Via slashdot:
A couple of days ago, WUWT carried a story that was rather shocking: some physicists published claims they have detected a variation in earthly radioactive decay rates, big news by itself, but the shocker is they attributed it to solar neutrinos.
The findings attracted immediate attention because they seemed to violate two known basic facts of physics:
1. Radioactive decay is a constant
2. Neutrinos very rarely interact with matter and are hard to detect when they do.
For example: trillions of the neutrinos are zipping through your body right now. So why would they interact with radioactive elements in a more detectable way?
Discover Magazine’s blog 80beats followed up on the initial story buzzing around the web this week and interviewed several physicists who work on neutrinos. The neutrino-affecting-radioactive decay theory is being questioned.
Excerpts:
“My gut reaction is one of skepticism,” Sullivan told DISCOVER. The idea isn’t impossible, he says, but you can’t accept a solution as radical as the new study’s with just the small data set the researchers have. “Data is data. That’s the final arbiter. But the more one has to bend [well-establish physics], the evidence has to be that much more scrutinized.”
Among the reasons Sullivan cited for his skepticism after reading the papers:
- Many of the tiny variations that the study authors saw in radioactive decay rates came from labs like Brookhaven National Lab—the researchers didn’t take the readings themselves. And, Sullivan says, some are multiple decades old. In their paper, Fischbach’s team takes care to try to rule out variations in the equipment or environmental conditions that could have caused the weird changes they saw in decay rates. But, Sullivan says, “they’re people 30 years later [studying] equipment they weren’t running. I don’t think they rule it out.”
- The Purdue-Stanford team cites an example of a 2006 solar flare, saying that they saw a dip in decay rates in a manganese isotope before the occurrence that lasted until after it was gone. Sullivan, however, says he isn’t convinced this is experimentally significant, and anyway it doesn’t make sense: Solar neutrinos emanate from the interior of the sun—not the surface, where flares emerge. Moreover, he says, other solar events like x-ray flares didn’t have the same effect.
- If it were true, the idea would represent a huge jump in neutrino physics. At the Super-Kamiokande detector, Sullivan says only about 10 neutrinos per day appeared to interact with the 20 kilotons of water. Sullivan says the Purdue-Stanford team is proposing that neutrinos are powerfully interacting with matter in a way that has never before been observed. “They’re looking for something with a very much larger effect than the force of neutrinos, but that doesn’t show up any other way,” he says.
Fischbach and Jenkins, who have published a series of journal articles supporting their theory on neutrinos and radioactive decay, emailed DISCOVER to respond to these criticisms of their work. Regarding the first one, the researchers defended the integrity of the data even though they didn’t take it themselves, saying the experiments “were carried out by two well-known and experienced groups. We have published an analysis of these experiments, in Nuclear Instruments and Methods … showing that the potential impact of known environmental effects is much too small to explain the annual variations.”
Scarlet Pumpernickel says:
August 27, 2010 at 3:39 pm
Ok this steps on the toes of everyone else’s research, so lets discredit them, and bury it just like famous scientists in the past
Hey! This is the modern era.
Let’s call them names as well…
So I guess that the alarmists [snip] dreams of a coming 2012 doomsday will have to be put on hold?
Note also in the Lockheed Martin graph of Galileo RTG output the comparison line with Voyager RTG. It took 8 years for Galileo to reach the orbit of Jupiter. Voyager had no gravitational assists and passed the orbit of Jupiter in 18 months and continued outward. Note that both RTGs performed identically for about a year after launch then Voyager’s RTG (RTG in Voyager and Galileo were identical modules) then performance began to slowly drift farther from Galileo’s as Voyager got much much farther from the sun than Galileo over the same period of time. There’s yet another anomaly that speaks to this not being due to mischaracterized thermopile degradation.
Paul Birch says:
August 27, 2010 at 3:08 pm
Stop handwaving Paul. You explained nothing.
Further on the Galileo RTG output anomalies during Venus and Earth gravity assist flybys…
The temporary decline in output power is the same for all three flybys. However, Venus has very little electromagnetic field compared to the earth so we can rule out planetary electromagnetic fields and their ability to deflect cosmic rays as a potential cause and it also seems to rule out neutrino flux as that would be much greater on the Venus flyby. Gravity fields would be about the same as the earth and venus mass about the same.
That leaves us with strength of gravitational field very close to the planets and inertial reference frames. I can’t think of anything else that would change on a flyby. There’s no glitch when Galileo encounters Jupiter which may or may not be meaningful. It would seem that somehow either the gravitational field and/or the inertial reference frame is responsible for either the change in performance of the thermopile or the decay rate of the Pu-238.
http://www.fas.org/nuke/space/gphs.pdf
See figure 13 above. This is a graph of the comparative performance of all Pu-238 RPGs flown as of 2006.
Two on earth orbiting satellites (LES 8 and 9), two on super long distance probes (Voyager I and II), and two on medium distance missions to Jupiter (Galileo and Ulysses). Ulysses was very short mission as it looped around Jupiter to get out of the ecliptic and raced back to the inner system to get a polar view of the sun.
Note how, without exception, the closer to the sun the less power the RTG delivered.
You can see some flattening in the decay rate on Ulysses as looped out around Jupiter.
At first blush I might blame this on change in the cold sink side of the thermopile changing with distance from the sun but the fins are so highly mirrored that incident light from the sun should have no significant effect. As well, some of the spacecraft rotate (Galileo) and some do not (Voyager) which appears to make no difference. There was some speculation that the position anomalies are related to rotating or not rotating as the non-rotating craft could have gas vents and heat sources that were pointed in a constant direction and could thus effect velocity.
Paul Birch says:
August 27, 2010 at 3:08 pm
Can you give me a single example of cosmic rays improving the performance of a thermopile?
There would be a lot of money in it for you. RTGs are bloody expensive with tens of kilograms of Pu-238 fuel in them. The US had to spin up a billion dollar Pu-238 process just to get enough to power more recent missions, especially Cassini as it had more Pu-238 in it than several previous missions combined. The weight of the RPG was 18% of the Cassini payload. So if there’s any possible way to irradiate the RPGs into better performance give JPL a call (get an NDA first) and make yourself rich. Otherwise I think you should just continue waving your hands around on blogs making claims that have no basis in reality.
Okay, I’ll buy that.
So you’re saying the delta emf could be positive or negative due to cosmic rays.
I guess that makes them insignificant, huh? rofl
Wait! I’ve got it!! It’s DARK PHOTONS!!!
The Total Idiot,
I like the name. I hope you keep it. 😉
I certainly hope that radioactive decay is a particle interraction, whatever the particle is. In nuclear reactors it is thermal neutrons which trigger decay, so a particle causing decay is not absurd.
The problem is worse if it is NOT a particle interraction. An atom may be stable for millions of years then suddenly decays. Why? Most, if not all, of science is based on cause and effect, here we have an effect and no clue as to the cause. What is the condition that arises in an atom to cause it to decay if there is no external influence? Saying ‘It just happens’ is not science. Believing that ‘It just happens’ is sufficient and should not be challenged is religion.
If the particle does originate from the Sun then the speed of radioactive decay would increase closer to the Sun. It would be interesting to know what effect this would have on the evolution of Venus.
Dave Springer says:
August 27, 2010 at 4:35 pm
“Stop handwaving Paul. You explained nothing.”
I explained why the prediction was as accurate as could reasonably be expected. It is apparent that the authors themselves did not expect anything better, and were unsurprised by the residual error. I explained why that error could have been in either direction. I explained how, for example, the marginal effect of cosmic rays on these thermopiles was not known, and why it could not have been known beforehand. That they would degrade over time was not in question; how much they would do so was inescapably uncertain, due to the inherent complexity of the materials phenomena. It has become evident to me that you have a strong emotional desire to believe that the behaviour of these power generators is anomalous and inexplicable in terms of conventional science, while paradoxically relying upon the endless capacity of that science to make highly accurate predictions of the performance of very complex devices. Presumably it has been made a lynchpin of some fringe pseudo-science theory you’re a fan of. I’ve some news for you; in this sort of engineering, glitches are the rule not the exception. It would be more surprising if there weren’t any.
I love 100% garbage!
NOT A SINGLE ROTATION!
Anna v, I am confused when you write “The same is true of the velocity of light, another so called constant, that is only locally constant.”
Perhaps I am misunderstanding your post, but the speed of light is a universal constant, and it is the variable rate of time itself that keeps the speed of light the same for every observer. Even gravity doesn’t change the measured speed of light, but shifts the wavelength and reduces its energy (in redshift).
Mac says:
August 27, 2010 at 8:57 am
Good stuff Mac. V. interesting with good explanations to keep the uninitiated in the loop. Never knew this Neutrino issue existed and i doubt Anna would agree that there is even a ‘Neutrino Issue’. Everything looking good then Peter Sturrock hijacks a UFO and lands it in the middle of the playing field for us all to crawl over!
Vince Causey says:
August 28, 2010 at 7:02 am
When space time topography is changing, what is the definition of a meter and a second?
http://edu-observatory.org/physics-faq/Relativity/SpeedOfLight/speed_of_light.html
In general relativity, the appropriate generalisation is that the speed of light is constant in any freely falling reference frame (in a region small enough that tidal effects can be neglected). In this passage, Einstein is not talking about a freely falling frame, but rather about a frame at rest relative to a source of gravity. In such a frame, the speed of light can differ from c, basically because of the effect of gravity (spacetime curvature) on clocks and rulers.
Speaking hypothetically, the interaction of a graviton with a proton or a photon happens in a non inertial frame, is all I am saying,( and it is a hypothesis).
I would like to wade into this subject, but not to a great depth.
I’m sure most, if not all, of the readers of this blog understands (far better than I) the physics of a LASER. The photon, which is ‘nothing’ but electromagnetic radiation’ stimulates the emission of another photon, having the same energy and coherently. Of course, the electron emitting the photon loses the appropriate energy. The electron, by virtue of it losing energy, ‘feels the effect’ of the passing photon, but does not interact with the stimulating photon.
I would postulate (assuming the observations under discussion prove to be real) that the neutrino, having a small but non-zero mass, may either be exerting a large, but very localized, gravitational field, due to it’s velocity, or a new type of field altogether – we really don’t have that much knowledge or data concerning masses traveling close to the speed of light! When this field passes by an atom on the verge of decaying, it disrupts the process, and delays the decay. I think this would fit into existing theories of physics without upsetting too many apple carts.
Vince Causey says:
August 28, 2010 at 7:02 am
“… the speed of light is a universal constant, and it is the variable rate of time itself that keeps the speed of light the same for every observer. Even gravity doesn’t change the measured speed of light, but shifts the wavelength and reduces its energy (in redshift).”
Making light of constants. 🙂
“A team of researchers from the Ecole Polytechnique Fédérale de Lausanne (EPFL) has successfully demonstrated, for the first time, that it is possible to control the speed of light – both slowing it down and speeding it up – in an optical fiber, using off-the-shelf instrumentation in normal environmental conditions. Their results, to be published in the August 22 issue of Applied Physics Letters, could have implications that range from optical computing to the fiber-optic telecommunications industry.
On the screen, a small pulse shifts back and forth – just a little bit. But this seemingly unremarkable phenomenon could have profound technological consequences. It represents the success of Luc Thévenaz and his fellow researchers in the Nanophotonics and Metrology laboratory at EPFL in controlling the speed of light in a simple optical fiber. They were able not only to slow light down by a factor of three from its well – established speed c of 300 million meters per second in a vacuum, but they’ve also accomplished the considerable feat of speeding it up – making light go faster than the speed of light.”
http://scienceblog.com/light.html
“http://scienceblog.com/light.html”
Wow, whoever wrote that article has no idea at all of index of refraction, speed of light in optical fiber, or what was the significant about the research in question. Makes me wonder what other misinformation is sitting out there on such blogs.
The phrase, “the speed of light is a constant,” is taken out of context. The correct wording is, “the speed of light IN A VACUUM is a constant.” The speed of light is dependent upon the medium it is traveling in, and can derived from the medium’s index of refraction. The speed of light in typical optical fiber is approximately 2/3 that of a vacuum (i.e., space). It has also long been known that some materials have indexes of refraction whose values are such that the speed of light is faster in the materials than in a vacuum.
What is significant about the research was the degree which the signal was slowed. Unfortunately Stimulate Brillion Scattering (SBS) also causes a frequency shift, which may limit its usefulness.
By applying an electric field across some materials, you can make small changes in its index of refraction, thus slowing or increasing the speed of light through the material. However, you can only achieve a very small delay in a reasonably sized electro-optic device. When we needed to delay a signal to a greater degree, we increased the optical path, i.e., added a coil of optical fiber. Of course, that’s not realistic if you want a chip-based device, and that’s where SBS may have a place.
There is also another news strongly suggesting that we should revise nuclear physics:
http://www.physorg.com/news202020721.html
So maybe they are not just blurry, fluctuating as in QM picture, but rather have some concrete spatial structure near (local?) energy minimum? (analogously to protein folding)
These energy minimas can have different shape – depth, width – and so different statistical dependence on energy carriers like Sun’s neutrinos – comparing such behavior of different isotopes could became the basic tool to finally understand the structure of nucleuses …
Jarek Duda says:
August 29, 2010 at 4:44 am
There is also another news strongly suggesting that we should revise nuclear physics:
Revising models, as this random matrix model might need revision, is not the same as destroying the size of coupling constants. Neutrinos cannot enter any induced radiation model because they would be accompanied by a factor of ten to the minus twelve, that is 1 divided by 10000000000. The interaction would be so minuscule that it would be undetectable, let alone give effects of 0.2%
missed two zeros there. sorry.
You are saying about direct absorption … what we need here is just helping nucleus to get out energy local minimum – tunneling – neutrino energy doesn’t really have to change while such process …
Does standard neutrino detection exclude such scenarios of decays only induced by neutrino? Evaluate their cross sections?
And generally I was told that decay time depends on temperature and pressure:
http://www.scienceforums.net/topic/40163-can-we-be-sure-that-decay-times-are-constant/
You are referring situations in which neutrino is absorbed … what if it could only help nucleus to get out of energy minimum – tunneling – only induce decay not losing own energy?
Does standard detection methods exclude such scenarios? Say something about their statistics?
And generally I was told that temperature and pressure influence decay times: http://www.scienceforums.net/topic/40163-can-we-be-sure-that-decay-times-are-constant/
The constance of particle decay times looks to be only an approximation: practical idealization of process we don’t really understand.
Jarek Duda says:
August 29, 2010 at 8:01 am
“You are referring situations in which neutrino is absorbed … what if it could only help nucleus to get out of energy minimum – tunneling – only induce decay not losing own energy?
Does standard detection methods exclude such scenarios? Say something about their statistics?”
Anna seems not to be giving sufficient attention to the distinction between induced and stimulated decays. An induced decay is one where the neutrino is absorbed; this is the process used in neutrino detectors. A stimulated decay is analogous to a laser; the stimulating particles are not absorbed. Both processes, under the standard theory, have the same coupling constant in their probabilities, so the cross-sections, for a single neutrino, will be of the same order of magnitude. However, stimulated decay is proportional to the square of the number of simultaneously interacting particles (the wave functions add in phase – thus by amplitude not intensity). This is how synchrotron emission and free electron lasers work. Which means that a sufficiently intense beam could increase the decay probabilities by many orders of magnitude – perhaps even to the 0.2% level reported. The question then is whether the solar neutrinos can be considered coherently simultaneous or only sequential, and this in turn hangs on their effective size or wavelength. For the most common energies (up to 400keV) this would be down to ~3e-12m. Now if the neutrino flux is ~3% of the total solar flux (ie ~40W/m2), this would mean ~6e14 neutrinos/m2/s (at 400keV), or ~2e6 neutrinos/m3. Their mean separation would then be of order a centimeter, very much greater than their wavelength. Thus the beam is “sparse”, and nuclei “see” only a single neutrino at a time, unless solar neutrinos are very strongly clustered, or some weird quantum entanglement makes them act as one over greater distances (I don’t know how that could work, but I wouldn’t want to rule it out absolutely). There is however independent evidence that the solar neutrinos do not form such an interaction-enhancing coherent beam; if they did, then the induced decays by which we detect them would also be enhanced. The solar neutrino problem would then have been the other way round; too many events detected, not too few.