What's "pmC"?

I was asked on a FB group, after showing my Newer tables, whether pmC was about the atmosphere and the amount of carbon 14.

First, it's not just the atmosphere, it's the atmosphere and any other sample.

Second, it's not exactly an amount. You can't take 1 theoretical kg of pure carbon 14 and call that so and so many pmC, unless you state in how many trillions of kg of carbon 12 it's diluted in.

Now, once you have both the quantity of carbon 14 and the quantity of carbon 12, usually the latter counted in grammes, you can indeed calculate what the pmC is, but it's not simply the ratio.

No, it's how that ratio compares to another ratio. And that other ratio is termed "modern carbon 14" and more precisely "corrected for pre-industrial values" ...

So, once you know that value and have termed it "[100 percent of] modern carbon 14" any value the scientist finds can be compared to it. Suppose for argument's sake that "100 pmC" means "1 unit carbon 14 per 1 000 000 000 units carbon 12", that means in turn that if what you find in a sample is (on the same assumption) "1 unit carbon 14 per 2 000 000 000 units carbon 12" the measure is "50 pmC" / 50 % of modern carbon.

That's the measuring part of the issue. And I don't do that. I do however theorise what pmC values succeeded each other in the atmosphere. BACK THEN.

Before I tell you more, one more check on the theory I share with evolutionists. Any carbon 14 will decay to half in 5730 years. The carbon 14 present in the atmosphere in 3705 BC or 1494 after Creation or 748 before the Flood, only half of it remains. If the atmosphere back then had been 100 pmC, a sample from the actual year 3730 BC would no doubt be 50 pmC today. If the atmosphere back then was instead 1 pmC, a sample from that year would now have a carbon 14 level of 0.5 pmC. AND, those 50 or 0.5 pmC or whatever, they are all the carbon 14 that remains from back then. Any level exceeding that has been added later by new production of carbon 14 in the atmosphere.

In a sample, usually no more carbon 14 is added. A plant once harvested ceases to get carbon dioxide into its fibres and sugars by photosynthesis. That's why the only relevant factors for the pmC in the sample are:

• original pmC in the atmosphere, for instance around 100 pmC in all AD times and about a millennium back before that;
• times a decimal fraction equalling the pmC value with the decimal comma moved two places back. So, since 3705 BC, "* 0.5" or since 840 BC, "* 0.70710678"

Whatever new carbon 14 is created in the atmosphere is however totally irrelevant to the value in the sample, even if it is highly relevant to the value at present in the atmosphere and therefore how we measure "100 pmC" ...

And here is the deal. 100 pmC isn't a constant per se. It's a quasi constant, resulting from a constant decay rate, but also from a quasi-constant, in the present, rate of carbon 14 production.

So, since 840 BC, only 70.711 pmC remain, in a sample, or in the atmosphere. But if instead of 70.711 we have c. 100 pmC (not really any longer, but in 1850 it was), this means that 29.289 pmC have been net produced in the meantime. Doesn't mean 14.6445 pmC was produced in each half of 1432.5 years, no, since in the second of them, no 14.6445 pmC could remain of the first half. You see, in 1432.5 years, 100 pmC goes down to 84.09 pm, meaning the original new 14.6445 pmC would be down in 12.3145 pmC. So, in each half, more than 14.6445 pmC is produced, in fact 15.91 pmC are produced. But the point is, over 2865 years, a net, production and its own decay compounded, of 29.289 pmC is produced.

What would have happened if 840 BC the atmosphere held 100 pmC, but only 14.6445 pmC had been produced since then? We'd be down in 85.3555 pmC instead of 100 pmC.

A sample of 85.3555 pmC dates as 1300 years old.

What would have happened if 840 BC the atmosphere held 100 pmC, but 58.578 pmC had been produced? We'd be up in 129.289 pmC.

A sample of 129.289 pmC dates as "-2120" or 2120 years into the future. (Such samples do exist, if for instance a sample has been exposed to a nuclear explosion).

The thing is, while this isn't what has happened, at least of the halflife really is 5730 years, and we can know that, within some credible possibility of discrepancy; it certainly could have happened, or the idea that it couldn't depends on making stars and the sun so much more deterministic than observation at a distance allows us to be about them. One of the factors for the speed of carbon 14 production is precisely, how much cosmic rays hits the outer atmosphere.

My proposal is, something like that did happen, a slower pmC rise before the Flood, a quicker between the Flood and the Fall of Troy.

This is the theoretical background to Newer Tables: Preliminaries · Flood to Joseph in Egypt · Joseph in Egypt to Fall of Troy. It is equally the theoretical background to all its predecessors back to Avec un peu d'aide de Fibonacci ... j'ai une table, presque correcte (ten years ago, or it will be so last of this month) and its ultraclumsy precursor on the 5 of the same month. I had in fact figured that my tables could be read by people who knew how carbon dating worked, but apparently, this is not the case with everyone who took an interest.
/Hans Georg Lundahl