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Author | Topic: New helium retention work suggests young earth and accelerated decay | |||||||||||||||||||
Tranquility Base Inactive Member |
Brad
Somehow I knew you'd be reading Wolfram. I wonder when the paperback version will come out?
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Tranquility Base Inactive Member |
Edge
I'll get back to you on that.
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Tranquility Base Inactive Member |
Nos
In the other thread http://EvC Forum: How about teaching evolution at Sunday school? -->EvC Forum: How about teaching evolution at Sunday school?I said quote: The you said:
quote: So what does that have to do with it? I suspect you are not up to scratch on these issues. Mechanical diffusion of nuclear decay generated helium is an indpendent way of trying to date rocks. This helium is generated during the uranium decay series. i.e. the billions of years half-life series used to date the planet. [This message has been edited by Tranquility Base, 11-05-2002]
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edge Member (Idle past 1732 days) Posts: 4696 From: Colorado, USA Joined: |
quote: No, it is a way of showing that [He] is not a very good clock. Humphreys appears to believe this and yet says that the same clock requires a young earth. Does this make sense to you?
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TrueCreation Inactive Member |
"No, it is a way of showing that [He] is not a very good clock."
--I wouldn't expect dating by He diffusion to be a reliable 'clock', though it could serve as a relative dating method. Tranquility and the RATE team seems to make the claim that the analysis is not cooperative with such 'Ga' scale ages given by isotopic measurements. Of course this is my assertion made without considering what the data actually does say about He diffusion. ------------------
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edge Member (Idle past 1732 days) Posts: 4696 From: Colorado, USA Joined: |
quote: So that fact that helium can diffuse out of zircon crystals does not bother you in using this method as a clock? After all of the discussions regarding argon loss and retention you are going back on the creationist position that these make radiodating undependable?
quote: Please follow the logic of my previous posts and tell me how a 6000 year old (according to Humphreys) zircon looks any different in He content than a 6 trillion year old zircon.
quote: Actually, it is irrelevant. Humphreys' data does not tell him what he thinks it does.
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wehappyfew Inactive Member |
[QUOTE]Originally posted by Tranquility Base:
[B]In all the kafuffle and misunderstandings between our Joe Meert and ICR's Russell Humphreys et al we have not been able to celebrate an important creationist result! Acts and Facts Magazine | The Institute for Creation Research On the face of it, it appears that the radioactively generated helium present in zircons suggests that the helium was generated only in the last 4,000 to 14,000 years rather than gradually over the last 1.5 billion years. There is simply too much of it (up to 58% compared to the long-age expected 0.0002%) still in the rocks. The diffusion rates are experimentally measured and, on the face of it, rule out the ancient ages. [/quote] [/b]Dos the RATE book contain these "experimentally measured" diffusion rates? quote: OK. Sounds like fun. I've been doing some research on the subject (obviously I need it after starting the whole -196C closure confusion). If you have the numbers from those diffusion experiments, we can use them to mathematically evaluate the Creation model WRT helium diffusion in zircons, etc. We can also compare them to the diffusion parameters measured by Reiners (the ones that Humphreys claims support his results)...http://www.geology.yale.edu/~reiners/zirconpaper040401.pdf If you would, please, consider the Arrhenius plots in Figure 2 and the data in Table 1 of Reiners. From them we can infer diffusion rates relevant to the Jimez zircons, and plug them into the equilibrium age equation (incorrectly labeled closure interval in eq 22 from Preprint of section 10) that Humphreys uses. I would like to see if you come up with the same results I did. I find it very interesting that Humphreys calculates a temperature of -196C (77K) for his "retention temperature". How can he do this? If you look at how the Arrhenius plots work, this requires extrapolating experimental data along the X-axis measured in the 12 to 18 range (the units are 10000/temp) up to 130 (10000/77 = 130). Does this seem reasonable? Did you notice that Humphreys calulates a closure temp for the Jimez zircons using standard geological assumptions? I wonder what the closure temp would be if we assumed a 4-14K age for the Earth and the extremely fast cooling rates implied by that. And what about the unspoken assumption in conventional science of unchanging radiodecay constants? If we use the decay acceleration required by the YEC timeframe, and plug that into Humphrey's definition of closure temp..."... a temperature at which the rates of loss and production are equal. That point is essentially what Dodson meant by the closure temperature." ... then we need to adjust our calculated closure temp upwards until we find a diffusion rate that is proportionally higher. Are you willing to give it a try, TB?
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Tranquility Base Inactive Member |
Wehappy
The RATE book contains the extrapolated helium diffusion constant from the argon experimental one: Extrap He: 10^-15 to 10^-17 cm^2/s (temp dependent)Expt Ar: 10^-19 to 10-22 cm^2/s (temp dependent) The experimental He diffusion (EDIT from fusion!) rate was mentioned to be in agreement with the extrapolated one last year: The Institute for Creation Research and represents a rapid diffusion coeffeicen about 5-orders of magnitude greater than what the long-age model needs. If He diffused at the Ar rate things would be all hunky-dory for you. I have it on good authority that the data will be presented at a creation conference and be up on the web some time in 2003. [This message has been edited by Tranquility Base, 11-08-2002]
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edge Member (Idle past 1732 days) Posts: 4696 From: Colorado, USA Joined: |
quote: Of course the diffusion rates are temperature dependent. Now what temperatures are we talking about?
quote: What do you mean 'fusion rate,' and what experimental rate are you talking about? You have given us an 'extrapolated' rate and then say that the experimental rate compares well with the 'extrapolated' rate from last year. Then explain how the experimental value was determined, and how that relates to natural conditions of the zircons.
quote: Please explain why such rates are a problem for us. I your own words, please. You have seen Humphreys' own data that shows an equilibrium [He] for the zircons in question. No matter what the diffusion rate, Humphreys says that the He concentration will always be the equilibrium value after the 'closure interval.' So, what does this have to do with diffusion and the age of the crystals?
quote: I can't wait.
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Tranquility Base Inactive Member |
^ Being a nuclear physicist at heart I sub-conciously substituted He fusion for He diffusion!
Temp: between 130C and 280C. The argon exp data is published: Grove M & Harrison TM American Minerologist 81, 940-951 (1996). The extrapolaitons are mainstream, what anyone would expect (helium is a lot smaller) and the He diff is now experimental too. I don't claim that I completely understand what Humphrey's is going on about on his website but I haven't spent time on it either. I suspect that you shouldn't assume that he doesn't know what he is talking about. [This message has been edited by Tranquility Base, 11-08-2002]
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edge Member (Idle past 1732 days) Posts: 4696 From: Colorado, USA Joined: |
quote: Well, since he tells us that there is too much He in zircons and then shows us why there can be only so much He in zircon, I think it's a good bet that he does not know what he's talking about. The fact that he invented the 'closure interval' to cover up his other errors is also evidence. Not to mention his magnetic reversal fiasco. All Humphreys has shown (if he is right) is that there should be a sill value of He concentration in zircons, and that He diffusion MIGHT occur at a faster rate than previously thought. Any other conclusions are only the wishful thinking of a die-hard creationist attempting to bend the facts to fit a preconceived idea. You still have not made the case that this is a 'problem for evolution,' either. So, He diffuses faster than previously thought. Where does it diffuse to? Even Humphreys admits that some He stays in the zircon. Why is it too much? This whole argument makes no sense at all. Perhaps that is why you do not fully understand what Humphreys is saying.
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wehappyfew Inactive Member |
Thanks for looking that up for us, TB.
Now... sorry to be a bother, but we really must be quite careful with terms and numbers here. What you gave us is not enough. As edge pointed out, a diffusivity value is relevant only at a specified temperature. A range of 130-280C is sufficient to make diffusivity vary by a factor of about a MILLION. So when you quote 10^-15 to 10^-17 cm^2/s, is that for 130degC or 280degC ??? Please clarify what you mean by "extrapolated helium diffusion constant from the argon experimental one." Are you saying the helium diffusion number is extrapolated from [i][b]argon[/i][/b] diffusion values??? That makes no sense. You must have meant something else. Please help us poor confused skeptics. And when you said this...quote: Did you realize that you are comparing apples to oranges? Argon diffusion is usually measured in K-feldspar or biotite - never zircon. Zircon contans no potassium, therefore no argon to diffuse out. When you get the values and temps straight, would you be willing to go through the calculations with me, TB? But just as an amusing side-note in the mean time... ...if we take your numbers at face value... i.e. the diffusivity at 280degC = 10^-15 cm^2/s, and diffusivity at 130degC = 10^-17 cm^2/s... ...then use those numbers to calculate the Ea (activation energy) and Do... ...then use that to calculate closure temperature, then we arrive at the value Tc = 77K, which, in Celsius is... ...you guessed it... exactly minus 196 degrees C !!! Of course I am not claiming that Humphreys actually did this. Its just an amusing coincidence, right? Right???
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Tranquility Base Inactive Member |
In the RATE book, the extrapolated He diffusion constants in biotite are (as measured from Fig 7-7, p348):
10^-15 cm^2/s @ 280 C10^-17 cm^2/s @ 160 C Neither the experimental argon nor extrapolated helium change by 6 orders of magnitude over that temperature range.
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edge Member (Idle past 1732 days) Posts: 4696 From: Colorado, USA Joined: |
quote: Since we are now talking about biotite, what are the He rates (experimental and extrapolated) in biotite? I thought you also had experimental He diffusion rates, too. So how much do they vary? Also, you keep talking about 'extrapolated' data. Just how far is this data extrapolated? And where do the data come from? Are we talking the same kind of extrapolation that we see in the c-decay stories where they include 19th century measurements in the data set? TB, please remember that the RATE book is not the Third Testament. You have no real commitment to it. If you truly have a PhD and are truly interested in science, it is your duty to crtitcally analyze what this book says. For some reason, I think have not taken the time to do this.
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wehappyfew Inactive Member |
Thanks TB,
Diffusion in biotite is, of course, nearly irrelevant to this discussion, as Humphreys hinted in the Impact 352 article. I was hoping it had the zircon data in it, too. Anyway, with the correct temps and diffusivity, we can now calculate Tc for [b][i]biotite[/b][/i], just for practice. I get about 30 to 40 degC. How about you? Like edge, I am also worried about that word "extrapolated". Did you mean to say that? I thought RATE had experimental data? Finally, you said:"Neither the experimental argon nor extrapolated helium change by 6 orders of magnitude over that temperature range." Correct. But now you have switched to biotite, not zircon as I was originally discussing, and you changed 130 to 160degC. According to the experimentally measured diffusivity for zircon from Reiners(2002), the difference between 280 and 160degC would be about 20,000 times - for zircon. From ICR Impact352:quote: This certainly seems to imply that zircon data is already published in the RATE book. From the recent AIG spin piece:quote: So what are Humphreys' "experimentally" derived diffusivity constants for zircon? Do they really agree with Reiners(2002)? If they do, then we can just use what Reiners has already published on the web:http://www.geology.yale.edu/~reiners/zirconpaper040401.pdf What do you think, TB, would you like to apply Humphreys' calculations to Reiners' data? *note to edge: Humphreys' Tci equation is not made-up. He copied it from Wolf(1998) or independently derived it in a similar fashion. Either way, he should have given credit for it to Wolf (who called it the equilibrium age), and he uses it wrong (no surprise there, heh?).*
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