Variable decay rates

[flip]

I found this interesting, and reminds me of some of the inclinations I had when investiagting Neptunium.

http://phys.org/news202456660.html

[flip]

All I can say at this point, is if there is a 33 day variance in decay rates, Carbon dating is going to have some very skewed numbers. Which, if I'm also correct about Neptunium, that the reason they didn't find it is because it wasn't there, means that radioactive dating itself may be giving skewed numbers. Now, don't get me wrong, I'm still not a young-earth creationist. Although I've said before, given the atomic and electromagnetic nature of all things, it is entirely possible. I still see it against His nature. He likes to plant seeds and watch them grow. There is much more to consider though, besides just radioactive dating, but a 33 day variance over a long time will give some very large discrepancies.

EDIT: And the clues are always, always, in the discrepancies.

[Jeff250]

The fluctuations are "fractions of a percent," so adjusting 4 billion years by fractions of a percent isn't going to help young earth creationism. Also, I'd imagine that the fluctuations average out over time and that this is only an issue for time spans on the order of months or shorter.

[Tunnelcat]

There is a lot more evidence that can be used to point to a very old earth than just using carbon decay rates as an indicator. All one has to look at is the time it takes to bend and deform rock to make mountains, then add onto that the additional time it takes for wind and water to erode and expose it. That's also not counting the time it took for the thousands of feet of sedimentary layers necessary to create that rock from the silt deposition in some ancient sea bed either, rock that contains ancient life forms that no longer appear today. Plate tectonics took longer than thousands of years to create the continents we see today as well. Geologic time takes far longer than Biblical time I'm afraid. Man's time on earth is just a mere blip in time.

[Top Gun]

An interesting finding to be sure, but as the article notes, the fluctuation in rates amounts to mere fractions of a percent. If you're talking about dating, the most that could do is tweak a decimal point here or there. I'd love to read the paper myself, but of course it's behind a bull★■◆● journal paywall.

[Jeff250]

Also, I'd imagine that the fluctuations average out over time and that this is only an issue for time spans on the order of months or shorter.

Actually, since radioactive decay is exponential, I'm not sure if this part is *exactly* true.

[flip]

Well, it still has to be confirmed and more data for sure. I'm more interested in this unknown particle, and what all it could be responsible for . Other than that, we all still agree so far.

[Jeff250]

I'd love to read the paper myself, but of course it's behind a bull★■◆● journal paywall.

It looks like it's on arxiv:

http://arxiv.org/abs/1007.0924

[Top Gun]

Oh cool, I'd forgotten about arXiv. I'll have to give it a read.

[flip]

It would be great if we could capture a nuclear explosion within an optical vortex and see if we could trap any as of yet unknown particles but I don't see that happening.

[Sirius]

"Decay rates" are an approximation by their nature - they derive from the stability of a nucleus, or the likelihood that it will decay from one instant to another. Because there are so many atoms in any appreciable amount of matter, reality does tend to stick very close to theory, but for extremely tiny samples it's quite plausible to see some variance.

[flip]

Yeah, but decay rates are based on a constant half-life.

[Sirius]

The article abstract seems to be suggesting that there are ways to affect it past what would be allowed by random variation - which is interesting, although I'm not surprised the effects are still minor.

[flip]

Maybe locally the effects would seem minor, but if your trying to date something from a billion years ago with a constant half-life, your going to start running into huge discrepancies. You would have to allow for an 33 day increase and decrease cycle over that whole period. On top of that, the effect from the Sun over that 1 billion year cycle was more likely stronger then than it is now, considering the shrinkage rate of the Sun.

[Sirius]

I'm not going to speculate too much on the physics, but apparently the sun is actually slowly getting brighter with age - at the same time as it's getting lighter. So presumably the rate of fuel consumption is increasing.

[flip]

Yeah, I'm not sure yet, presumably the Sun was bigger back then so also closer, but I also don't think the visible portion of the spectrum is what's responsible.

[flip]

This argument comes from a paper published in 1979 by astronomer John Eddy. After studying observations from 1836 through the 20th century, he found the sun had contracted 2 arc seconds. He had found proof of what atronomers had suspected and know for a fact today: that the sun's diameter oscillates in an 80 year cycle. It does not constantly shrink.

Within the sun, and every star, there are 2 opposing forces: the intense gravity of the star, trying to crush it, and the intense heat of nuclear fusion, trying to blow it apart. As the gravitational field causes the surface to shrink ever so slightly, it builds incredible pressure inside the star, which speeds up the fusion reactions (think of a pressure cooker). The increased fusion then pushes the surface back out again, and the cycle starts over. Because the sun is truly gigantic, about 1 million times the size of Earth, this cycle plays out on what we would consider a slow scale: every 80 years.

If this checks out, add another variable over an 80 year cycle.

[snoopy]

Maybe someone can fill me in on this question that I have about carbon dating, and maybe generally radiometric dating: - apart from the variable decay rate that's brought up

The dating method is predicated upon everything starting with a standard C12 to C14 ratio when it dies, right? But, why do living things have a standard ratio, and what gives us confidence that it's always been that way? In other words: how do you differentiate between the current ratio being a product of decay and it being the product of a different starting point?

[flip]

I was thinking along the same lines last night Snoopy.

­The carbon-14 atoms that cosmic rays create combine with oxygen to form carbon dioxide, which plants absorb naturally and incorporate into plant fibers by photosynthesis. Animals and people eat plants and take in carbon-14 as well. The ratio of normal carbon (carbon-12) to carbon-14 in the air and in all living things at any given time is nearly constant. Maybe one in a trillion carbon atoms are carbon-14. The carbon-14 atoms are always decaying, but they are being replaced by new carbon-14 atoms at a constant rate. At this moment, your body has a certain percentage of carbon-14 atoms in it, and all living plants and animals have the same percentage.

This makes me wonder if this variance we see is simply the constant replenishment of C-14 we see through the atmosphere. I know it is supposedly only living things that feed upon this exchange, but curious if a little bit seeps back in to that which is decaying also.

EDIT: That was also my hesitation Snoopy when studying Neptunium. I in fact believe that radio-metric dating is the key to dating, but unfortunately, it was discovered how to do it after who knows how much atmospheric nuclear testing was done. Which is essentially what happens when cosmic rays hit the atmosphere, but instead done within the atmosphere. There's never going to be any empirical data comparison before and after.

The primary natural source of carbon-14 on Earth is cosmic ray action upon nitrogen in the atmosphere, and it is therefore a cosmogenic nuclide. However, open-air nuclear testing between 1955–1980 contributed to this pool.

The above-ground nuclear tests that occurred in several countries between 1955 and 1980 (see nuclear test list) dramatically increased the amount of carbon-14 in the atmosphere and subsequently in the biosphere; after the tests ended, the atmospheric concentration of the isotope began to decrease.

I imagine this decrease we observed was the biosphere taken in whatever amount needed to re-achieve balance.

[Top Gun]

Maybe someone can fill me in on this question that I have about carbon dating, and maybe generally radiometric dating: - apart from the variable decay rate that's brought up

The dating method is predicated upon everything starting with a standard C12 to C14 ratio when it dies, right? But, why do living things have a standard ratio, and what gives us confidence that it's always been that way? In other words: how do you differentiate between the current ratio being a product of decay and it being the product of a different starting point?

I was about to start in on this the other night when suffering from some ridiculous DST-induced insomnia (God I hate that concept), but I didn't get around to it until now. I'm gonna start out with a bit of background info, so bear with me if you already know that part.

Any type of atom with a certain specific amount of protons and neutrons, including different isotopes of the same elements, is what we call a nuclide. There are a few different ways in which all the nuclides we see on Earth were formed. Primordial nuclides are those that have been around since the Earth was created: either they're completely stable, or they're radioactive but have long enough half-lives that they can still be found in nature. (In either case, those would have been remnants of material present in the nebula from which the Solar System formed.) Other nuclides are called radiogenic; they form as the decay products of other radioactive nuclides, and can wind up being either stable or radioactive themselves. A third type are those formed by various natural nuclear reactions, such as naturally-occurring fission, or collisions with free neutrons. As flip helpfully pointed out, carbon-14 is formed via neutrons from cosmic rays bombarding nitrogen atoms in the atmosphere; it's called a cosmogenic nuclide as a result. (Fun fact: cosmic rays aren't "rays" at all, but instead extremely high-energy particles. It's a long story.)

So, on to the dating part. As flip said, the carbon-14 atoms produced by cosmic rays wind up forming carbon dioxide in the atmosphere. Just about every living organism on the planet (minus some freaky deep-sea thermal vent stuff) winds up incorporating atmospheric carbon into their bodies: plants absorb CO2, animals eat those plants, other animals eat those animals, humans eat just about everything, you get the idea. As a result, a small percentage of all the carbon atoms in our bodies (and we're made of a LOT of carbon) are the isotope carbon-14. Organisms keep incorporating new carbon-14 atoms as they live, by virtue of photosynthesis or eating stuff. However, at the instant an organism dies, it stops incorporating any carbon at all, including carbon-14, so it's left with whatever amount it had when it died. As time passes, those carbon-14 atoms start decaying, and so we can use the amount left to date how old the organic material is.

Now, you do have a point in that there's nothing saying that the rate of production of carbon-14 (and thus the starting ratio in organisms) has to be constant, and in fact it isn't: because the original production depends on cosmic ray activity, there are periodic fluctuations based on solar and geomagnetic cycles that would affect the production rate at any given time. The fortunate thing is that we can use tree rings to produce a sort of "calibration" for the levels: because trees have a "ring" for each year of new growth, we can take samples from very old wood and see how the remaining carbon-14 in them compares with the expected amount. (Apparently there's been recent work done in using stalagmites/stalactites in caves to push this calibration back even further, which is pretty wild.) There's also the fact that the natural carbon cycle means that different parts of the biosphere receive atmospheric carbon faster or slower than other parts: for example, since atmospheric carbon takes a very long time to cycle into the deep ocean, the baseline for organisms from there would have less carbon-14 than expected. There are some other more local variations that have to be taken into account, too: this section in the Wiki article contains an interesting list of them.

Now, flip is also right in saying that atmospheric nuclear testing in the 40s and 50s wound up artificially spewing a bunch of nuclides, including carbon-14, into the atmosphere, so any organism from after that time will have a higher-than-expected uptake of carbon-14; fortunately that's something we know about and can account for. However, where he gets it wrong is in assuming that that would affect older organic samples. Because organisms stop incorporating atmospheric carbon when they die, the more modern elevated levels of carbon-14 won't affect them at all. A random carbon-14 atom can't magically incorporate itself into the organic molecules of a deceased organism: it's completely external to that sample, and so couldn't affect it. The same would be true for any of the other nuclides released by nuclear testing; elevated neptunium levels in the atmosphere can't in any way affect the composition of a rock buried deep underground.

One last thing to keep in mind is that, because the half-life of carbon-14 is only a little over 5000 years, it can only be used with reasonable accuracy for dating objects going back to 50 or 60 thousand years ago. There are a number of other radioisotopes with far longer half-lives that are used to date much older material, such as geologic samples. Most of those would fall under the category of primordial nuclides, so they're fortunately not subject to the same variations in production rate that carbon-14 is, and so wouldn't require similar calibrations to correct their results.

There...thing that's everything I have for now.

[flip]

All that is correct TG, but that's not what im saying at all. You just described on C-14 is produced and then taken in. The article is talking about decay rates.

[snoopy]

Thanks TG,

Let me if I can summarize it correctly:

The starting point isn't constant, but....

By using things that have a characteristic aging pattern (I.E. tree rings that correspond to years) we can "calibrate" the starting point by time, locality and account for those variations.

[flip]

The point is, we are talking about decay rates in general, C-14 was just an example.

[Top Gun]

Thanks TG,

Let me if I can summarize it correctly:

The starting point isn't constant, but....

By using things that have a characteristic aging pattern (I.E. tree rings that correspond to years) we can "calibrate" the starting point by time, locality and account for those variations.

Yep, pretty much. With the tree rings, we can actually take samples from a ring corresponding to a certain year and look at the remaining C-14 directly. If the amount is a bit more or less than what would have been expected if C-14 formation rates were constant, it basically sends the message, "Oh hey, the rate of production that year varied a bit," and that can be taken into account when dating objects in general.

And yes flip, I'm aware of that. I was answering snoopy's question, not addressing the original topic.

[flip]

Ok, I just wanted make sure we were talking about decay rates in general, then carbon-dating specifically. We have not even touched on other methods of radio-active dating yet.

[snoopy]

Ok, I just wanted make sure we were talking about decay rates in general, then carbon-dating specifically. We have not even touched on other methods of radio-active dating yet.

The tree-ring-calibration technique would also apply generally to variable decay rates, too...

If I have a set of tree rings that I know are 0-100 years old, I can calibrate for 0-100 regardless of starting point or variation of decay rate.... as long as the starting point and decay rate of the measurand matches that of the calibration standard.

[flip]

Yes, as far as carbon-dating goes, but the increase of C-14 is just another variable in this discussion. Are tree rings distinct enough to account for a 33 day cycle spread over an 80 year cycle too? Those are just 3 variables affecting the outcome, there are more.

[vision]

I love how all of you religious folk try to interject uncertainty into well tested methods yet have no doubt about your own personal beliefs. Try turning your skepticism on yourself for a change. That's what a good skeptic does (the opposite of a dogmatist).

[flip]

You have a hard time being impartial and objective I see. No one has brought religion into this thread except you. Why is it that the people who always derail the threads can't see that they are responsible. If you wanna talk religion, E&C is for that