Radioactive decay[ edit ] Example of a radioactive decay chain from lead Pb to lead Pb. The final decay product, lead Pb , is stable and can no longer undergo spontaneous radioactive decay. All ordinary matter is made up of combinations of chemical elements , each with its own atomic number , indicating the number of protons in the atomic nucleus. Additionally, elements may exist in different isotopes , with each isotope of an element differing in the number of neutrons in the nucleus. A particular isotope of a particular element is called a nuclide. Some nuclides are inherently unstable. That is, at some point in time, an atom of such a nuclide will undergo radioactive decay and spontaneously transform into a different nuclide.
Age of the earth
History[ edit ] All the elements and isotopes we encounter on Earth, with the exceptions of hydrogen, deuterium, helium, helium-3, and perhaps trace amounts of stable lithium and beryllium isotopes which were created in the Big Bang , were created by the s-process or the r-process in stars, and for those to be today a part of the Earth, must have been created not later than 4. All the elements created more than 4. At the time when they were created, those that were unstable began decaying immediately.
There are only two other methods to create isotopes:
Some survivors and their descendants received compensation under the Radiation Exposure Compensation Act in
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Because uranium ores emit radon gas, and their harmful and highly radioactive daughter products , uranium mining is significantly more dangerous than other already dangerous hard rock mining Uranium is a chemical element in the periodic table that has the symbol U and atomic number Heavy, silvery-white, toxic, metallic , and naturally- radioactive , uranium belongs to the actinide series and its isotope U is used as the fuel for nuclear reactors and the explosive material for nuclear weapons.
Uranium is commonly found in very small amounts in rocks , soil , water , plants , and animals including humans. Notable characteristics When refined, uranium is a silvery white, weakly radioactive metal, which is slightly softer than steel. It is malleable, ductile, and slightly paramagnetic.
Chamberlain pointed out that Kelvin's calculations were only as good as the assumptions on which they were based.
Reference to a case where the given method did not work This is perhaps the most common objection of all. Creationists point to instances where a given method produced a result that is clearly wrong, and then argue that therefore all such dates may be ignored. Such an argument fails on two counts: First, an instance where a method fails to work does not imply that it does not ever work. The question is not whether there are "undatable" objects, but rather whether or not all objects cannot be dated by a given method.
The fact that one wristwatch has failed to keep time properly cannot be used as a justification for discarding all watches.
Can science prove the age of the earth? No scientific method can prove the age of the earth and the universe, and that includes the ones we have listed here. Further, it has to be assumed that the clock was never disturbed. There is no independent natural clock against which those assumptions can be tested. For example, the amount of cratering on the moon, based on currently observed cratering rates, would suggest that the moon is quite old.
However, to draw this conclusion we have to assume that the rate of cratering has been the same in the past as it is now.
The invention of the first mass spectrometer by Thomson was followed by the work of Dempster and Ashton , who designed the mass spectrographs which they used in subsequent years to discover the naturally occurring isotopes of most of the elements in the periodic table and to measure their masses and abundances.
At the time that Darwin's On the Origin of Species was published, the earth was "scientifically" determined to be million years old. By , it was found to be 1. In , science firmly established that the earth was 3. Finally in , it was discovered that the earth is "really" 4. In these early studies the order of sedimentary rocks and structures were used to date geologic time periods and events in a relative way. At first, the use of "key" diagnostic fossils was used to compare different areas of the geologic column.
Although there were attempts to make relative age estimates, no direct dating method was available until the twentieth century. However, before this time some very popular indirect methods were available.
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With time, it became apparent that this classification scheme was much too simple. A fourth category, known as spontaneous fission, also had to be added to describe the process by which certain radioactive nuclides decompose into fragments of different weight. Alpha decay is usually restricted to the heavier elements in the periodic table. Only a handful of nuclides with atomic numbers less than 83 emit an -particle.
Some of the progress in finding very old samples of rock on the Earth are summarized in the following comments.
Decay routes[ edit ] The above uranium to lead decay routes occur via a series of alpha and beta decays, in which U with daughter nuclides undergo total eight alpha and six beta decays whereas U with daughters only experience seven alpha and four beta decays. The term U—Pb dating normally implies the coupled use of both decay schemes in the 'concordia diagram' see below.
However, use of a single decay scheme usually U to Pb leads to the U—Pb isochron dating method, analogous to the rubidium—strontium dating method. Finally, ages can also be determined from the U—Pb system by analysis of Pb isotope ratios alone. This is termed the lead—lead dating method. Clair Cameron Patterson , an American geochemist who pioneered studies of uranium—lead radiometric dating methods, is famous for having used it to obtain one of the earliest estimates of the age of the Earth.
Mineralogy[ edit ] Although zircon ZrSiO4 is most commonly used, other minerals such as monazite see:
How Old is the Earth
See this page in: Hungarian , Russian , Spanish People who ask about carbon 14C dating usually want to know about the radiometric  dating methods that are claimed to give millions and billions of years—carbon dating can only give thousands of years. People wonder how millions of years could be squeezed into the biblical account of history. Clearly, such huge time periods cannot be fitted into the Bible without compromising what the Bible says about the goodness of God and the origin of sin, death and suffering —the reason Jesus came into the world See Six Days?
First, an instance where a method fails to work does not imply that it does not ever work.
Radiometric dating In , shortly after the discovery of radioactivity , the American chemist Bertram Boltwood suggested that lead is one of the disintegration products of uranium, in which case the older a uranium-bearing mineral the greater should be its proportional part of lead. Analyzing specimens whose relative geologic ages were known, Boltwood found that the ratio of lead to uranium did indeed increase with age.
After estimating the rate of this radioactive change, he calculated that the absolute ages of his specimens ranged from million to 2. Though his figures were too high by about 20 percent, their order of magnitude was enough to dispose of the short scale of geologic time proposed by Lord Kelvin. Versions of the modern mass spectrometer were invented in the early s and s, and during World War II the device was improved substantially to help in the development of the atomic bomb.
Soon after the war, Harold C. Wasserburg applied the mass spectrometer to the study of geochronology. This device separates the different isotopes of the same element and can measure the variations in these isotopic abundances to within one part in 10, By determining the amount of the parent and daughter isotopes present in a sample and by knowing their rate of radioactive decay each radioisotope has its own decay constant , the isotopic age of the sample can be calculated.
For dating minerals and rocks, investigators commonly use the following couplets of parent and daughter isotopes:
While there are numerous natural processes that can serve as clocks, there are also many natural processes that can reset or scramble these time-dependent processes and introduce uncertainties. To try to set a reasonable bound on the age, we could presume that the Earth formed at the same time as the rest of the solar system. If the small masses that become meteorites are part of that system, then a measurement of the solidification time of those meteorites gives an estimate of the age of the Earth.
Lifetime of long-period comets orbital period greater than years that are sun-grazing comets or others like Hyakutake or Hale—Bopp means they could not have originated with the solar system 4.
Please visit Site Map and Disclaimer. Use "Back" to return here. The uranium and thorium decay systems offer a multitude of radiometric dating options. Uranium decays through a series of steps to Lead Uranium decays to lead , and Thorium decays to lead In addition there is another stable isotope, lead , that is entirely primordial and does not form via radioactive decay at all.
Thus any of the radioactive isotopes and its lead daughter product can be used for dating, or a combination may be used. In addition, some of the longer-lived intermediate daughter products have uses in dating. Uranium minerals themselves are too uncommon to be very useful in dating. The most common dating method involves the use of minerals like zircon and monazite that are relatively common in granitic rocks.
Zircon is especially useful because it frequently contains uranium in substitution for zirconium, but does not incorporate lead as shown by the absence of Lead Thus all the lead in the zircon can be assumed to be radiogenic. U decays much faster than U my and my, respectively. Also, Lead forms only from the decay of U and Lead only from the decay of U
The Age of the Earth
These are K-Ar data obtained on glauconite, a potassium-bearing clay mineral that forms in some marine sediment. Woodmorappe fails to mention, however, that these data were obtained as part of a controlled experiment to test, on samples of known age, the applicability of the K-Ar method to glauconite and to illite, another clay mineral. He also neglects to mention that most of the 89 K-Ar ages reported in their study agree very well with the expected ages.
Evernden and others 43 found that these clay minerals are extremely susceptible to argon loss when heated even slightly, such as occurs when sedimentary rocks are deeply buried. As a result, glauconite is used for dating only with extreme caution.
These discoveries had a long-lasting influence on crystallography because they led to the development of the X-ray powder diffractometer, which is now widely used to identify minerals and to ascertain their crystal structure.
As with all cruise missiles, its range is a function of payload, propulsion, and fuel volume, and can thus vary greatly. Alpha particle A positively charged particle ejected spontaneously from the nuclei of some radioactive isotopes. It has low penetrating power and a short range a few centimeters in air. The most energetic alpha particle will generally fail to penetrate the dead layers of cells covering the skin and can be easily stopped by a sheet of paper.
Alpha particles are hazardous when an alpha-emitting isotope is inside the body. Al-Qaeda or Al-Qa'ida A radical Islamist terrorist organization established by Osama bin Laden now deceased , responsible for a number of attacks in the United States and worldwide, including the September 11, attacks on the World Trade Center and Pentagon. Antarctic Treaty The Antarctic Treaty was opened for signature on December 1, , and entered into force on June 23, The Antarctic Treaty internationalizes and demilitarizes the Antarctic continent.
It specifies that Antarctica be used for peaceful purposes only; all activities of a military nature, including testing of any type of weapon, are prohibited. No military activities, armaments, or prohibited nuclear activities have been observed on the continent during inspections by member states since the treaty went into force.