From Tam Anderson
A left-handed neutrino with mass will appear right-handed, Amanda Gefter writes, if you travel past it, turn around and look back at it (20 January, p 26). But turning around is forbidden by very special relativity.
I know I am out of my depth here, but surely if the spacecraft had a rear-facing observation window there would be no need for it to turn around.
Kirkcaldy, Fife, UK
