LittleNipper wrote: Science is a powerful tool; however, it pales in comparison to GOD's direct revelation.
Actually it disproves "god's direct revelation."
The short version:
The Oklo natural reactor disproves a young earth. How? To make a reactor run we need a higher concentration of U-235 compared to U-238 than we find in nature. There has to be enrichment of U-235 compared to U-238. How does that happen naturally? It doesn't. The only way to get enrichment of U-235 relative to U-238 in nature is to go back in time nearly two billion years. Why? Because the decay rates of U-238 and U-235 happen to be different. U-235 decays faster than U-238. You have to rewind the clock that much to get a ratio of U-235 to U-238 that will allow a natural reactor to run.
***************************************************************
The long version:
Uranium was apparently formed in supernovas about 6.6 billion years ago. While it is not common in the solar system, today its slow radioactive decay provides the main source of heat inside the Earth, causing convection and continental drift.
Like other elements, uranium occurs in several slightly differing forms known as 'isotopes'. These isotopes differ from each other in the number of uncharged particles (neutrons) in the nucleus. Natural uranium as found in the Earth's crust is a mixture largely of two isotopes: uranium-238 (U-238), accounting for 99.3% and uranium-235 (U-235) about 0.7%.
The isotope U-235 is important because under certain conditions it can readily be split, yielding a lot of energy. It is therefore said to be 'fissile' and we use the expression 'nuclear fission'.
Meanwhile U-238, like all radioactive isotopes, decays. But U-238 decays very slowly, its half-life being about the same as the age of the Earth (4500 million years). This means that it is barely radioactive, less so than many other isotopes in rocks and sand. Nevertheless it generates 0.1 watts/tonne as decay heat and this is enough to warm the Earth's core. U-235 decays faster.
The nucleus of the U-235 atom comprises 92 protons and 143 neutrons (92 + 143 = 235). When the nucleus of a U-235 atom captures a moving neutron it is relatively unstable and splits in two (fissions) and releases some energy in the form of heat, also two or three additional neutrons are thrown off. If enough of these expelled neutrons cause the nuclei of other U-235 atoms to split, releasing further neutrons, a fission 'chain reaction' can be achieved.
Fission may take place in any of the heavy nuclei after capture of a neutron. However, low-energy (slow, or thermal) neutrons are able to cause fission only in those isotopes of uranium and plutonium whose nuclei contain odd numbers of neutrons (e.g. U-233, U-235, and Pu-239). (The cross section for the capture of thermal neutrons is high.)
The fuel elements in a reactor are surrounded by a substance called a moderator to slow the speed of the emitted neutrons and thus enable the chain reaction to continue. Water, graphite and heavy water are used as moderators in different types of reactors. In a natural reactor water is the moderator.
Whereas the U-235 nucleus is 'fissile', that of U-238 is said to be 'fertile'. This means that it can capture one of the neutrons which are flying about in the core of the reactor and become (indirectly) plutonium-239, which is fissile. Pu-239 is very much like U-235, in that it fissions when hit by a neutron and this also yields a lot of energy.
Because there is so much U-238 in a reactor core (most of the fuel), these reactions occur frequently, and in fact about one third of the fuel's energy yield comes from "burning" Pu-239.
Uranium may also be mined by in situ leaching (ISL), where it is dissolved from a porous underground ore body in situ and pumped to the surface.
The end product of the mining and milling stages, or of ISL, is uranium oxide concentrate (U3O8). This is the form in which uranium is sold.
Before it can be used in a reactor for electricity generation, however, it must undergo a series of processes to produce a usable fuel.
For most of the world's reactors, the next step in making the fuel is to convert the uranium oxide into a gas, uranium hexafluoride (UF6), which enables it to be enriched. Enrichment increases the proportion of the uranium-235 isotope from its natural level of 0.7% to 4 - 5%. This enables greater technical efficiency in reactor design and operation, particularly in larger reactors, and allows the use of ordinary water as a moderator.
The Oklo natural nuclear reactor formed when a uranium-rich mineral deposit became inundated with groundwater that acted as a neutron moderator, and a nuclear chain reaction took place. The heat generated from the nuclear fission caused the groundwater to boil away, which slowed or stopped the reaction. After cooling of the mineral deposit, the water returned and the reaction started again. These fission reactions were sustained for hundreds of thousands of years, until a chain reaction could no longer be supported.
How does enrichment occur naturally such that a natural reactor is possible? It doesn't. A natural reactor today is impossible due to the low level of U-235 compared to U-238. But remember that U-235 decays faster than U-238. This means that in the past the relative concentration of U-235 was greater than at present. If we go far enough back in time we arrive at a point in the past where the necessary concentration of 4-5% U-235 is achieved. How far back do we need to go to achieve this? Just under 2 billion years which coincidentally is the age determined for the Oklo natural reactor.
You might be wondering why natural nuclear reactors at Oklo developed in uranium deposits only two billion years ago, when uranium-235 had already been depleted to less than 4% of uranium. Wouldn’t fission reactors have been even more likely to develop earlier in Earth’s history, when the uranium-235 levels were even higher? Remember that a high isotopic abundance of uranium-235 is just one of four conditions required for a natural nuclear reactor to develop. Another important condition is that uranium be concentrated. It turns out, no significant concentrations of uranium developed on Earth prior to about two billion years ago. The reason for this is simple: oxygen.
In most rocks on Earth, uranium is present only in trace quantities (parts per million or parts per billion). Uranium is generally concentrated by hydrothermal circulation, which picks up uranium and concentrates it in a new hydrothermal deposit. In order for this hydrothermal circulation to concentrate uranium, that uranium must be soluble (able to be picked up in water). However, uranium solubility is a little tricky. When uranium is in its reduced form (U4+), uranium tends to form very stable compounds that are not easily brought into solution. However, when uranium is in its oxidized form (U6+), uranium easily forms soluble complexes. There was very little oxygen in Earth’s very early atmosphere. So, it would have been very difficult to concentrate a significant amount of uranium since there was no oxygen to transform uranium into its soluble forms.
However, starting around 2.4 billion years ago, there was an event called the “Great Oxidation Event” during which the levels of oxygen in the atmosphere rose significantly, from <1% to ≥15%. This significant rise in atmospheric oxygen was a result of photosynthetic cyanobacteria producing oxygen. For a while, the oxygen produced by these bacteria was taken up by minerals which became oxidized. However, when these minerals became saturated in oxygen, this oxygen began to accumulate in the atmosphere. This increase of atmospheric oxygen allowed uranium to become mobile and to be concentrated through hydrothermal circulation.
Coincidentally the Oklo natural reactor is found in the early Proterozoic portion of the geologic column. It could have falsified the concept of a geologic column if it had been found somewhere else, but it wasn't.
***************************************************************
This ties in with evolution as well!
After about a billion years photosynthesis evolved.
Photosynthesis is the process by which carbon dioxide is fixed into usable sugars by the splitting of a water molecule. The process of photosynthesis produces oxygen, which is highly dangerous for cells; it can screw up the internal redox potential, create dangerous free-radicals and precipitate ions out into soluble forms. This means that from the point of view of every other organism the newly-evolved photosynthetic blobs were floating around spewing toxic gas into the atmosphere.
The arrival of this new resource (oxygen) lead to a change in the way organisms respired as well. Up until what is sometimes called the Great Oxidation Event most respiration was anoxic, probably similar to anaerobic respiration, or fermentation, in anaerobic bacteria around today. This process, while enough to keep life going, is around sixteen times less efficient than aerobic respiration. The proto-bacteria that managed to use the oxygen would therefore have gained a major energy boost.
This energy boost allowed the oxygen-using bacteria to go forth and multiply, leaving the anoxic bacteria clinging to the few environmental niches where no oxygen could penetrate. Some of these oxygen-using bacteria were swallowed up by larger cells who then used them as specialised intracellular breathing compartments. The bacteria became mitochondria, and the cells with mitochondria grew bigger and formed more intracellular compartments. They became eukaryotic cells, the kind of cells that all multicellular animals are made from.
So even now, when you breath, it’s ancient bacteria inside your cells that process the oxygen. The only part of the human cell that does oxidative-respiration is the mitochondria. Sure, the human part of the cell can produce small amounts of energy in the cytoplasm, but then the whole process is shuttled into the mitochondria in order to get the massive oxygen energy boost.
One biochemical trick that evolved around two billion years ago to take advantage of oxygen is still being used for respiration by all multicellular life on earth.
Kolob’s set time is “one thousand years according to the time appointed unto that whereon thou standest” (Abraham 3:4). I take this as a round number. - Gee