Do nuclear decay rates depend on our distance from the sun?


Here’s an interesting conundrum involving nuclear decay rates.

We think that the decay rates of elements are constant regardless of the 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 the curious periodic variations in the decay rates of silicon-32 and radium-226 observed by groups at the Brookhaven National Labs in the US and at the Physikalisch-Technische Bundesandstalt in Germany in the 1980s.

Today, the story gets even more puzzling. Jere Jenkins and pals at Purdue University in Indiana have re-analysed the raw data from these experiments and say that the modulations are synchronised with each other and with Earth’s distance from the sun. (Both groups, in acts of selfless dedication,  measured the decay rates of silicon-32 and radium-226 over a period of many years.)

In other words, there appears to be an annual variation in the decay rates of these elements.

Jenkins and co put forward two theories to explain why this might be happening.

First,  they say a theory developed by John Barrow at the University of Cambridge in the UK and Douglas Shaw at the University of London, suggests that the sun produces a field that changes the value of the fine structure constant on Earth as its distance from the sun varies during each orbit. Such an effect would certainly cause the kind of an annual variation in decay rates that Jenkins and co highlight.

Another idea is that the effect is caused by some kind of interaction with the neutrino flux from the sun’s interior, which could be tested by carrying out the measurements close to a nuclear reactor (which would generate its own powerful neutrino flux).

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.

And numerous groups disagree over the decay rate for elements such as titanium-44, silicon-32 and cesium-137. Perhaps they took their data at different times of the year.

Keep em peeled beause we could hear more about this. Interesting stuff.

Ref: Evidence for Correlations Between Nuclear Decay Rates and Earth-Sun Distance

81 Responses to “Do nuclear decay rates depend on our distance from the sun?”

  1. Kestas says:

    That is a pretty unsettling thought.

  2. Rebel Dreams says:

    It’s only a matter of time before fundies grasp onto this strw in the hopes of bolstering YEC.

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

  3. Rebel Dreams says:


    …here’s a more unsettling thought for you — when the page refreshed, the ad on the right-hand side of the page was for a book claiming to link “Null Physics” and “modern cosmology”. I thought this was a science blog? >:(

  4. Tom says:

    May this in any way affect how many scientists date the earth and materials found from past societies? (a link to another info article may suffice, I am actually curious and thought this to be a good place to ask.)

  5. But… look at the data. The correlation is *terrible*. The phase is off.

    Since the perihelion is right around Jan 1, by the way, this data equally well correlates with season.

  6. Vernon Nemitz says:

    The best thing about this is the possibility of eventually being able to deliberately speed up decay rates of, for example, nuclear waste. It can then become a significant energy source, while it lasts (and the long-term storage problem is eliminated).

  7. gransee says:

    I hope this interests further research. It would be handy to control the decay rate of radioactive material. This could be used to more efficiently throttle reactors (instead of just soaking up part of the energy in graphite), converting current waste to useful energy and use radioactive materials that are normally fairly safe and cheap for sources of high energy.

  8. Elizabeth says:

    To Mr. Landis’s comment:

    Yes, the correlation isn’t a great fit, but it is clear that the trending is consistent. In fact, it appears as though there is a time lag associated with fluctuations, which is quite interesting in and of itself. However, as others have already pointed out, the scale is quite small. Thankfully it is measurable, but indeed very small. I would be curious to see similar studies done on Carbon-14 and other isotopes which are closely related to organic matter radiocarbon dating.

  9. Marshall says:

    Looks like a 90 deg phase shift to me. Wonder if it is actually correlated with the direction of the velocity vector (i.e., could this be a violation of the principal of equivalence ?).

    But, how can this be real ? The Earth’s eccentricity is only a few per cent. The fluctuations are a few tenths of a per cent. Assume that the effect depends on the square of the variation in the potential (or on some coupling constant of order 1/10 x the variation in the potential). We sent radioactive isotope spacecraft to Mars (Viking Landers) and into deep space (Pioneer, Voyager, Cassini, etc.). Wouldn’t all of these have seen an anomalous INCREASE in their power output (which is tracked closely) of order 50% ? Wouldn’t the radioactive decay of Nickel seen in supernovae also show gross anomalies (as the decaying nickel gets further away from central star) ? Likewise, as they themselves say in the article, the fine structure constant has been tested astrophysically to better than the variation they need to explain this.

    Somebody should try and construct a very small test of this (a few milligrams of radioactive material, a counter or thermocouple of some sort, should be possible to do it in a few 100 grams in all) for inclusion in, say, the upcoming Russian Phobos mission. It would be a neat spaceborne test, even if it is unlikely to be real.

    Anyone want to get a pool on how long it takes for the first paper connecting this to the Pioneer anomaly ? I would put down for a week.

  10. Arthur says:

    It may be worthwhile to note that while the sun produces a nearly-pure flux of neutrinos, nuclear reactors produce mostly antineutrinos. Depending on what nuclear interactions the neutrinos are thought to stimulate in these nuclei, a reactor antineutrino flux may not produce a similar effect.

  11. AnonyMoose says:

    “Since the perihelion is right around Jan 1, by the way, this data equally well correlates with season.”

    It probably correlates well with the summer decrease in carbon dioxide in the northern hemisphere, due to the growing season. But the Mauna Loa carbon dioxide levels have been increasing, so if CO2 is relevant the decay rates should slightly increase. Well, at least it is a lot easier to introduce CO2 to the experiment than neutrinos.

  12. AnonyMoose says:

    Oops. Forgot some other things which vary with the seasons: temperature, daylight (relevant to photons and the amount of mass between the experiment and the Sun), angle to the flow of the interstellar medium.

  13. dropout scientist says:

    I am wondering if this is’nt nuclear proof of time travel ie, like the twin astronaut who came back from a shuttle mission a tiny fraction older than his twin

  14. Alexis says:

    Is it possible that the equipment used to make the measurements in the 1960s was subject to annual fluctuation in performance?

  15. Lawrence says:

    I’m reminded of the annual variation in the DAMA/Nal experiment (proposed explanation: dark matter detection); any similarities in detection apparatus?

  16. MarkusQ says:

    Thomas –

    That Google trends link is worthless; it just shows that the two terms “Nuclear Decay” and “Distance Of Earth From Sun” have used by people on google for years. It doesn’t indicate that they were used at the same time, or even by the same people. So the graph doesn’t tell us anything one way or another.


  17. Maxwell Lamb says:

    Well… I’d actually say the better question is, what timeframe are they using as their reference for this? It’d make more sense that their clock is slowing and speeding due to relativistic effects caused by the variation in the earth’s velocity as it approaches and recedes from the sun, and how far we are into the gravity well.

  18. Nabal says:

    Rebel Dreams: In the words of Phillip Johnson, “Are you willing to follow the evidence wherever it leads?” Why are you worried that the evidence may support YEC? Is this not objective science? Should not the chips fall where they may?

  19. Crito says:

    “It’d make more sense that their clock is slowing and speeding due to relativistic effects caused by the variation in the earth’s velocity as it approaches and recedes from the sun, and how far we are into the gravity well.”


  20. Arthur says:

    “It’d make more sense that their clock is slowing and speeding due to relativistic effects caused by the variation in the earth’s velocity as it approaches and recedes from the sun, and how far we are into the gravity well.”

    No, this would not be the case. There would have to be significant movement in the separation between the sample and the experiment’s timing apparatus for the gravitational well to have any effect. I’m betting they were in the same building of a laboratory. Also, since the timing device and the sample are both in the same inertial frame (no apparent motion between them) changes in the Earth’s velocity would have no measurable effect on how the clocks run.

  21. Evan says:

    Well, here’s a thought. Ever wonder whether our historical perception of time could be warped? What if scientists controlled the “dates” for every significiant thing in history. What if everything is wrong, and lucy is really 5 millions years old and not a few hundred thousand years?

    Why do we not know what happened to civilization before the ice age?

    I think controlling time and history is a big giant conspiracy.

  22. a'Akova says:

    Maxwell Lamb and Crito: A clock only measures the rate at which things happen. If the clock slows down, all other processes in the vicinity (same gravitational well) of the clock will as well.

  23. Believer says:

    Astrology is vindicated !

  24. Jay says:

    more likely their equipment is sensitive to electric fields and distance to sun

  25. Martin says:

    If the cause is a chance in the value of the fine structure constant: does this have any effect on hyperfine transitions? If so, our definition of time is in trouble, too (IMHO).

  26. George William Herbert says:

    It would be very useful to see the raw data and more about the experimental methods used.

    The BNL methodology was reported to be regular calibration comparisons of the 32Si sample with a 36Cl source assumed to be constant (order 1E-5 variation due to decay over the 4 year test). However, systematic background variations might be significant compared to the relative 32Si and 36Cl decay rates. If absolute count rates varied much seasonally (due to atmospheric gases, different ventilation changing radon buildup in lab, whatever) then that’s a credible source of experimental bias towards this type of result.

    One could easily engineer a test to take some of these effects out of play – put a set of test samples and a detector into a vaccum chamber with good shielding against background decay and cosmic rays, and test over time. Best location might be down one of the mines that are being used for neutrino detectors, to eliminate GCR time variation and most near-surface effects…

  27. Cletus says:

    Does this have any effect on atomic clocks? And if so, does this not jeopardize any measurements based thereon?

  28. Richard Kirk says:

    A cautionary tale: people used to believe that your colour resolution varied with the seasons. This was tested by matching a yellow light using a mixture of red and green in something called a Nagel anomaloscope. This seemed to go up and down – not by very much but enough to be checked on a yearly basis. In fact, the problem was the change of temperature of a few degrees in the room where the measurements were taken ws enough to alter the dispertion of the glass in the instrument.

  29. ifatree says:

    @Martin: our definition of time has been in trouble since Einstein and is still evolving. [E8] symmetries, transactional interpretation of QM, etc… even if none of them are “right”, they show that physics is unsatisfied with a single-valued, constant “time”. it’s past time to move on, we just haven’t figured out where (or should I say when?) to move toward…

  30. Jim Van Zandt says:

    1) The phase difference suggests to me that the source is not the sun. Did they estimate the period of the fluctuation? A period slightly greater than a year would suggest one of the outer planets. Otherwise the source could be outside the solar system, and the phase suggests which direction. 2)If this were neutrino induced decay, wouldn’t it imply a pretty large cross section for a neutrino interaction? 3) Did they look for a daily variation, as might be due to the earth shielding out an effect of the sun? That shouldn’t work for neutrinos, but see (2). (But surely a daily variation would have been noticed by now.)

  31. geoff says:

    Some very interesting ideas here – good thinking all round. I like the relativistic shifting idea, but that shouldn’t be relevant at a guess – the samples and clocks are both in the same inertial reference frame (ie the clocks will be affected in exactly the same way as the dacay, cancelling out).

    The first thing we need however, is a few independent confirmations of the experiments…when I was at high school we measured half lives of various isotopes….get a bunch of schools all over the world doing the same and you should get a big enough sample to pick up deviations of the order suggested. And it’s a great school grade experiment to get people into science, presuming schools are still allowed to play with radioactive samples.

  32. Diggers says:

    Marshal: haven’t read article yet or looked at specific isotopes, but look into the mechanism of decay for the ones they examine and the ones used to power the satellite booms. Perhaps only one decay pathway is influenced

  33. OnceAPhysicist says:

    Why do they mention 2 crazy theories, but ignore gamma ray perturbation? Gamma rays are a standard part of nuclear interactions, the amount of gamma rays we receive varies with our distance from the sun. This to me seems the most logical explanation.

  34. [...] dating? Tag: Science — doug @ 11:38 pm I’m grateful to Nick Knisely for a link to this story. The trends reported suggest that there is a seasonal variation to nuclear decay which is being [...]

  35. hithere says:

    I wonder if this supports Young Earth whatever C stands for.


  36. The implications are hairy for archaeologists. If carbon-14 decay and/or production are affected by neutrino flux, all dates prior to commencement of the current cooling period of the Sun’s core are labeled wrong.

  37. John Brawley says:

    I say Bingo.
    My first thought was to exactly that: the variation of solar gravitational field intensity during the year. This implies that spacecraft near earth (we don’t have to put the test on a Marscraft) could be employed to test whether gravity is the cause of the variation.
    (Maybe even a good mountain-climb, up, down, up, down, etc., could also show it?)

  38. Bruce says:

    Nabal: “In the words of Phillip Johnson, “Are you willing to follow the evidence wherever it leads?” Why are you worried that the evidence may support YEC? Is this not objective science? Should not the chips fall where they may?

    Sorry Nabal, but YECs will have to keep fishing – this article does you no good.

    First, the variations being talked about are about 0.3%. So instead of the earth being 4.5 billion years old, it would be 4.48 billion years old. Big deal.

    Second, if you look at the article, the rate is slowing down for half the cycle, and speeding up for half the cycle. Net effect: zero over one cycle.

    When are YECs going to start letting the “chips fall where they may?” Yeah, right.

  39. Nabal says:

    Bruce: Thanks for the reply. Please explain 4.5 billion year age going to 4.48 billion. If we don’t know what is causing this, how can we make any calculations? Wouldn’t the age of the earth (as measured by radioactive decay) be an integral of the history of this effect on decaying elements? We don’t know what the effect is, so how can we integrate it?

  40. Neil Craig says:

    Amazing but lets see if it can be verified elsewhere.

    If it is so we might expect isotope ratios in rocks that formed in the cometary belt to be significantly different from those formed at the same time here. This presupposes that we know when they were formed.

  41. Bob Randles says:

    Some years ago NASA reported that the plutonium power sources used in the Explorer mission seemed to be lasting longer than expected. I emailed them at the time and suggesterd that this could be the effect of the reduced solar neutrino flux at the outer limits of the solar system. They replied that the effect was most likely to be caused by instrument error.

    My suggestion was based on the observation that if the beta decay rate of chlorine 36 could be used to measure solar neutrino flux then so might the alpha decay of plutonium 238 be affected by the flux.

  42. Peter Kirk says:

    Surely the most obvious solutions are far less obscure: possibly variation in the clock speed for thermal rather than relativistic reasons, and even more probably thermal expansion and contraction of the measuring apparatus. If the distance from the source to the detector increases by 0.1% in summer relative to winter, the detection rate drops by 0.2%, at least for some geometries. Is any further explanation needed?

  43. Rebel Dreams says:


    I didn’t say that I feared the result or that YECs would have a point if they seized on this; as Bruce rightly points out, it’s a miniscule and self-canceling effect. I was just looking forward to the first YECist to try to *use* the result, thus proving their complete lack of understanding of the issue! :)

    I’ll try and explain to you about 4.5GY turning into 4.48GY.

    4,500,000,000 years x 0.997 = 4,486,500,000 years.

    Now, IF the effect is real, we can still factor it in, even if we don’t understand the cause. Let me give you an example: We don’t really *understand* the “cause” of gravity (yes, we know there’s a field, curvature of space-time etc, but not the real inner workings of gravitation in a QM sense) but we can actually “factor in” gravity in calculations with no problem. IF there is an effect, no matter the cause, we can still use that effect as a constant in our calculations. It’s pretty simple. I’m guessing any 3rd grader could do it.

    Bruce was pointing out that the “true” age of the Earth might differ from the “measured” age of the Earth by as much as 0.3%, given that this is a real effect and ignoring the fact (that he points out) that the 0.3% shift reverses itself in the other half of the year and gives a net change of 0.0% in isotopic decay.

    He was merely pointing out that any attempt to use this result to cast doubt on radioisotopic dating is baseless.

  44. Rebel Dreams says:

    I say we wait for more results.. there’s a reason this is on arXiv right now, and not in the ournals (yet). Nothing wrong at all with arXiv, but it’s got to be reffed first, right?

  45. Rebel Dreams says:

    The only worrying thing to me is the idea that somoene might invoke a hitherto-unknown and unrecorded “fine-structure-constant-variation field” as an explanation…

    Surely if such a thing even *might* exist, there’d be astronomical observations to support it… or are Barrow/Shaw saying the sun is “unique” in that respect? Wouldn’t *any* G2 create such a field? Yeah… it’s fishy.

  46. Alsee says:

    This has no bearing on YEC, because YEC has always been proven wrong by pretty much everything on earth. If you dig in the arctic or antarctic icepack you can count the visible yearly layers. If you dig down 1929 layers you can find traces of volcanic ash from the famous volcanic eruption that destroyed Pompeii in 79 A.D. By digging and counting yearly layers you can find traces of every major volcanic eruption in recorded history. There are well over a hundred thousand visible countable yearly layers in the ice pack, and they are scattered with exactly the traces of volcanic eruptions you’d expect over that time span. Actually there’s about 800,000 years worth of layered icepack, but beyond about a hundred-odd-thousand years down the layers get squeezed too thin and blur too close together to individually count.

    So the earth is visibly countably well over a hundred thousand years old. In addition, there was no possible Global Flood, at least not within the last hundred-odd thousand years anyway. It would have melted underlying snowpack, and it would have left a huge visible layer of mud deposit in the ice. It’s just Not There.

    Another example is the Grand Canyon. Yeah, it’s been suggested it was carved quickly by a huge fast torrent of water after Noah’s Flood, but that suggestion is blatantly bogus if you think about it… a huge fast torrent of water would blast its way in STRAIGHT LINES cutting through anything in its way. It would easily wash up and over any minor dirt bumps in the way. If you look at the Grand Canyon, it is riddled with countless U-turns. Often tight U-turns twisting around trivially small bumps in the ground. Bumps that fast water would easily wash over. It doesn’t take a geology PhD to see that the Grand Canyon was not carved quickly – it follows exactly the sort of winding looping path you’d get from a reasonably small slow flow of water twisting around every tiny obstacle.

    There are hundreds and thousands of other examples, the basic point is that any sort of “young” timeline for earth is total fiction, and YEC’ers are twisting and bending the facts trying to support the answer they desperately WANT to get. The earth is Old.

  47. [...] This first link is potentially very, very interesting, and potentially reveals some very new and unsettling physics.

  48. Jukka says:

    More than in this proof to it from the expansive Sun radiates expansive neutrino, which move to their business energy Globe to expansive to the atoms’ cores. Neutrino so expand and radiate enegy away towards themselves. Produce radiation can’t observe. Let think about galaxies to be big neutrino! In the galaxies’ centres are colossal particle which is developed themselves round from the energy field’s star which radiate extremely small particle in the relationship galaxy centre to colossal energiaconcentration (to big vestige). Galaxies so are big particles which are originated really a long distance visible outside visible universe , as being energy from concentrating on which still to explode and radiates energy waves which have galaxies personality. On his journey galaxies centres explode energyconcentration have interacted themselves avutuvien with the energy waves , which have atom personality. Stars so are originated from the galaxy’s centre and they radiate to their energy and so on. At same time in the way to the neutrino born around themselves energy field and to the herring!

    Now pioneerproblem gets their explanation so that from Sun come neutrino interact it with the more atoms cores, what further off from Sun they get, because they have time to interact with each other and develop for itself energy field which radiates neutrino business energy to the atoms’ cores!

    In other words should pioneerprobes of expansive speed then accelerate according to this thought ? Yes, but expansive gas planets the pace picks up more and like this pioneerprobes is observed towards the inexplicable acceleration, Sun!

    In other words expansive neutrino don’t move to their kineticenergy of fixed to the atoms’ cores so much as gaseous ingredients.

    Crucial is of course understand it that in the planets’ centre is hard pressure and neutrino move to their business energy to the planets’ centres powerfully and from there its come across atom from the atom to all to the planets’ atoms and also to the planets’ moons. Truly moons atoms get business energy from the neutrino also direct!