The JUNO detector, a huge sphere full of 20,000 tonnes of transparent organic goop, is detecting antineutrinos produced by two nuclear reactors each located the same distance away. After just 2 mont...
There are 3 kinds of neutrinos with different masses - they're called 'mass eigenstates'. But there are also 3 kinds of neutrinos that interact differently with matter - they're called 'flavor eigenstates'. And the mass eigenstates are not the same as the flavor eigenstates!
Instead, each mass eigenstate is a kind of blend - technically, a linear combination - of all 3 flavor eigenstates. And vice versa: each flavor eigenstate is a blend of all 3 mass eigenstates.
When a neutrino gets created by some process involving matter, it starts out in a definite flavor eigenstate. But as it shoots through empty space, it oscillates between different flavor eigenstates. If we could create a neutrino in a definite mass eigenstate, it would stay like that as it shoots through space. But we can't.
The three mass eigenstates have boring names: ν₁,ν₂,ν₃. The first has mass m₁, the second has m₂... okay, you probably get it.
The three flavor eigenstates have wacky names: the electron neutrino, the mu neutrino and the tau neutrino. This was back when physicists were more creative.
And here's the cool part:
• the ν₁ is 68% electron neutrino, 10% mu neutrino and 22% tau neutrino. These are the probabilities that if you let a ν₁ interact with matter that it will interact in three different ways.
• the ν₂ is 30% electron, 36% mu and 34% tau. This is the most "democratic" of the mass eigenstates.
• the ν₃ is 2% electron, 48% mu and 50% tau.
These numbers took a shitload of work to measure. JUNO will help measure them more accurately - or more precisely, some numbers you can use to calculate these numbers.
Nobody knows why reality works this way!!! 😧
(2/n, n = 2)
https://arxiv.org/abs/2511.14593
Instead, each mass eigenstate is a kind of blend - technically, a linear combination - of all 3 flavor eigenstates. And vice versa: each flavor eigenstate is a blend of all 3 mass eigenstates.
When a neutrino gets created by some process involving matter, it starts out in a definite flavor eigenstate. But as it shoots through empty space, it oscillates between different flavor eigenstates. If we could create a neutrino in a definite mass eigenstate, it would stay like that as it shoots through space. But we can't.
The three mass eigenstates have boring names: ν₁,ν₂,ν₃. The first has mass m₁, the second has m₂... okay, you probably get it.
The three flavor eigenstates have wacky names: the electron neutrino, the mu neutrino and the tau neutrino. This was back when physicists were more creative.
And here's the cool part:
• the ν₁ is 68% electron neutrino, 10% mu neutrino and 22% tau neutrino. These are the probabilities that if you let a ν₁ interact with matter that it will interact in three different ways.
• the ν₂ is 30% electron, 36% mu and 34% tau. This is the most "democratic" of the mass eigenstates.
• the ν₃ is 2% electron, 48% mu and 50% tau.
These numbers took a shitload of work to measure. JUNO will help measure them more accurately - or more precisely, some numbers you can use to calculate these numbers.
Nobody knows why reality works this way!!! 😧
(2/n, n = 2)
https://arxiv.org/abs/2511.14593