Isotope clock reset debunks earth's age?

[starseeker]

<< Mentor Note -- typo fixed below with strikethrough history shown >>

I am in a heated debate with a client climate change denier (he created some of the software for their instruments, he says all evidence of how Earth's age is determined is flawed because the Earth's crust is continually recycled, this is what he says:

"Yes.. We did that and many other rocks, diamonds for exploration... and many post docs and their theses as well, but the fact still remains... the radio isotope clock can be reset.
The dating works for this time period, but is this the only time period of that sample, maybe or maybe not.

"

How can i counter this argument with true scientific evidence.

 

[Vanadium 50]

Sure. Some rocks are younger than the Earth as a whole. Why is that a problem?

 

[PeroK]

How can i counter this argument with true scientific evidence.

In order to argue a case there needs to be the possibility of an open mind. Without that you are wasting your time.

It's like presenting evidence in court of law to a judge and jury who have already made up their minds. It doesn't matter how compelling the evidence is, it won't change their verdict.

 

[berkeman]

Thread closed for a bit for Moderation...

 

[PeterDonis]

the radio isotope clock can be reset

He is correct when he says this, but he is incorrect when he says it invalidates dating by radio isotopes. "Resetting" the clock just means the date you get from a given rock is the date of the last "reset". So if you date a rock as 4.6 billion years old, that means that was the date of the last "reset". Which means the materials that made up the rock could be older than that, but they can't be younger.

Much more information about how radio isotope dating is actually done, which goes into how it deals with a number of possible sources of error, is here:

http://www.talkorigins.org/faqs/isochron-dating.html

 

[berkeman]

Thread is reopened. As @PeterDonis has done, all assertions in the technical PF forums must be backed by mainstream scientific sources. This is a reminder to all posters in this thread please -- this can be a useful scientific discussion as long as we stick to the science, and steer clear of politics and personal agendas. Thanks folks.

 

[starseeker]

He is correct when he says this, but he is incorrect when he says it invalidates dating by radio isotopes. "Resetting" the clock just means the date you get from a given rock is the date of the last "reset". So if you date a rock as 4.6 billion years old, that means that was the date of the last "reset". Which means the materials that made up the rock could be older than that, but they can't be younger.

Much more information about how radio isotope dating is actually done, which goes into how it deals with a number of possible sources of error, is here:

http://www.talkorigins.org/faqs/isochron-dating.html

Thanks to everyone for their valuable replies and a valuable source thanks for that it is certainly going to help.

The main argument revolves around climate change, not the Earth's age but he is trying to pin climate change to be false based upon the Earth's age.

He is trying to use an argument that the methods used to determine the history and age of the Earth is inaccurate or not valid because of the clock resetting at various times in the history, and because climate change evidence is based on past evidence and timelines, he argues that the age of the Earth cannot be determined therefore all climate change timeline figures based on past occurrences is incorrect.

Obviously he does have some insight if you look at his quote below, but certainly he cannot be correct in his statement that climate science is incorrect however it could hold some merit if past climate estimates are based on exact timelines ? But that would suggest as he is doing that the methods used to determine the age of the Earth is incorrect.

This argument is going on at a forum with a big crowd so would like to set him straight.

"I know as I wrote the software for our specific lab that calculated the ages..etc, so besides having to know how each specific test equipment works (Mass-spec, Ion Probes..etc), not to mention repairs these when faulty, I had to know the theory/methods behind the concepts - a study in itself but not difficult at all.

"

@berkeman
Thanks for the grammar check on my first post, i had a really long day yesterday.. :)

 

[PeterDonis]

he cannot be correct in his statement that climate science is incorrect

He is incorrect in his statements about the Earth's age. If his statements about our understanding of the Earth's age being wrong were correct, that would indeed invalidate our current understanding, not just of climate science, but just about any science.

How good our current understandings of various areas of science are (climate science or any other science), given that our general understanding of the Earth's age is correct, is a separate question that's really beyond the scope of this thread.

Obviously he does have some insight if you look at his quote below

He might know how the software works, but given his other statements that clearly does not mean he understands the underlying physics.

 

[starseeker]

Thank you Peter

How would you reply to his argument, i basically replied by saying isochrons are also used and explained part of the process, so now waiting to see if he has a counter reply.

Also another member seem to be wanting to place doubt on the dating methods by saying this:

Decay sequence from uranium 238 to lead 206:
Uranium 238 decays with a half-life of 4.46 billion years to Thorium 234 (24.1 days) to Protactinium 234 (46.69 hours) to Uranium 234
( 245500 years) to Thorium 230 (75400 years) to Radium 226 (1599 years) to Radon 222 (3.82 days) to Polonium 218 ( 3.04 minutes) to
Lead 214 ( 27 minutes) to Bismuth 214 (19.9 minutes) to Polonium 210 (0.16 milliseconds) to Lead 206 (which is stable).
When you measure with different cameras eg a GeLi detector / gamma camera, you get one curve coming out (the sum of all the activity within the energy band you have set up the camera on) so it takes quite a bit of math to de-convolute. A further complication in trying to de-convolute the decay curve is where some of the "in-between" daughter products can migrate or are absorbed or adsorbed differently eg Radon is a gas which can disperse in the atmosphere, or dissolve into water and be carried elsewhere before decaying further (and depositing the polonium). I personally had very little success targeting Polonium and virtually zero success on lead. perhaps I was just too impatient to occupy equipment for the long count times?

incidentally, decent UV monitors have only been around for about 30 odd years. (our CSIR developed Goldilux monitor was one of the first "decent" UV monitors) - so a lot of the data prior to the early 80's is possibly not that brilliant. There were also very few satellite passes over the poles in those old days!
even with the multiple passes these days, you can still get "gaps" in the data between passes

 

[mfb]

That post is too incoherent to address it properly.
All the intermediate states are very short-living and in equilibrium in all samples where you would might use uranium for dating, it is trivial to take them into account if you use radioactive decays today at all.

I personally had very little success targeting Polonium and virtually zero success on lead.

No idea what they tried, but it doesn't sound like a scientific approach. Holding a geiger counter at samples?

incidentally, decent UV monitors have only been around for about 30 odd years. (our CSIR developed Goldilux monitor was one of the first "decent" UV monitors) - so a lot of the data prior to the early 80's is possibly not that brilliant. There were also very few satellite passes over the poles in those old days!
even with the multiple passes these days, you can still get "gaps" in the data between passes

What does that have to do with anything?

 

[PeterDonis]

How would you reply to his argument

First, a general comment: if your friend wants to defend his position here, he should open an account and post on his own behalf. Discussions by proxy are not a good idea.

Second, my basic reply to what seems to be his argument (to the extent he has one) is in post #5: the fact that "resets" are possible in rock ages means that the age we get from radioisotope dating might be younger than the actual age of the rock. It can never mean that the age we get from radioisotope dating is older than the actual age of the rock. So we could, based solely on radioisotope dates, possibly think the Earth is younger than it actually is. But we could never think that the Earth is older than it actually is. So his claim, which basically amounts to the claim that scientists all think the Earth is older than it actually is, is not supported by the argument he makes based on radioisotope date "resets" being possible.

 

[PeterDonis]

another member seem to be wanting to place doubt on the dating methods by saying this:

Sounds to me like this person needs to read the actual scientific literature instead of trying to home-brew experiments himself.

 

[starseeker]

First, a general comment: if your friend wants to defend his position here, he should open an account and post on his own behalf. Discussions by proxy are not a good idea.

Second, my basic reply to what seems to be his argument (to the extent he has one) is in post #5: the fact that "resets" are possible in rock ages means that the age we get from radioisotope dating might be younger than the actual age of the rock. It can never mean that the age we get from radioisotope dating is older than the actual age of the rock. So we could, based solely on radioisotope dates, possibly think the Earth is younger than it actually is. But we could never think that the Earth is older than it actually is. So his claim, which basically amounts to the claim that scientists all think the Earth is older than it actually is, is not supported by the argument he makes based on radioisotope date "resets" being possible.

Thank you but to laymen this sounds like the age of the Earth cannot really be determined, how do we know which samples is the oldest and the youngest if it continuously resets.

 

[starseeker]

Sounds to me like this person needs to read the actual scientific literature instead of trying to home-brew experiments himself.

i agree thanks he is not my friend btw...

 

[starseeker]

That post is too incoherent to address it properly.
All the intermediate states are very short-living and in equilibrium in all samples where you would might use uranium for dating, it is trivial to take them into account if you use radioactive decays today at all.No idea what they tried, but it doesn't sound like a scientific approach. Holding a geiger counter at samples?What does that have to do with anything?

i asked the question, will let you know how he responds.

 

[russ_watters]

Thank you but to laymen this sounds like the age of the Earth cannot really be determined, how do we know which samples is the oldest and the youngest if it continuously resets.

? The older ones are older and the younger ones are younger...I'm not sure you understand what people were telling you. The samles' ages are what they are. It sounds like you think they indicate the age of Earth could be any of them. No, they indicate the age is at least the age of the oldest of them (which google tells me is 4.4 billion years).

 

[PeterDonis]

to laymen this sounds like the age of the Earth cannot really be determined

Not if you insist on only looking at radioisotope dating and assuming that every single rock you date was reset at least once in between the Earth being formed and now, no. But of course there is no reason why geologists must do either of those things. The age we currently accept for the Earth is the result of looking at multiple lines of evidence.

how do we know which samples is the oldest and the youngest if it continuously resets

You don't, strictly speaking. But you do know that the Earth has to be at least as old as the oldest age you get from any sample.

For example, if you have two rocks, one dated at 4.6 billion years old, the other at 2 billion years old, it is true that the second one could have been reset 2 billion years ago and could be even older than 4.6 billion years all told. But either way, the Earth is at least 4.6 billion years old.