# How do we know the rate of decay for radiometric dating is constant?

http://www.purdue.edu/newsroom/research/2010/100830FischbachJenkinsDec.html

The link above talks about a research paper from Purdue University that the researchers had detected slight fluctuations in radioactive isotope decay rates and might affect how we uses radiometric dating. Young Earth creationists did used this to claim that radiometric dating is not accurate and that it is base on assumptions. https://www.discovercreation.org/blog/2012/10/26/80-years-of-scientific-fact-wrong-radioactive-decay-rates-not-constant/ Could the rate of radioactive decay be different in the past that today?

• the people that have posted the articles belive the earth is 6000 years old,i think it is clear for most people that this is slightly off when it comes to the age of the solar system.i think this question might be a duplicate but i have not yet been able to find it. – trond hansen Jul 9 '19 at 5:10
• Occam's Razor, for a simple explanation. We know quite a bit about nuclear physics &c. For decay rates to change significantly, without changing all the other things we observe, would require massively complicating the laws of physics. Since we have no evidence whatsoever that shows that decay rates do change, we keep the simple physics. Also, decay releases energy. If they changed significantly enough to make a 6000 year old Earth possible, the energy released would probably convert the Earth into a cloud of plasma. – jamesqf Jul 9 '19 at 5:29
• en.wikipedia.org/wiki/Radiometric_dating – trond hansen Jul 9 '19 at 9:05
• @jamesqf: In fact their 'theory' requires an extremely hot plasma (several 100 MK) to bring down the decay constants of some elements, as found by reputable laboratory studies. I'm just reading into some of this creation stuff, I may post later to pick apart their narrative. – AtmosphericPrisonEscape Jul 9 '19 at 19:51

First of all, you shouldn't take creationists seriously; like flat earthists, their views are totally out of touch with reality. Rates of radioactive decay have been tested many times in the laboratory and found to be accurate. However, there have been some instances where a substantial change of temperature or the formation of a chemical compound involving the radioactive isotope produces a small change in the rate of decay. When used for radiometric dating, this is not a source of error. The main source of error is the minuteness of the samples that labs have to work with. For example, only one potassium atom in 100 is potassium 40,the half life of which is I,300,000,000 years. In argon potassium dating the volcanic tuffs the lab has to analyse contain only a tiny amount of potassium 40,and only 11 percent of that decays to form argon 40 (the remainder forms calcium 40). The lab has to detect and measure the tiny trace of argon which has formed in the sample since it was emitted by a volcano a few million years ago.

Sometimes several dating methods are used on the same fossil or artefact, and if they are in rough agreement the dating is reliable. If you are looking for pin point accuracy, you won't get it with radiometric dating, but if accuracy to within a few percent is good enough, then that is usually achievable. The colossal orders-of-magnitude errors which creationists try to convince you of never happen.

Firstly, there are simplified analytical cases that even undergrad students are able to master that inform us how decay rates generally depend on other natural constants and available energy levels.

Those cases, while not describing full reality, give us important information, namely that if a decay constant would not be constant, then either other natural constants would also vary (which would be observed in many other experiments) or somehow the number of available decay energy levels changes based on exterior conditions.
The latter would mean, that effectively the only way a decay constant could change, is when it would depend on the atomic shell structure of the atom.

Well, it turns out that in some very special cases nuclear decay rates can be quite sensitive to their ionization state.

To quote the wikipedia on this

Rhenium-187 is another spectacular example. 187Re normally beta decays to 187Os with a half-life of 41.6 × $$10^9$$ years,[27] but studies using fully ionised 187Re atoms (bare nuclei) have found that this can decrease to only 33 years. This is attributed to "bound-state β− decay" of the fully ionised atom – the electron is emitted into the "K-shell" (1s atomic orbital), which cannot occur for neutral atoms in which all low-lying bound states are occupied.[28]

Those examples, while academically very interesting, do not impact the terrestrial radiometric dating methods because
1.) the elements used for dating do not show this variability in laboratory experiments
2.) no terrestrial extreme environment even existed where elements like 187Re could be fully ionized - the temperatures needed for that correspond to 100's of Million Kelvin!

What those creation websites do is say "because one element has some obscure conditions under which its decay constant is not constant, therefore all decay constants for all elements must be in doubt! (also God did it)", which is an obvious generalization fallacy, and a massive insult to the scores of physicists working on those topics.
The other insult to logic here that is happening is by cherrypicking the 176Lu->176Hf system and a temperature they like (and i'm quoting here from cration.com, creationist journal)

Thus, at 600 MK, the effective t½ of 176Lu is only about 8 days!11 This is short enough that if, as discussed earlier, all of the atoms in the universe had been created in a very hot state—which just means very high kinetic energies—(and maintained that way for several hours on the First Day), all the excess 176Hf in existence would have been generated within that short period.

to argue for a seven-day creation scenario.
To a layman this might seem convincing, hell, they even quote the reputable physics journals on those results! So the way they go is take actual science, and cherrypick from it until they find something that fits their narrative.

In the 'uniformitarian geologist'(sic) worldview, we do consider all available elements, all decay routes, and if those converge onto one single message, then this must be the truth. That's why cherrypicking is as unscientific as it gets.

• Just pointing out that there is some speculation by physicists that some fundamental constants actually might sloooowly change over time. Not enough of a difference to even remotely validate cretinism, however. – Spencer Jul 10 '19 at 17:44
• Well, according to the standard big bang theory, the universe WAS created in a very hot state. Like 10^32K hot :-) Unfortunately for the creationists, that means you don't even get hydrogen for about 400K years, stars come along 100-200 million years later. And a while after that, a few of them go supernova and start making things like 187Re. – jamesqf Jul 10 '19 at 18:13
• @jamesqf: Yeah, of course creationists also like to ignore how well cosmological and astrophysical timescales would play into terrestrial and biological ones. Another strong point of not ignoring all the evidence. – AtmosphericPrisonEscape Jul 11 '19 at 9:39