A Scientist using carbon 14 dating is actually measuring the?
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Shanna and Geo06 have got this just about right.  The only thing I can add is that radiocarbon dating can not be used for more than about 70,000 years ago, and is more accurate for living things that died within the last 8,000 years.\n\nMost geologists measure rock ages in millions, or even billions, of years, so the age of the earth and the age of almost all igneous rocks is well beyond the range of carbon dating.  On top of that, igneous rocks contain very little if any carbon,  so carbon dating is not applicable here.  \n\nSo the only thing carbon 14 can be used for is to determine the time that an exchange of carbon with the atmosphere stopped, ie, the death of a living thing - the third item on your list of choices for your homework.\n\nThe half life of C-14, the radioactive isotope of carbon, is about 5730 years.  Therefore, if you know the ratio between C-14 and C-12 in the atmosphere when the organism died, and you know the ratio now, the difference in the ratio can be calculated backwards, using the half life, to estimate when the organism died. \n\nAtmospheric C-14 has not been in a constant ratio with C-12, as previously thought, so there are some serious problems with the accuracy of C-14 dating.  The problem is that the natural ratio of the carbon isotopes in the atmosphere (carbon dioxide) varies because cosmic ray bombardment of the outer atmosphere produces C-14 but not C-12.  The ratio can be predicted accurately using the ratios in old trees, where the tree rings can be used to accurately determine the age of each ring with its annual ratio, with a maximum of about 8,000 years -that's how old the oldest trees are which can establish a reference ratio.\n\nDating of artifacts is a best guess, the best method is to measure the amount of lichens growing on them, or the age of carbon in ashes found in the same spot.
153391
I'm assuming that that refers to giving the age of two things relative to one another, rather than identifying the absolute ages of things.  For instance, when you take two trees that lived in similar times and places, you can look at the width of the tree rings to get an idea as to the conditions (especially moisture) during a given year.  If you have two such wood samples, you should be able to see a pattern between the two.  Using taht information, you could count rings and figure out how much older one piece of wood was relative to the other.  But without knowing the year the trees dies, or without knowing the particular calendar years behind the droughts, you wouldn't know that absolute age of either.  I'd imagine that there are similar things with radioisotope dating if you have a reason to think that the atmospheric conditions creating certain isotopes might change, but not knowing the exact concentrations at the time an organism lived.
1048589
I cant tell you its value, but go to a geological estimator and ask to have a carbon test done for an estimated date of formation. With that date, an accurate value will be easier to ascertain with the services of an experienced fossil valuator.
50952
like any physical parameter derived from measurement, results should be reported with a +/- experimental uncertainty.  unfortunately when these numbers are repeated in the media, rarely do they get repeated.  (and in fact, often scientists neglect to even publish them.  jerks.)\n\nanyway, a typical error bar for radiocarbon dating seems to be anywhere from 30-50 years.  so you can consider it accurate to within that margin of uncertainty.  however, depending on the data, sometimes this can increase to an error margin of several centuries!  (see 2nd link)
1140549
science of dating the ages of trees
75199
well, you are right.  the validity of radiocarbon dating depends on the assumption that the half-life of carbon-14 isotopes does not change with time.\n\nbut, one of the principles of most use in scientific investigations is occam's razor, which says that when presented with a choice, usually the simplest answer is the most correct.  so, it is -assumed- that the half-life was not different a thousand years ago.  however, it is possible.  \n\nbut radiocarbon dates have been validated by other methods (such as counting rings on big trees, for instance) and there is no evidence for any change in the half-life of carbon in the time that the method has been in use.  also, a time-invariant half-life fits in with the current understanding of nuclear decays, so it seems pretty unlikely that it would change over time.\n\nas for the moon, it is not a candidate for carbon dating, which only works on samples that were alive at some point - bones, trees, antlers etc.  the basic idea is that the living organism exchanges carbon with the environment while it's alive, and stops doing so when it dies.  since the proportion of radioactive carbon in the environment is fixed, then when the organism dies, it's decaying carbon-14 content stops being replenished by eating, breathing etc.  so since the moon is mostly rock, and no biological processes exist (that we know of) on the moon, carbon dating doesn't work there.\n\nso anyway, in general i agree that everyone should be a skeptic.  nobody should blindly accept something just because they are told "it is so" but should try to understand the whys and hows and come to understand it themselves!  these days science is treated with almost as much reverence as religion once was.  \n\nlong ago, if the pope said something was so, it was so - and now, if a scientist says something is so, people accept it as so!  unfortunately this is just one of the fundamental problems of human nature - we often accept what we are told because it's told to us by an authority.   so it makes me happy when someone asks questions that challenge the assumptions!
776734
It's called radio-carbon dating.\nhttp://en.wikipedia.org/wiki/Radio-carbon_dating
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.
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No. Radiocarbon dating relys on Carbon 14 which has a half-life of 5730±40 years. Most answers for carbon dating give a range of 100-200 years over when a sample might be from.\n\nIn addition to the half-life, you also need to know something about where the carbon in the sample came from, because different sources have different starting amounts of C14. \n\nThis means that carbon dating something modern would tell you it was made in the last 100 years. You could probably get a better estimate of the age, just by looking at it.
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Scientific data is ambiguous and conflicting as it pertains to "global warming." Current data only exists for a few hundred years. The rest is from computer "models" which use differing assumptions and yield differing results.\n\nSince no conclusive data exists upon which to base conclusions, actions ought not be based on inconclusive data. Those are facts rarely discussed or admitted globally.
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Archaeologist here. There are several ways that an arrow head can be dated (though they are usually called points, I know, I had to get used to it too).\n\n1. Stratigraphy/geomorphology. The location of an artifact can   be at least estimated, sometimes very closely, by its surroundings. A good geologist can usually tell pretty well how old a particular formation or soil layer is. This isn't exact, however.\n\n2. Dates can be estimated by the type of point it is. Tool types change over time, and each style has a general age range. If I was digging in North America and found what I identified as a Clovis point, I'd assume it was probably between 12,000 and 9,000 years old (roughly). As you can see, this isn't all that exact either, and these dates had to come somewhere in the first place, right?\n\n3. Funny enough, all the people who said carbon dating are correct. True enough that stone artifacts cannot be dated, but they are not usually found alone either. Many times they are found as part of a camp, near a hearth, and charcoal from the old hearth CAN be dated using carbon dating. We call this association. There is a chance (sometimes big sometimes small), that the point is not actually associated with the hearth, but we've dated enough this way to see when something doesn't match up right. If we're really lucky, as someone already suggested, we might find a point actually embedded in a person or animal! It has happened, a bone excavated with a point stuck in it.
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Carbon-14 is only reliable for dating objects up to about 60,000 years old.  The website below explains the equation in detail if your interested.
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Radiocarbon and luminescence dating methods were used
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they have found remains of a huge wooden construction on Mount Arakat and the carbon dating looks about right .\nso it is very possible that it has been found.
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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.
853493
Dendrochronology or tree-ring dating is the method of scientific dating based on the analysis of tree-ring growth patterns. This technique was invented and developed during the 20th century originally by A. E. Douglass, the founder of the Laboratory of Tree-Ring Research at the University of Arizona. The technique can date wood to exact calendar years.\n\nclick here:http://en.wikipedia.org/wiki/Dendrochronology#Overview
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Although some of the answers you have received are accurate they aren’t exactly succinct or to the point.\nYou haven’t however said what age the kids are you need to explain it to, please forgive me if this explanation seems too simplistic.\nThe theory of radioactive dating works along these lines.\n\n1. SOME ELEMENTS “DECAY” (CHANGE) FROM ONE THING TO ANOTHER, e.g. from Potassium to Argon or from one isotope to another e.g. C14 to C12\n2. THIS RATE OF CHANGE IS KNOWN, the speed at which it changes is known as the half life, i.e. how long before half of the total has changed\n3. A COMPARISON IS MADE i.e. you work out how much there was and how much has changed\n4. THE AGE IS CALCULATED. Once you know how much has decayed you can compare the amounts on well-known charts e.g. if you know halve the amount of C14 has changed to C12 then the sample is 5730 years old.\n\nIt is considered accurate because the rate of radioactive decay is absolute, measurable and observable. It has been tested numerous times and can be experimented on. The same results can be achieved and repeated by numerous people at many different labs. On the whole the decayed products (e.g. C12 etc.) are not found naturally. The original material is created at the time the sample is formed or moved (e.g. when the plant, animal grew).\n\nHowever the problems are\n1. In order to calculate the percentage of element changed you have to know how much there was. Sometimes the sample can have some of the original material removed or more of the original material can be added, e.g. new living fungi can grow and die on a log hundreds of years after the log was originally felled and buried.( this would give a younger date)\n2. The resulting product can be removed or further altered e.g. Argon from potassium can escape as it is a gas ( this would give you a later date because it would seem not as much or the argon had been formed)\n3. This time clock can be reset due to outside influences. A fire can reset the amount of C14/C12 because the carbon from the fire is different from the carbon formed in the living thing (e.g. the problems with dating the shroud of Turin)\n\nThis of coarse assumes that the equipment used is accurate and that no contamination was added e.g. someone touching or sneezing on the sample.\n\nOn the whole though in theory the method should be extremely accurate. Given perfect samples, good laboratory practice and accurate measurements the results seem impressive. This shouldn’t automatically however be taken for granted.\n\nThe final thing to remember though is that there is no other way of giving empirical, measurable dates on extremely ancient rocks or artefacts.