Nuclear Decay May Vary With Earth-Sun Distance

KentuckyFC writes "We've long thought that nuclear decay rates are constant regardless of ambient conditions (except in a few special cases where beta decay can be influenced by powerful electric fields). So that makes it hard to explain two puzzling experiments from the 1980s that found periodic variations over many years in the decay rates of silicon-32 and radium-226. Now a new analysis of the raw data says that changes in the decay rate are synchronized with each other and with Earth's distance from the sun. The physicists behind this work offer two theories to explain why this might be happening (abstract). First, some theorists think the sun produces a field that changes the value of the fine structure constant on Earth as its distance from the sun varies. That would certainly affect the rate of nuclear decay. Another idea is that the effect is caused by some kind of interaction with the neutrino flux from the sun's interior which also varies with distance. Take your pick. What makes the whole story even more intriguing is that for years physicists have disagreed over the decay rates of several isotopes such as titanium-44, silicon-32, and cesium-137. Perhaps they took their data at different times of the year?"

Carbon Dating

[Jaysyn (203771)]

Does this have any ramifications for carbon dating?

Re:Carbon Dating

[by Anonymous Coward]

Yes, you can now only date graphite. Diamonds are no longer acceptable dating material.

Re:Carbon Dating

[Vectronic (1221470)]

I dated graphite once, she wasnt very original, kinda flaky, and left dark marks on me... Diamonds, is still playing hard to get though...

Re:Carbon Dating

[The Standard Deviant (869317)]

I take it you don't play with bucky balls then!

Re:Carbon Dating

[mcvos (645701)]

Diamonds are generally best friends, not dating material.

Re:Carbon Dating

[necro81 (917438)]

I get your joke, but it presents an opening to state the following little known fact:

Diamonds are not, in fact, forever

Under normal temperature and pressure conditions, diamond is not the most stable form of carbon - graphite is. Using thermodynamic arguments and building a free energy curve, one can show that some fraction of a diamond must decay to graphite in order to achieve a minimum energy state. It does take a very long time for this to happen - geologic time - but even a "long time" is not forever. If you aren't that patient, heat the diamond up to, say, 1500 C to speed things up. Oh, but be sure to do that in the absence of oxygen, because diamond burns just like other forms of carbon.

Some references: [1] [uoguelph.ca], [2] [everything2.com], [3] [wikipedia.org]

openings for little known facts

[BitterAndDrunk (799378)]

Are the reasons your extensive diamond knowledge will never come in handy.

Re:Carbon Dating

[meringuoid (568297)]

I'd expect not. The variation would be over the course of a year, and carbon dating works on a timescale of centuries to millennia; it would even out. Besides that, we have other clocks to calibrate carbon dating against; you can carbon-date a historic artefact of known age, you can count tree rings or ice layers, stuff like that.

On a timescale of billions of years, however, the luminosity of the Sun has increased substantially, and if that accelerates radioactive decays by some neutrino interaction then the uranium-lead clock would be off and the Earth might be considerably older than we thought.

Re:Carbon Dating

[kmac06 (608921)]

Probably not. The change in decay rate was on the order of .1% (see Fig. 1 of the paper), which is I believe smaller than the error in carbon (or other radioactive) dating. Also, it is only these two isotopes that are mentioned, presumably because most other isotopes tested do not have this sort of periodic effect.

Re:Carbon Dating

[kmac06 (608921)]

Also, it is only these two isotopes that are mentioned, presumably because most other isotopes tested do not have this sort of periodic effect.

I stand corrected! From the paper:

Although there are hundreds of potentially useful nuclides whose half-lives have been measured, the data from many of the experiments we examined were generally not useful, most often because data were not acquired continuously over sufficiently long time periods.

So the possible ramifications of this increase!

Re:Carbon Dating

[Bob-taro (996889)]

Also, it is only these two isotopes that are mentioned, presumably because most other isotopes tested do not have this sort of periodic effect.

I wouldn't presume that. The very thing that makes this so interesting is that "the modulations are synchronised with each other and with Earth's distance from the sun." To me, that makes it likely to be a general effect on all radioactive materials. I don't know if this will lead to anything that supports a young earth theory, but it'll be interesting to see what comes from it. The article also mentions:

It turns out, that the notion of that nuclear decay rates are constant has been under attack for some time. In 2006, Jenkins says the decay rate of manganese-54 in their lab decreased dramtically during a solar flare on 13 December.

This is a good example of how many holes there might be in our theories about the universe. We have been making measurements for a few 1000 years in one solar system (mostly just on one planet) and things that we don't see changing, like radioactive decay rates, we consider constant. It's exciting to think how much more there may still be to discover.

Re:Carbon Dating

[clickety6 (141178)]

Yes - but not enough to account for the difference between Joan Rivers' apparent and actual age.

Seriously : No

[DrYak (748999)]

Does this have any ramifications for carbon dating?

Seriously : No.
For 2 reasons.

I. - Effect on carbon
For now carbon isn't on the list of the elements that seem affected by the distance to the sun.

II. - Not a significant variation.
in TFA, variation seem to be very well correlated with the distance *BUT* these variations are really small : only a small fraction of percent (~0.15%). To cite one of the commenters on TFA's blog thread :

That said, itâ(TM)s not *terribly* unsettling to me; the variations are small (measurable,but small) and to me itâ(TM)s all part of the Wonderful World of the Weird that is QM.

If we discover that carbon is among the elements influenced by the sun too, those mere ~0.15% of variation will be insignificant compared to the skew that happens with varying concentration of carbon-14 in the atmosphere [wikipedia.org] (see wikipedia's graph of variation) - which already requires that we do calibrations anyway.
(Current carbon dating doesn't extrapolate the age purely by deducing the levels from the decay rate, but instead uses tables where corrections have been inserted based on the carbon dating of thing with known age)

So in short : for now it doesn't have any ramification and anyway it couldn't have any more than we already compensate for.

Re:Carbon Dating

[Watson Ladd (955755)]

Actually a cesium clock uses the hyperfine structure which is not known to be affected these effects.

Re:Carbon Dating

[paeanblack (191171)]

I am more concerned about the other end of that - time-keeping --- the communications networks get their time hacks from clocks based upon the decay rate of isotopes (e.g. a cesium clock).

Caesium clocks have nothing to do with nuclear decay rates. They measure electron state transition times. You can relax now.

Re:Carbon Dating

[kmac06 (608921)]

You bring up a good point.

The communications networks get their time hacks from clocks based upon the decay rate of isotopes (e.g. a cesium clock).

It's actually based on the frequency of a transition in cesium, but the point is that these transitions are sensitive to the fine structure constant. If some field from the sun is changing that, it should be detectable in atomic clocks.

How To Test It

[eldavojohn (898314)]

First, some theorists think the sun produces a field that changes the value of the fine structure constant on Earth as its distance from the sun varies. That would certainly affect the rate of nuclear decay. Another idea is that the effect is caused by some kind of interaction with the neutrino flux from the sun's interior which also varies with distance. Take your pick.

You left out the best part of the paper, where they propose how to test these theories:

These conclusions can be tested in a number of ways. In addition to repeating long-term decay measurements on Earth, measurements on radioactive samples carried aboard spacecraft to other planets would be very useful since the sample-Sun distance would then vary over a much wider range. The neutrino flux hypothesis might also be tested using samples placed in the neutrino flux produced by nuclear reactors.

Sounds like we could test the latter relatively easily.

Also, Jeeeeeeeeeeeeeeeeeere H. Jenkins!!!

Re:How To Test It

[Watson Ladd (955755)]

Actually the more radioactive something is the faster it decays. Uranium in waste is not the problem, the minor actinides are.

Cool!

[kmac06 (608921)]

If this turns out to be true, and not a product of some experimental error, it sounds like it could lead to some very interesting new theories. If it's due to neutrino flux, that indicates neutrinos interact much more strongly than previously thought.

Two counter-examples

[Wills (242929)]

We've long thought that nuclear decay rates are constant regardless of ambient conditions (except in a few special cases where beta decay can be influenced by powerful electric fields).

If you count the presence or absence of observation as part of "ambient conditions", there are two cases where nuclear decay rates are affected by ambient conditions: The quantum Zeno effect [wikipedia.org] and the quantum anti-Zeno effect. [wikipedia.org]

It's a trick!

[NuclearError (1256172)]

They are just trying to force me to buy new updated nuclear engineering text books. I won't fall for it!

Phlogiston

[Migraineman (632203)]

It's the Phlogiston, [wikipedia.org] released by the central furnace of the sun. Doesn't seem quite so funny now, does it Pinkerton?

Now if you'll excuse me, I have an appointment with my Phrenologist.

Fine structure constant

[kmac06 (608921)]

One possible explanation proposed in this paper is:

In their theory, the Sun produces a scalar field which would modulate the terrestrial value of the electromagnetic fine structure constant EM.

The fine structure constant [wikipedia.org] (about 1/137) has been measured to a whopping 10 significant digits, one of the most precisely measure physical constants. If there is a seasonal variation enough to influence decay rates by .1%, wouldn't this show up in different experiments measuring the fine structure constant?

Re:Fine structure constant

[Watson Ladd (955755)]

They mention that in the paper. They suggest modifying the electron-proton mass ratio as well as the electromagnetic interaction strength. So we might find out what's going on on October 10.

But the data is awful

[Geoffrey.landis (926948)]

But... look at the data [arxivblog.com]. That correlation is *terrible*. The phase is off.

Also, note that since the perihelion is right around Jan 1, only about eleven days after solstace-- this data equally well correlates with season.