September 28, 2011

University Recognizes 100 Year Anniversary of the Atom’s Discovery

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Physicist Ernest Rutherford once explained the surprise results of his famed gold foil experiment to be “as if you fired a 15-inch naval shell at a piece of tissue paper and it came back and hit you.”Today, one hundred years after the general physics community has incorporated Rutherford’s nuclear model of the atom, we often take this scientist’s major discovery for granted.  That is at least what Dr. John Campbell, Research Associate in the Department of Physics and Astronomy at University of Canterbury, New Zealand, and biographer of Rutherford, believes.

The University’s Physics Department invited Campbell to give a lecture last Wednesday on 21 September 2011 to celebrate the centennial year of the nuclear atom.  Campbell’s lecture, titled “Rutherford’s Path to the Nuclear Atom,” was more than just an anniversary of the nuclear atom—it was a celebration of the life and work of a great and, arguably, under-appreciated physicist.

“No one quotes the original paper,” said Campbell, describing the fate of truly foundational discoveries— for instance, Faraday’s Laws.

Nevertheless, Rutherford was awarded the Nobel Prize in 1908.  Surprisingly though, Rutherford won the Nobel Prize in Chemistry—despite his being a physicist, explained Campbell.  And what is perhaps even more surprising, Rutherford is one of the few scientists to win the award before producing the work for which he is most well-known.

In this case, he received it three years prior to postulating that small, dense, positively charged nucleus surrounded by electrons (and mostly empty space) that we today refer to as the nuclear atom.In fact, said Campbell, he was first nominated in 1907 for his work at McGill University on “the transmutation of elements.”  In his work on the decay of radon Rutherford proved that atoms are not immutable; in other words, he showed that one atom can transform into a distinct other atom.He also, at this time, discovered the mathematical relationship between a radioactive element’s half-life and its decay constant.

Campbell went on to explain that the “Geiger Counter,” a device used for measuring levels of radioactivity, was first known as the “Rutherford-Geiger Counter,” as a preliminary version of the device came out of Rutherford’s lab in 1908.  Rutherford’s principal lab assistant and “workhorse,” according to Campbell, was the German physicist Hans Geiger.

The first unit of radioactivity was even dubbed the “Rutherford,” said Campbell.

Later— after his postulation of the nuclear atom—Rutherford would transform atoms of Nitrogen into Oxygen by bombarding them with alpha rays (a type of radioactive emission he named earlier in his work along with “beta rays”), and in so doing would discover and name the “proton.”

“I’ve often wondered why it took so long for him to come his conclusion [of the existence of the nuclear atom],” said Campbell, explaining that Rutherford had just about all the pieces necessary from his work in Canada prior to 1911.  “Only in the last 2-3 months have I looked at it and understood why,” Campbell continued, “there were just so many things going on in his lab—so many unfinished puzzles from his time at McGill [University]—this was just one of many.”

Campbell is the creator of the first documentary on his favorite scientist’s life and achievements. “There has never before been a documentary about Rutherford,” said Campbell, “but now there is.”

Lecture attendees received a six-minute preview of the unreleased documentary.  The three-hour homage, based on Campbell’s book, Rutherford: Scientist Supreme, will be released later this year (just in time for the centennial).

At the lecture’s end, Campbell said, “…and that’s the story behind that one line you get in your science textbook today that says, ‘In 1911 Ernest Rutherford discovered the atomic nucleus.’”

Original Author: Bob Hackett