactions Royal Society of Canada Vol. 2 p. 9

[13] Rutherford, E “A Radioactive Substance Emitted From Thorium Compounds” Philosophical Magazine, Jan 1900p. 1

[14] Soddy, Fredrick “Advances in Radioactivity” The McGill University Maggazine Vol 2 p. 48

[15], using amount of gold 30 UK pounds = 220 g gold = $9,991 today

[16] Rutherford, E (who also added that the price increased by 12x), “Forty Years of Physics” Background to Modern Science 1938 p. 54

[17] Rutherford, E, Brooks, H, “The New Gas From Radium” reprinted in The Chemical News and Journal of Physical Science, Vol 85 April, 1902 p. 196

[18] Reeves, Richard A Force of Nature: The Frontier Genius of Ernest Rutherford p. 48

[19] Soddy, Fredrick “It was subjected to such chemical treatment that every known gas, with the exception of the recently-discovered members of the argon family, would have been absorbed and removed, but the emanation in each case was unaffected” “Advances in Radioactivity” The McGill University Maggazine Vol 2 p. 52

[20] Soddy, Fredrick, quoted in Schwoerer, H., Magil, J. Beleites, B. Lasers and Nuclei p. 131

[21] Supposedly, he liked teasing local geologists about it, as recorded by Eve, A.S. Rutherford p. 107

[22] Rutherford to Thomson March 26, 1901 quoted in Eve, A.S. Rutherford p. 77

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