13
Neutrinos Oscillate and Hence They Weigh
Oscillation is a day-to-day phenomenon. When you take little children into
the park and they go on the swing, the swing goes back and forth and that is
called oscillation. The swing oscillates because of the force of gravity pulling it
down when it stops at its highest point. Without the force of gravity, the swing,
once pushed, instead of oscillating back and forth would just go around the
pole in big circles with the strings remaining rigid. That would not be much
fun since the child sitting on the swing would be upside down at the top,
but would not come down, since there would be no gravitational force to pull
him or her down. There always has to be some force for the oscillation to take
place. Thus, just like gravitational force makes the swing go back and forth and
makes it oscillate, it follows that any oscillation phenomenon is an indication
of the existence of a force of some kind.
13.1 From Oscillating Swing to Oscillating
Neutrino
One could view the up going and the down coming swings as two states
of the same swing. The states of coming down of the swing and the up
going of the swing can be thought of as the mixing of two states caused by
gravity. Hence, gravity can be thought of as converting one state to another.
In particle physics (and in quantum mechanics), a particle is represented by a
state, and oscillations can therefore be thought of as resulting from two states
or two particles when they mix with each other due to a force. In addition,
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer
Nature Switzerland AG 2021
R. N. Mohapatra, The Neutrino Story: One Tiny Particle’s Grand Role in the Cosmos,
https://doi.org/10.1007/978-3-030-51846-2_13
91
Neutrinos Oscillate and Hence They Weigh
Oscillation is a day-to-day phenomenon. When you take little children into
the park and they go on the swing, the swing goes back and forth and that is
called oscillation. The swing oscillates because of the force of gravity pulling it
down when it stops at its highest point. Without the force of gravity, the swing,
once pushed, instead of oscillating back and forth would just go around the
pole in big circles with the strings remaining rigid. That would not be much
fun since the child sitting on the swing would be upside down at the top,
but would not come down, since there would be no gravitational force to pull
him or her down. There always has to be some force for the oscillation to take
place. Thus, just like gravitational force makes the swing go back and forth and
makes it oscillate, it follows that any oscillation phenomenon is an indication
of the existence of a force of some kind.
13.1 From Oscillating Swing to Oscillating
Neutrino
One could view the up going and the down coming swings as two states
of the same swing. The states of coming down of the swing and the up
going of the swing can be thought of as the mixing of two states caused by
gravity. Hence, gravity can be thought of as converting one state to another.
In particle physics (and in quantum mechanics), a particle is represented by a
state, and oscillations can therefore be thought of as resulting from two states
or two particles when they mix with each other due to a force. In addition,
© The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer
Nature Switzerland AG 2021
R. N. Mohapatra, The Neutrino Story: One Tiny Particle’s Grand Role in the Cosmos,
https://doi.org/10.1007/978-3-030-51846-2_13
91