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Nuclear Decay May Vary With Earth-Sun Distance 418

Posted by kdawson
from the not-so-fast-there dept.
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?"
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Nuclear Decay May Vary With Earth-Sun Distance

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  • Carbon Dating (Score:5, Interesting)

    by Jaysyn (203771) <jaysyn+slashdot&gmail,com> on Friday August 29, 2008 @09:05AM (#24793149) Homepage Journal

    Does this have any ramifications for carbon dating?

  • How To Test It (Score:5, Interesting)

    by eldavojohn (898314) * <eldavojohn&gmail,com> on Friday August 29, 2008 @09:06AM (#24793155) Journal

    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!!!

  • Pioneer Anomaly (Score:4, Interesting)

    by andyh3930 (605873) * on Friday August 29, 2008 @09:08AM (#24793193)
    Could this be the cause of the Pioneer Anomaly [planetary.org] ?
  • Cool! (Score:5, Interesting)

    by kmac06 (608921) on Friday August 29, 2008 @09:08AM (#24793197)
    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.
  • Re:How To Test It (Score:4, Interesting)

    by nine-times (778537) <nine.times@gmail.com> on Friday August 29, 2008 @09:14AM (#24793269) Homepage

    My question would be, once they discover the cause, can we use that information? First application that comes to mind that I'd love to see is, if we can shorten something's half-life, can that be used to help dispose of radioactive nuclear waste, thereby removing the main objection to nuclear power?

  • by arkham6 (24514) on Friday August 29, 2008 @09:17AM (#24793327)
    Could perhaps the distance between the earth and the sun and the relationship for nuclear decay be in some way effected by the gravitational field fluctuations that occur as well? Time is dilated by gravity, so perhaps are we seeing a further proof of Special relativity?

    Or are they simply looking for casual relationships where none actually exist. Perhaps the decay rate relates to the amount of pastafarians on earth.
  • Re:Carbon Dating (Score:5, Interesting)

    by kmac06 (608921) on Friday August 29, 2008 @09:21AM (#24793361)

    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!

  • by kmac06 (608921) on Friday August 29, 2008 @09:28AM (#24793453)
    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?

  • by Watson Ladd (955755) on Friday August 29, 2008 @09:31AM (#24793499)
    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.
  • Re:Carbon Dating (Score:5, Interesting)

    by Bob-taro (996889) on Friday August 29, 2008 @09:34AM (#24793541)

    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.

  • Radioactive waste (Score:4, Interesting)

    by IceCreamGuy (904648) on Friday August 29, 2008 @09:45AM (#24793697) Homepage
    So could this possibly lead to a way to "drain" radioactive waste by exposing it to a high neutrino flux? Or is it the other way around... does a higher flux slow it down and we're already near the limit of the highest speed of decay?
  • Re:Carbon Dating (Score:5, Interesting)

    by es330td (964170) on Friday August 29, 2008 @09:48AM (#24793729)
    I'm more interested to know if this has any impact on nuclear waste. If decay can be sped up artificially one of the biggest objection points against widescale adoption of nuclear power in the US goes away.
  • by Muad'Dave (255648) on Friday August 29, 2008 @09:53AM (#24793823) Homepage

    This graph [arxivblog.com] seems to indicate that the correlation is between the decay rate and the radius of Earth's orbit squared, not just r.

    Could it be that the correlation between decay rates is with Earth's orbital velocity [wikipedia.org], acceleration, or dTheta/dT (rate of change of the Earth/Sun vector due to Earth's elliptical orbit)?

    Additionally, there seems to be a phase shift between peak r^2 and peak decay rates with the decay rate peak seemingly correlated with our peak acceleration toward the sun.

  • by xonar (1069832) <xonar@@@smagno...com> on Friday August 29, 2008 @09:55AM (#24793843) Homepage
    This reminds me of Asimov's book "The Gods Themselves" [wikipedia.org] where the exchange of electrons between parallel universes, creating limitless and wasteless energy, increases the strength of the nuclear force [wikipedia.org] in our universe. Thus making our huge sun (by parallel universe standards) likely to explode/implode.
  • by Zenaku (821866) on Friday August 29, 2008 @09:58AM (#24793887)

    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.

    This makes me wonder about the http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator [wikipedia.org]power sources on board the Voyager spacecraft, as they are based on the decay of radioactive material. Has our earth-centric understanding of the universe led us to build probes designed to push the boundaries of the solar system and continue into interstellar space, that will gradually lose power the further they get from the sun?

    Whoops.

  • by LWATCDR (28044) on Friday August 29, 2008 @10:22AM (#24794247) Homepage Journal

    Note really because it is on the order of .1%
    So if the power supply was going to last say 1000 years it would now only last 999. Most engineers would use a safety factor as small as .1%.
    Those that do will soon find themselves unemployed.

  • by Anonymous Coward on Friday August 29, 2008 @10:31AM (#24794375)

    If the "real" rate of decay is 100 it could be (100-0.15) here on earth, (100-0.25) on Venus and (100-07) on the solar surface.

    Moving to Saturn could have it go to (100-0.01).

    After all, the change doesn't have to change linearly with distance but inversely.

  • Re:Carbon Dating (Score:5, Interesting)

    by fatphil (181876) on Friday August 29, 2008 @10:35AM (#24794451) Homepage
    Take an old vinyl record. Punch a new hole just off-centre. Play the record. Sometimes it's too high pitched (fast) and sometimes it's too low pitched (slow). Yet the song still takes the same length of time to play.

    I.e. no.
  • Re:Carbon Dating (Score:5, Interesting)

    by Scott Carnahan (587472) on Friday August 29, 2008 @10:49AM (#24794699) Homepage

    It does take a very long time for this to happen - geologic time - but even a "long time" is not forever.

    The idea that a diamond will decay into graphite in geologic time is a popular fiction. The activation energy barrier for the diamond-graphite transition is high enough that substantial decay at STP will take far longer than the Earth will last, and the time scale is therefore not geologic. Several samples of diamond have been found that crystallized before the formation of the solar system, and some carbonados [wikipedia.org] exhibit Xenon isotope concentrations in inclusions that suggest that they formed in distant supernovas and fell to earth.

  • by elrond2003 (675701) on Friday August 29, 2008 @11:18AM (#24795205)
    As someone who made the equipment that the scientist probably used to do the counting, I have one possible explanation. Most Multichannel Analyzers (MCAs) of the time used a line clock to determine the time. They assume that the power company delivered 60Hz power (or 50 Hz in Europe), This frequency was almost never precise but varied by .1 to .2% (one plant where I measured the frequency put out 58.8Hz for example, a real mess for us) from time to time. A systemic variation due to power loads (heating in winter/ AC in summer) could easily bias the power frequency by about the right amount with the right periodicity. The universe might well be safe.
  • Re:Carbon Dating (Score:1, Interesting)

    by Anonymous Coward on Friday August 29, 2008 @11:43AM (#24795681)

    It may be more complicated then that.
    If something like the nutrino field of the sun affects atomic decay. Then you have to know that the natrino field is relatively constant througout the time you are examining and averaging against.

    Not to say the effect is caused by the nutino field it could be caused by anything or even some force yet unkown to physics.

    The point is unless you know that force was also on average stable over the period of time under discussion aks millions of years. You can't trust radio carbon dating.

    Which means you first have to identify the cause.
    Or prove the carbon isotope is does not suffer from the effect.

    Proving if it does or doesn't seems like an experiment that can be done in about a year.

    Knowing the cause of the effect may take some time.

  • Re:Seriously : No (Score:3, Interesting)

    by Rich0 (548339) on Friday August 29, 2008 @11:52AM (#24795837) Homepage

    Still, it makes you wonder whether other astronomical events could have had an impact. Suppose some supernova nearby blasted the earth with neutrinos and caused 10% of a sample of isotope to decay in seconds - then return to normal rates of decay? Suppose the sun drifted into some cloud of dark matter a billion years ago and that messed things up?

    We always assume the laws of physics are the same everywhere. This is probably true at a fundamental level, but it doesn't mean we understand all the laws of physics. A few hundred years ago you could have convinced a scientist that you could manipulate gravity (with hidden electromagnets). The reality isn't that gravity didn't work right, but rather that there was a previously-unknown force at work. There could be all kinds of fields at work in the universise that haven't been apparent to us simply because they're flat on the scale that we've experienced them. If a force only causes local effects but only within certain regions of the univerise and we're not in one of them then we'd never know it exists until the earth happens to pass into such a region and all kinds of stuff goes haywire.

  • by Zenaku (821866) on Friday August 29, 2008 @11:58AM (#24795927)

    If the rate of decay increases with distance from the sun, that would explain the accelleration -- faster decay means more heat being turned into power. The probes could be accelleration because they are overpowered.

    It would also explain the better than expected performance of the thermocouple -- it only looks more efficient than it should be because we are starting off with more input heat than we think we are.

    All of this is speculation, of course. I'm no physicist, and it's way to early to know what this discovery means.

  • Re:Carbon Dating (Score:4, Interesting)

    by torkus (1133985) on Friday August 29, 2008 @11:59AM (#24795951)

    For what it's worth, my stepdaughter has a keychain toy with more memory and processing power than we went to the moon with. I have a PDA that processes and stores what would have taken...a skyscraper full of discrete transistors and core memory. Give or take, but the point of scaling down by multiple orders of magnitude is obvious.

    Will we be evaporating nuclear waste next year? Nah. Do we have the possibility to develop the precursor technology in the next 10-20 years for properly disposing of stored long half-life waste 50 years down the road? Quite possibly. That makes nuclear waste storage much, much more practical.

    After all, we don't necessarialy need MORE of the secret sauce. We may just need to concentrate it, tune it, shape it...or what have you to make it many times more effective. First we need to understand it thought :)

    Does this remind anyone else of the 'rules' behind FTL drive in most sci-fi books? Ya-da ya-da gravity well means no FTL but once you move away from the singularity ... zooooooooom. Granted I'm now comparing sci-fi "physics" with a minor observed variation in real life....but shhhh!

  • by Zenaku (821866) on Friday August 29, 2008 @12:06PM (#24796083)

    What gives you the idea that the percentage change in distance has to equal the percentage change in decay rate? I would expect them to be related in an exponential or logarythmic way, but even if they were related linearly, that wouldn't mean that a 3.2 change in distance should mean a 3.2 change in decay rate.

    What if the decay rate increases by .1 percent for every 4.8 million km? What if it increases by the square of the distance times some constant?

    What you've pointed out here is kind of meaningless.

  • Re:Seriously : No (Score:3, Interesting)

    by avandesande (143899) on Friday August 29, 2008 @12:10PM (#24796133) Journal

    You are assuming that the neutrino flux from the sun is constant. I don't think it is unreasonable to think that this may have some effect on carbon 14 dating.

  • by dpilot (134227) on Friday August 29, 2008 @12:23PM (#24796397) Homepage Journal

    Sorry, doesn't wash. The probes are not in powered flight, they're simple ballistic projectiles. No ion engines at work, which might show the effects you suggest.

    It would clearly be interesting to construct a probe to test this effect using a greater distance that the difference between the Earth's perihelion and apihelion

  • by mysticgoat (582871) on Friday August 29, 2008 @12:55PM (#24796997) Homepage Journal

    TFA's frame of reference is the Earth's orbit about the Sun, and reports a small but significant correlation between aphelion - perihelion and decay rates of some radioactive nuclides. TFA suggests that the 4% change between Earth's closest approach to the Sun and its most distant point is a possible cause for the change in decay rates.

    When the frame of reference is expanded to galactic distances, we find that Earth's aphelion point is coincidentally very close to a line drawn from the Sun to the center of the galactic core. So it could also be that some shielding or suppressive effect of the Sun's local environment is reducing decay rates when the Earth is behind the Sun relative to the galactic core.

    Proposed hypothesis: the changes in radioactive decay rates are related in an unknown fashion to the annual changes in the geometry of the Earth - Sun - galactic core.

    This could probably be ruled out with a couple of tests of the existing data:

    Aphelion occurs on Jan 4, while Earth's fullest exposure to any presumed galactic core influence occurs on Dec 17. Does the data suggest that increased activity centers around aphelion, or 18 days earlier?

    If TFA's heliocentric model is correct, the change in rates of decay from month to month will be a smooth sinusoidal curve over the course of the year. But if the galactic core is involved, the changes in rates of decay will depart from this since the ecliptic does not parallel the galactic plane, and the degree of the Earth's "exposure" to galactic core will vary in a more complex way. Does the data support either of these conjectures?

    I'm not going to cite my references here: they would be a distraction. Key words for google: aphelion, perihelion, solstice, galactic core, "plane of the ecliptic", "galactic plane". Um, a quick review of high school trigonometry might be useful, too.

    Kudos to all the researchers and lab assistants who contributed to this work. It sounds like years of seemingly mindless drudge data collection went into this database. Yet the results are stunning: something Out There is affecting "constants" that we thought were intrinsic and immutable. That changes things. That changes everything.

  • Re:Carbon Dating (Score:3, Interesting)

    by HiThere (15173) <charleshixsn@NOSPAM.earthlink.net> on Friday August 29, 2008 @01:00PM (#24797083)

    Why not gravitational field strength? That could be checked (though not easily) on the moon...or an asteroid.

    The standard model should be able to predict what effect changes in neutrino flux would produce. Changes in gravitational strength would be more difficult, as gravity hasn't been integrated into the standard model. Additionally, one would expect gravitational field strength to vary with the distance from the sun, so that matches. (Yes, earth's gravitational field is predominant by a large amount on the surface of the earth, but solar gravitation is not insignificant. It raises tides nearly as great as the lunar tides, and tides are based on change in field strength, not absolute strength.)

  • Diamonds burn? (Score:4, Interesting)

    by Anonymous Coward on Friday August 29, 2008 @02:40PM (#24798571)

    Trivia: Believe it or not, I once asked a chemist, who studied diamonds, the temperature at which they burned. His reply was that they didn't. Instead, according to him, at about 2000 F they break down into graphite and then the graphite burns.

  • by vigour (846429) on Friday August 29, 2008 @06:46PM (#24803183)
    Actually, the parent is partially correct.
    One of the hypotheses put forward to explain the Pioneer acceleration anomalies include thermal gradients across the craft. According to one group in JPL:

    Turyshevs team calculated the emissions from the Pioneer spacecraft, it found that heat is given off in some directions preferentially, enough to account for 28-36% of the anomalous acceleration.

    Source [symmetrymagazine.org]
    . The mainstream view is that the effect is most likely due to outgassing from the surface, or thermal radiation pressure Ubiquitous Wiki Link [wikipedia.org]. Having said that, I'm not fully convinced by the pre-print. They still need to make sure they have covered more conventional effects, such as ambient temperature effects on detectors. The variation is small, if significant, and I'd rather wait til it gets through peer review (and their hopefully insightful) comments. If their hypothesis is true, then it's certainly very interesting.

  • by Neoporcupine (551534) on Friday August 29, 2008 @08:23PM (#24804333) Homepage
    Oh sweet Orion! Astrology may be true! Stars have some unknown influence on local physical properties depending upon distance. Is it any massive body? Moon/Planets? You just know this research is going to be abused, right?

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