Massless

I, I map out a heavy path in life

But some things are massless

And take a different road



And they, they ride a null-length vector flow

Cause when you are massless

Your worldline's always null



That's why they fly at the speed of light

And as they fly they perceive no time

They don't change



Now you need to know about neutrinos

We thought they were massless

Purely Weyl chiral



Then Super-K and SNO confirmed they oscillate

And cannot be massless

Though they're very close



But they don't fly at the speed of light

For as they fly they proceed through time

And they change



Now they're defined by a CKM

Mapping from mass to flavour kets

And now we ask why do they seem so light?

And now we're not sure why but we theorize

A see-saw!



Sudbury's spherical screen

Resolved the mystery

Of neutrino oscillation

Tau, mu and electron

For none is...



Massless