Carbon dating is wrong
Libby was right, and won a Nobel Prize in Chemistry in 1960.
C-14 remains the gold standard for dating although debate continues about how far back it works, and how dates can end up looking 'too young' or 'too old' because of various things like contamination. There's a really interesting story about the discovery of lead dating, which goes much further back then carbon. The short story is that the guy who figured it out first had to deal with the fact that basically everything in the world since like 2000 years ago is contaminated with lead.
Evidence from North Atlantic sediments suggests that the Earth’s magnetic field may have dipped around 40 thousand years ago, but this would still only account for – at best – half of the observed peak in carbon-14 concentrations.
Beck’s team concludes that either a jump in the cosmic ray flux or a fundamental change in the carbon cycle must have produced the sudden increase of carbon-14.
This raises questions about the accuracy of carbon dating for very old objects.
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.
Or so we thought, as before C-14, we didn't have a very good idea how old most things really were.
But Beck and colleagues believe that the ratio of stable and radioactive carbon in the atmosphere may have changed considerably over the last 50 thousand years.
Once he learned how to clean all the lead out of his laboratory he was able to measure the age of the Earth very precisely.
Then he spent a few decades trying to convince everyone that they are being poisoned by lead.
“We should take this as a warning that climate change may affect the carbon cycle in previously unexpected way”, says Beck.
Two chemists, Martin Kamen and Samuel Ruben, were looking into ways to essentially radio-tag carbon so they could track it performing various metabolic tasks in living animals.