So, in other words, we have a pretty solid way to calibrate raw radiocarbon dates for the most recent 12,594 years of our planet's past.
But before that, only fragmentary data is available, making it very difficult to definitively date anything older than 13,000 years.
It was the first absolute scientific method ever invented: that is to say, the technique was the first to allow a researcher to determine how long ago an organic object died, whether it is in context or not.
Shy of a date stamp on an object, it is still the best and most accurate of dating techniques devised.
The new isotope is called "radiocarbon" because it is radioactive, though it is not dangerous.
It is naturally unstable and so it will spontaneously decay back into N-14 after a period of time.
Trees maintain carbon 14 equilibrium in their growth rings—and trees produce a ring for every year they are alive.
Although we don't have any 50,000-year-old trees, we do have overlapping tree ring sets back to 12,594 years.
Reliable estimates are possible, but with large /- factors.
As you might imagine, scientists have been attempting to discover other organic objects that can be dated securely steadily since Libby's discovery.