Carbon clock could show the wrong timeA study led by physicist Warren Beck of the University of Arizona discovered an enormous peak in the amount of carbon-14 in the atmosphere between 45 thousand and 11 thousand years ago. Living organisms and some geological features absorb stable carbon-12 and radioactive carbon-14, which are present in the air in a well-known ratio. Scientists use carbon dating to determine when objects ceased to absorb carbon by measuring how much of the carbon-14 - which has a half-life of 5730 years - has decayed. Beck and colleagues tested slices of a half-metre long stalagmite that grew between 45 000 and 11 000 years ago in a cave in the Bahamas. Galactic cosmic rays create most of the carbon-14 in our atmosphere, while solar cosmic rays generate a smaller fraction. The Earth is partially shielded from galactic cosmic rays by its own magnetic field and the solar magnetic field, which fluctuates as the solar cycle proceeds. These effects are predictable and are thought to have changed little in the last million years - which means they cannot explain the glut of carbon-14. The team speculates that a supernova shock wave could have produced a flurry of cosmic rays.
The carbon clock is like me looking at rust on a nail and guessing how old it is.