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This is a Most important question of gk exam. Question is : The age of the earth can be estimated by - , Options is : 1. Uranium dating, 2. Carbon dating, 3. Atomic clocks, 4. Biological clocks, 5.
Many naturalists were influenced by Lyell to become " uniformitarians " who believed that changes were constant and uniform. Inthe physicist William Thomson, 1st Baron Kelvin published calculations that fixed the age of Earth at between 20 million and million years. His calculations did not account for heat produced via radioactive decay a then unknown process or, more significantly, convection inside the Earthwhich allows the temperature in the upper mantle to remain high much longer, maintaining a high thermal gradient in the crust much longer.
Geologists such as Charles Lyell had trouble accepting such a short age for Earth. For biologists, even million years seemed much too short to be plausible. In Darwin's theory of evolutionthe process of random heritable variation with cumulative selection requires great durations of time. According to modern biology, the total evolutionary history from the beginning of life to today has taken place since 3.
In a lecture inDarwin's great advocate, Thomas H. Huxleyattacked Thomson's calculations, suggesting they appeared precise in themselves but were based on faulty assumptions.
The age of the earth can be estimated by uranium dating
The physicist Hermann von Helmholtz in and astronomer Simon Newcomb in contributed their own calculations of 22 and 18 million years respectively to the debate: they independently calculated the amount of time it would take for the Sun to condense down to its current diameter and brightness from the nebula of gas and dust from which it was born.
However, they assumed that the Sun was only glowing from the heat of its gravitational contraction. The process of solar nuclear fusion was not yet known to science. In John Perry challenged Kelvin's figure on the basis of his assumptions on conductivity, and Oliver Heaviside entered the dialogue, considering it "a vehicle to display the ability of his operator method to solve problems of astonishing complexity.
Other scientists backed up Thomson's figures. Charles Darwin 's son, the astronomer George H. Darwinproposed that Earth and Moon had broken apart in their early days when they were both molten. He calculated the amount of time it would have taken for tidal friction to give Earth its current hour day.
Creation Radiometric Dating and the Age of the Earth
His value of 56 million years added additional evidence that Thomson was on the right track. The last estimate Thomson gave, inwas: "that it was more than 20 and less than 40 million year old, and probably much nearer 20 than 40".
By their chemical nature, rock minerals contain certain elements and not others; but in rocks containing radioactive isotopes, the process of radioactive decay generates exotic elements over time. By measuring the concentration of the stable end product of the decay, coupled with knowledge of the half life and initial concentration of the decaying element, the age of the rock can be calculated.
InThomson had been made Lord Kelvin in appreciation of his many scientific accomplishments. Kelvin calculated the age of the Earth by using thermal gradientsand he arrived at an estimate of about million years. InJohn Perry produced an age-of-Earth estimate of 2 to 3 billion years using a model of a convective mantle and thin crust,  however his work was largely ignored.
The discovery of radioactivity introduced another factor in the calculation.
After Henri Becquerel 's initial discovery inMarie and Pierre Curie discovered the radioactive elements polonium and radium in ; and inPierre Curie and Albert Laborde announced that radium produces enough heat to melt its own weight in ice in less than an hour. Geologists quickly realized that this upset the assumptions underlying most calculations of the age of Earth. These had assumed that the original heat of the Earth and Sun had dissipated steadily into space, but radioactive decay meant that this heat had been continually replenished.
George Darwin and John Joly were the first to point this out, in Radioactivity, which had overthrown the old calculations, yielded a bonus by providing a basis for new calculations, in the form of radiometric dating.
Ernest Rutherford and Frederick Soddy jointly had continued their work on radioactive materials and concluded that radioactivity was due to a spontaneous transmutation of atomic elements. In radioactive decay, an element breaks down into another, lighter element, releasing alpha, beta, or gamma radiation in the process.
Science Confirms a Young Earth—The Radioactive Dating Methods are Flawed
They also determined that a particular isotope of a radioactive element decays into another element at a distinctive rate. This rate is given in terms of a " half-life ", or the amount of time it takes half of a mass of that radioactive material to break down into its "decay product".
Some radioactive materials have short half-lives; some have long half-lives. Uranium and thorium have long half-lives, and so persist in Earth's crust, but radioactive elements with short half-lives have generally disappeared.
This suggested that it might be possible to measure the age of Earth by determining the relative proportions of radioactive materials in geological samples. In reality, radioactive elements do not always decay into nonradioactive "stable" elements directly, instead, decaying into other radioactive elements that have their own half-lives and so on, until they reach a stable element.
These " decay chains ", such as the uranium-radium and thorium series, were known within a few years of the discovery of radioactivity and provided a basis for constructing techniques of radiometric dating. The pioneers of radioactivity were chemist Bertram B. Boltwood and the energetic Rutherford. Boltwood had conducted studies of radioactive materials as a consultant, and when Rutherford lectured at Yale in Boltwood was inspired to describe the relationships between elements in various decay series.
Late inRutherford took the first step toward radiometric dating by suggesting that the alpha particles released by radioactive decay could be trapped in a rocky material as helium atoms. At the time, Rutherford was only guessing at the relationship between alpha particles and helium atoms, but he would prove the connection four years later.
Soddy and Sir William Ramsay had just determined the rate at which radium produces alpha particles, and Rutherford proposed that he could determine the age of a rock sample by measuring its concentration of helium. He dated a rock in his possession to an age of 40 million years by this technique. Rutherford wrote. I came into the room, which was half dark, and presently spotted Lord Kelvin in the audience and realized that I was in trouble at the last part of my speech dealing with the age of the Earth, where my views conflicted with his.
To my relief, Kelvin fell fast asleep, but as I came to the important point, I saw the old bird sit up, open an eye, and cock a baleful glance at me! Then a sudden inspiration came, and I said, "Lord Kelvin had limited the age of the Earth, provided no new source was discovered.
That prophetic utterance refers to what we are now considering tonight, radium! Rutherford assumed that the rate of decay of radium as determined by Ramsay and Soddy was accurate, and that helium did not escape from the sample over time. Rutherford's scheme was inaccurate, but it was a useful first step. Boltwood focused on the end products of decay series.
Inhe suggested that lead was the final stable product of the decay of radium. It was already known that radium was an intermediate product of the decay of uranium. Rutherford joined in, outlining a decay process in which radium emitted five alpha particles through various intermediate products to end up with lead, and speculated that the radium-lead decay chain could be used to date rock samples. Boltwood did the legwork, and by the end of had provided dates for 26 separate rock samples, ranging from 92 to million years.
He did not publish these results, which was fortunate because they were flawed by measurement errors and poor estimates of the half-life of radium. Boltwood refined his work and finally published the results in Boltwood's paper pointed out that samples taken from comparable layers of strata had similar lead-to-uranium ratios, and that samples from older layers had a higher proportion of lead, except where there was evidence that lead had leached out of the sample. His studies were flawed by the fact that the decay series of thorium was not understood, which led to incorrect results for samples that contained both uranium and thorium.
However, his calculations were far more accurate than any that had been performed to that time. Refinements in the technique would later give ages for Boltwood's 26 samples of million to 2. Although Boltwood published his paper in a prominent geological journal, the geological community had little interest in radioactivity.
Rutherford remained mildly curious about the issue of the age of Earth but did little work on it. Robert Strutt tinkered with Rutherford's helium method until and then ceased.
However, Strutt's student Arthur Holmes became interested in radiometric dating and continued to work on it after everyone else had given up. Holmes focused on lead dating, because he regarded the helium method as uvizyonbarkod.comomising. He performed measurements on rock samples and concluded in that the oldest a sample from Ceylon was about 1.
For example, he assumed that the samples had contained only uranium and no lead when they were formed. More important research was published in Such techniques are called isochron methods.
Earth processes we observe today also operated in the past at about the same rates. Before the development of isotope dating methods, scientists estimated the age of the Earth by: 1. Counting generations in the bible (James Usherr) Uranium. Radioactive Parent: Uranium Radiogenic Daughter: Lead. Potassium. 1) Uranium dating, 2) Carbon dating, 3) Atomic clocks, 4) Biological clocks. The median age of Korean War veterans is estimated to be 69 years, with an estimate under age 65, million aged 65 to 74, and an estimate aged 75 or older.
They are mathematically clever, and we may explore them in a future article. However, like the model-age method, they are known to give incorrect answers when applied to rocks of known age.
Nov 29, In the s, Earth's age crept up toward 3 billion years, making it for a time even older than the universe, which was then estimated to be about billion years old. Uranium comes in two common isotopes with atomic weights of and (we'll call them U and U). Both are unstable and radioactive, shedding nuclear particles in a cascade that doesn't stop until they become lead (Pb). The two cascades are different-U becomes Pb and U becomes vizyonbarkod.com: Andrew Alden. ADVERTISEMENTS: By Age of the Earth is understood the total time since the earth has existed in its present physical state as a planet. In Geology, this problem has always been found as one of the most complicated and controversial topics. Many conclusions were suggested on different lines but were rejected by equally strong objections.
And neither the model-age method nor the isochron method are able to assess the assumption that the decay rate is uniform. As we will see below, this assumption is very dubious. Years ago, a group of creation scientists set out to explore the question of why radiometric dating methods give inflated age estimates.
We know they do because of the aforementioned tests on rocks whose origins were observed. But why? Which of the three main assumptions initial conditions are known, rate of decay is known, the system is close is false? To answer this question, several creation geologists and physicists came together to form the RATE research initiative R adioisotopes and the A ge of T he E arth.
This multi-year research project engaged in several different avenues of study, and found some fascinating results. As mentioned above, the isochron method uses some mathematical techniques in an attempt to estimate the initial conditions and assess the closed-ness of the system.
However, neither it nor the model-age method allow for the possibility that radioactive decay might have occurred at a different rate in the past.
In other words, all radiometric dating methods assume that the half-life of any given radioactive element has always been the same as it is today. If that assumption is false, then all radiometric age estimates will be unreliable. As it turns out, there is compelling evidence that the half-lives of certain slow-decaying radioactive elements were much smaller in the past. This may be the main reason why radiometric dating often gives vastly inflated age estimates. First, a bit of background information is in order.
Most physicists had assumed that radioactive half-lives have always been what they are today. Many experiments have confirmed that most forms of radioactive decay are independent of temperature, pressure, external environment, etc.
In other words, the half-life of carbon is years, and there is nothing you can do to change it. Given the impossibility of altering these half-lives in a laboratory, it made sense for scientists to assume that such half-lives have always been the same throughout earth history. But we now know that this is wrong. In fact, it is very wrong.
More recently, scientists have been able to change the half-lives of some forms of radioactive decay in a laboratory by drastic amounts.
However, by ionizing the Rhenium removing all its electronsscientists were able to reduce the half-life to only 33 years! In other words, the Rhenium decays over 1 billion times faster under such conditions. Thus, any age estimates based on Rhenium-Osmium decay may be vastly inflated. The RATE research initiative found compelling evidence that other radioactive elements also had much shorter half-lives in the past. Several lines of evidence suggest this. But for brevity and clarity, I will mention only one.
This involves the decay of uranium into lead Unlike the potassium-argon decay, the uranium-lead decay is not a one-step process. Rather, it is a step process. Uranium decays into thorium, which is also radioactive and decays into polonium, which decays into uranium, and so on, eventually resulting in lead, which is stable. Eight of these fourteen decays release an alpha-particle: the nucleus of a helium atom which consists of two protons and two neutrons.
The helium nucleus quickly attracts a couple of electrons from the environment to become a neutral helium atom. So, for every one atom of uranium that converts into lead, eight helium atoms are produced. Helium gas is therefore a byproduct of uranium decay. And since helium is a gas, it can leak through the rocks and will eventually escape into the atmosphere.
The RATE scientists measured the rate at which helium escapes, and it is fairly high. Therefore, if the rocks were billions of years old, the helium would have had plenty of time to escape, and there would be very little helium in the rocks. However, the RATE team found that rocks have a great deal of helium within them. In fact, the amount of helium in the rocks is perfectly consistent with their biblical age of a few thousand years!
It is wildly inconsistent with billions of years. But the fact that such helium is present also indicates that a great deal of radioactive decay has happened; a lot of uranium atoms have decayed into lead, producing the helium. At the current half-life of uranium, this would take billions of years. But if it actually took billions of years, then the helium would have escaped the rocks.
The only reasonable explanation that fits all the data is that the half-life of uranium was much smaller in the past. That is, in the past, uranium transformed into lead much faster than it does today. The RATE team found similar evidence for other forms of radioactive decay. Apparently, during the creation week and possibly during the year of the global flood, radioactive decay rates were much faster than they are today.
The RATE team also found that the acceleration of radioactive decay was greater for elements with longer half-lives, and less for elements with shorter half-lives. All radiometric dating methods used on rocks assume that the half-life of the decay has always been what it is today.
But we now have compelling evidence that this assumption is false. And since the decay rate was much faster in the past, those who do not compensate for this will end up with age-estimates that are vastly inflated from the true age of the rock.
This of course is exactly what we observe. We already knew that radiometric dating tends to give ages that are much older than the true age. Now we know why. For whatever reason, many people have the false impression that carbon dating is what secular scientists use to estimate the age of earth rocks at billions of years. Carbon dating is not used on rocks, because rocks do not have much carbon in them. And with a half-life of only years, carbon does not last long enough to give an age estimate if something were truly millions of years old.
All the carbon would be gone after one million years. To estimate the ages of rocks, secular scientists use elements with much longer half-lives, such as uranium, potassium, and rubidium Animals and plants contain abundant carbon. Carbon dating is therefore used most frequently on animal or plant remains.
The method gives an estimation of how long ago the organism died. Most carbon is c; the nucleus contains six protons and six neutrons.
The age of the earth can be estimated by. A) uranium dating: B) carbon dating: C) atomic clocks: D) biological clocks: Correct Answer: A) uranium dating: Part of solved Physics questions and answers: General Science Physics. Login to Bookmark: Previous Question. Oct 27, "Science has proved that the earth is billion years old." We have all heard this claim. We are told that scientists use a technique called radiometric dating to measure the age of rocks. We are also told that this method very reliably and consistently yields ages of millions to billions of years, thereby establishing beyond question that the earth is immensely old - a . The best age for the Earth comes not from dating individual rocks but by considering the Earth and meteorites as part of the same evolving system in which the isotopic composition of lead, specifically the ratio of lead to lead changes over time owing to the decay of radioactive uranium and uranium, respectively. Scientists have.
Carbon is stable. A small fraction of carbon is c, which contains eight neutrons rather than six. Carbon is produced in the upper atmosphere when cosmic rays produce neutrons that interact with nitrogen atoms, converting them to c The c naturally decays back into nitrogen with a half-life of years.
Animals then eat the plants, by which c is integrated into their body. So all plants, animals, and people have a small, but measurable quantity of c in their body. That c is slowly but continually decaying into nitrogen. But, while alive, plants and animals replenish the c by taking in additional carbon from their environment.
Therefore, the ratio of c to c in a living animal or plant is roughly the same as it is in the atmosphere. But when an organism dies, it ceases to replenish its supply of c The c simply decays, and therefore the c to c ratio in a dead organism will be somewhat less than that of the atmosphere.
The older the organism, the lower the ratio. Third, zircon is widespread in igneous rocks as a primary mineral.
This makes it especially valuable for dating these rocks, which have no fossils to indicate their age. Fourth, zircon is physically tough and easily separated from crushed rock samples because of its high density. Other minerals sometimes used for uranium-lead dating include monazite, titanite and two other zirconium minerals, baddeleyite and zirconolite.
However, zircon is so overwhelming a favorite that geologists often just refer to "zircon dating. But even the best geologic methods are imperfect. Dating a rock involves uranium-lead measurements on many zirconsthen assessing the quality of the data. Some zircons are obviously disturbed and can be ignored, while other cases are harder to judge.
In these cases, the concordia diagram is a valuable tool. Consider the concordia: as zircons age, they move outward along the curve.
But now imagine that some geologic event disturbs things to make the lead escape. That would take the zircons on a straight line back to zero on the concordia diagram.
The straight line takes the zircons off the concordia. This is where data from many zircons is important.
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