Problems with Radiometric Dating?

And, despite all the possible misgivings, radiometric dating actually works!The geologic time scale was already worked out by geologists long before radioactivity was discovered. All radiometric dating has done is give us actual absolute dates, whereas before all they had were relative dates (these rocks are older than those rocks).When radiometric dating was first done, the dates were consistent with the already known geologic time scale. If radiometric dates were subject to arbitrary errors, we would expect that the dates would be inconsistent with the geologic time scale. Formations that were known to be older than other formations might have been radio-dated as younger -- yet this hasn't happened.Further, radiometric dating uses different radioactive materials that produces different daughter isotopes that are found in different crystals. If such things as initial amounts of materials and/or rates at which material escapes or is added to the crystal were a problem, it would cause different amounts of errors for all the different techniques. Therefore, different radiometric techniques should give wildly different dates for the same formation.Yet, this doesn't happen either. Different techniques give the same ages for the same formations.So these possible errors, although they might potentially be a problem, are seen to be no problem at all.As far as the rate of decay being constant: we understand very well the physics behind radioactive decay. If decay rates were different in the past, then we know which laws of physics would have been different in the past. Then we can tell what other things should be seen in the archeological/geologic record. For example, other elements that would normally be stable would have been radioactive as well, and we can tell which ones would have been radioactive, and what the daughter isotopes would have been, and we can then check whether we see this different radioactive phenomenon. But we don't see these things.So we can conclude that radioactive decay rates have essentially been the same over the time scales that we are observing.One other thing, is that there are two forms of radioactive decay that we observe that are relevant to dating: alpha decay and beta decay. These two types are governed by different laws of physics. There is no reason to suspect that they would have been different in the past by exactly the same amounts. Thus, two different dating techniques relying on these different types of decay modes should, as before, produce different ages for the same formations. Yet they don't. All techniques give essentially the same ages.Again, the test on whether our assumptions are reliable is to see whether the dating actually works. And it does.

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Speaking personally, I find few things more awesome than contemplating this vast and majestic process of evolution, the ebb and flow of successive biotas through geological time. Creationists and others who cannot for ideological or religious reasons accept the fact of evolution miss out a great deal, and are left with a claustrophobic little universe in which nothing happens and nothing changes.
-- M. Alan Kazlev

I'll give a very short (and perhaps inaccurate) reply until someone more knowledgeable comes along.In regards to using radioisotopes to date geologic materials, it isn't necessary to know how much stuff formed during the Big Bang. The radiometric date relies on knowing how much of the materials were present in the solid crystals in the rocks when they first solidified from the melt.When a crystal forms, a certain radioisotope will be trapped in the crystal structure. As it decays, it will turn into a certain daughter isotope. At the beginning, there will parent isotope and no daughter isotope. As time goes one, parent atoms will disappear and daughter atoms will appear, so the ratio of daughter to parent will increase from zero to some value that depends on the age of the rock. The more daughter isotope compared to parent, the older the rock.One doesn't need to know exactly how much parent was present initially, since all one needs to know is the relative amount of parent compared to daughter. And one can usually assume that there is was no daughter present (or such a miniscule amount that it doesn't affect the age determination much) initially since the known physics and chemistry of the formation of the crystal from the melt allows scientists to determine that none or very, very little daughter should become trapped in the crystal as if forms.Again, we can be fairly certain that these assumptions are good since different dating techniques relying on different isotopes in different crystals which have different structures give the same ages for the same rocks, and that these dates are consistent with what geologists knew about the ages before radioactivity was discovered. If scientists were wrong about the initial amounts of parent and daughter, or were wrong about how much parent and daughter might travel into or out of the crystal over time, then the differing amounts of parent and daughter and the different travelling abilities would cause the different dating techniques to give wildly different ages for the same materials.Finally, there are dating techniques that do not rely on making any assumptions about the initial amounts of the materials at all. Isochron dating is an important dating method that does not rely on any assumptions about the initial amounts of isotopes in the crystals.- Now, if you are interested in the Big Bang, scientists are able to determine the relative abundances by apply the laws of thermodynamics to the physical conditions that occurred when atoms were first able to form. There was a time when the universe was so hot and so dense that protons and neutrons could not stay together to form stable atomic nuclei. As the universe expanded and cooled, there was a time when the protons and neutrons could stick together and stay together as atomic nuclei. Apply the laws of thermodynamics to knowledge of how the forces that hold nuclei together operate, they have been able to determine that all that formed during the Big Bang were hydrogen and helium, with some trace amounts of lithium (and maybe some beryllium -- my memory is hazy about this).All the other elements were mostly formed in the cores of large stars and then scattered in the universe when the stars exploded in super novae.- I don't know how exact the knowledge is, but scientists can observe the present amounts of radioactive isotopes and their daughter isotopes, and work backwards to figure out how much of each isotope was present 4.5 billion years ago.Also, as Lord Kelvin pointed out about a century ago, the interior of the earth should be much cooler than it is now. Assuming that the extra heat came from radioactive decay, they can figure out how much decay there was. By looking at the relative abundances that exist today, as well as the ability of denser crystals and materials to sink into the interior during the molten phase of the earth's history, they can get some estimates as to the abundances of the various radioactive materials. I don't know how accurate these abundances are, though.

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Speaking personally, I find few things more awesome than contemplating this vast and majestic process of evolution, the ebb and flow of successive biotas through geological time. Creationists and others who cannot for ideological or religious reasons accept the fact of evolution miss out a great deal, and are left with a claustrophobic little universe in which nothing happens and nothing changes.
-- M. Alan Kazlev