by cofty 81 Replies latest watchtower beliefs
Thanks Hortensia I will get it finished this time.
The article by Dr Wiens is really excellent. I will be posting some more explanation about radiometirc dating hopefully tomorrow.
The sophistication of the multiple dating techniques is really impressive.
cofty, I'm enjoying your summaries as well. It's been a while since I reviewed the dating techniques. I recall the first time I actually comprehended how it worked and how amazed I was that anyone could have ever denied that radiometric dating actually works.
I don't get enough time for reading anymore. This thread makes me miss being in university.
mamochan - If I had my life to live again I would defintely be in biological science or genetics - assuming I got turned down by the astronaut programme and Manchester Utd in that order :)
Just something I want to clarify that I should have explained in my last post...
There is no such thing as a carbon proton or a copper proton or a gold proton etc. A proton is a proton is a proton. Its the number of them that are in the nucleus of an atom that determines what element it is.
Carbon 14 next...
Thank you cofty. I too am enjoying your write-ups. The fox experiment is fascinating. I am also the same as Hortensia re: the way elements can change. I do not recall being taught this in high school Science. Of course, I'm kinda old so maybe it came after I graduated. Or maybe I forgot.
I do recall the experiment where our Science teacher was demonstrating electro-static energy by rubbing cat fur on an ebonite rod. He turned his back to us and started rubbing the rod. Weeeeellll.... we all cracked up at that... 'cause it looked like he was ... you know.
Science teachers tend to be hilarious. I had one who spent ages setting up an elaborate glass distillation unit. He turned around to the class and waved towards his creation with a flamboyant gesture and sent it all flying across the floor.
Another time he was mixing chemicals as he dictated notes until it suddenly flared up and foamed all over the floor releasing noxious fumes as the linoleum dissolved. Happy days.
I read the article about the dating methods using half-lives of elements. I have to comment about the bristlecone pines -- they're in the high Sierras near Bishop, California. If you ever have a chance to see them, be sure to do it. It's an amazing place, ove 10,000 feet up, kind of barren looking and then there are all these amazing trees and rocks. One of my favorite places and the rangers talk about the tree ring dating and there are cross-sections of old trees so you can see the rings and how old they are.
Part 8
Chapter 4 - Silence and Slow Time ... continued
Before the advent of radioactive clocks geologists had built up a picture of the sequence of layers of rock that can be readily identified all over the world. Sedimentary rocks like limestone or sandstone consists of layers of mud or sediment laid down on the floor of a sea, lake or estuary. It becomes compacted over ages and hardens to form rock.
These layers had been identified and given names like Cambrian, Ordovician, Devonian, Jurassic, Cretaceous, Eocene, Oligocene and Miocene. The same layers have the same appearance and contain the same sets of fossils wherever they are found. Logically the oldest layers are found below the younger layers and although a complete collection of layers may not be found in any one location, by daisy-chaining and jigsawing your way around the world the relative age of each layer can be known. Apart from where they have been turned on their side or even upside down by movements of the earth's crust these layers are always found in the same sequence. The micro-fossils called foraminifera and radiolaria that are found in each layer is totally predictable and are used by geologists to locate oil. Young earth creationists don't have much success in oil exploration.
Now here’s the challenge, the fossils we want to date are all found in sedimentary rocks; the radioactive clocks are all found in igneous rocks that did not originate in mud but in molten lava.
When lava or magma comes to the surface of the earth and begins to cool it crystallises. At that moment in time all the radioactive clocks it contains are set to zero. For example it may contain a quantity of the isotope of Potassium called Potassium-40. Over time it will decay to become Argon-40 but at the moment of formation the ratio is 100% in favour of Potassium-40. Exactly 1.26 billion years the ratio of Potassium-40 to Argon-40 will be 50:50. After another 1.26 billion years it will be 75:25 and so on. The same is true of all the other clocks contained in the same rock sample each with their own unique half-life.
Since the same layers of sedimentary rock are to be found all over the world, wherever igneous rock is found above, below or within a layer of sedimentary rock it, and the fossils it contains can be dated. The accuracy of these dates can be confirmed by comparing numerous clocks from numerous samples. Not just the relative ages, but also the actual ages of sedimentary rock layers are now known with certainty.
Of the 118 known elements on earth there are 308 isotopes, 150 of which are stable and 158 unstable; that is they will decay to form other elements. If young earth theories were correct you would expect all of these 158 unstable elements to still exist. In fact only 37 of these have not gone extinct already and every one of these have a half-life greater than 700 million years. When we look at the 121 that have gone extinct, every single one of them has a half-life less than 200 million years. The only unstable isotopes we find on earth are those that have a half-life long enough to survive on a very old planet.
All the radioactive clocks agree at placing the age of the earth at between 4 and 5 billion years. For the earth to only be 6000 years old each of these clocks would have to be fiddled individually to have their half-life adjusted to a radically different rate.
An example of an unstable isotope with a short half-life that still exists in abundance is carbon-14. Unlike the extinct isotopes carbon-14 is constantly being produced in our upper atmosphere when cosmic rays bombarding nitrogen atoms turning one of the protons into a neutron. About 1 carbon atom in a trillion is the 14 isotope. The rate of this process is more or less constant and comparing samples with results from dendrochronology, which is accurate to the very year, minor adjustments can be made.
Carbon-14 is absorbed by plant life, which is then eaten by herbivores and spreads through the food chain. At the moment a living thing dies it ceases to absorb new carbon-14 molecules and those it already contains begins to decay to Nitrogen-14 at a half-life rate of 5,730 years. With modern techniques such as mass spectrometry only a small sample is now required to measure the proportion of carbon-14 to nitrogen-14 in a sample and calculate the date of its demise.
Creationists are fond of telling stories about examples of inaccurate results that are obtained from samples of carbon 14. Firstly it should be noted that carbon 14 is never used to date fossils, its half-life is far too short to be used for that purpose. Secondly, the various factors that cause anomalous results are well understood by scientists. It is not creationists who discovered how to use carbon-14 dating effectively it was scientists who openly publish papers about the intricacies of the process - papers which are then quote-mined by creationists to cast doubt on dates that don't fit with their religious dogma.
Finally, going back to the layers of sedimentary rocks that are to be found all over the earth, each with their own distinct collections of fossils, creationists have their greatest opportunity to attack evolution. If the world could be explained by the action of a creator and the layers of rock by a world-wide flood then we ought to find fossils of all sorts of animals in each of the layers. If evolution is correct then there should be a very precisely ordered sequence of increasing complexity as we search through the layers from the oldest to modern times.
For a theory to be truly scientific it must be falsifiable and nowhere is evolution more vulnerable than her in the hard evidence of fossils. Just one good example of a mammal that died and got fossilised in an undisturbed Cambrian rock layer and the whole structure of evolution comes crashing down.
What we in fact find is that every fossil without exception is exactly where we would expect it to be. New creatures appear only after a given date, never before, no exceptions.
One prize-winning creationists website attempts to explain the data with a “head for the hills” theory. In other words when Noah’s flood started invertebrates would perish first followed by amphibians close to the sea as the waters rose and so on up to humans who would cling to logs and climb mountains to escape the rising water.
It hardly merits a response, but consider for a moment. At least a few humans would have failed to make it to higher ground, some mammals, the old, sick or sound asleep would have perished at the bottom of the pile. We may find a statistically significant change in the kinds of fossils in the layers but there would still be a good mixture. This is absolutely not what is found. Not a single mammal is found anywhere in the lower layers, everything is in exactly the order evolution predicts.
Again I would highly recommend reading the paper I mentioned in part 7 whether or not you have any doubts about the reliability of dating techniques.
Radiometric Dating - A Christian Perspective by Dr. Roger C. Wiens
Coming next - "Before Our Very Eyes" examples of evolution in real time
Part 9
Chapter 5 –Before Our Very Eyes
In this chapter Dawkins presents some astonishing examples of evolution taking place in real time, examples that can be observed and measured.
He opens with some interesting thoughts on the changes in tusk size that have been observed among elephants. Males are under two opposing evolutionary pressures, the desirability of growing huge tusks to impress female elephants and intimidate opposing young males, and in recent centuries, the desirability of not getting shot by poachers who want to turn your tusks into ivory trinkets.
With one of the longest generational turnovers in the animal kingdom you would expect any detectable change to take millennia but in fact data from the Uganda Game Dept from 1925 – 1958 shows significantly decreasing tusk size. There is a need for caution in interpreting the results but there does appear to be a case of rapid evolutionary change taking place in African Elephants.
A second example relates to two islets off Croatia called Pod Kopiste and Pod Mrcaru. The former had a good population of insect eating lizards but prior to 1971 the latter had none. In that year 5 pairs were released as an experiment. In 2008 a group of Belgian scientists visited to see how things had developed in 37 years. They found a flourishing population descended from the original 5 pairs of ancestors. But as they studied the population they made remarkable a discovery. The Mrcaru lizards had moved towards a mainly vegetarian diet. Their head size had changed significantly becoming longer, wider and taller. This had translated into a markedly greater bite force allowing then to grind the cellulose of their plant diet.
Most herbivores have an adaptation of their gut called a caecum (of which our appendix is a vestige) a kind of blind alley that contains bacteria that aids digestion. Amazingly the lizards of Mrcaru had begun to develop a Caecal valve that was absent in the original population. In other changes the population density was greater and they had become less territorial.
In just 37 years there was already strong evidence of the kind of evolutionary changes that Darwin himself observed among the finches and tortoises of Galapagos.
Although both of these examples concern relatively minor changes within species the speed of change is what makes them remarkable. Most of the reminder of the chapter consists of a description of an ongoing experiment began in 1988 by Ricahard Lenski and his team at Michigan State University on E-Coli bacterium.
The results of this remarkable experiment is one of the most powerful pieces of evidence of the power of natural selection I have ever heard and I will summarise Dawkin's description of it next...
man I love this stuff
