From the (captions under photographs) in the article:
'Located 2.1 kilometers underground in the Creighton mine in Ontario, Canada, the Sudbury Neutrino Observatory’s detector (left) was filled with “heavy” water, which features deuterium in place of hydrogen atoms. Its findings provided evidence that neutrinos can change, or “oscillate,” between different flavors.'
"China’s Jiangmen Underground Neutrino Observatory (JUNO), seen here under construction in 2023, is currently the world’s largest neutrino detector. It began collecting data in August 2025; one of its main goals is to determine the outstanding mystery of how heavy each flavor of neutrino is."
The second caption implies that some "flavors" of neutrino may be heavier than other flavors. The first caption says that neutrinos oscillate between different flavors. If the first caption is correct, then wouldn't each flavor of neutrino be just as heavy as the others?
That would be a wild thing to accomplish, given that neutrinos are created at relativistic speeds, have virtually zero mass, and don’t react with anything but gravity and the weak force.
Whatever gravity “trap” you make is going to pale in comparison to the gravity wells around us (earth, the sun, etc) and the weak force scales exponentially with energy. So a slow-moving neutrino would interact even less with the weak force than a relativistic one.
Could a physicist comment on this? I've been reading on the CNO cycle [1], where it says neutrinos produced in the beta-decay steps can have any share of the resulting energy. Does it mean the Sun is shrouded in a rarefied cloud of such low-energy neutrinos which failed to achieve escape velocity?
The Super Kamiokande had a terrible engineering event where the delicate sensor bulbs shattered, and the pressure delta from one shattering caused neighbors to shatter, in a chain reaction that destroyed large amounts of sensors.
>Neutrinos come in three different “flavors” (electron, muon, and tau) and can oscillate, or switch, between them. To do so, neutrinos must have mass
Why? What actually is "Neutrino oscillation" and why does it require the neutrino have mass? My already feeble understanding of particle and quantum physics always breaks down at these sorts of points.
How are we sure that the neutrino is in fact a single particle that should use the same sort of mathematical machinery as all others? Am I even asking a question that means something? I know literally every physicist ever graduated has spent time thinking everything in physics is wrong and tried poking at such ideas, so I guess I'm more interested in what those kids end up finding that brings them back to "No this makes more sense" of neutrinos in the standard model.
For a particle to "oscillate", it must "experience" time. All massless particles travel at the speed of light. As a consequence of special relativity, they don't "experience" time.
Therefore, neutrinos must be traveling slower than light, and they must have mass.
It's kind of useful to only think of these things as "particles" in a nominal sense. You need to adopt a "quantum imagination". I tend to think of them as a wave or field of probabilities of energy. It sounds weird, but similar to "spin", "flavour" describes a particular relationship between waves or fields of probabilities of energy as it moves through space over time.
A simplified summary: The discovered mass emerges out of this relationship between detection and probability.
This is making it sound way more complicated than it is. Sibling comment is much better. Thing changes over time -> thing experiences time -> it's not going the speed of light -> it has mass.
There is a good exhibit on this at the Miraikan in Odaiba, Tokyo. Detecting things and proving we detected what we detected we previously couldn't is always a fascinating exercise, especially whilst so much matter is still unrecognised.
HN automangled the title, should have a “how” at the beginning. The change makes the headline sound like this is news, but it’s just a description of neutrino detectors.
From the (captions under photographs) in the article: 'Located 2.1 kilometers underground in the Creighton mine in Ontario, Canada, the Sudbury Neutrino Observatory’s detector (left) was filled with “heavy” water, which features deuterium in place of hydrogen atoms. Its findings provided evidence that neutrinos can change, or “oscillate,” between different flavors.'
"China’s Jiangmen Underground Neutrino Observatory (JUNO), seen here under construction in 2023, is currently the world’s largest neutrino detector. It began collecting data in August 2025; one of its main goals is to determine the outstanding mystery of how heavy each flavor of neutrino is."
The second caption implies that some "flavors" of neutrino may be heavier than other flavors. The first caption says that neutrinos oscillate between different flavors. If the first caption is correct, then wouldn't each flavor of neutrino be just as heavy as the others?
For anyone wondering about the title, by "trap" they mean "detect destructively": there are no stable neutrinos in a bottle in this article.
That would be a wild thing to accomplish, given that neutrinos are created at relativistic speeds, have virtually zero mass, and don’t react with anything but gravity and the weak force.
Whatever gravity “trap” you make is going to pale in comparison to the gravity wells around us (earth, the sun, etc) and the weak force scales exponentially with energy. So a slow-moving neutrino would interact even less with the weak force than a relativistic one.
What if you make the trap move at relativistic speed?
Damn it. Heart rate sky-rocketed from excitement.
Could a physicist comment on this? I've been reading on the CNO cycle [1], where it says neutrinos produced in the beta-decay steps can have any share of the resulting energy. Does it mean the Sun is shrouded in a rarefied cloud of such low-energy neutrinos which failed to achieve escape velocity?
[1] https://en.wikipedia.org/wiki/CNO_cycle
Wonderful pictures!
The Super Kamiokande had a terrible engineering event where the delicate sensor bulbs shattered, and the pressure delta from one shattering caused neighbors to shatter, in a chain reaction that destroyed large amounts of sensors.
https://www.youtube.com/watch?v=YoBFjD5tn_E
Unrelated:
>Neutrinos come in three different “flavors” (electron, muon, and tau) and can oscillate, or switch, between them. To do so, neutrinos must have mass
Why? What actually is "Neutrino oscillation" and why does it require the neutrino have mass? My already feeble understanding of particle and quantum physics always breaks down at these sorts of points.
How are we sure that the neutrino is in fact a single particle that should use the same sort of mathematical machinery as all others? Am I even asking a question that means something? I know literally every physicist ever graduated has spent time thinking everything in physics is wrong and tried poking at such ideas, so I guess I'm more interested in what those kids end up finding that brings them back to "No this makes more sense" of neutrinos in the standard model.
Disclaimer: I'm not a physicist.
For a particle to "oscillate", it must "experience" time. All massless particles travel at the speed of light. As a consequence of special relativity, they don't "experience" time.
Therefore, neutrinos must be traveling slower than light, and they must have mass.
It's kind of useful to only think of these things as "particles" in a nominal sense. You need to adopt a "quantum imagination". I tend to think of them as a wave or field of probabilities of energy. It sounds weird, but similar to "spin", "flavour" describes a particular relationship between waves or fields of probabilities of energy as it moves through space over time.
A simplified summary: The discovered mass emerges out of this relationship between detection and probability.
This is making it sound way more complicated than it is. Sibling comment is much better. Thing changes over time -> thing experiences time -> it's not going the speed of light -> it has mass.
There is a good exhibit on this at the Miraikan in Odaiba, Tokyo. Detecting things and proving we detected what we detected we previously couldn't is always a fascinating exercise, especially whilst so much matter is still unrecognised.
HN automangled the title, should have a “how” at the beginning. The change makes the headline sound like this is news, but it’s just a description of neutrino detectors.
Rehowed now. Thanks!
Now howed, brown cow?