Radio Carbon Dating (Earth, choice, pray)

[pray4me]

Okay, here's what I don't understand. If something loses half it's carbon in 5,700 years wouldn't logic say that in 11,400 all of it would be gone? Why would the process slow to half the speed that it was originally decaying at? And if the above were true, wouldn't that mean, if we cannot find anything that used to be alive completely devoid of carbon, that the world is less than 11,400 years old or at least all life on the earth is that young? Someone please explain this reasoning to me.

[Jayhawker Soule]

Originally Posted by pray4me

Okay, here's what I don't understand. If something loses half it's carbon in 5,700 years wouldn't logic say that in 11,400 all of it would be gone?

Pour a cup of sugar into a bowl and place it on the counter. Every morning, upon waking, remove exactly one half the sugar. Let me know when it's all gone ...

[michel]

I haven't the faintest clue, but I'll pray you!

Originally Posted by Jay

Pour a cup of sugar into a bowl and place it on the counter. Every morning, upon waking, remove exactly one half the sugar. Let me know when it's all gone ...

How dreadfully painstakingly boring; but a good point!

[Jayhawker Soule]

Originally Posted by michel

How dreadfully painstakingly boring; but a good point!

It's interesting to note that starting with two cups would be no more or less boring.

By the way: I've missed you. I hope you're well.

[pray4me]

I still don't get it, why every 5,700 years. If you keep pouring the cup of sugar on the table at the same speed it's your choice to stop at half and do half the next day. Why would it stop and half itself every 5,700 years?

[Ringer]

Originally Posted by pray4me

I still don't get it, why every 5,700 years. If you keep pouring the cup of sugar on the table at the same speed it's your choice to stop at half and do half the next day. Why would it stop and half itself every 5,700 years?

A quote from the internet....

The rate of decay of 14C is such that half of an amount will convert back to 14N in 5,730 years (plus or minus 40 years). This is the “half-life.” So, in two half-lives, or 11,460 years, only one-quarter of that in living organisms at present, then it has a theoretical age of 11,460 years. Anything over about 50,000 years old, should theoretically have no detectable 14C left. That is why radiocarbon dating cannot give millions of years. In fact, if a sample contains 14C, it is good evidence that it is not millions of years old.

[pray4me]

okay, now how did they come up with 5,730 years? No human being has lived that long. How was it discovered in the first place and can anything manipulate the rate of decay?

[yossarian22]

Originally Posted by pray4me

okay, now how did they come up with 5,730 years? No human being has lived that long. How was it discovered in the first place and can anything manipulate the rate of decay?

Any nuclear decay is a first order reaction, and the rate is determined by the equation
ln(A)=-kt-H0(A), where A is concentration of product (or reactant), t is time, and k is the rate constant.
Determining the rate constant is possible from experimentation, but it is a painful process. Measuring concentrations is a royal pain in the ***. Long half lives are pretty easy to measure compared to smaller versions, which necessarily decay more rapidly.

The half life of a first order reaction is constant, and can be calculated from k with no trouble at all.
ln(2)/k. K is the same as the above equation.

edit:
A simpler way to look at this is to examine the equaton y=1/2^X. The resulting graph approaches zero, but will never reach it.

And to answer your question, there is no way to alter the process of radioactive decay.

[pray4me]

You mean long half lives as in, something that is newer versus something that is older right?

[pray4me]

I don't understand all the symbols in equations can you put it into + x - a