The age of known artefacts from Egypt were too young when measured by radiocarbon dating.
A scientist from the Netherlands (Hessel de Vries) tested this by radiocarbon dating tree rings of know ages (de Vries, 1958).
When a plant or animal dies it no longer exchanges CO with the atmosphere (ceases to take 14C into its being). 14C decays by emitting an electron, which converts a neutron to a proton, converting it back to its original 14N form.
The History of Radiocarbon Dating Willard Libby invented radiocarbon dating in the late 1940s.
Hereafter these isotopes will be referred to as 12C, 13C, and 14C.
14C is radioactive and has a half-life of 5730 years.
Calibration In the 1950s it was observed that the radiocarbon timescale was not perfect.
The gas counter detects the decaying beta particles from a carbon sample that has been converted to a gas (CO, methane, acetylene).
A liquid scintillation measurement needs the carbon to be converted into benzene, and the instrument then measures the flashes of light (scintillations) as the beta particles interact with a phosphor in the benzene.
His first publication showed the comparisons between known age samples and radiocarbon age (Libby et al, 1949; Libby, 1952). For the first time it was possible to obtain ages for many events which occurred over the past ~50,000 years.
In 1960 Libby was awarded the Nobel Prize for chemistry for this contribution.