8 ms·

What could explain the gallium anomaly?

215 points by ars 2y ago

CamperBob2 2y ago
Photo caption: In the lab that houses the BEST experiment, fish serve as an early warning system about any leaking radiation. Never change, Russia. Never change.
- dylan604 2y ago
  You can't get them all right. To be fair, they used pencils while NASA spent time and money to have a pen that writes in 0g.
  - spankalee 2y ago
    That's just a myth, you know: https://www.scientificamerican.com/article/fact-or-fiction-nasa-spen/ https://www.scientificamerican.com/article/fact-or-fiction-n...
  - dflock 2y ago
    Fischer made the space pen as a commercial product, all R+D entirely at their own expense. NASA just bought some of the pens from them.
  - Etheryte 2y ago
    This is a myth, using a pencil in space isn't clever or thrifty, it's a disaster waiting to happen. The graphite from pencils breaks off in small fragments while writing and the fragments can create shorts in electronics and to top it off they're also flammable. None of those are properties you want to bring into a spacecraft.
    - effie 2y ago
      I wonder how graphite can create shorts, when all electronics board and components on them can be easily covered with protective nonconducting PCB varnish.
    - sterlind 2y ago
      dumb question but how well do sharpies work in space? the ink diffuses through the felt tip - that doesn't require gravity. wouldn't that work pretty well? also crayons seem like a better bet than pencils - they're still flammable and prone to flaking but at least they're not conductive.
      - mypalmike 2y ago
        Your question piqued my curiosity, so I did some googling... Apparently sharpies do work in space, though NASA seems to prefer the Duro brand of marker. https://airandspace.si.edu/stories/editorial/saga-writing-space https://airandspace.si.edu/stories/editorial/saga-writing-sp...
      - crazygringo 2y ago
        Sharpies and markers generally run out waaay quicker than pens or pencils. They also dry out if you're not careful, and dry out temporarily if you use them for more than a few minutes at a time. Crayons just aren't dark enough, and are too wide. Accurately reading numbers and symbols written in crayon at a normal handwritten size is not something I want to do. Not to mention the constant sharpening.
    - hinkley 2y ago
      And we licensed the pens from a dude who spent a fortune developing them.
  - mrguyorama 2y ago
    After Fisher, the pen company, spent their own couple millions to develop a pen that could write in zero gravity, they convinced NASA to use it, and a few years later the Soviets bought 100 of them for their own space program. NASA was never involved in the development of the space pen, though they supposedly had their own effort that was quickly abandoned as it got expensive. Before that they also used pencils. The pen is just a better writing implement in space. It cost $3 in the 60s, with wide availability.
- sterlind 2y ago
  coal miners carried canaries to warn of CO. chemical weapons workers brought bunnies in cages to monitor nerve gas leaks. it's an old tradition - it's simple, and it works. though why not Geiger counters for radiation? there must be a reason.
  - CamperBob2 2y ago
    If there's enough CO to kill a canary, you still have time to get to safety. If there's enough nerve gas to kill a rabbit, you still have time to get to safety. If there's enough radiation to kill a fish, you're a walking dead man... and the 'walking' part is temporary.
    - dudinax 2y ago
      Maybe the fish get less shielding.
      - qup 2y ago
        Maybe it's concentrated in his water
    - postalrat 2y ago
      What if you have a potential worrisome alpha emitter already in water. Keeping some fish in that water might give you heads up when something is going wrong.
      - CamperBob2 2y ago
        Then, lacking the availability of an ISO-standard fish, you should probably use a scintillator or surface-barrier detector. Like everyone else who has to deal with such matters.
    - labster 2y ago
      If you teach a man a fish, he will eat for one lifetime. If you give a man a radioactive fish, he will eat for many half-lives.
- lossolo 2y ago
  Did you know that mussels and clams are sensitive to changes in water quality and can absorb pollutants? They are often used as bioindicators to detect harmful substances like heavy metals and toxins in the water. They are used in United States and in Europe to check if water is clean.
  - hinkley 2y ago
    I remember someone creating a sensing system to see if the shells were open or closed. Given enough mussels, the odds of them all closing at once due to random chance instead of pollution drops to zero.
    - LeifCarrotson 2y ago
      This Tom Scott video? https://youtu.be/i0RkEs3Xwf0 https://youtu.be/i0RkEs3Xwf0 Clams at 2:22.
      - hinkley 2y ago
        I believe Tom is the second time I heard of this, as was the experience of a number of his chattier viewers.
ars 2y ago
Would sterile neutrinos as an oscillation really change anything about dark matter? The total mass of neutrinos doesn't change, just the lepton number.
- AnimalMuppet 2y ago
  It might mean 20% more neutrinos exist than we think. That would change the total mass of neutrinos. Much more interesting (and not touched on by the article as far as I noticed): The electron neutrino is the "partner" to the electron. The muon neutrino is the partner to the muon, and the tau neutrino to the tau. What's the sterile neutrino the partner to? (Or doesn't it have one, and that's what makes it "sterile"?) If there is a partner to it, does the partner have mass? Does it interact in any way besides gravitationally? If not...
  - torrefatto 2y ago
    IIRC, there is another quantum number, the chirality. All the neutrinos measured are left chiral. The sterile neutrino, which does not pair with other lepton, is right chiral.
    - AnimalMuppet 2y ago
      Is that the only possible sterile neutrino? Because if I recall correctly, a right chiral neutrino cannot change into one of the other types, because of the chirality. (That's why it's "sterile".) So either they aren't produced by beta decay, or they are but they can't be captured by gallium, or we're seeing a sterile neutrino in a different sense. ("Sterile" because it can't interact with gallium, but not sterile due to chirality.) If I understand, the conversion of gallium into germanium is exactly a beta interaction. (But I may not understand, because it seems to me that gallium->germanium should emit a neutrino, not absorb one.) So I have a hard time seeing how a neutrino could be emitted by the source, but not absorbed by gallium. I could more readily see it as saying that there's a fourth type of neutrino that they cycle through, and while in that fourth state it can't convert gallium. But that wouldn't be "sterile" in the chirality sense.
Terr_ 2y ago
> sterile neutrinos It's funny when one encounters serious real-world discussion on something previously seen as sci-fi technobabble. In this case, I'm thinking of the Destiny universe, such as this apocalyptic alert from a military AI. [0] > Multiple distributed ISR assets report a TRANSIENT NEAR EXTRASOLAR EVENT. Event duration ZERO POINT THREE SECONDS. Event footprint includes sterile neutrino scattering and gravity waves. Omnibus analysis detects deep structure information content (nine sigma) and internal teleonomy. No hypothesis on event mechanism (FLAG ACAUSAL). Bootstrap simulation suggests event is DIRECTED and INIMICABLE (convergent q-Bayes/Monte Carlo probability approaches 1). No hypothesis on deep structure encoding (TCC/NP-HARD). ______ > In the lab that houses the BEST experiment, fish serve as an early warning system about any leaking radiation. I'm curious how this works, it looks as if there's one central underwater valve and two above-water valves, perhaps supposedly-breathable air is getting bubbled up through the tank? > SAGE used a tank of 57 metric tons of gallium. Some napkin-math [egregious mistake corrected] to visualize how much that is, and I get "45 oil drums". Line item Amt Units Gallium Mass 5.70E+01 metric tons Gallium Mass 5.70E+04 kg Gallium Mass 5.70E+07 grams Liq. Gallium Density 6.10E+00 grams/cm3 Gallium Vol 9.35E+06 cm3 Oil Drum Volume 5.50E+01 gallons Vol Ratio 3.79E+03 gallons/cm3 Oil Drum Volume 2.08E+05 cm3 Gallium Volume 4.49E+01 oil drums ____ [0] https://www.ishtar-collective.net/cards/ghost-fragment-darkness?highlight=%22sterile%20neutrino%22 https://www.ishtar-collective.net/cards/ghost-fragment-darkn...
- auspiv 2y ago
  double check that math - olympic pool is 50x25x2 meters, or 2500m3. 1 m3 of water is roughly 1 metric ton (1 g/cc = 1 kg/L = 1 t/m3) depending on temperature and such. 57000000g / 5.9 g/cc = 9661017 cc = 9.661m3
  - deleted 2y ago
    [deleted]
  - Terr_ 2y ago
    Whoops, yeah, made a few mistakes. Next time I'll do the usual and open a throwaway spreadsheet. Also, picking gallium-density from a slightly higher temperature where it's liquid.
bawolff 2y ago
> While Russia’s invasion of Ukraine “has complicated things,” Elliott said, the collaboration between the U.S. and Russia on BEST is still ongoing, for now. Nice to hear in these uncertain times.
- geuis 2y ago
  How is that "nice"? The fact that 3 years in we are still collaborating with Russia on the ISS and in other scientific programs is deeply disturbing. I get that the ISS is a special circumstance and a difficult knot to unravel. That's an extremely unique situation and it's not worth digging into at length for this situation. Life support onboard for all occupants relies on a continuing collaboration. Beyond the ISS situation we should have completely cut all ties with Russia. They have killed hundreds of thousands of Ukrainians. Stolen children, assaulted women, and killed Ukrainian elderly and children. Not even digging into their internal recruitment policies, but the way they drag innocent Russian civilians into supporting their invasion is worth its own war crimes investigation. Yes, this experiment is interesting and it's intriguing to me. But it's not "nice" when a few physicists are getting results at the expense of all the collective suffering going on right now. I'm generally pragmatic about things, but in this situation cooperation is entirely uncalled for. Meanwhile the US ignores joint efforts with China. They (China) have some interesting things going on right now. For an international space station, it's awful that a Chinese crew hasn't even been invited to the ISS despite allowing numerous rich folks going up for a week long vacation. To be clear, I'm NOT supporting China. Their government is antithetical to a free society and is deeply partnered with Russia, N. Korea, and other states hostile to the EU and US. But they are a major player in humans in space, and it's important to engage them at that level. Again, the ISS is a unique scenario.
  - jpgvm 2y ago
    The problem is these joint scientific efforts were and continue to be effective tools to diffuse more dangerous possibilities. In case you have forgotten Russia is still the 2nd largest nuclear power and their arsenal is enough to eliminate pretty much all life on Earth. The war in Ukraine is terrible but don't underestimate how much worse things could get. If things do get worse it's back channels like space collaboration/UN/other symbolic things that can keep people talking enough to not end up cleansing the Earth in nuclear fire. Just because those things are ineffective at stopping a proxy war doesn't mean they aren't worth doing. For the same reason I also agree that China should be welcomed into the international space community. They are flying state of the art rockets and have their own modern space station... you couple that with the fact they too are an increasingly powerful military nation then more collaboration rather than less is the way to go.
qnleigh 2y ago
Is there any reason to think that Gallium would be a particularly good source of sterile neutrinos? Or is it more that if regular neutrinos oscillate into sterile neutrinos, then this would be the first experiment that could detect so at this scale?
- pavel_lishin 2y ago
  The gallium isn't what's producing the neutrinos; there's a radioactive source that the gallium is being irradiated by, and I believe that's the source: > In an underground lab shielded by a mountain of rock, highly radioactive material sits inside a vat of liquid gallium, blasting out particles called neutrinos that break the gallium down into atoms of germanium.
- gus_massa 2y ago
  Gallium is not a source of sterile neutrino. Gallium is a good "electonic neutrino" target. The problem is that they only detect the 80% of the "electonic neutrino" that they expect and they have no clue of the cause. One of the posibilities is that the other 20% of the "electonic neutrinos" mutate to "sterile neutrinos" during the trip. (Note that there are 3 types of neutrinos and it's possible that there are also a few types of sterile neutrinos (3 is a good guess).)
  - dmurray 2y ago
    I'd still like to ask a version of the same question, is gallium so special that it only makes sense to do this experiment with gallium? If sterile neutrinos cause the production of germanium from gallium to be 80% of what we thought it was, will there be other nuclear reactions that we now don't understand? E.g. a given plutonium reaction produces 100g of uranium, currently consistent with the theoretical model, after sterile neutrinos are confirmed will we be saying hang on, this should only produce 80g of uranium with the new model, something else is wrong? Presumably not, at least with well-understood reactions, so why is gallium so special here?
    - gus_massa 2y ago
jarsdel 2y ago
Given the potential implications of discovering sterile neutrinos, what other anomalies or unexplained phenomena in particle physics might be re-evaluated in light of this new understanding?
kseistrup 2y ago
A Capella Science: Massless (Muse neutrino parody): https://youtu.be/dBxcC8zV46E https://youtu.be/dBxcC8zV46E
keepamovin 2y ago
Could the gallium anomaly be explained by something far more prosaic? For example, in water, there are all kinds of species of different anions and cations present, existing in equilibrium with each other. Water forms complex semi-crystalline structures by virtue of hydrogen bonds. Although they are not true crystals, the supramolecular structures of individual water molecules and the valence species create a sophisticated structure, even in a seemingly homogenous substance. Now, consider if something similar happens with gallium. What if the electron configuration of gallium's orbitals means that gallium, in its liquid form, also has various anions and cations? Moreover, what if gallium can form analogs to hydrogen bonds, leading to semi-crystalline or structured forms? This structured form could provide some shielding to the gallium atoms, making them less likely to be converted via neutrinos to germanium. Instead of impacting a nucleus at the expected rate, the overlapping orbital bonds and electron resonance might offer a form of shielding. This shielding could make the gallium atoms more stable and less reactive, thereby reducing their conversion to germanium. While this idea applies a chemical concept to nuclear chemistry or physics, and may not align perfectly with the traditional views of high-energy particle physicists and astronomers, it offers a potentially more prosaic explanation for the gallium anomaly. This perspective might not have been top of mind for those focused on high-energy interactions and could be worth considering further.
- baxtr 2y ago
  Unfortunately many physicists believe chemistry is just applied physics. In reality most physicists have no clue of chemistry beyond the H2 molecule. Based on that, your “less prosaic” could be a good candidate for an explanation.
- aw1621107 2y ago
  > This structured form could provide some shielding to the gallium atoms, making them less likely to be converted via neutrinos to germanium. Instead of impacting a nucleus at the expected rate, the overlapping orbital bonds and electron resonance might offer a form of shielding. This shielding could make the gallium atoms more stable and less reactive, thereby reducing their conversion to germanium. Might this be covered by this bit from the article? > Another proposed explanation was that physicists had miscalculated the probability of neutrinos from the source interacting with the gallium. But in September 2023, Haxton and his colleagues also ruled out this possibility. “You can’t get rid of the anomaly,” he said. Maybe they don't consider the scenario you outlined in their calculations, but I lack the training to understand the paper [0]. In addition, speaking more generally I'd be curious how your proposed mechanism would work physically. Given the size of the nucleus compared to that of the electron cloud, the fact that (known) neutrinos only interact via the weak interaction and gravity, and the range of the weak interaction, a big question to me is how big your proposed effect could have in this case, if any. [0]: https://arxiv.org/abs/2303.13623 https://arxiv.org/abs/2303.13623
jnurmine 2y ago
Gallium likes to form alloys with other metals, does this anomaly happen with the gallium-containing alloys as well?
tlogan 2y ago
Question for experts: If sterile neutrinos exist, would they be the best candidate for dark matter? Additionally, would it be impossible to detect them since they do not interact with anything and possess only mass? EDIT: My reasoning is as follows: - Low-energy neutrinos might not be relativistic. For example, relic neutrinos from the Big Bang, which have a temperature of around 1.95 K, would travel at approximately 4.5% of the speed of light. - I've also read that sterile neutrinos are hypothesized to have a large mass (though I'm not sure). So "slow neutrino" + "not so light like normal neutrino" => dark matter
- d_silin 2y ago
  All neutrinos are relativistic (moving at almost speed of light) and our current model assumes dark matter is "cold" (moving at relatively slow speeds).
  - tlogan 2y ago
    Thank you. I updated my question with my reasoning. But I assume that in order for these sterile neutrinos to be dark matter they need to be really slow ...
    - eigenket 2y ago
      The known (non-sterile) neutrinos are very light, but there's no particular reason a hypothetical sterile neutrino would be.You can cook up sterile neutrinos with very large masses if you want to https://arxiv.org/abs/1303.6912 https://arxiv.org/abs/1303.6912
  - raattgift 2y ago
    There is excellent evidence for then-relativistic cosmic neutrinos from the cosmic microwave background acoustic oscillations. As with the CMB, these neutrinos cooled into a "relic" field with the metric expansion. A cooling gas of relativistic neutrinos becomes non-relativistic when the average neutrino momentum becomes comparable to their rest mass. The present cosmic neutrino background (CNB) temperature is about 1.9 kelvins corresponding to ~ 1.7e-04 eV/c^2 which is smaller than some neutrino masses. This is still "hot" compared to Cold Dark Matter, and CNB also only a small fraction of the required CDM energy density. The lightest cosmic neutrino background mass eigenstates could be relativistic at present, so how the CNB is split between (FLRW) radiation and dark matter is ripe for research. It will mostly be "hot" DM because of the heavier, colder species. But not hot enough to leave clusters of galaxies, unlike neutrinos produced by present-day astrophysics (and our own laboratory experiments and nuclear power generation). https://en.wikipedia.org/wiki/Cosmic_neutrino_background https://en.wikipedia.org/wiki/Cosmic_neutrino_background https://bigthink.com/starts-with-a-bang/cosmic-neutrino-background/ https://bigthink.com/starts-with-a-bang/cosmic-neutrino-back...

215 points by ars 2y ago

Photo caption: In the lab that houses the BEST experiment, fish serve as an early warning system about any leaking radiation. Never change, Russia. Never change.

dylan604 2y ago
You can't get them all right. To be fair, they used pencils while NASA spent time and money to have a pen that writes in 0g.
- spankalee 2y ago
  That's just a myth, you know: https://www.scientificamerican.com/article/fact-or-fiction-nasa-spen/ https://www.scientificamerican.com/article/fact-or-fiction-n...
- dflock 2y ago
  Fischer made the space pen as a commercial product, all R+D entirely at their own expense. NASA just bought some of the pens from them.
- Etheryte 2y ago
  This is a myth, using a pencil in space isn't clever or thrifty, it's a disaster waiting to happen. The graphite from pencils breaks off in small fragments while writing and the fragments can create shorts in electronics and to top it off they're also flammable. None of those are properties you want to bring into a spacecraft.
  - effie 2y ago
    I wonder how graphite can create shorts, when all electronics board and components on them can be easily covered with protective nonconducting PCB varnish.
  - sterlind 2y ago
    dumb question but how well do sharpies work in space? the ink diffuses through the felt tip - that doesn't require gravity. wouldn't that work pretty well? also crayons seem like a better bet than pencils - they're still flammable and prone to flaking but at least they're not conductive.
    - mypalmike 2y ago
      Your question piqued my curiosity, so I did some googling... Apparently sharpies do work in space, though NASA seems to prefer the Duro brand of marker. https://airandspace.si.edu/stories/editorial/saga-writing-space https://airandspace.si.edu/stories/editorial/saga-writing-sp...
    - crazygringo 2y ago
      Sharpies and markers generally run out waaay quicker than pens or pencils. They also dry out if you're not careful, and dry out temporarily if you use them for more than a few minutes at a time. Crayons just aren't dark enough, and are too wide. Accurately reading numbers and symbols written in crayon at a normal handwritten size is not something I want to do. Not to mention the constant sharpening.
  - hinkley 2y ago
    And we licensed the pens from a dude who spent a fortune developing them.
- mrguyorama 2y ago
  After Fisher, the pen company, spent their own couple millions to develop a pen that could write in zero gravity, they convinced NASA to use it, and a few years later the Soviets bought 100 of them for their own space program. NASA was never involved in the development of the space pen, though they supposedly had their own effort that was quickly abandoned as it got expensive. Before that they also used pencils. The pen is just a better writing implement in space. It cost $3 in the 60s, with wide availability.
sterlind 2y ago
coal miners carried canaries to warn of CO. chemical weapons workers brought bunnies in cages to monitor nerve gas leaks. it's an old tradition - it's simple, and it works. though why not Geiger counters for radiation? there must be a reason.
- CamperBob2 2y ago
  If there's enough CO to kill a canary, you still have time to get to safety. If there's enough nerve gas to kill a rabbit, you still have time to get to safety. If there's enough radiation to kill a fish, you're a walking dead man... and the 'walking' part is temporary.
  - dudinax 2y ago
    Maybe the fish get less shielding.
    - qup 2y ago
      Maybe it's concentrated in his water
  - postalrat 2y ago
    What if you have a potential worrisome alpha emitter already in water. Keeping some fish in that water might give you heads up when something is going wrong.
    - CamperBob2 2y ago
      Then, lacking the availability of an ISO-standard fish, you should probably use a scintillator or surface-barrier detector. Like everyone else who has to deal with such matters.
  - labster 2y ago
    If you teach a man a fish, he will eat for one lifetime. If you give a man a radioactive fish, he will eat for many half-lives.
lossolo 2y ago
Did you know that mussels and clams are sensitive to changes in water quality and can absorb pollutants? They are often used as bioindicators to detect harmful substances like heavy metals and toxins in the water. They are used in United States and in Europe to check if water is clean.
- hinkley 2y ago
  I remember someone creating a sensing system to see if the shells were open or closed. Given enough mussels, the odds of them all closing at once due to random chance instead of pollution drops to zero.
  - LeifCarrotson 2y ago
    This Tom Scott video? https://youtu.be/i0RkEs3Xwf0 https://youtu.be/i0RkEs3Xwf0 Clams at 2:22.
    - hinkley 2y ago
      I believe Tom is the second time I heard of this, as was the experience of a number of his chattier viewers.

ars 2y ago

Would sterile neutrinos as an oscillation really change anything about dark matter? The total mass of neutrinos doesn't change, just the lepton number.

AnimalMuppet 2y ago
It might mean 20% more neutrinos exist than we think. That would change the total mass of neutrinos. Much more interesting (and not touched on by the article as far as I noticed): The electron neutrino is the "partner" to the electron. The muon neutrino is the partner to the muon, and the tau neutrino to the tau. What's the sterile neutrino the partner to? (Or doesn't it have one, and that's what makes it "sterile"?) If there is a partner to it, does the partner have mass? Does it interact in any way besides gravitationally? If not...
- torrefatto 2y ago
  IIRC, there is another quantum number, the chirality. All the neutrinos measured are left chiral. The sterile neutrino, which does not pair with other lepton, is right chiral.
  - AnimalMuppet 2y ago
    Is that the only possible sterile neutrino? Because if I recall correctly, a right chiral neutrino cannot change into one of the other types, because of the chirality. (That's why it's "sterile".) So either they aren't produced by beta decay, or they are but they can't be captured by gallium, or we're seeing a sterile neutrino in a different sense. ("Sterile" because it can't interact with gallium, but not sterile due to chirality.) If I understand, the conversion of gallium into germanium is exactly a beta interaction. (But I may not understand, because it seems to me that gallium->germanium should emit a neutrino, not absorb one.) So I have a hard time seeing how a neutrino could be emitted by the source, but not absorbed by gallium. I could more readily see it as saying that there's a fourth type of neutrino that they cycle through, and while in that fourth state it can't convert gallium. But that wouldn't be "sterile" in the chirality sense.

Terr_ 2y ago

> sterile neutrinos It's funny when one encounters serious real-world discussion on something previously seen as sci-fi technobabble. In this case, I'm thinking of the Destiny universe, such as this apocalyptic alert from a military AI. [0] > Multiple distributed ISR assets report a TRANSIENT NEAR EXTRASOLAR EVENT. Event duration ZERO POINT THREE SECONDS. Event footprint includes sterile neutrino scattering and gravity waves. Omnibus analysis detects deep structure information content (nine sigma) and internal teleonomy. No hypothesis on event mechanism (FLAG ACAUSAL). Bootstrap simulation suggests event is DIRECTED and INIMICABLE (convergent q-Bayes/Monte Carlo probability approaches 1). No hypothesis on deep structure encoding (TCC/NP-HARD). ______ > In the lab that houses the BEST experiment, fish serve as an early warning system about any leaking radiation. I'm curious how this works, it looks as if there's one central underwater valve and two above-water valves, perhaps supposedly-breathable air is getting bubbled up through the tank? > SAGE used a tank of 57 metric tons of gallium. Some napkin-math [egregious mistake corrected] to visualize how much that is, and I get "45 oil drums". Line item Amt Units Gallium Mass 5.70E+01 metric tons Gallium Mass 5.70E+04 kg Gallium Mass 5.70E+07 grams Liq. Gallium Density 6.10E+00 grams/cm3 Gallium Vol 9.35E+06 cm3 Oil Drum Volume 5.50E+01 gallons Vol Ratio 3.79E+03 gallons/cm3 Oil Drum Volume 2.08E+05 cm3 Gallium Volume 4.49E+01 oil drums ____ [0] https://www.ishtar-collective.net/cards/ghost-fragment-darkness?highlight=%22sterile%20neutrino%22 https://www.ishtar-collective.net/cards/ghost-fragment-darkn...

auspiv 2y ago
double check that math - olympic pool is 50x25x2 meters, or 2500m3. 1 m3 of water is roughly 1 metric ton (1 g/cc = 1 kg/L = 1 t/m3) depending on temperature and such. 57000000g / 5.9 g/cc = 9661017 cc = 9.661m3
- deleted 2y ago
  [deleted]
- Terr_ 2y ago
  Whoops, yeah, made a few mistakes. Next time I'll do the usual and open a throwaway spreadsheet. Also, picking gallium-density from a slightly higher temperature where it's liquid.

bawolff 2y ago

> While Russia’s invasion of Ukraine “has complicated things,” Elliott said, the collaboration between the U.S. and Russia on BEST is still ongoing, for now. Nice to hear in these uncertain times.

geuis 2y ago
How is that "nice"? The fact that 3 years in we are still collaborating with Russia on the ISS and in other scientific programs is deeply disturbing. I get that the ISS is a special circumstance and a difficult knot to unravel. That's an extremely unique situation and it's not worth digging into at length for this situation. Life support onboard for all occupants relies on a continuing collaboration. Beyond the ISS situation we should have completely cut all ties with Russia. They have killed hundreds of thousands of Ukrainians. Stolen children, assaulted women, and killed Ukrainian elderly and children. Not even digging into their internal recruitment policies, but the way they drag innocent Russian civilians into supporting their invasion is worth its own war crimes investigation. Yes, this experiment is interesting and it's intriguing to me. But it's not "nice" when a few physicists are getting results at the expense of all the collective suffering going on right now. I'm generally pragmatic about things, but in this situation cooperation is entirely uncalled for. Meanwhile the US ignores joint efforts with China. They (China) have some interesting things going on right now. For an international space station, it's awful that a Chinese crew hasn't even been invited to the ISS despite allowing numerous rich folks going up for a week long vacation. To be clear, I'm NOT supporting China. Their government is antithetical to a free society and is deeply partnered with Russia, N. Korea, and other states hostile to the EU and US. But they are a major player in humans in space, and it's important to engage them at that level. Again, the ISS is a unique scenario.
- jpgvm 2y ago
  The problem is these joint scientific efforts were and continue to be effective tools to diffuse more dangerous possibilities. In case you have forgotten Russia is still the 2nd largest nuclear power and their arsenal is enough to eliminate pretty much all life on Earth. The war in Ukraine is terrible but don't underestimate how much worse things could get. If things do get worse it's back channels like space collaboration/UN/other symbolic things that can keep people talking enough to not end up cleansing the Earth in nuclear fire. Just because those things are ineffective at stopping a proxy war doesn't mean they aren't worth doing. For the same reason I also agree that China should be welcomed into the international space community. They are flying state of the art rockets and have their own modern space station... you couple that with the fact they too are an increasingly powerful military nation then more collaboration rather than less is the way to go.

qnleigh 2y ago

Is there any reason to think that Gallium would be a particularly good source of sterile neutrinos? Or is it more that if regular neutrinos oscillate into sterile neutrinos, then this would be the first experiment that could detect so at this scale?

pavel_lishin 2y ago
The gallium isn't what's producing the neutrinos; there's a radioactive source that the gallium is being irradiated by, and I believe that's the source: > In an underground lab shielded by a mountain of rock, highly radioactive material sits inside a vat of liquid gallium, blasting out particles called neutrinos that break the gallium down into atoms of germanium.
gus_massa 2y ago
Gallium is not a source of sterile neutrino. Gallium is a good "electonic neutrino" target. The problem is that they only detect the 80% of the "electonic neutrino" that they expect and they have no clue of the cause. One of the posibilities is that the other 20% of the "electonic neutrinos" mutate to "sterile neutrinos" during the trip. (Note that there are 3 types of neutrinos and it's possible that there are also a few types of sterile neutrinos (3 is a good guess).)
- dmurray 2y ago
  I'd still like to ask a version of the same question, is gallium so special that it only makes sense to do this experiment with gallium? If sterile neutrinos cause the production of germanium from gallium to be 80% of what we thought it was, will there be other nuclear reactions that we now don't understand? E.g. a given plutonium reaction produces 100g of uranium, currently consistent with the theoretical model, after sterile neutrinos are confirmed will we be saying hang on, this should only produce 80g of uranium with the new model, something else is wrong? Presumably not, at least with well-understood reactions, so why is gallium so special here?
  - gus_massa 2y ago

jarsdel 2y ago

Given the potential implications of discovering sterile neutrinos, what other anomalies or unexplained phenomena in particle physics might be re-evaluated in light of this new understanding?

kseistrup 2y ago

A Capella Science: Massless (Muse neutrino parody): https://youtu.be/dBxcC8zV46E https://youtu.be/dBxcC8zV46E

keepamovin 2y ago

Could the gallium anomaly be explained by something far more prosaic? For example, in water, there are all kinds of species of different anions and cations present, existing in equilibrium with each other. Water forms complex semi-crystalline structures by virtue of hydrogen bonds. Although they are not true crystals, the supramolecular structures of individual water molecules and the valence species create a sophisticated structure, even in a seemingly homogenous substance. Now, consider if something similar happens with gallium. What if the electron configuration of gallium's orbitals means that gallium, in its liquid form, also has various anions and cations? Moreover, what if gallium can form analogs to hydrogen bonds, leading to semi-crystalline or structured forms? This structured form could provide some shielding to the gallium atoms, making them less likely to be converted via neutrinos to germanium. Instead of impacting a nucleus at the expected rate, the overlapping orbital bonds and electron resonance might offer a form of shielding. This shielding could make the gallium atoms more stable and less reactive, thereby reducing their conversion to germanium. While this idea applies a chemical concept to nuclear chemistry or physics, and may not align perfectly with the traditional views of high-energy particle physicists and astronomers, it offers a potentially more prosaic explanation for the gallium anomaly. This perspective might not have been top of mind for those focused on high-energy interactions and could be worth considering further.

baxtr 2y ago
Unfortunately many physicists believe chemistry is just applied physics. In reality most physicists have no clue of chemistry beyond the H2 molecule. Based on that, your “less prosaic” could be a good candidate for an explanation.
aw1621107 2y ago
> This structured form could provide some shielding to the gallium atoms, making them less likely to be converted via neutrinos to germanium. Instead of impacting a nucleus at the expected rate, the overlapping orbital bonds and electron resonance might offer a form of shielding. This shielding could make the gallium atoms more stable and less reactive, thereby reducing their conversion to germanium. Might this be covered by this bit from the article? > Another proposed explanation was that physicists had miscalculated the probability of neutrinos from the source interacting with the gallium. But in September 2023, Haxton and his colleagues also ruled out this possibility. “You can’t get rid of the anomaly,” he said. Maybe they don't consider the scenario you outlined in their calculations, but I lack the training to understand the paper [0]. In addition, speaking more generally I'd be curious how your proposed mechanism would work physically. Given the size of the nucleus compared to that of the electron cloud, the fact that (known) neutrinos only interact via the weak interaction and gravity, and the range of the weak interaction, a big question to me is how big your proposed effect could have in this case, if any. [0]: https://arxiv.org/abs/2303.13623 https://arxiv.org/abs/2303.13623

jnurmine 2y ago

Gallium likes to form alloys with other metals, does this anomaly happen with the gallium-containing alloys as well?

tlogan 2y ago

Question for experts: If sterile neutrinos exist, would they be the best candidate for dark matter? Additionally, would it be impossible to detect them since they do not interact with anything and possess only mass? EDIT: My reasoning is as follows: - Low-energy neutrinos might not be relativistic. For example, relic neutrinos from the Big Bang, which have a temperature of around 1.95 K, would travel at approximately 4.5% of the speed of light. - I've also read that sterile neutrinos are hypothesized to have a large mass (though I'm not sure). So "slow neutrino" + "not so light like normal neutrino" => dark matter

d_silin 2y ago
All neutrinos are relativistic (moving at almost speed of light) and our current model assumes dark matter is "cold" (moving at relatively slow speeds).
- tlogan 2y ago
  Thank you. I updated my question with my reasoning. But I assume that in order for these sterile neutrinos to be dark matter they need to be really slow ...
  - eigenket 2y ago
    The known (non-sterile) neutrinos are very light, but there's no particular reason a hypothetical sterile neutrino would be.You can cook up sterile neutrinos with very large masses if you want to https://arxiv.org/abs/1303.6912 https://arxiv.org/abs/1303.6912
- raattgift 2y ago
  There is excellent evidence for then-relativistic cosmic neutrinos from the cosmic microwave background acoustic oscillations. As with the CMB, these neutrinos cooled into a "relic" field with the metric expansion. A cooling gas of relativistic neutrinos becomes non-relativistic when the average neutrino momentum becomes comparable to their rest mass. The present cosmic neutrino background (CNB) temperature is about 1.9 kelvins corresponding to ~ 1.7e-04 eV/c^2 which is smaller than some neutrino masses. This is still "hot" compared to Cold Dark Matter, and CNB also only a small fraction of the required CDM energy density. The lightest cosmic neutrino background mass eigenstates could be relativistic at present, so how the CNB is split between (FLRW) radiation and dark matter is ripe for research. It will mostly be "hot" DM because of the heavier, colder species. But not hot enough to leave clusters of galaxies, unlike neutrinos produced by present-day astrophysics (and our own laboratory experiments and nuclear power generation). https://en.wikipedia.org/wiki/Cosmic_neutrino_background https://en.wikipedia.org/wiki/Cosmic_neutrino_background https://bigthink.com/starts-with-a-bang/cosmic-neutrino-background/ https://bigthink.com/starts-with-a-bang/cosmic-neutrino-back...