To Jenkins’ Spoiler-Laden Guide to Isaac Asimov Introduction Though perhaps best known throughout the world for his science fiction, Isaac Asimov was also regarded as one of the great explainers of science. His essays exemplified his skill at making complex subjects understandable, and were written in an unformal style, liberally sprinkled with personal anecdotes that endeared him to a legion of faithful readers. It was all a labor of love; in particular Asimov often remarked that of all his writing, his essays for The Magazine of Fantasy and Science Fiction were his favorite, despite the fact that he received the lowest word-rate payment for them. From November to February , an essay of his appeared in the magazine every month, without fail. With the advent of Isaac Asimov’s Science Fiction Magazine in , he began a series of editorials that appeared at the beginning of each issue. In addition he wrote essays and introductions for literally hundreds of magazines, newspapers, books, and trade publications. All together he wrote over essays.
How Carbon-14 Dating Works
Introduction to Geology Chapter 2 – Basic Geologic Principles The science of geology is founded on basic principles that are useful for making observations about the world around us. This chapter presents a mix of information that is essential fundamental to all following chapters. This chapter is an introduction to rocks and minerals, and the rock cycle. Basic chemistry is important to all sciences, especially geology!
The isochron method. Many radioactive dating methods are based on minute additions of daughter products to a rock or mineral in which a considerable amount of daughter-type isotopes already exists.
The isochron method Many radioactive dating methods are based on minute additions of daughter products to a rock or mineral in which a considerable amount of daughter-type isotopes already exists. These isotopes did not come from radioactive decay in the system but rather formed during the original creation of the elements. In this case, it is a big advantage to present the data in a form in which the abundance of both the parent and daughter isotopes are given with respect to the abundance of the initial background daughter.
The incremental additions of the daughter type can then be viewed in proportion to the abundance of parent atoms. In mathematical terms this is achieved as follows. This term, shown in Figure 1, is called the initial ratio. The slope is proportional to the geologic age of the system. In practice, the isochron approach has many inherent advantages. When a single body of liquid rock crystallizes, parent and daughter elements may separate so that, once solid, the isotopic data would define a series of points, such as those shown as open circles designated R1, R2, R3 in Figure 1.
With time each would then develop additional daughter abundances in proportion to the amount of parent present. If a number of samples are analyzed and the results are shown to define a straight line within error, then a precise age is defined because this is only possible if each is a closed system and each has the same initial ratio and age.
The uncertainty in determining the slope is reduced because it is defined by many points. A second advantage of the method relates to the fact that under high-temperature conditions the daughter isotopes may escape from the host minerals. In this case, a valid age can still be obtained, provided that they remain within the rock.
Tiny Fossils May Be Oldest Evidence of Life on Earth
Articles home page Creation vs. Evolution 0. Introduction and table of contents The following is an organized presentation on the creation vs. evolution controversy.
General considerations Distinctions between relative-age and absolute-age measurements Local relationships on a single outcrop or archaeological site can often be interpreted to deduce the sequence in which the materials were assembled. This then can be used to deduce the sequence of events and processes that took place or the history of that brief period of time as recorded in the rocks or soil. For example, the presence of recycled bricks at an archaeological site indicates the sequence in which the structures were built.
Similarly, in geology, if distinctive granitic pebbles can be found in the sediment beside a similar granitic body, it can be inferred that the granite, after cooling, had been uplifted and eroded and therefore was not injected into the adjacent rock sequence. Although with clever detective work many complex time sequences or relative ages can be deduced, the ability to show that objects at two separated sites were formed at the same time requires additional information.
A coin, vessel, or other common artifact could link two archaeological sites, but the possibility of recycling would have to be considered. It should be emphasized that linking sites together is essential if the nature of an ancient society is to be understood, as the information at a single location may be relatively insignificant by itself. Similarly, in geologic studies, vast quantities of information from widely spaced outcrops have to be integrated.
Some method of correlating rock units must be found.
Accuracy of Fossils and Dating Methods
January Fossils provide a record of the history of life. Smith is known as the Father of English Geology. Our understanding of the shape and pattern of the history of life depends on the accuracy of fossils and dating methods. Some critics, particularly religious fundamentalists, argue that neither fossils nor dating can be trusted, and that their interpretations are better. Other critics, perhaps more familiar with the data, question certain aspects of the quality of the fossil record and of its dating.
G. Brent Dalrymple’s classic debunking of the young-earth ‘scientific’ creationism’s dating methods with a short explanation of how geologists know the age of the earth.
Measurement of N, the number of 14 C atoms currently in the sample, allows the calculation of t, the age of the sample, using the equation above. The above calculations make several assumptions, such as that the level of 14 C in the atmosphere has remained constant over time. The calculations involve several steps and include an intermediate value called the “radiocarbon age”, which is the age in “radiocarbon years” of the sample: Radiocarbon ages are still calculated using this half-life, and are known as “Conventional Radiocarbon Age”.
Since the calibration curve IntCal also reports past atmospheric 14 C concentration using this conventional age, any conventional ages calibrated against the IntCal curve will produce a correct calibrated age. When a date is quoted, the reader should be aware that if it is an uncalibrated date a term used for dates given in radiocarbon years it may differ substantially from the best estimate of the actual calendar date, both because it uses the wrong value for the half-life of 14 C, and because no correction calibration has been applied for the historical variation of 14 C in the atmosphere over time.
A Guide to Isaac Asimov’s Essays
The Radiometric Dating Game Radiometric dating methods estimate the age of rocks using calculations based on the decay rates of radioactive elements such as uranium, strontium, and potassium. On the surface, radiometric dating methods appear to give powerful support to the statement that life has existed on the earth for hundreds of millions, even billions, of years.
We are told that these methods are accurate to a few percent, and that there are many different methods.
The age of a fossil may be specified in both relative terms (how old it is in relation to other fossils or rock units) and in absolute terms (approximately how many years old it is). One principle of relative dating is called superposition, which holds that in any one place, the lower rock layers (and fossils in them) are older than higher ones, unless there is evidence that the layers have.
Renaissance Now, let’s look at some specific examples. One type of atom that does not normally react is Neon. See the picture to the left. It already has the correct number of electrons in it’s outside electron layer so Neon does not react. Neon, along with Helium and Argon are known as non-reacting gasses because they do not need to react to be stable. Other types of atoms such as Hydrogen, Carbon, and Oxygen do not have the correct number of electrons to be stable by itself. Instead they have to share electrons in molecules to get the correct number of electrons in their outside electron layer.
Since we only have to look at the atom that is in the center of the molecule to find out it’s shape, we will concentrate only on Carbon and Oxygen. All the molecules illustrated on this page either have a Carbon or an Oxygen as the center atom. Carbon will especially be of interest since Carbon is the center atom for all the different Amino Acids.
Oldest Fossils Ever Found Dated to 3.5 Billion Years Ago
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.
U of A anthropologist Willoughby believes that the items found prove continuous occupation of the areas over the last , years, through what is known as the “genetic bottleneck” period of the last ice age.
How accurate are carbon-dating methods? All methods of radioactive dating rely on three assumptions that may not necessarily be true: Rate of Decay It is assumed that the rate of decay has remained constant over time. This assumption is backed by numerous scientific studies and is relatively sound. However, conditions may have been different in the past and could have influenced the rate of decay or formation of radioactive elements.
Evolutionists assume that the rate of cosmic bombardment of the atmosphere has always remained constant and that the rate of decay has remained constant. Thus radioactive dating relies purely on assumptions. We could put forward the following counter arguments to the constancy of these assumptions:
Changing Views of the History of the Earth
The ratio of carbon to carbon at the moment of death is the same as every other living thing, but the carbon decays and is not replaced. The carbon decays with its half-life of 5, years, while the amount of carbon remains constant in the sample. By looking at the ratio of carbon to carbon in the sample and comparing it to the ratio in a living organism, it is possible to determine the age of a formerly living thing fairly precisely.
Introduction Though perhaps best known throughout the world for his science fiction, Isaac Asimov was also regarded as one of the great explainers of science.
Leibnitz reworked Descartes’s cosmogony. Protogea was published much later in An essay toward a Natural History of the Earth. Woodward came down fairly strongly for the view that the flood was an act of God that could not be accounted for by normal physical processes. He also postulated hydrological sorting to account for the ordering of fossils. Whiston added comets to Burnet’s cosmogony as the source of the waters of the flood.
Lectures and Discourse of Earthquakes and Subterranean Eruptions.
Natural History Museum of Los Angeles County
Funde von in Gesteinen enthaltenen marinen Lebewesen auf dem Festland erregten bereits im Altertum und im Mittelalter von China bis Europa Aufmerksamkeit, und sie wurden von mehreren Gelehrten u. Hingegen wurden sie vom altgriechischen Philosophen Aristoteles und den auf seinen Lehren aufbauenden Scholastikern als Launen der Natur Lusus naturae betrachtet. Jahrhundert hinein Petrefaktenkunde genannt. Neben dem Begriff Fossil als Substantiv wird das Wort auch als Adjektiv verwendet, um damit Objekte oder Bildungen zu charakterisieren, die geologisch relativ alt sind.
Das Gegenteil zum Adjektiv fossil lautet rezent. Es bezeichnet alle Bildungen, die geologisch relativ jung sind.
Isochron Dating By Chris Stassen The article is well illustrated and well written. There is an introduction to the generic problem of radiometric dating, but this article concentrates on one well established method called the “isochron method”.
There are lots of ways to guesstimate ages, and geologists knew the earth was old a long time ago and I might add that they were mostly Christian creationist geologists. But they didn’t know how old. Radiometric dating actually allows the measurement of absolute ages, and so it is deadly to the argument that the earth cannot be more than 10, years old. Radiometric methods measure the time elapsed since the particular radiometric clock was reset.
Radiocarbon dating, which is probably best known in the general public, works only on things that were once alive and are now dead. It measures the time elapsed since death, but is limited in scale to no more than about 50, years ago. Generally applied to igneous rocks those of volcanic origin , they measure the time since the molten rock solidified. If that happens to be longer than 10, years, then the idea of a young-Earth is called into question.
If that happens to be billions of years, then the young-Earth is in big trouble. As of January, , The oldest rocks found on earth are 4.
Oldest Fossils Ever Found Dated to 3. In the more recent past, at least the fossils are large enough to see with the naked eye. Some potential fossils were identified in a rock more than 20 years ago that was dated to an age of about 3.
Learn about different types of radiometric dating, such as carbon dating. Understand how decay and half life work to enable radiometric dating. Play a game that tests your ability to match the percentage of the dating element that remains to the age of the object.
Generally, major earthquakes are followed by a larger number of aftershocks, decreasing in frequency with time. Albedo — The amount of solar radiation that is reflected back off a surface. Alum — A chemical compound that can be processed from clays. It has been used for industrial purposes e. Altitude — Height above sea level. Amplitude — The maximum height of a wave crest or depth of a trough.
Anglian — One of the glaciations during the last Ice Age, about half a million years ago, when glaciers reached as far south as the Severn—Thames estuaries. Anticline — Upwardly arched folds of Sedimentary rocks put under pressure by movement in the Earth. See syncline Aquifer — One of many types of permeable rock. Pore spaces tiny holes between the grains, or fractures cracks allows water to flow through and accumulate in an aquifer rock.
Aquiclude — An impermeable layer of rock which water cannot flow through because there are no pore or fracture voids, or such voids are not connected together. Aquitard — A rock with limited permeability that allows some water to pass through it, but at a very reduced rate.