How accurate is Radiometric Dating?

[Objectivist]

My friend said his friend James Hincley at his church told him that this method is proved wrong constantly. He said they tried to date the pyramids and were way off. That an independent study was more accurate not using that method. He also said they tried to date how old a shark was and they were wrong as hell. He claims they are disproven all the time a nd that science is making this stuff up. Now I personally believe in scientists but do some of them make mistakes or he just cherry picking?

I am assuming he is talking about carbon dating.  As I understand it, carbon dating has been varified back to about 50,000 years using lake varves, ice cores, and ocean floor sediment layers.  Tree rings also varify it back thousands of years as well.  My understanding is that other forms of radiometric dating have been varified by multiple methods, but I am no expert.

[Objectivist]

Well I'm 41 years old and from the DFW area. I am 5'9 and 190 lbs. I have brown hair an d br eyes, and I'm white. I'm a die hard liberal and an atheist. Are scientist wrong sometimes? Should we throw all  of them under the bus for being wrong somteimes?

No, of course not, just as the fact that we all make errors doesn't mean we throw out all our knowledge. The fact that scientists aren't perfect does not warrant throwing out scientific findings in all cases.

[BrianSoddingBoru4]

Well I'm 41 years old and from the DFW area. I am 5'9 and 190 lbs. I have brown hair an d br eyes, and I'm white. I'm a die hard liberal and an atheist. Are scientist wrong sometimes? Should we throw all  of them under the bus for being wrong somteimes?

No, of course not, just as the fact that we all make errors doesn't mean we throw out all our knowledge. The fact that scientists aren't perfect does not warrant throwing out scientific findings in all cases.

^This. Science largely works out what's right by winnowing out what's wrong.

Boru

[Anomalocaris]

It’s not the inconstancy of the rate of decay that puts unavoidable error bars on radiometrid dating.    It is the uncertainty surrounding just how much of the parent element there were at the moment of the event you are trying to date, whether certain quantity of daughter element had already been there at that moment,  and if there was some way we have not yet been able to think of or control for that allows some of the parent and daughter element to escape or be removed, thus screwing up the ratio of parent to daughter elements and thus the implied radiometrid age.

However, the possibility of such disturbances to parent-daughter element ration screwing up radiomatric dating can be reduced by cross check several different radioactive decay clocks, if these are available.     The chance that several radiometrid clocks are disturbed by the exact same amount so they all agree on the wrong age is virtually nil.

If several different radiometric clocks disagree in statisistically significant way, then you have some thinking, anssessment and experimentation to do to figure out which one(s) could have been disturbed.

It should also be pointed out that Rb-Sr dating is self-correcting in this way. You need to have several different crystals from the same rock, but you can derive the amount of the parent isotope from the measurements.

But Rb-Sr dating is  still susceptible to the amount of Rb and various Sr be changed by low grade metamorphosis after rock body formation.     You still need corroboration from other dating methods, or have ways for controlling for impact of low grade metamorphosis, such as good agreements in Rb-Sr dates across stratigraphically correlated rock formations over an area large enough to be implausible for the different rock samples to have undergone the same metamorphic history.

[Paleophyte]

My friend said his friend James Hincley at his church told him that this method is proved wrong constantly. He said they tried to date the pyramids and were way off. That an independent study was more accurate not using that method. He also said they tried to date how old a shark was and they were wrong as hell. He claims they are disproven all the time a nd that science is making this stuff up. Now I personally believe in scientists but do some of them make mistakes or he just cherry picking?

Speaking as somebody who has actually done radiometric dating, the ages produced are typically both accurate and robust if the techniques are appropriate and applied properly.

Given the complete lack of context it's difficult to say much other than "Don't trust Christian apologists when it comes to science!" When somebody tells me that some Creationist organization has once again tried to get a radiometric age and gotten the wrong one what I here is that an amateur with an obvious bias has misused a tool that they didn't understand and gotten a poor result. A bit like claiming that hammers don't work because they're no good for changing light bulbs.

Take this poor shark for example. Why is some fool trying to date a living organism?!? Of course it's going to throw errors! The radiocarbon clock doesn't start ticking until you die. In a similar attempt, apologists tried to show that geological ages were wrong by dating fresh lava. That proved only that they were using the wrong technique and, amusingly, that the 37,000 year age that they obtained was entirely correct once you accounted for the +/-100,000 year error of the method that was used.

Trying to date a pyramid would be tricky and is way younger than anything that I typically work with but if I were to take a stab at it I'd try and date the grave goods. Dating the rock is pointless. You'd just find out when the rock formed if you managed that much. By contrast, the grave goods would be amenable to radiocarbon, dendrochronology on any wood, fission track dating on pottery or glass, and if you want to get flashy you can try for some of the secular uranium daughter product equilibrium schemes. Given a reasonable number of analyses by several different methods you ought to be able to bracket the date of the funeral to within a couple of decades. This is assuming that the pyramid contained grave goods and hasn't been looted.

[Paleophyte]

So then u think the scientists can make mistakes? How bout the age of the Earth? Is that accurate?

Individual scientists can make mistakes but science tends to winnow these errors away. The age of the Earth has been established by so many different scientists using so many independent dating techniques that the chances of it being grossly wrong are effectively nil.

At this point the real problem has become a bit interesting because it's one of "Which age of the Earth do you want?" The formation of the solar system took a significant amount to time and we can now resolve events within that process. So now we have to get specific about which event in the formation of the Earth we're reporting an age for. That said, 4.54 billion years give or take 50 million works well for most purposes.

[Paleophyte]

It should also be pointed out that Rb-Sr dating is self-correcting in this way. You need to have several different crystals from the same rock, but you can derive the amount of the parent isotope from the measurements.

But Rb-Sr dating is  still susceptible to the amount of Rb and various Sr be changed by low grade metamorphosis after rock body formation.     You still need corroboration from other dating methods, or have ways for controlling for impact of low grade metamorphosis, such as good agreements in Rb-Sr dates across stratigraphically correlated rock formations over an area large enough to be implausible for the different rock samples to have undergone the same metamorphic history.

Metamorphism typically isn't a problem for Rb-Sr ages because the closure temperatures for most minerals are high enough that any event hot enough to reset them becomes pretty obvious. We actually use the closure temperatures of different minerals to produce different ages that result in chronologies of metamorphic events.

K-Ar and Ar-Ar systematics are much more prone to resetting or loss at lower temperatures and are rarely used much anymore except on pristine materials or when trying to actually track low temperature events. That's because the argon daughter product is a noble gas and doesn't bind into any crystal structure, so the system is leaky as hell.

For really robust ages go with U-Pb concordia ages in zircon. You get two independent uranium decay series working side by side in a mineral that gleefully refuses to reset in anything up to and including having its host rock melt. On a bright day you can pull a Th-Pb date as a bonus. Just make sure you aren't analyzing detrital grains by accident or you're totally buggered.

[Anomalocaris]

But Rb-Sr dating is  still susceptible to the amount of Rb and various Sr be changed by low grade metamorphosis after rock body formation.     You still need corroboration from other dating methods, or have ways for controlling for impact of low grade metamorphosis, such as good agreements in Rb-Sr dates across stratigraphically correlated rock formations over an area large enough to be implausible for the different rock samples to have undergone the same metamorphic history.

Metamorphism typically isn't a problem for Rb-Sr ages because the closure temperatures for most minerals are high enough that any event hot enough to reset them becomes pretty obvious. We actually use the closure temperatures of different minerals to produce different ages that result in chronologies of metamorphic events.

K-Ar and Ar-Ar systematics are much more prone to resetting or loss at lower temperatures and are rarely used much anymore except on pristine materials or when trying to actually track low temperature events. That's because the argon daughter product is a noble gas and doesn't bind into any crystal structure, so the system is leaky as hell.

For really robust ages go with U-Pb concordia ages in zircon. You get two independent uranium decay series working side by side in a mineral that gleefully refuses to reset in anything up to and including having its host rock melt. On a bright day you can pull a Th-Pb date as a bonus. Just make sure you aren't analyzing detrital grains by accident or you're totally buggered.

I think the problem with using Rb-Sr to date the time of closure temperature is both Rb and Sr are alkaline elements can be diffusion into or out of the parent mineral by carbonated hydrothermal fluids at below closure temperatures.    So lower grade metamorphism that exposes the rock to hydrothermal fluids can alter RN-Sr dating results without subjecting the rocks to closure temperature again.

[Paleophyte]

Metamorphism typically isn't a problem for Rb-Sr ages because the closure temperatures for most minerals are high enough that any event hot enough to reset them becomes pretty obvious. We actually use the closure temperatures of different minerals to produce different ages that result in chronologies of metamorphic events.

K-Ar and Ar-Ar systematics are much more prone to resetting or loss at lower temperatures and are rarely used much anymore except on pristine materials or when trying to actually track low temperature events. That's because the argon daughter product is a noble gas and doesn't bind into any crystal structure, so the system is leaky as hell.

For really robust ages go with U-Pb concordia ages in zircon. You get two independent uranium decay series working side by side in a mineral that gleefully refuses to reset in anything up to and including having its host rock melt. On a bright day you can pull a Th-Pb date as a bonus. Just make sure you aren't analyzing detrital grains by accident or you're totally buggered.

I think the problem with using Rb-Sr to date the time of closure temperature is both Rb and Sr are alkaline elements can be diffusion into or out of the parent mineral by carbonated hydrothermal fluids at below closure temperatures.    So lower grade metamorphism that exposes the rock to hydrothermal fluids can alter RN-Sr dating results without subjecting the rocks to closure temperature again.

Not typically a problem. The closure temperature is where the daughter product is no longer capable of diffusing within the mineral grains. Below that any fluids that might be lurking are either left stripping a few atoms off the grain boundaries or producing large degrees of metasomatism. The former is negligible and the latter is pretty obvious. Single grain, fractional grain, and in situ analyses can be used to check for this type leakage.

[Statler Waldorf]

My friend said his friend James Hincley at his church told him that this method is proved wrong constantly. He said they tried to date the pyramids and were way off. That an independent study was more accurate not using that method. He also said they tried to date how old a shark was and they were wrong as hell. He claims they are disproven all the time a nd that science is making this stuff up. Now I personally believe in scientists but do some of them make mistakes or he just cherry picking?

I think you are getting a few of your terms confused.  Radiometric dating is only used to date igneous rocks, so it could not be used on the pyramids or organic matter.  Radiocarbon dating is used on organic matter  I hope that helps :-)