Evidence for an earth much older than 6,000 years

[Astridhere]

I am quite familiar with the "creationist" literature. The British Journal Nature is probably the top science journal on the planet. New Scientist is a magazine about science. It is not a scientific journal.


This thread is not about the age of the earth, it is about dating methods that show the earth is older than 6,000 years.

You will have to find a dating method that is credible before you can have that conversation with anyone. The earth is not a closed system and only the hopefull would assume that no ground water, heat or anything else has interfered with your sample.

Quite frankly it is your face that is being slapped because you have cited a paper that does not support what you claim it does. That is why I keep asking you to give your critique of it. I know you have only read the abstract, not the paper itself. You have absolutely no idea what the U238/U235 ratio is or what it means. Here's a clue, that ratio has nothing to do with decay rates. And here's a fact you are completely ignorant of because you haven't read the actual paper. The ratio correction is only a difference of 700 k years at 4.5 Ga. The age of the earth is currently estimated at 4.54 Ga. +/- 1%. That 700 k is less than the current reported margin of error.

Yeah, like I said, you haven't a clue what that 137.88 ratio means. You also don't know that that ratio reported in your link, 30 March 2012 in Science, has been in use several years already any way. Brennecka. et al, published that ratio in 2009.

Oh really? The British Geological Survey states the following in a March news release concerning the paper we are discussing.

"A major effect of this work will be to decrease all previous uranium-lead (U-Pb) age determinations, by up to 700,000 years for samples that are about 4.5 billion years old – the age of the Earth. In particular, the new 238U/235U ratio will allow geologists to place more accurate limits on the exact timing of a broad range of geological processes, from the initial formation of our planet, continents and economic mineral deposits, to past evolutionary events and climate change."

In Uranium-Lead dating, scientists measure the relative amount of U238 and U235 isotopes present in a sample, and then calculate the age. Too bad they keep getting it wrong. Do you reckon they got it right this time, finally?

You may minimize all you wish. Don't forget that this is the 4th change where each time you would have thought you've got it now. Well you didn't, and the sm146 half life is still changing.

You really should try reading the paper dear, instead of trying to give a spin to a subject of which you are completely ignorant.

Like I said above, "a field in which you are completely ignorant of". There are two kinds of isotopes, stable and unstable. Stable isotopes do not decay. Unstable isotopes decay at a specific constant rate. Unstable does not mean a varying rate.

No, but you do.

I would suppose the polite thing would be to say that you are uninformed and mistaken. But in reality....well, we all know, the roll you are playing, and it is more than obvious.

You can think what you like RickG. I suggest you were not aware of the research I posted.

The point still remains. You have 2 methods to date the earth and both of them have fallen into disrepute with one of them having the half life re-evaluated 4 times over 60 years.

The 'better' method did not confirm the previous sm146 dates but altered them every time. True scientists call this date different, despite the fact that it may be small in comparison to 4 billion years. True scientists also don't like this discepency, because a discrepency in dating is what it is, whether or not you care to admit it.

The same requirements are necessary as with all radiometric dating. You need a closed system you do not know you have. Once you get past this assumption, with Uranium used for dating, you then again assume that there was no lead present to begin with. The same goes for argon.

Your scientists can enter different insertion values as they please when guestimating. They sometimes assume 50% lead and 50% uranium initial quantities, or others assume 50% lead / 50% uranium initial quantities in addition to a loss of 50% uranium per half life with the loss of uranium through leaching with weak acids, another hopefull guestimate.

There appears to be many assumptions that you are able to adjust to give an intended ball park age that aligns somewhat with your preconcieved assumptions of what the age should be.

Despite all your credentials the above is the true state of the matter. Everchanging half lives only add to the assumptions that you have had to assume already.

Is it not so that in actual fact the result wanted will inform the insertion value to get the required date?

You guys have to have something and this is the best you've got. It seriously is no better that the 'any possible scenario' that litters all evolutionary literature.

In actual fact scientists have no idea what the initial content of the rock was and can only hope and guestimate at best. It is unlikely that any rock remains in a closed system for a million years let alone 4 billion. Now they do not even have reliable half life dates either, it would appear. Now you can have as many conversations you want and a boot load of credentials and still those facts will never go away.

Radiometric dating sadly tells us nothing for either side of the debate.

That is the state of your dating methods. Your dating methods demonstrate that some people like to play with assumptions. However it is another assumption to suggest they are credible or accurate.

 

[Naraoia]

In Uranium-Lead dating, scientists measure the relative amount of U238 and U235 isotopes present in a sample, and then calculate the age.

You can correct me if I'm wrong, but I thought uranium-LEAD dating measured the relative amounts of the corresponding uranium and LEAD isotopes (238U/206Pb or 235U/207Pb) in a sample. Which has nothing whatsoever to do with the relative amounts of the two uranium isotopes.

 

[Astridhere]

You can correct me if I'm wrong, but I thought uranium-LEAD dating measured the relative amounts of the corresponding uranium and LEAD isotopes (238U/206Pb or 235U/207Pb) in a sample. Which has nothing whatsoever to do with the relative amounts of the two uranium isotopes.

It does not matter what you are measuring. Whatever it is you are measuring it is incorrect.

You say..."I thought uranium-LEAD dating measured the relative amounts of the corresponding uranium and LEAD isotopes (238U/206Pb or 235U/207Pb) in a sample." That is what I said in a less complicated manner. Your scientists have found that that different isotopes of the element uranium don't always appear in all geologic samples at the same ratio. However these are still what are measured.

238U/235U Systematics in Terrestrial Uranium-Bearing Minerals

When scientists evaluated the measurements used to arrive at the 137.88 value, they came to a dead end: the value could not be traced back to standard units such as the kilogram. Their new work shows that many naturally occurring uranium-rich minerals, such as zircon, actually have a 238U/235U value of 137.818 ± 0.045 and demonstrate significant natural variability. Agreement between these results, other rocks, and meteorites indicate the new average 238U/235U value may also be representative of the Earth’s ‘bulk’ uranium isotopic composition.
MIT EAPS: Adjusting the Rock Clock

So now they have a new 'average' and still guestimate the amount of lead originally in the sample and leaching until they get a result they want. They have a new average for an isotope, and still have no idea what the initial composition of the rock is, if it remained in a closed system for over 4 billion years.

You have a 30% drop in sm146 that changed the oldest rocks by 700,000 years. So if it was a 90% difference what? The earth would still be only a about 2my younger? Then we have other research that dates the moon as being 200 million years younger than previously thought, meaning that all the earth or a part of it, depending on which model you like, must also be 200my younger, and another researcher refuting this research on the basis of what the magma may or may not have done.


RickG asked if I knew about an article I presented. That unfortunately has nothing to do with the points I present in that post.

Further to that I like to check the underlying credibility of both YEC and non YEC views. The assumptions you make appear to make any refute you have to YEC dating methods a hypocritical refute. For example this one.

Helium Diffusion Age of 6,000 Years


You cannot possibly know if uranium, or any other isotope for that matter, has been affected by water or heat or leeched to give a closed system. You cannot possibly know what the initial content of lead in the initial rock sample was. Now worst of all, and the icing on the cake, is that decay rates are not constant in sm146 and you have an average uranium ratio that differs remarkably. Now you cannot say decay rates are stable. You have proof in at least one shorter lived isotope that this is not the case.

There is nothing that either you or RickG can say to refute the points above. This reduces any conversation anyone has about dating rocks older than 6,000 years to chatting about assumptions.

 

[Mr Strawberry]

It does not matter what you are measuring. Whatever it is you are measuring it is incorrect.

This could be your catchphrase.

 

[RickG]

You can correct me if I'm wrong, but I thought uranium-LEAD dating measured the relative amounts of the corresponding uranium and LEAD isotopes (238U/206Pb or 235U/207Pb) in a sample. Which has nothing whatsoever to do with the relative amounts of the two uranium isotopes.

The 238U/235U ratio is used primarily in the oldest rocks, therefore, meteorites, moon rocks and zircons. She hasn't the foggiest idea how the uranium series works or that 238U and 235U are two completely independent decay chains that eventually end up as two different Pb (lead) isotopes or that the uranium series is used to date samples quite young as well. It is quite a versatile method.

I have asked Astrid several times to critique the paper she linked but she refuses to even read the paper she criticizes so strongly and horribly incorrect. I'll lay out the series for all to see. I'll use the symbol -> to denote alpha decay and the symbon => to denote beta decay.

238U series:

238U -> 234Th => 234Pa -> 234U -> 230Th -> 226Ra -> 222Rn -> 206Pb

235U series:

235U -> 231Th => 231Pa -> 227Ac => 227Th -> 207Pb

There is also a Thorium series involved as well.

232Th -> 228Ra => 226Ac => 228Th ->208Pb.

The U238/U235 ratio used over the past 35 years has been 137.88. The newly determined ratio is 137.818. All it does is make very precise dates over those 35 years even more precise now as I have already explained to Astrid. It seems she just can't stand for scientist to obtain new information that allows them to become more and more precise with radiometric measurements. It doesn't invalidate any of those earlier measurements, they can now be updated more precisely. I mean really! An error of 700,000 years at the range of 4.5 Ga. That is an incredibly small error.

Here's some critiques of the paper by the British Geological Survey:

"Minerals naturally capture uranium when they form, which in turn undergoes a chain of radioactive decays to other elements, ending with lead. This new research has shown that, by more accurately measuring the relative amount of the uranium isotopes 238U and 235U, we now have a better understanding of how much time has passed since a mineral or rock has formed."

"A major effect of this work will be to decrease all previous uranium-lead (U-Pb) age determinations, by up to 700,000 years for samples that are about 4.5 billion years old – the age of the Earth. In particular, the new 238U/235U ratio will allow geologists to place more accurate limits on the exact timing of a broad range of geological processes, from the initial formation of our planet, continents and economic mineral deposits, to past evolutionary events and climate change."

---------------
Post Script: I just wanted to point out that in the above sequence of the two uranium series and one thorium series, I did not include some of the minor decay routes. Perhaps I'll include them in a later post.

 

[RickG]

This could be your catchphrase.

Originally Posted by Astridhere

It does not matter what you are measuring. Whatever it is you are measuring it is incorrect.​

Yes, it speaks volumes for her.

 

[Astridhere]

This could be your catchphrase.

Basically as an 'old' earther, I would have to agree with you.

 

[Astridhere]

It does not matter what you are measuring. Whatever it is you are measuring it is incorrect.

You say..."I thought uranium-LEAD dating measured the relative amounts of the corresponding uranium and LEAD isotopes (238U/206Pb or 235U/207Pb) in a sample." That is what I said in a less complicated manner. Your scientists have found that that different isotopes of the element uranium don't always appear in all geologic samples at the same ratio. However these are still what are measured.

238U/235U Systematics in Terrestrial Uranium-Bearing Minerals

When scientists evaluated the measurements used to arrive at the 137.88 value, they came to a dead end: the value could not be traced back to standard units such as the kilogram. Their new work shows that many naturally occurring uranium-rich minerals, such as zircon, actually have a 238U/235U value of 137.818 ± 0.045 and demonstrate significant natural variability. Agreement between these results, other rocks, and meteorites indicate the new average 238U/235U value may also be representative of the Earth’s ‘bulk’ uranium isotopic composition.
MIT EAPS: Adjusting the Rock Clock

So now they have a new 'average' and still guestimate the amount of lead originally in the sample and leaching until they get a result they want. They have a new average for an isotope, and still have no idea what the initial composition of the rock is, if it remained in a closed system for over 4 billion years.

You have a 30% drop in sm146 that changed the oldest rocks by 700,000 years. So if it was a 90% difference what? The earth would still be only a about 2my younger? Then we have other research that dates the moon as being 200 million years younger than previously thought, meaning that all the earth or a part of it, depending on which model you like, must also be 200my younger, and another researcher refuting this research on the basis of what the magma may or may not have done.


RickG asked if I knew about an article I presented. That unfortunately has nothing to do with the points I present in that post.

Further to that I like to check the underlying credibility of both YEC and non YEC views. The assumptions you make appear to make any refute you have to YEC dating methods a hypocritical refute. For example this one.

Helium Diffusion Age of 6,000 Years


You cannot possibly know if uranium, or any other isotope for that matter, has been affected by water or heat or leeched to give a closed system. You cannot possibly know what the initial content of lead in the initial rock sample was. Now worst of all, and the icing on the cake, is that decay rates are not constant in sm146 and you have an average uranium ratio that differs remarkably. Now you cannot say decay rates are stable. You have proof in at least one shorter lived isotope that this is not the case.

There is nothing that either you or RickG can say to refute the points above. This reduces any conversation anyone has about dating rocks older than 6,000 years to chatting about assumptions.

So RickG, you want Astrid to critique a load of woffle and assumption as opposed to your stepping up to refute the above post namely this....

You cannot possibly know if uranium, or any other isotope for that matter, has been affected by water or heat or leeched to give a closed system. You cannot possibly know what the initial content of lead in the initial rock sample was. Now worst of all, and the icing on the cake, is that decay rates are not constant in sm146 and you have an average uranium ratio that differs remarkably. Now you cannot say decay rates are stable. You have proof in at least one shorter lived isotope that this is not the case.

Well RickG, it a sad day for you and all your credentials if you are unable to address some fairly straight forward points that directly affect the credibility of any dating method.

 

[Astridhere]

<staff edit>

Well you seem to think you have all the answers..refute this...

You cannot possibly know if uranium, or any other isotope for that matter, has been affected by water or heat or leeched to give a closed system. You cannot possibly know what the initial content of lead in the initial rock sample was. Now worst of all, and the icing on the cake, is that decay rates are not constant in sm146 and you have an average uranium ratio that differs remarkably. Now you cannot say decay rates are stable. You have proof in at least one shorter lived isotope that this is not the case.

Last chance...or else everyone will conclude you have no idea how to.

 

[Wiccan_Child]

You cannot possibly know if uranium, or any other isotope for that matter, has been affected by water or heat or leeched to give a closed system.

Yes, we do. Besides knowing what such contamination looks like (cracking or weathering of the rock, etc), we take multiple samples and use multiple, independant dating techniques, giving us very good certainty indeed that any given rock hasn't (or has) been contaminated. Contamination would affect the samples asymmetrically, and contaminated samples show different errors for different individual samples and techniques - which actually yields important information about how contamination occurs.

If it hasn't been contaminated, the various dating techniques across all the various samples will all match up. Since this is what we observe, this provides very good evidence that the age is accurate.

In essence, the techniques we use to date things have a built-in 'check', and the possibility of contamination, and the subsequent absence of its tell-tale signs, bolsters radiometric dating.

You cannot possibly know what the initial content of lead in the initial rock sample was.

Yes, we can. Besides knowing how the rock formed, uranium-lead dating works because there are two chains - Uranium-238 to Lead-206, and Uranium-235 to Lead-207 - which can be used to independently date the same samples. We don't need to know how much lead was initially in the sample, only the ratio of the two isotopes of lead.

Now worst of all, and the icing on the cake, is that decay rates are not constant in sm146

Yes, they are. Samarium 146 is synthetic, in that no naturally occurring deposits exist on Earth today - it's all decayed into Neodymium 142. Initial estimates on its half-life allowed us to estimate the age of certain rocks. Later, when we synthesised Samarium 146, we got a better idea of its half-life, thereby getting a better idea of the age of these rocks - and that age has gone from 4.4000 billion to 4.3993 billion. Hardly an Earth-shattering change.

The half-life of [sup]146[/sup]Sm hasn't changed.

and you have an average uranium ratio that differs remarkably.

No, we don't. Initial estimates were 137.88, and new estimates are 137.81. This is not a remarkable difference.

Now you cannot say decay rates are stable.

Yes, we can. Stability has precise meanings in science, none of which you're using right. Isotopes are 'stable' if they don't decay, and 'unstable' if they do. All decay rates are constant. You've cited no evidence that decay rates change.

 

[Naraoia]

You cannot possibly know if uranium, or any other isotope for that matter, has been affected by water or heat or leeched to give a closed system.

*straight face* I'm pretty sure no one before you ever thought of leeching uranium.

 

[Astridhere]

Yes, we do. Besides knowing what such contamination looks like (cracking or weathering of the rock, etc), we take multiple samples and use multiple, independant dating techniques, giving us very good certainty indeed that any given rock hasn't (or has) been contaminated. Contamination would affect the samples asymmetrically, and contaminated samples show different errors for different individual samples and techniques - which actually yields important information about how contamination occurs.

If it hasn't been contaminated, the various dating techniques across all the various samples will all match up. Since this is what we observe, this provides very good evidence that the age is accurate.

In essence, the techniques we use to date things have a built-in 'check', and the possibility of contamination, and the subsequent absence of its tell-tale signs, bolsters radiometric dating.

That's the way. I have been waiting for someone to mention this. It is not about 2 methods of dating it is about several both from with uranium and other isotopes. However, you know as hard as I tried I could not get this without having to hand the baby over to you. Well done!

I spoke to isochron dating in my first post and am amazed no one hit on that. As I stated in my first post isochron dating is the hardest to refute and that is because it negates the assumption of initial quantities. However there are still some concerns noted.

Yes, we can. Besides knowing how the rock formed, uranium-lead dating works because there are two chains - Uranium-238 to Lead-206, and Uranium-235 to Lead-207 - which can be used to independently date the same samples. We don't need to know how much lead was initially in the sample, only the ratio of the two isotopes of lead.


Yes, they are. Samarium 146 is synthetic, in that no naturally occurring deposits exist on Earth today - it's all decayed into Neodymium 142. Initial estimates on its half-life allowed us to estimate the age of certain rocks. Later, when we synthesised Samarium 146, we got a better idea of its half-life, thereby getting a better idea of the age of these rocks - and that age has gone from 4.4000 billion to 4.3993 billion. Hardly an Earth-shattering change.

The half-life of [sup]146[/sup]Sm hasn't changed.


No, we don't. Initial estimates were 137.88, and new estimates are 137.81. This is not a remarkable difference.


Yes, we can. Stability has precise meanings in science, none of which you're using right. Isotopes are 'stable' if they don't decay, and 'unstable' if they do. All decay rates are constant. You've cited no evidence that decay rates change.

Indeed on this last point above I have actually supplied evidence of sm146 having its decay rate/half life reduced by 30% and over the 4 times it has been measured over the past 60 years the half life has been different each time and remarkably so. Hence the decay rate in sm146 cannot be constant and the article speaks to this. This isotope has a shorter half life so errors would be more readily noted than one that has a 4.5Ka half life. That is not in dispute as far as I am concerned.

Dating rocks by these radioactive timekeepers is simple in theory, but the laboratory procedures are complex. The numbers of parent and daughter isotopes in each specimen are determined by various kinds of analytical methods. The principal difficulty lies in measuring precisely very small amounts of isotopes. That is what is meant to be 'improving'.

I understand that any equation does not work with 2 unknown values, initial lead content and time, in relation to uranium. I believe zero takes the place of intial lead content in most equations.

Lets change the assumption. Let's say that lead in the sample initially had a 5% lead content. 10% is the upper limit for its' appearance in ore.

Now can we calculate how this would change the result of the equation you use?

Then apply it to this equation

where D0 is the amount of daughter isotope present at the start.

I understand that the assumption of lead being present initially will shorten the result (t) time, greatly, even in the equations you use.

Can someone please speak to this?

 

[Wiccan_Child]

That's the way. I have been waiting for someone to mention this. It is not about 2 methods of dating it is about several both from with uranium and other isotopes. However, you know as hard as I tried I could not get this without having to hand the baby over to you. Well done!

I spoke to isochron dating in my first post and am amazed no one hit on that. As I stated in my first post isochron dating is the hardest to refute and that is because it negates the assumption of initial quantities. However there are still some concerns noted.

Such as?

The independent corroboration is the hardest to dispute.

Indeed on this last point above I have actually supplied evidence of sm146 having its decay rate/half life reduced by 30% and over the 4 times it has been measured over the past 60 years the half life has been different each time and remarkably so. Hence the decay rate in sm146 cannot be constant and the article speaks to this. This isotope has a shorter half life so errors would be more readily noted than one that has a 4.5Ka half life. That is not in dispute as far as I am concerned.

The decay rate is constant. Our measurements of it may be refined over time, but the decay rate itself is unchanging. And, as I said, the refinement hasn't changed much of anything - something whose age is measured in the billions of years has had its age changed by millions of years. That is a small change. 4,500,000,000 to 4,499,000,000 -a change, yes, but not really a significant one.

You also need to be careful in that reducing the half-life of [sup]146[/sup]Sm by 30% doesn't reduce the rocks' ages by 30%. The effective reduction is more like 0.02%.

Dating rocks by these radioactive timekeepers is simple in theory, but the laboratory procedures are complex. The numbers of parent and daughter isotopes in each specimen are determined by various kinds of analytical methods. The principal difficulty lies in measuring precisely very small amounts of isotopes.

To be fair, if you're going to copy text wholesale from another site, it's simply good manners to do so (not doing so makes you look suspicious, and your position untenable). This is the original source, though it's also quote-mined by Creationist sites as well. If you didn't take it from the original source, then you couldn't have known that the rest of the article goes into how we overcome those difficulties.

I understand that any equation does not work with 2 unknown values, initial lead content and time, in relation to uranium. I believe zero takes the place of intial lead content in most equations.

For good reasons. Analysis of the rock itself lets us know how it formed, and the creation of the crystalline material occurs in such a way that lead is physically rejected. Once the crystal has formed, its inner matrix is locked. Thus, we know that any lead that was there would be physically ejected, rather like water and oil.

And, even if you take "Pb[sub]t=0[/sub] = 0" to be a baseless assumption done to make the maths easier, it's fully justified in the corroboration with other, independent techniques (and, of course, when it doesn't match up, that's good evidence there was initial lead)

Lets change the assumption. Let's say that lead in the sample initially had a 5% lead content. 10% is the upper limit for its' appearance in ore.

Now can we calculate how this would change the result of the equation you use?

Then apply it to this equation


where D0 is the amount of daughter isotope present at the start.

I understand that the assumption of lead being present initially will shorten the result (t) time, greatly, even in the equations you use.

Can someone please speak to this?

While you're right that raising the initial lead count would shorten the age of the material, the fact remains that we have good reasons for believing that the initial lead count is zero.

 

[Astridhere]

The decay rate is constant. Our measurements of it may be refined over time, but the decay rate itself is unchanging. And, as I said, the refinement hasn't changed much of anything - something whose age is measured in the billions of years has had its age changed by millions of years. That is a small change. 4,500,000,000 to 4,499,000,000 -a change, yes, but not really a significant one.

An international group of investigators recently announced that the value for the half-life of samarium-146, previously thought to be 103 million years, is in fact 68 million years. The new number is very important, since 146Sm is heavily used in a number of dating methods.
The actual value for the element's half-life is around 34 percent smaller than the previous one, and this has the potential to change our current understanding of processes that led to the development of the solar system.

http://news.softpedia.com/news/Half-Life-of-Samarium-146-Refined-262741.shtml

Scientists have measured samarium-146's half-life &#8211; the time taken for exactly half of a sample of atoms to decay radioactively - four times over the past 60 years, and got different answers each time.

They found that the half-life is just 68 million years, 30 per cent shorter than thought.

Age of oldest rocks off by millions of years - space - 29 March 2012 - New Scientist

Now what is it exactly that you do not understand about this article?

The time taken for half of the atoms to decay radioactively on 4 occasions got different answers each time. That to me strongly suggests you have evidence that indeed the decay rate is not constant.

Are you suggesting that the other findings are total rubbish and this 30% reduction is the new finding and next time they measure it, and from then on, it will remain the same? If so, on what basis are you making that assumption?

It appears that I have PROOF that the decay rate is not constant in sm146. You, on the other hand have hope that it is constant, and not much else. Do you see the difference?

There is no point pursuing the algorithmic consequence of a 5% initial lead composition (which no one has responded to) if you are unable to get past the point above.

 

[Astridhere]

Seriously you guys and gals, it is OK for you to string along as you do and be so hopeful. However you cannot truly deny that YECs have at least cause for skepticism. This is really looking like flavour of the month stuff.

You now have an extra 35 million years, out of every 1,000,000 years for over 4,000,000,000 years for this isotope to half. This means an extra 140,000 years more time to halve. This is enough time for sm146 to halve twice more over 4 billion years, at a 68my half life, than previously thought.

This is meant to amount to dating of only 700,00 years less according to your scientists, even though the half life rolled over twice more in giving your measured amount of lead in your samples. Something is very much amiss with these calculations you guys come up with. They do not make any sense.

30% is a huge woopsie by anyones standards. This strongly suggests to me that these researchers are groping in the dark. You may be hopeful that these scientists know what they are doing, however I am not and I am not even a YEC.

No one is going to do a calculation assuming some lead content in the intial rock and I can understand why. It would demonstrate the extent the dating will change with just a small change in one assumption.

 

[Wiccan_Child]

An international group of investigators recently announced that the value for the half-life of samarium-146, previously thought to be 103 million years, is in fact 68 million years. The new number is very important, since 146Sm is heavily used in a number of dating methods.
The actual value for the element's half-life is around 34 percent smaller than the previous one, and this has the potential to change our current understanding of processes that led to the development of the solar system.

Half-Life of Samarium-146 Refined - Softpedia

Scientists have measured samarium-146's half-life &#8211; the time taken for exactly half of a sample of atoms to decay radioactively - four times over the past 60 years, and got different answers each time.

They found that the half-life is just 68 million years, 30 per cent shorter than thought.

Age of oldest rocks off by millions of years - space - 29 March 2012 - New Scientist

Now what is it exactly that you do not understand about this article?

Nothing. Previous estimates of the halflife of [sup]146[/sup]Sm have been refined now that we can directly measure it, and the haflife has gone down by 34%.

The time taken for half of the atoms to decay radioactively on 4 occasions got different answers each time. That to me strongly suggests you have evidence that indeed the decay rate is not constant.

Are you suggesting that the other findings are total rubbish and this 30% reduction is the new finding and next time they measure it, and from then on, it will remain the same? If so, on what basis are you making that assumption?

The fact that the previous findings were predictions of [sup]146[/sup]Sm's halflife based on theoretical models of Samarium and isotopes of that weight (it's the same process that predicts an 'island of stability' in the high 120's). Now, we have the technology to directly synthesis and measure the halflife of [sup]146[/sup]Sm (as attested in your cited articles), and it turns out the previous findings were wrong.

So the previous findings were roughly correct (its halflife is in the millions of years, not microseconds, for instance), but now direct measurements have shown them to be off by 34%

It appears that I have PROOF that the decay rate is not constant in sm146. You, on the other hand have hope that it is constant, and not much else. Do you see the difference?

Were that the case, yes. However, as I explained, there is a quantitative difference in theoretical predictions of what a given atom's half-life will be, and direct measurements of it.

Remember, the figure of 1.03×10[sup]8[/sup] years is the one we got from direct measurement, and the others were theoretical models. This does not constitute proof that the decay rate is not constant: those same theoretical models will still give the incorrect half-life. If, as you say, the half-life is changing, then each measurement should change with it - but they don't. Rather, each model is surpassed by a better one.

So I disagree that you have proof, or even evidence, that the half-life of Samarium-146 is changing, only that theoretical models were off by 34% of the real, physical measurement.

Consider this analogy. Suppose you find a skull, and from what evidence you have you deduce the man's height. You later find some more bones, and you recalculate his height based on this new evidence, and find your old estimate was too small. Now, you've found the complete skeleton, and your latest calculation is larger still.

Does this mean that the man is still growing? No, it means our conclusion is changing. The man's height when he died is a constant. That our measurements change, isn't necessarily indicative of change in the measured object. Rather, in this case, it's clear that the change is due to methodology: we have new evidence, so we have a refined conclusion that differs from previous ones.

The same is true of the half-life of [sup]146[/sup]Sm: you haven't found evidence that it's changing, only that our measurements are getting better as we accumulate more evidence. 106 million was pretty good, but 68 million is better.

Again, it's the methodology that has changed, not the atom. We went from theoretical predictions to direct measurement, and the latter was 34% different from the former. You say this is due to the atom itself changing, that its half-life is physically different - but it's not. The change is because our theoretical models (which are unchanging; they still say 106 million) were wrong.

There is no point pursuing the algorithmic consequence of a 5% initial lead composition (which no one has responded to) if you are unable to get past the point above.

First, the point about [sup]146[/sup]Sm is unrelated to the point about initial lead content; I don't see why we can't pursue both lines of discussion.

Second, I responded to it - it turns out to be moot. A 5% initial lead content would reduce the calculated age, but since we know it was 0%, not 5%, that conclusion seems asinine.

 

[Astridhere]

Nothing. Previous estimates of the halflife of [sup]146[/sup]Sm have been refined now that we can directly measure it, and the haflife has gone down by 34%.


The fact that the previous findings were predictions of [sup]146[/sup]Sm's halflife based on theoretical models of Samarium and isotopes of that weight (it's the same process that predicts an 'island of stability' in the high 120's). Now, we have the technology to directly synthesis and measure the halflife of [sup]146[/sup]Sm (as attested in your cited articles), and it turns out the previous findings were wrong.

So the previous findings were roughly correct (its halflife is in the millions of years, not microseconds, for instance), but now direct measurements have shown them to be off by 34%


Were that the case, yes. However, as I explained, there is a quantitative difference in theoretical predictions of what a given atom's half-life will be, and direct measurements of it.

Remember, the figure of 1.03×10[sup]8[/sup] years is the one we got from direct measurement, and the others were theoretical models. This does not constitute proof that the decay rate is not constant: those same theoretical models will still give the incorrect half-life. If, as you say, the half-life is changing, then each measurement should change with it - but they don't. Rather, each model is surpassed by a better one.

So I disagree that you have proof, or even evidence, that the half-life of Samarium-146 is changing, only that theoretical models were off by 34% of the real, physical measurement.

Consider this analogy. Suppose you find a skull, and from what evidence you have you deduce the man's height. You later find some more bones, and you recalculate his height based on this new evidence, and find your old estimate was too small. Now, you've found the complete skeleton, and your latest calculation is larger still.

Does this mean that the man is still growing? No, it means our conclusion is changing. The man's height when he died is a constant. That our measurements change, isn't necessarily indicative of change in the measured object. Rather, in this case, it's clear that the change is due to methodology: we have new evidence, so we have a refined conclusion that differs from previous ones.

The same is true of the half-life of [sup]146[/sup]Sm: you haven't found evidence that it's changing, only that our measurements are getting better as we accumulate more evidence. 106 million was pretty good, but 68 million is better.

Again, it's the methodology that has changed, not the atom. We went from theoretical predictions to direct measurement, and the latter was 34% different from the former. You say this is due to the atom itself changing, that its half-life is physically different - but it's not. The change is because our theoretical models (which are unchanging; they still say 106 million) were wrong.


First, the point about [sup]146[/sup]Sm is unrelated to the point about initial lead content; I don't see why we can't pursue both lines of discussion.

Second, I responded to it - it turns out to be moot. A 5% initial lead content would reduce the calculated age, but since we know it was 0%, not 5%, that conclusion seems asinine.

You have spent the entire post trying to word up 'wrong'.

Wrong is wrong. There is no reason to believe the current value is any more correct than the last at the moment. Perhaps your precision has a long way to go.

As for you calculation, what does turns out to be mute mean. I'll take a guess. It means it does not matter if the earth was young you would never be able to see it. I have read that lead being present in the initial rock would drastically decrease the age of the earth.

You see before this finding you and RickG would have argued black and blue with me or anyone else that the 103my half life was correct. You would have strutted your stuff and told me all about it and why it is so accurate. Some would ridicule me for having said it was wrong 3 times before so why suggest it is right this time. You are presenting the very same argument.


Thanks for your reply. You see you have faith in your researchers, obviously I do not and they do not make sense.

 

[Wiccan_Child]

You have spent the entire post trying to word up 'wrong'.

Wrong is wrong. There is no reason to believe the current value is any more correct than the last at the moment.

What? Yes we do. My entire post explained that in exhaustive detail. Old figures came from theoretical predictions, new figures come from direct measurement. The latter supersedes the former. That right there is a very good reason indeed for believing the old figures, which were good, weren't as accurate as the new ones.

As for you calculation, what does turns out to be mute mean. I'll take a guess. It means it does not matter if the earth was young you would never be able to see it. I have read that lead being present in the initial rock would drastically decrease the age of the earth.

'Moot', not 'mute', means the answer to the question has no bearing on the discussion at hand, it has no relevance.

Initial lead content of 5% would decrease the calculated age. But so what? We know that the initial lead content was 0%, so pondering what would happen if it was 5% is a futile exercise.

The point is moot, because the 'what if' scenario is irrelevant.

You see before this finding you and RickG would have argued black and blue with me or anyone else that the 103my half life was correct. You would have strutted your stuff and told me all about it and why it is so accurate. Some would ridicule me for having said it was wrong 3 times before so why suggest it is right this time. You are presenting the very same argument.

Arguing that the 68 million figure is the current and most accurate is not the same as arguing that it is the absolute and unwavering truth. Science works with evidence, any any conclusion are couched in probability.

The 68 million year figure is the current and most accurate figure we have for the half-life of [sup]146[/sup]Sm. It's certainly possible that this will be refined in the future, but the fact remains that this is the most accurate figure to date. There are good reasons for the 34% refining over the last figure - we now have direct samples to measure.

Now, if future, direct measurements showed a continuous decline in half-life, you'd have a point. But the change is due to methodology, not an actual change in half-life. I explained this throughout in my previous post, but given your terse reply, it's evident you didn't even bother to read it.

 

[Astridhere]

What? Yes we do. My entire post explained that in exhaustive detail. Old figures came from theoretical predictions, new figures come from direct measurement. The latter supersedes the former. That right there is a very good reason indeed for believing the old figures, which were good, weren't as accurate as the new ones.


'Moot', not 'mute', means the answer to the question has no bearing on the discussion at hand, it has no relevance.

Initial lead content of 5% would decrease the calculated age. But so what? We know that the initial lead content was 0%, so pondering what would happen if it was 5% is a futile exercise.

You absolutely cannot possibly know what the actual initial lead content was at all wiccan. That is a throw off and you know it. You already know that there is a lead component in ore. There is absolutely no basis to suggest that the inital rock content was devoid of any lead what so ever. In fact I would strongly suggest that it is much more likely that the initial rock did have lead in it than not.

'Moot' means you refuse to entertain any other possible scenario than the one required regardless of it being highly unlikely.

Indeed you MUST adhere to the ridiculous suggestion that mystically these rocks you sample were totally non reflective of what we observe today to give the results you seek. That is the basis of my skepticism.

Arguing that the 68 million figure is the current and most accurate is not the same as arguing that it is the absolute and unwavering truth. Science works with evidence, any any conclusion are couched in probability.

The 68 million year figure is the current and most accurate figure we have for the half-life of [sup]146[/sup]Sm. It's certainly possible that this will be refined in the future, but the fact remains that this is the most accurate figure to date. There are good reasons for the 34% refining over the last figure - we now have direct samples to measure.

Now, if future, direct measurements showed a continuous decline in half-life, you'd have a point. But the change is due to methodology, not an actual change in half-life. I explained this throughout in my previous post, but given your terse reply, it's evident you didn't even bother to read it.

So how many times does a naturalist need to find conflicting results before they accept there is something amiss? 2,3,4 times is obviously not sufficient for the scientific mind.

Obviously with a 34% difference your previous methods were extremely erraneous not just a little off. The 'most accurate figure to date' can hardly be used as any more than speculation at this point.

Hence you still have 2 insertion values, intial lead content and decay rate, as assumptive insertion values to can play with to demonstrate the results you want.

I can't see a reply to this from my previous post.

This 34% change gives enough time for sm146 to halve twice more over 4 billion years, at a 68my half life, than previously thought.

This is meant to amount to dating of only 700,00 years less according to your scientists, even though the half life rolled over twice more in giving your measured amount of lead in your samples. Something is very much amiss with these calculations you guys come up with. They do not make any sense.

I don't want to hang around here forever. If you can just explain the above, that will do me. I see this as an endless discussion about something I do not particularly care about. RickG can then continue his discussions with you all.

 

[Wiccan_Child]

You absolutely cannot possibly know what the actual initial lead content was at all wiccan.

I've already explained why we can, in fact, know that. We know how the crystals are formed, and as they form, they absorb uranium and thorium into their matrix, and eject any lead present. The result is something with a regular amount of uranium, and zero lead. More evidence comes from the fact that this conclusion corroborates with other independent techniques.

'Moot' means you refuse to entertain any other possible scenario than the one required regardless of it being highly unlikely.

First, that is not what 'moot' means. Second, I keep addressing it, over and over.

So how many times does a naturalist need to find conflicting results before they accept there is something amiss? 2,3,4 times is obviously not sufficient for the scientific mind.

On the contrary, anomalies are a staple of science. Rooting down the cause of the error is important, and you don't seem to be able to grasp that different results can be caused by something other than a change in what's being measured.

Obviously with a 34% difference your previous methods were extremely erraneous not just a little off.

34% is a big change, sure, but it only reduces the ages of rocks by 0.02%. It turns out that what constitutes 'statistically significant' is not straightforward.

Hence you still have 2 insertion values, intial lead content and decay rate, as assumptive insertion values to can play with to demonstrate the results you want.

Err... you realise that they're different dating techniques, right?

I can't see a reply to this from my previous post.

This 34% change gives enough time for sm146 to halve twice more over 4 billion years, at a 68my half life, than previously thought.

This is meant to amount to dating of only 700,00 years less according to your scientists, even though the half life rolled over twice more in giving your measured amount of lead in your samples. Something is very much amiss with these calculations you guys come up with. They do not make any sense.

I don't want to hang around here forever. If you can just explain the above, that will do me.

Err, first, why are you talking about lead? Samarium-Neodymium dating has nothing to do with lead - are you getting confused with Uranium-Lead dating? They're... they're not the same.

Anyway, as I explained before, these things don't change linearly. A basic derivative shows that the age of the rock is negatively proportional to the half-life, so you might well naïvely think that the new age reduces by 34% as well - it doesn't. I've noticed your eyes tend to glaze over if I go into too much technical detail, so I'll simply point out that reducing the half-life of [sup]146[/sup]Sm also changes other factors in radiometric dating, namely the initial samarium content.

Long story short, we're now able to directly measure the half-life of Samarium, and it's 34% shorter than its theoretical estimate. But this also alters calculations regarding initial count, and the end result is that rocks once dated at 4.4 billion years old are 700,000 years younger.