Because Libby believed that the Earth was millions of years old, he assumed that there had been plenty of time for the system to be in equilibrium.
This means that he thought that C was entering the atmosphere as fast as it was leaving—calculations show that this should take place in about 30,000 years, and of course the Earth was much older than that, said the geologists.
Always be prepared to excuse yourself if you feel unsafe or uncomfortable.
Even if you are getting on like a house on fire and you’re ready to pop some corks in your own mind stay calm and sensible.
We’ve seen that it would have been the same as in the atmosphere at the time the specimen died. Do scientists assume that it was the same as it is now? It is well known that the industrial revolution, with its burning of huge masses of coal, etc.It is assumed that the ratio has been constant for a very long time before the industrial revolution. (For on it hangs the whole validity of the system.) Why did W. Libby, the brilliant discoverer of this system, assume this?Libby knew that C was entering and leaving the atmosphere (and hence the carbon cycle).As soon as it dies, however, the C ration gets smaller.In other words, we have a ‘clock’ which starts ticking at the moment something dies.