Radioactive carbon, as mentioned earlier, forms in the atmosphere from radiation striking nitrogen, and that radiation is randomly introduced into the atmosphere. Also, I have had evolutionists personally tell me that it is impossible to know for sure because the earth's magnetic field fluctuation also effects how much radiation comes through the atmosphere, so there again, the constant for C14 in the atmosphere today is a complete uniformitarian assumption.
In addition, even if it were possible to test for a constant level of C14 in the air, it would not be possible to test and prove that all life had the exact same amount.
One cannot even conceive of how such a task could be accomplished with mankind's limited ability, and that is for something we can see (e.g.
grasshoppers), let alone what is invisible to the naked eye (e.g. No consistent amount of C14 has ever been calculated in the atmosphere, nor is it possible for mankind to do such a thing without having a device that, at minimum, spanned the circumference of the atmosphere.
Perhaps we can put together the melted wax and find out tall the candle was before it was lit?
Even doing so, we must recognize some wax evaporates with the burning of the candle, irretrievably lost.
When the water reaches that steady state, it is called equilibrium.
C14 is continually being made by the sun's rays striking nitrogen (water pouring in), and continually decaying from the half-life mentioned earlier (water pouring out).
Let's say you and I were building framework for a house, but our tape measures were using two different standards for an inch.
We wouldn't be able to complete the project because nothing would fit together properly.
Once viewed in this light (no pun intended :), it seems childish to make these assmuptions without any credible historical evidence backing it.
The historical record God gives us is the main reason why the Biblical Christian model is far superior to any evolutionary interpretation.
So we cannot determine a constant measuring standard, and we cannot verify that standard measurement in all life on earth, but now we get a uniformitarian assumption that even IF there was a standard, and IF we could verify all life for that standard, the evolutionist still C14 amounts and the half-life rate of C14 has been the same for thousands and millions of years.