Today in Science History – March 4 – Carbon-14 Dating

Willard Libby
Willard Libby (1908 – 1980)
Nobel Foundation

March 4 marks the anniversary of the first use of the carbon-14 radioactive dating technique. It was used to determine the age of Egyptian artifacts where the age was already known by other means.

Carbon 14 is an isotope of carbon created naturally in the atmosphere by cosmic rays. Living creatures breathe out carbon dioxide and take in carbon by eating. Plants take up carbon through photosynthesis. Overall, every living thing has a stable natural ratio of carbon-14 to carbon-12. When the living thing dies, it stops absorbing new carbon-14. The natural ratio begins to change as carbon-14 decays.

Carbon-14 decays into nitrogen by beta decay, but this process takes a long time. The half-life of carbon-14 is 5,720 years, meaning after 5,720 years, the organism will have half the carbon-14 levels it did when it was alive. If you measure the amount of carbon-14 in a once living object, you can determine the approximate age of the organism.

On March 4, 1947, Willard Frank Libby dated a piece of wood from the Third Dynasty Pharaoh Djoser’s tomb that was about 4,700 years old. He found the concentration of carbon-14 was nearly half the concentration of carbon-14 found today. This test was successful and proved his technique was valid.

Libby performed further tests using tree ring data to calibrate his technique and discovered the ratio of carbon-14 and carbon-12 varied over time. This made the technique less accurate until more was known about the variations. Samples from the tree rings helped gather data on variations during the life of the tree. This information was incorporated into the dating formula and improved the accuracy of Libby’s tool. The technique’s accuracy is constantly being increased with more and more data of materials where the dates are known.

Carbon-14 dating is still considered a valuable tool to determine the approximate age of objects that were of biological origin. This technique would earn Libby the 1960 Nobel Prize in Chemistry.

Notable Science History Events for March 4

2012 – Simon van der Meer died.

Simon van der Meer
Simon van der Meer (1925 – 2011)

Simon van der Meer was a Dutch physicist who, together with Carlo Rubbia, first detected the existence of W and Z particles during a series of experiments at the CERN Super Proton Synchrotron in 1983. Their discovery confirmed the electroweak theory of subatomic particles that unify the electromagnetic force and weak nuclear force. They are also important to the Standard Model of particle physics.

W and Z particles are the carriers of the weak nuclear force, one of the four fundamental forces of physics. The W particles carry a charge of either +1 or -1 and the Z particle carries no charge. They are massive particles, approximately 100 times the mass of a proton, but have a half-life of only 3 x 10-25 seconds. They are typically present when beta nuclear decay occurs. During β- decay, one of the down quarks in the neutron becomes an up quark, turning the neutron into a proton and emits a W particle. The W particle quickly decays and produces an electron (beta particle) and an anti-neutrino.

The discovery of W and Z bosons would earn both men the 1984 Nobel Prize in Physics. Van der Meer’s largest contribution was to the discovery of the technique of stochastic cooling of particle beams. This process uses electric fields to keep the individual particles of a beam close together. This effectively lowers the entropy of the beam system or ‘cools’ the beam. This focusing of the beams allows accelerators to greatly increase the overall kinetic energy of the particles. This increase was enough to bring the proton and anti-proton beams at CERN to enough energy to produce W and Z protons when the beams collided with each other.

1962 – First Antarctic atomic power plant begins operations.

PM3A facility
PM-3A nuclear reactor facility at McMurdo Station, Antarctica

The PM-3A atomic power plant began operations to become the first atomic power plant in Antarctica. The US Navy installed the reactor to provide power and desalinization for McMurdo Research Station. PM was the Navy’s designation for Portable, Medium output and 3 was the third of this series. The A designation was added because this plant was the first to be used in the field. “Portable” to the Navy meant all the components could be boxed up into cargo units that fit inside LC-130 aircraft. The components could then be assembled on site.

The plant would continue operations until 1972 when it was decommissioned.

1952 – Charles Scott Sherrington died.

Charles Scott Sherrington
Charles Scott Sherrington (1857 – 1952)

Sherrington was an English physiologist who shared the 1932 Nobel Prize in Medicine with Edgar Adrian for their research into the function of neurons. He discovered when one set of muscles is stimulated, muscles opposing the action of the first are simultaneously inhibited. He also coined the terms synapse and neuron to describe the parts of a nerve cell that receive or transmit nervous impulses from one cell to another.

1947 – First use of Carbon-14 dating technique.

1927 – Ira Remsen died.

Ira Remsen
Ira Remsen (1846 – 1927)

Remsen was an American chemist and educator who brought many German chemical techniques to America. He founded the chemistry department at Johns Hopkins University and served as the second president of the university. He also founded the American Chemical Journal and acted as its editor for 35 years. This journal was later combined with the Journal of Analytical and Applied Chemistry to form the modern Journal of the American Chemical Society.

Remsen is most known for the actions of one of his post-doctoral researchers, Constantin Fahlberg. Fahlberg was a young chemist who apparently did not wash his hands after working with chemicals all day. During dinner one day, he noticed his dinner roll tasted extra sweet. He asked his wife if she did anything special with the rolls. She replied she hadn’t done anything new and her roll was not sweet at all. He figured the sweetness was caused by something left on his hands from the lab.

Fahlberg had been working on coal tar derivatives and spent the next day tasting his work. Remsen and Fahlberg identified the sweetness was caused by an oxidation of o-toluenesulfonamide. Fahlberg quickly recognized the economic potential of a new sweetener and patented the discovery as ‘saccharine’ and claimed the discovery as his own. As the head researcher, Remsen was entitled to partial credit. This slight caused a rift between the two chemists which lasted a lifetime.

1923 – Patrick A. C. Moore was born.

Moore is an English author and amateur astronomer and the famous face of the BBC program The Sky at Night. He is credited with raising general awareness, popularity and education for astronomy in Britain.

1915 – William Willett died.

William Willett (1856 - 1915)
William Willett (1856 – 1915)

Willett was a British home builder who invented Daylight Savings Time as it is used today. He arrived at the idea for changing clocks for the summer months when he was out for an early morning ride on a summer day and noticed several houses still had blinds down. While the idea for Daylight Savings Time had been proposed before by others, Willett continuously campaigned the British government to pass it into law.

1903 – William Clouser Boyd was born.

Boyd was an American immunologist who, together with his wife, Lyle were best known for their worldwide survey of blood types and the discovery blood type is an inherited trait not influenced by the environment. They grouped populations by blood types and hypothesized there were 13 distinct races with different blood group profiles.

1881 – Richard C. Tolman was born.

Tolman was an American physicist who demonstrated the charge carrying capacity in electricity is electrons moving through a conductor.  He authored the standard statistical mechanics book in use for much of the mid 20th Century.

During the Manhattan Project, he served as scientific adviser to the military head of the program, General Groves.

1854 – William Napier Shaw was born.

Shaw was a British meteorologist who conducted major studies of the upper atmosphere and air pollution. He also introduced the unit of pressure ‘millibar’. 1 millibar = 1/1000 bar and 1 bar = 1 atm.

Shaw invented the tephigram diagram used in weather forecasting. The tephigram is a plot of temperature versus entropy and used to calculate air stability and convective available potential energy (CAPE).

1679 – John Flamsteed was appointed Britain’s first Astronomer Royal.

John Flamsteed
John Flamsteed (1646-1719) Self Taught English Astronomer and first Astronomer Royal.

John Flamsteed was appointed Britain’s first Astronomer Royal. Flamsteed would compile a catalog of over 3000 accurate star position readings. His work was initiated to aid in navigation techniques but was not paid to run the unfunded Greenwich Royal Observatory. He took in students to pay for equipment and daily expenses, leading him to feel the data he compiled belonged to him. This would generate a famous feud between contemporaries Issac Newton and Edmond Halley.