It is an accurate way to date specific geologic events. This is an enormous branch of geochemistry called Geochronology. There are many radiometric clocks and when applied to appropriate materials, the dating can be very accurate. As one example, the first minerals to crystallize condense from the hot cloud of gasses that surrounded the Sun as it first became a star have been dated to plus or minus 2 million years!! That is pretty accurate!!! Other events on earth can be dated equally well given the right minerals.
Other events on earth can be dated equally well given the right minerals. For example, a problem I have worked on involving the eruption of a volcano at what is now Naples, Italy, occurred years ago with a plus or minus of years.
Yes, radiometric dating is a very accurate way to date the Earth. We know it is accurate because radiometric dating is based on the radioactive decay of unstable isotopes. For example, the element Uranium exists as one of several isotopes, some of which are unstable. When an unstable Uranium U isotope decays, it turns into an isotope of the element Lead Pb.
We call the original, unstable isotope Uranium the "parent", and the product of decay Lead the "daughter". From careful physics and chemistry experiments, we know that parents turn into daughters at a very consistent, predictable rate. A geologist can pick up a rock from a mountainside somewhere, and bring it back to the lab, and separate out the individual minerals that compose the rock.
They can then look at a single mineral, and using an instrument called a mass spectrometer, they can measure the amount of parent and the amount of daughter in that mineral. The ratio of the parent to daughter then can be used to back-calculate the age of that rock.
The reason we know that radiometric dating works so well is because we can use several different isotope systems for example, Uranium-Lead, Lutetium-Halfnium, Potassium-Argon on the same rock, and they all come up with the same age. This gives geologists great confidence that the method correctly determines when that rock formed. Hope that helps, and please ask if you'd like more details!
I think that I will start by answering the second part of your question, just because I think that will make the answer to the first question clearer. Radiometric dating is the use of radioactive and radiogenic those formed from the decay of radioactive parents isotopes isotopes are atoms of the same element that have different numbers of neutrons in their nuclei to determine the age of something. It is commonly used in earth science to determine the age of rock formations or features or to figure out how fast geologic processes take place for example, how fast marine terraces on Santa Cruz island are being uplifted.
Radiometric dating relies on the principle of radioactive decay. All radioactive isotopes have a characteristic half-life the amount of time that it takes for one half of the original number of atoms of that isotope to decay.
By measuring the parent isotope radioactive and the daughter isotope radiogenic in a system for example, a rock , we can tell how long the system has been closed in our example, when the rock formed. The process of radiogenic dating is usually done using some sort of mass spectrometer.
A mass spectrometer is an instrument that separates atoms based on their mass. Because geochronologists want to measure isotopes with different masses, a mass spectrometer works really well for dating things.
I do think that radiometric dating is an accurate way to date the earth, although I am a geochronologist so I have my biases. Most estimates of the age of the earth come from dating meteorites that have fallen to Earth because we think that they formed in our solar nebula very close to the time that the earth formed. The fact that the age we calculate is reproducible for these different systems is significant. We have also obtained a very similar age by measuring Pb isotopes in materials from earth.
I should mention that the decay constants basically a value that indicates how fast a certain radioactive isotope will decay for some of these isotope systems were calculated by assuming that the age of the earth is 4. The decay constants for most of these systems have been confirmed in other ways, adding strength to our argument for the age of the earth.
Scientist Realizes Important Flaw in Radioactive Dating
Radiometric dating depends on the chemistry and ratios of different elements. It works like this:. Take, for example, zircon, which is a mineral; its chemical formula is ZiSiO 4 , so there is one zirconium Zi for one silicon Si for four oxygen O. One of the elements that can stand in chemically for zircon is uranium. Uranium eventually decays into lead, and lead does not normally occur in zircon, except as the radioactive decay product of uranium.
Therefore, by measuring the ratio of lead to uranium in a crystal of zircon, you can tell how much uranium there originally was in the crystal, which, combined with knowing the radioactive half-life of uranium, tells you how old the crystal is. Obviously, if the substance you are measuring is contaminated, then all you know is the age since contamination, or worse, you don't know anything, because the contamination might be in the opposite direction - suppose, for example, you're looking at radio carbon carbon 14, which is produced in the atmosphere by cosmic rays, and which decays into nitrogen.
Since you are exposed to the atmosphere and contain carbon, if you get oils from your skin onto an archeological artifact, then attempting to date it using radio carbon will fail because you are measuring the age of the oils on your skin, not the age of the artifact.
Unfortunately, that discarded data might be what gives us real insight. Young-earth creationists have a hard time explaining the general results of long-lived isotopes and their daughter products being present.
On the other side, old-earthers have a hard time explaining all the discordance.
Can radiometric dating be wrong
If radioactive dating is so reliable, why do different methods yield different results? Why are some of those differences really, really large? As is often the case, there are problems on both sides. The side you end up coming down on often depends on which problems you are most comfortable trying to deal with. Physicists already theorize that dark matter would affect nuclear decay rates; what if the leftover energy went to the dark matter? The heat problem occurs everywhere there are radioactive isotopes, so throughout the crust and mantle of the earth, for example.
The dark matter would have to be there in order to take the heat. You can think of dark matter here as a lot like the luminiferous ether: Since its interaction with normal matter is incredibly weak, it can very easily pass through the earth.
Not to mention that different models of dark matter would lead to different interactions. Are we able to calculate the mass of the earth from our knowledge of its contents, and not just the gravitational force we detect? I think if there were much dark matter in the earth, it would be noticeable.
We also know the overall composition of the crust and mantle from samples. Thus, the only real unknown is the composition of the core.
Using the mass and all those other measurements, we deduce that the core is mostly iron with some nickel. I fear it is more a matter of philosophy rather than hard science: The problem with that, is that, in the first case, there appear to be no transitional fossils when there should be millions , and to make the assumption previously herein stated, evolutionary conclusions are more akin to a combination of wishful thinking combined with a sympathetic magic mindset, than to observable examples.
Evolution is taught as established fact, and scientific enquiry is severely trammelled by those who prefer a status quo. Every fossil between organisms alive now and abiogenesis is a transitional fossil, Tony.Why Dating Methods Can Date Nothing
There are also transitional fossils and organisms in the misguided definition of the word you are using. I admire your faith, Cromwell. Yet you state it as fact. Then, you claim that all fossils are a transition between that unrealistic event and the life we see now.
Thanks for writing an informative article. Error bars have their place, but you are correct in pointing out that they are often misunderstood not only by the general public, but by scientists who are not savvy in radiometric dating. I would have worded this sentence differently: I am not convinced that differential diffusion of isotopes will be all that significant.
After all, fractionation of light elements, such as oxygen, provides us with all sorts of insights into geologic processes because the mass difference between O and O is rather significant, whereas the mass difference between Sr and Sr is not all that great, in terms of ratios.
The differences are even less significant for more massive isotopes such as in samarium-neodymium dating Nd and Nd If fractionation does turn out to be important for isochrons, one would expect that there would be a trend, with lighter nuclides e. Rb-Sr being more affected than heavier nuclides e. I am also wondering if Dr. Hays addressed how isotope fractionation would affect U-series concordia diagrams. As it is, there is a general correlation of dates obtained by radiometric dating from the top to the bottom of the geologic column.
Strongly discordant dates happen and young-Earth creationists focus on these , but roughly concordant dates are common; otherwise geologists would not trust the methods.
It seems strange, if diffusion is a problem, that nuclides with very different masses are effected in the same way.
Perhaps Earth is only 3. This would require similar diffusion rates in cold meteorites as in warm crustal zircons.
This would be very interesting, and would cause geologists to have to re-write many books, but the general story of geology would stand. This is because geologists do not believe Earth is billions of years old because of radiometric dating. Radiometric tools merely give us firm pegs to hang our signs on for the various eras, periods, and epochs of Earth history.
Thanks for your comment, Kevin. I would have to disagree with your suggested change in wording, however. While most definitely not all geochronologists do understand that there are false isochrons, that is never the way it is presented to students or the general public. This is unfortunate, of course, but it seems to be the norm when propaganda replaces science.
I think what you are missing is the chemistry involved. When we are dealing with trace elements not substances that are part of the crystal lattice , differential diffusion can have a significant effect.
It is also not clear that there would be a general trend like you suggest. Diffusion also depends on chemical issues. When you are dealing with different elements, you are dealing with completely different diffusion scenarios.
Radiometric Dating is Accurate
Hayes discussing uranium-series dating. Since concordia diagrams also involve isotope ratios, however, I suspect that this problem exists there as well.
In fact, they might even be the majority. I have no doubt that those who want to believe in an old earth will be able figure out a way to keep the overall story of geology the same, regardless of how important this effect turns out to be, if that can even be determined to any reasonable precision.
Yes, there are other issues at play as is the case with any over-arching scientific idea , but to her, radiometric dating is the most important reason she believes in an old earth.
I have no idea whether she is the norm or the exception, but she does exist. I was wondering how diffusion made any sense…. When I started my journey from old earth-evolutionism, it was much easier to see the flaws in evolutionary theory than those in the old age model. Thanks for your personal story, SJ. I guess that makes at least two geologists for whom radioactive dating was a big factor in their belief in an old earth.
I am glad that you eventually saw the problems associated with that. Rubidium readily substitutes for potassium in the crystal lattice of minerals, and strontium readily substitutes for calcium. Rb and Sr are still considered to be trace elements, even when incorporated into the lattice.
When Rb decays to Sr, the resulting strontium ion is chemically out of place in the lattice structure. Dr Wiles, Thanks for your response. What might we find if we can dip into the magma and test it immediately? Seems like that might be a good calibration for these radioisotopes. Many radioactive dating systems start with an assumption about what happens at the point of solidification. Thus, any argon in the rock must have come from radioactive decay.
In all cases, there is a lot of argon in the rock, indicating that the assumption is false. I am not sure what directly testing mantle magma will tell us about radioactive dating, because lots of things happen to the lava as it is flowing over the surface of the earth.
Obviously, directly sampling mantle magma will tell us a lot, but I am not sure if it will tell us anything about radioactive dating. The samples from the mantle would not be magma, but solid rock. The mantle is almost entirely solid. We already have samples of the mantle, in the form of inclusions e. Ophiolites have, in general, been altered from their original form, so pieces of raw, unaltered mantle rock would make for a number of interesting studies.
It is a bit in between. April 3, at April 3, at 1: April 4, at