Rate of decay remains constant

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Rate of decay remains constant

#1  Postby z8000783 » Aug 24, 2011 6:54 am

I know we have been over this many times but I am just having a conversation with someone who has quoted this to backup up his 6000 year old creation myth.

It's on FB so I don't want to post screeds of stuff but I have forgotten the key points. I know we normally say we have not observed a change in rate but if it happened over long time periods doing an experiment over 3 weeks or even 50 years would not highlight it.

What would have to happen to the numbers to make it fit a young Earth scenario and what would be the implications if it did.

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Re: Rate of decay remains constant

#2  Postby 95Theses » Aug 24, 2011 7:02 am

Response:

The constancy of radioactive decay is not an assumption, but is supported by evidence:

The radioactive decay rates of nuclides used in radiometric dating have not been observed to vary since their rates were directly measurable, at least within limits of accuracy. This is despite experiments that attempt to change decay rates (Emery 1972). Extreme pressure can cause electron-capture decay rates to increase slightly (less than 0.2 percent), but the change is small enough that it has no detectable effect on dates.

Supernovae are known to produce a large quantity of radioactive isotopes (Nomoto et al. 1997a, 1997b; Thielemann et al. 1998). These isotopes produce gamma rays with frequencies and fading rates that are predictable according to present decay rates. These predictions hold for supernova SN1987A, which is 169,000 light-years away (Knödlseder 2000). Therefore, radioactive decay rates were not significantly different 169,000 years ago. Present decay rates are likewise consistent with observations of the gamma rays and fading rates of supernova SN1991T, which is sixty million light-years away (Prantzos 1999), and with fading rate observations of supernovae billions of light-years away (Perlmutter et al. 1998).

The Oklo reactor was the site of a natural nuclear reaction 1,800 million years ago. The fine structure constant affects neutron capture rates, which can be measured from the reactor's products. These measurements show no detectable change in the fine structure constant and neutron capture for almost two billion years (Fujii et al. 2000; Shlyakhter 1976).

Radioactive decay at a rate fast enough to permit a young earth would have produced enough heat to melt the earth (Meert 2002).

Different radioisotopes decay in different ways. It is unlikely that a variable rate would affect all the different mechanisms in the same way and to the same extent. Yet different radiometric dating techniques give consistent dates. Furthermore, radiometric dating techniques are consistent with other dating techniques, such as dendrochronology, ice core dating, and historical records (e.g., Renne et al. 1997).

The half-lives of radioisotopes can be predicted from first principles through quantum mechanics. Any variation would have to come from changes to fundamental constants. According to the calculations that accurately predict half-lives, any change in fundamental constants would affect decay rates of different elements disproportionally, even when the elements decay by the same mechanism (Greenlees 2000; Krane 1987).


http://www.talkorigins.org/indexcc/CF/CF210.html

But essentially you are fucked trying to argue with a nutter who can just say 'But then my magic man did some magic'
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Re: Rate of decay remains constant

#3  Postby z8000783 » Aug 24, 2011 7:58 am

Thanks.

No problem though, if I can't prove him wrong then I am happy to point out that he is simply setting the conditions to show that the God hypotheses works. In any case case there are usually implications which kills the argument like this:
Radioactive decay at a rate fast enough to permit a young earth would have produced enough heat to melt the earth (Meert 2002).

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Re: Rate of decay remains constant

#4  Postby 95Theses » Aug 24, 2011 8:33 am

Indeed, but I don't know where he goes from 'Here is some evidence that decay rates were the same 1.8 Billion Years ago' when he thinks the universe is 6,000 years old except for 'My magic man did some magic'
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Re: Rate of decay remains constant

#5  Postby z8000783 » Aug 24, 2011 8:50 am

That's always a killer. I normally go back to source at that point since it all comes from the Bible. Bart Ehrman and Francesca Stavrakopoulou have done excellent work show how the Bible came about.

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Re: Rate of decay remains constant

#6  Postby Calilasseia » Aug 24, 2011 11:31 am

Actually, if this individual is trying to use the "accelerated decay" nonsense erected by Russell Humphreys and the RATEtards, then the amount of heat dumped into the planet by speeding up U238 decay to the point where it would fit the mythical "universe is only 6,000 years old" fairy tale, would do more than just melt the planet - it would raise temperatures at the core to the point where helium fusion became possible. The planet would become a very short-lived dwarf nova. I'd like to see a wooden barge survive that.

Plus, strictly speaking, decay rates over the long term aren't 'constant', they obey an exponential decay law. Which I've expounded upon in complete detail in another thread. However, because the decay law in question is mathematically precise when dealing with large numbers of atoms (and even a rock sample containing 0.01% U238 contains trillions of atoms of Uranium, courtesy of that well known constant named after Avogadro), we're able to use radionuclide decay as an atomic clock over geological time, by appropriate application of that mathematically precise law.

As for electron capture, well, the problem facing mythology fetishists is quite simply this. In the case of an isotope such as Re187, it is possible to alter the rate of electron capture slightly by ionising the atoms. However, in order to exert a measurable effect upon electron capture decay rates in Re187, you have to strip away 74 of its 75 electrons, and create the Re74+ ion. Now, one of the basic rules of physics, with respect to ionisation, is that the amount of energy required to remove an additional electron increases with each new electron you wish to remove. Whilst it may only take a small amount of energy to remove the first electron from a neutral atom, the result is a positively charged ion, and removal of the second electron requires more energy to overcome the net positive charge of the ion that binds the remaining electrons more tightly. As you remove each successive electron, you increase the positive charge of the ion, and increase the amount of energy needed to overcome the increasingly strong electrostatic force binding the remaining electrons to the atom. Consequently, it takes a lot of energy to remove 74 electrons from a single Rhenium atom. The usual means of producing highly ionised atoms in nature is the mechanism seen in stars - heat them up to a high temperature. To produce Re74+ ions, however, that temperature has to be very high indeed - high enough for the substance to be a plasma. If you run the numbers, you end up needing a temperature of around 65,000 Kelvins. This isn't going to occur on Earth unless some truly remarkable processes are unleashed. Even if some magic process occurs that produces these highly ionised atoms without turning the entire planet into a plasma, the resulting contraction of half-life is way smaller than the several orders of magnitude needed to be consistent with creationist fantasies.

And, of course, the above mechanism is only valid for electron capture. It doesn't affect U238 or other alpha-decaying radionuclides. Whose half-lives remain resolutely unaffected by physical state, as data from supernovae and the Oklo natural nuclear reactor clearly demonstrate. Plus, we have other experiments determining that the fine-structure constant, which has an impact upon radionuclide decay rates, has remained precisely that - a constant. Any variation in that constant has been empirically determined to be less than 10-8, which again is way too small to be of use to support the myth that the entire universe is only 6,000 years old. Indeed, some experiments suggest that the upper bound for variation of α is as low as 10-15, which is entirely consistent with a 13.6 billion year old universe, and wholly inconsistent with a universe only 6,000 years old.

All of which leaves creationists with no other recourse but to play duplicitous apologetics with science.
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Re: Rate of decay remains constant

#7  Postby Sovereign » Aug 24, 2011 12:17 pm

Hey Calilasseia, I did have one person try to use a recent event as proof decay rates change. The person claimed that there is something in the sun we don't know about that changes the decay rates of materials and that whatever it was, affected the Earth in a way to make it look billions of years old(the rates of change were so miniscule that billions would still be billions imo). I'm going off of memory and I lost the link they sent me but what the link showed was that two labs did have a slight change in the decay rates of (I forgot which ones specifically) certain isotopes before a solar event. I don't know if you know about that article, I will try to find it as I meant to post it awhile back but got busy and forgot, but was the article a fake, the lab results a fluke, or do certain isotopes have a very miniscule change in decay rates preceding solar events due to an unknown mechanism?
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Re: Rate of decay remains constant

#8  Postby Calilasseia » Aug 24, 2011 12:43 pm

Ah, this would be the paper that claims decay rates undergo fluctuations in accordance with solar neutrino flux. The trouble being of course that again, any such fluctuations are extremely small. The neutrino flux required to make a significant change, even if this hypothesis is valid, would equivalent to the simultaneous output of several billion simultaneously detonating supernovae all concentrated on our small planet, and somehow, I think that isn't going to happen.
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Re: Rate of decay remains constant

#9  Postby Rumraket » Aug 26, 2011 4:05 pm

Sovereign wrote:Hey Calilasseia, I did have one person try to use a recent event as proof decay rates change. The person claimed that there is something in the sun we don't know about that changes the decay rates of materials and that whatever it was, affected the Earth in a way to make it look billions of years old(the rates of change were so miniscule that billions would still be billions imo). I'm going off of memory and I lost the link they sent me but what the link showed was that two labs did have a slight change in the decay rates of (I forgot which ones specifically) certain isotopes before a solar event. I don't know if you know about that article, I will try to find it as I meant to post it awhile back but got busy and forgot, but was the article a fake, the lab results a fluke, or do certain isotopes have a very miniscule change in decay rates preceding solar events due to an unknown mechanism?

The study done on the changing decay rates in response to seasonal changes or solar output is highly doubted in the scientific community. One of the reasons is that other studies have shown similar seasonal changes in decay rates, but they managed to track the "source" of the seasonal variations to seasonal changes in the performance of the measuring equipment, not to some external factor actually affecting decay-rates. It would seem a lot more likely that the measuring equipment is subject to seasonal and periodic changes in local atmospheric conditions, than the sun by some hitherto undetected and unknown force of nature can seasonally manipulate the fundamental constants of nature and change decay rates of isotopes locked in lead-chambers over 150 million kilometers away. And in any case, these variations are miniscule.
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Re: Rate of decay remains constant

#10  Postby susu.exp » Aug 26, 2011 11:28 pm

Calilasseia wrote:Plus, strictly speaking, decay rates over the long term aren't 'constant', they obey an exponential decay law.


Strictly speaking that´s wrong. Rates are expected numbers per unit time (wiki says probabilities, but that´s merely the special case where the random variable is an index function of an event). If you have a process where events occur both continuously and with a constant rate, then the waiting time between two events follows an exponential distribution and so does the waiting time for the first event from an arbitrary starting time. The activity of a particular ammount of radioactive material follows an exponential decay law, because in this case we are looking at the waiting times for the first events (decays) and these are exponentially distributed. This then leads to an exponentially decreasing number of expected decays per unit time and if the ammount of the substance is high the law of large number provides an approximately deterministic law.
You seem to mix up the decay rate with the expected activity and the observed activity there.
Note: Rates are often not constant in similar processes. An example are mutation and fixation rates for substitutions used in molecular clock estimates for divergence dates. That´s why they have to be callibrated using fossils and preferably a lot of them - this allows you to track the way these rates have changed over time and thus calculate divergence dates.
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