Radio Carbon Dating (Earth, choice, pray)

[pray4me]

there was something on that site howstuffworks.com that said "However, radioisotope dating may not work so well in the future. Anything that dies after the 1940s, when Nuclear bombs, nuclear reactors and open-air nuclear tests started changing things, will be harder to date precisely." Does anyone know how this would change the accuracy of radioisotope dating?

[misanthropic_clown]

I think the general idea is that when a nuclear bomb goes off, lots of radioactive by-products can result, so if a bomb were to create a large amount of carbon 14 in the atmosphere, and this be absorbed by the plant, then the ratios are going to be skewed, and so analysis unreliable.

I don't know much about the carbon 14 emissions of nuclear activity, but I would assume that relatively speaking it is small enough for it not to have a major effect on the carbon 14 content of the majority of living things.

[painted wolf]

it seems impossible that everything no matter the length of it's existance has absorbed the same amount of carbon 14. Wouldn't something that died relatively young have much less carbon 14 than something that died older? Can anything (such as pollution) effect the amount of carbon 14 created in the atmosphere and thus effect the amount absorbed by plants?

You are looking at the ratio of the elements... not the total amount of the element.
If one animal has ten million C14 atoms and another has one hundred million c14 atoms and they died at the same time then they would have the same ratio of C to H.

And bombs don't have any barring on things that died prior to the 1940's.
Scientist are actually using the spike to track the rates of nuclear war fallout over time. You're teeth contain a record of the bombs dropped and can pinpoint when during the above ground testing period you were born.

As a side note C14 is just one of the many radiometric dating tecniques used. Nukes have no effect on the others.

Pollution, Earthly magnetics and water have nothing to do with atomic decay.

wa:do

[yossarian22]

Originally Posted by pray4me

it seems impossible that everything no matter the length of it's existance has absorbed the same amount of carbon 14. Wouldn't something that died relatively young have much less carbon 14 than something that died older? Can anything (such as pollution) effect the amount of carbon 14 created in the atmosphere and thus effect the amount absorbed by plants?

The initial amount of carbon 14 present is irrelevant to the calculations. Half life is independent of initial concentration for first order reactions. It [carbon 14] decays into Nitrogen 14 (through beta decay). So we have a ratio of Nitrogen 14 and Carbon 14. We use that ratio to determine age. The only way to falsify carbon dating would be to show that something very common can effect the rate of decomposition. Even then, we could just adjust calculations.