Something radioactive dating is used to find answer
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If you want to know how old someone or something is, you can generally rely on some combination of simply asking questions or Googling to arrive at an accurate answer. This applies to everything from the age of a classmate to the number of years the United States has existed as a sovereign nation and counting as of But what about the ages of objects of antiquity, from a newly discovered fossil to the very age of the Earth itself? Sure, you can scour the Internet and learn rather quickly that the scientific consensus pins the age of of the planet at about 4. But Google didn't invent this number; instead, human ingenuity and applied physics have provided it. Specifically, a process called radiometric dating allows scientists to determine the ages of objects, including the ages of rocks, ranging from thousands of years old to billions of years old to a marvelous degree of accuracy.
If the points lie on a straight line, this indicates that the data is consistent and probably accurate.
Using radioactive dating scientists can determine. the absolute age of rocks, the half life of a radioactive element, and the amount of a radioactive element in a rock. Radioactive dating is a technique used to find how old an object is. One such example is potassium-argon dating, where potassium decays into argon. The proportion of potassium to argon suggests how old the object in question is. Radiometric dating is a means of determining the "age" of a mineral specimen by determining the relative amounts present of certain radioactive elements. By "age" we mean the elapsed time from when the mineral specimen was formed. Radioactive elements "decay" (that is, change into other elements) by "half lives.".
An example of this can be found in Strahler, Fig However, if strontium 87 was present in the mineral when it was first formed from molten magma, that amount will be shown by an intercept of the isochron lines on the y-axis, as shown in Fig Thus it is possible to correct for strontium initially present.
Comparing figures The age of the sample can be obtained by choosing the origin at the y intercept.
Radioactive dating uses the decay rates of radioactive substances to measure absolute ages of rocks, minerals and carbon-based substances, according to How Stuff Works. Scientists know how quickly radioactive isotopes decay into other elements over thousands, millions and even billions of years. Rubidium-strontium (Rb-Sr) dating: Radioactive rubidium decays into strontium with a half -life of billion years. Not surprisingly, Ru-Sr dating is used to date very old rocks (as old as the Earth, in fact, since the Earth is "only" around billion years old). Sedimentary rocks can be dated using radioactive carbon, but because carbon decays relatively quickly, this only works for rocks younger than about 50 thousand years. So in order to date most older fossils, scientists look for layers of igneous rock or .
In Fig Note that the amounts of rubidium 87 and strontium 87 are given as ratios to an inert isotope, strontium However, in calculating the ratio of Rb87 to Sr87, we can use a simple analytical geometry solution to the plotted data. Again referring to Fig. Since the half-life of Rb87 is Therefore: log.
When properly carried out, radioactive dating test procedures have shown consistent and close agreement among the various methods. If the same result is obtained sample after sample, using different test procedures based on different decay sequences, and carried out by different laboratories, that is a pretty good indication that the age determinations are accurate. Of course, test procedures, like anything else, can be screwed up.
Mistakes can be made at the time a procedure is first being developed. Creationists seize upon any isolated reports of improperly run tests and try to categorize them as representing general shortcomings of the test procedure. This like saying if my watch isn't running, then all watches are useless for keeping time. Creationists also attack radioactive dating with the argument that half-lives were different in the past than they are at present.
There is no more reason to believe that than to believe that at some time in the past iron did not rust and wood did not burn. Furthermore, astronomical data show that radioactive half-lives in elements in stars billions of light years away is the same as presently measured.
On pages and of The Genesis Flood, creationist authors Whitcomb and Morris present an argument to try to convince the reader that ages of mineral specimens determined by radioactivity measurements are much greater than the "true" i.
Biblical ages. The mathematical procedures employed are totally inconsistent with reality. Henry Morris has a PhD in Hydraulic Engineering, so it would seem that he would know better than to author such nonsense.
Apparently, he did know better, because he qualifies the exposition in a footnote stating:. This discussion is not meant to be an exact exposition of radiogenic age computation; the relation is mathematically more complicated than the direct proportion assumed for the illustration.
Nevertheless, the principles described are substantially applicable to the actual relationship. Morris states that the production rate of an element formed by radioactive decay is constant with time. This is not true, although for a short period of time compared to the length of the half life the change in production rate may be very small.
Radioactive elements decay by half-lives. At the end of the first half life, only half of the radioactive element remains, and therefore the production rate of the element formed by radioactive decay will be only half of what it was at the beginning.
The authors state on p. If these elements existed also as the result of direct creation, it is reasonable to assume that they existed in these same proportions. Say, then, that their initial amounts are represented by quantities of A and cA respectively.
This is not correct; radioactive elements decay by half lives, as explained in the first paragraphs of this post. There is absolutely no evidence to support this assumption, and a great deal of evidence that electromagnetic radiation does not affect the rate of decay of terrestrial radioactive elements. He then calculates an "age" for the first element by dividing its quantity by its decay rate, R; and an "age" for the second element by dividing its quantity by its decay rate, cR.
Radioactive dating is used to find
Of course, the mathematics are completely wrong. For a half life of years, the following table shows the fraction remaining for various time periods:. In all his mathematics, R is taken as a constant value. We may therefore set R as equal to the initial rate in the above table:.
Radioactive Dating of Fossils Fossils are collected along with rocks that occur from the same strata. These samples are carefully cataloged and analyzed with a mass spectrometer. The mass spectrometer is able to give information about the type and amount of isotopes found in the rock. 8 rows Effective Dating Range (years) Dating Sample: Key Fission Product: Lutetium . Radiometric dating (often called radioactive dating) is a technique used to date materials such as rocks or carbon, usually based on a comparison between the observed abundance of a naturally occurring radioactive isotope and its decay products, using known decay rates.
Morris' equations would indicate that after years the amount of parent element would be completely gone, but the daughter element would nevertheless continue to be formed!
Click on the web site of Dr. Roger Wiens of Cal Tech for a detailed analysis of the accuracy of radioactive dating.
Additional information is also available in talk. A half-life measures the time it takes for one half of a radio isotope's atoms to break down into another element. For instance, if an object has 50 percent of its decay product, it has been through one half-life. A popular way to determine the ages of biological substances no more than 50, years old is to measure the decay of carbon into nitrogen This process begins as soon as a living thing dies and is unable to produce more carbon Plants produce carbon through photosynthesis, while animals and people ingest carbon by eating plants.
Carbon has a half-life of 5, years. Scientists determine the ages of once-living things by measuring the amount of carbon in the material. For biological objects older than 50, years, scientists use radioactive dating to determine the age of rocks surrounding where the material was found. By dating rocks, scientists can approximate ages of very old fossils, bones and teeth.
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