How do scientists determine the age of once-living organisms when using Carbon-14?
813528
C-14 is a radioactive isotope of carbon.  This means it is always spontaneously changing the composition of its nucleus, in this case by beta decay.  The carbon changes to Nitrogen-14.\n\nIn LIVING things the amount of C-14 stays the same, however, because living tissue is always making cells which constantly replaces any C-14 lost.  It does this because the N-14 in the living cells reacts with neutrons from cosmic radiation and forms C-14 which gets incorporated into the living tissue.\n\nOnce the living tissue dies, the C-14 that is lost is not replaced anymore.  The amount of C-14 steadily decreases according to the half-life of the C-14 (the time it takes for half of the C-14 to change to N-14) which is 5730 years.  The ratio of the amount of C-14 in the dead tissue and the amount of C-14 in the living tissue is compared and the time is then calculated.\n\nIf you want the equations and the math, here they are:\n\nN-14 + neutron = C-14 + H-1 (replenishment of C-14 in live cells)\n\nC-14 = electron + N-14 (decay of C-14; the electron is the beta particle)\n\ncalculation of time:\n\nN= activity of C-14 in the dead tissue\nNo = activity of C-14 in living tissue (always 14 disintegrations per second)\nL (really should be the Greek letter "lambda" ) = 0.693/half-life\n    (half life of C-14 is 5730 years).  This works out to be 0.00012\n\nln = the natural logrithim\nThe equation is:\n\nln N/No = -Lt   or \n\nln N/14 = -.00012t (don't forget the minus sign)\n\nAll you need to do is measure the activity of the C-14 in the dead tissue and then solve for time.
411413
Usually it's an isotope of uranium or rubidium that's used to date something that is millions of years old.  These elements have much longer half-lives than C-14 and take much longer to decay.  Often more than one element is used to date an artifact for certainty.  In other words, the object will be dated using uranium, then with strontium, and the results checked against each other.\n\nRadiocarbon dating is not accurate for very recent artifacts and anything older than 60,000 years.  So, whatever this story is about living clam shells being misdated, it's not surprising nor does it disprove radiometric dating.  Variation in carbon levels make it difficult to accurately date a contemporary object.  Also, people sometimes state that all radiocarbon dating is wrong because of a few errors, this is misleading since it is very easy to contaminate objects with recent carbon and skew the results.
116378
Well I did some searching for Guanlong wucaii and I was not able to find anything about it on the internet. There is some chinese pottery named wucai that is from the Ming period, from about 1368-1642 CE. So I really have no idea what object it is you are referring to in your question. \n\nAnyway, carbon dating is not used dating objects as old as 190 million years. Carbon 14, a radioactive isotope of carbon, is not much good for dating things older than 60,000 years of age, because all the radioactive carbon will have decayed away if one looks at objects much older than that. However, there are dozens of radiometric dating techniques, some that are good for objects billions of years old (like potassium-argon dating, or uranium-lead dating).\n\nThere are many other techniques besides radioactive dating. One can count tree rings. One can count layers of ocean bottom mud. One can count rings of coral growth. One can look at the changes in the protein structure since a creature died (the handedness of the organic molecules changes with time). And there are many other techniques (see references). These methods can be cross-referenced against each other for checking and improving confidence, and reducing error bars.
569167
because the margin of error becaomes incredibly large. after a very long time, a very tiny percentage of c14 is is left with a very tiny mass. the extraction process is not perfect, so we might lose or gain a certain amount of error, and the measuremt itself is not perfect, so we get more error. after 50,000 years the expected amount of carbon 14 is on the order of the error or smaller, so it becomes basically meaningless.
976654
Looking at astoriods because the whole solar system was formed from the same stuff and the rocked in the Earth is being renewed by subduction a creation zones so you can never tell how old that rock is because it will have been remade many times since the formation of the Earth.\n Radioactive dating not the most accurate but radioactive particles are in everything and they all decay so you can tell how old something is by looking at how much the radioactive particles have decayed \nalso there is carbon dating. You have to set things on fire for this so obviously you cnt do this on everything so it's not terribly accurate \nALSO I'M ONLY 12 YEARS OLD
1109602
Scientific evidence suggests that the Earth is actually around 4 billion years old.  We have shown that many fossils are more than 6000 years old by using carbon-testing and other accurate tests.  We have used geological evidence as well.  Thus, that prediction of the Bible is probably incorrect, although that doesn't mean that you should disregard the Bible.
205601
If you're referring to a human skeleton, yes, a good approximation can be done because our teeth have limited growth (they're brachydont) and we only have 2 generations, like most mammals. Therefore, an expert could see if the teeth are part of the milk or definitive dentition, and also assess the wear of the occlusal (grinding) surfaces. And not only the external appearance of the teeth is examined, but also the tissues (dentine, cement, enamel, pulp cavity).\nThere are standards to calculate age and they're normally used by forensic experts.\nA list of bibliography on the subject:\nhttp://users.breathe.com/malt/agedet.htm\nI've tried to find articles but none are free :-(\n\nHowever, other mammals have permanently-growing teeth, and therefore age determination is more difficult. And in other vertebrates that have more dental generations, other methods are used for age determination.
68920
As one might expect NIST (the modern name for NBS) also helps with standards for radio carbon dating. The main two callibration methods are to the so-called "1890 wood" and the oxalic acid samples, as described below, although the ANU sugar standard is also used. \n\nThe original callibration materials used when the technique was developed was from wood found in an Egyptian tomb, and a sample of the Dead Sea Scrolls. \n\nI suspect you are asking this question because you do not believe radioactive dating, since it conflicts with  Bishop Usher's derived age of the earth. I might point out that counting rings of coral, like counting tree rings, shows that we have had continuous growth of some corals that go back tens of millions of years.
1068442
There are a lot of different dating techniques.  (The second link talks about some) Usually, when dating something, you don't just use one technique one one sample--you try to find a few different ways, and use them to build up a case for the age of something.\n\nSome dating systems are relative, in that they can only tell you which came first.  This is useful because it lets people assemble a chronology of things, even though it won't have absolute dates.  Once you have this chronology, you can use absolute dates to start finding approximate ages for things. For example, there's a distinctive layer of iridium in many rocks. If you find something below that layer, it's a good bet that it's older than the layer is.  Once you know that the layer was put down about 65 million years ago, you can start to narrow down the date of the things beneath it.\n\nRelative techinques are also useful as a test for the absolute techniques--if you know what order things happened in, you can use that to check that other techniques are giving sensible results.\n\nThere are also a lot of different absolute techniques--see the third link for a disscussion. Some, like counting tree rings, are very accurate, but only go back a few hundred or thousand years. Others, like carbon-14 dating, work on things that were once alive.  Still others, like Uranium-Thorium dating or archaeomagnetism, only work on certain kinds of rocks. Carbon-14 and U-T dating work by looking at how much radioactive materials in the sample have broken down, and archaeomagnetism works because the Earth's magnetic field has changed over the ages, leaving signs in some minerals.\n\nFinally, you can just look at the things that are near a sample.  So, if an archelogical dig contains a kind of pottery that you know was used 3000 years ago, that's a clue that the site is about that old.  If a layer of rock is full of fossils of animals that lived 300-200 million years ago, the rock was probably formed around then.
541684
Carbon 14 dating cannot be used to determine the age of the Earth itself.  It has a half-life of only 5730 years, and can only be used on organic materials.  Current techniques can produce accurate results up to about 100 000 years old with Carbon 14, but this is not nearly old enough for the origins of the Earth.\n\nOther methods, such as U-238, or Potassium/Argon (K/Ar) dating can be used on igneous rocks (like volcanic ash, obsidian or granite) to find out when it formed, and have been used to date some of the oldest rocks in the world:  Precambrian granites exposed as part of the Canadian Shield when glaciers scraped all the top layers away during the most recent ice ages (the last of which was a mere 10,000 years ago) have been dated to about 4.2 billion years old, and some Australian zircons have been found to be at least 4.4 billion years old.\n\nHowever even these oldest rocks don't really give us the age of the Earth.  They show us that the Earth must be at least that old, but not exactly when the Earth itself formed.\n\nThe Earth has undergone constant vulcanism and reforming, with oceanic plates sliding under continental plates and being melted and reformed, and even continental plates dividing, subducting, transforming, eroding and being buried under new lava flows.  The oldest ocean beds are Triassic in age, perhaps a mere 300 million years old or less.\n\nHowever meteorites have not undergone this same reworking.  Presumably, most of them would have been formed at the dawn of the solar system, as the sun and planets were accreting from the gas cloud into more solid, spinning forms.  A meteorite from Canyon Diablo has been used as the sort of benchmark test, it is a very large metallic nickel-iron meteorite with sulfide materials, and ideal for most forms of radiometric dating.\n\nThe Canyon Diablo meteorite comes out to 4.567 billion years old.  Other extra-terrestrial rocks, such as the moon rocks, Mars rocks, and other meteorites come out to about the same ages, between 4.53 to 4.58 billion years old.  This range has been determined through a number of different techniques on a wide number of different samples, and they always come out in the same range, thus indicating that it probably accurate.\n\nSo the age of the Earth is generally taken to be about 4.5 to 4.6 billion years.
624262
An increment borer is the only accurate way to tell a live trees age. It is essentially a hand operated drill that you manually drill through the tree at 4.5 feet from the ground (On hardwoods like oak it can be really hard). An extracter is put into the bit and is removed from the tree with a core sample. Then you just look closely and count the rings, and remove the main bit from the tree.\n\nContrary to popular belief, a trees age cannot be told by how tall or how big around the trunk is. Some species are slow growers and some trees live in repressed situations. I have seen a White Oak that was about 8 in (in circumferance) at DBH (4.5 feet) and only about 40 feet tall that was over 75 years old. A person not knowing would probably guess that tree to be about 20.
172046
for treating cancer, and dating old objects using carbon 14.
321150
Carbon-14 dating is reliable for dating objects up to about 60,000 years old, the half-life of the isotope (5730 years) does not allow for accurate dating on objects much older than that.  Also, it is difficult to accurately date recent objects, as changing levels of carbon due to use of fossil fuels and nuclear explosions have changed the equilibrium of C-14 with its atmospheric production rate.  \n\nAlso, experiments have failed to show that half-lives of isotopes have changed as time has passed, therefore we can consider half-lives to be stable.  \n\nIn summary, we can consider radiocarbon dating accurate, as long as we are not considering objects older than about 60,000 years, (other radiometric dating methods are used for older objects) or recent objects.  People who claim that scientists misdate dinosaur bones as weeks old are misleading, as dinosaur bones are dated with uranium and rubidium, rather than C-14 (since they are millions of years old).  \n\nHope this is helpful.
878348
Here is the basic information including some alchemy (second two references).  Carbon is so old in human time that its history will never really be known.
664010
carbon dating cannot be used for very old fossils. Radioactive dating is a better method used extensively by geologists. Carbon 14 is fairly reliable for fossils that are not too old.
548762
You can use the scales to calculate the age of the fish. If you look at a scale with a strong magnifying glass in good light, you count the darker lines ( these are called annuli) their is one of these lines for each year, it is the same as counting the rings on a tree. This technique is useful especially if you dont want to kill the fish. If you want to try another technique you can use the otoliths but this involves fine dissection and scientific knowledge.
425880
Assessing the age of a living tree is straightforward enough -- just extract a core from the tree's circular trunk and count the number of lines in the core formed by the tree's annual growth rings. (The rings of ancient bristlecone pines like Methuselah are more challenging to count, because the trunks are so distorted that new rings may form at right angles to ones formed long before.) But there's much more information to be gleaned from growth rings than simply a tree's age. This information comes to us through the science of dendrochronology.