It was an allusion to an issue in physics, which I thought the OP might appreciate, even though he regrettably
read maths and philosophy rather than physics.
Suppose you are trying to describe to someone over the telephone which is left and which is right - in this case, which is the left speaker and which is the right. You're on the phone so you can't point. Everything you can describe is relative to something else - which side of the orchestra the violins sit on, which side of the road we drive on, which side of our body the heart is. So how do you know that their entire world is not reversed compared to ours? You could send them a labelled drawing by a fax, or a jpeg or a gif, but how do you tell them which side of the picture the bits start?
Under classical physics, we used to think that there was no way it was possible to check whether a remote person has the same left and right as you - left and right have meaning as opposites of each other but, in absolute terms, are arbitrary. In classical physics, the violins in a distant alien orchestra could sit on the other stage of the stage, they could still call it "right", and neither we nor they could ever tell that it wasn't the same as ours. In physicists' jargon, this is called conservation of all properties under reversal of parity, or "parity conservation".
Then along came quantum physics, and sometime in the 1950s (my undergraduate physics is too long ago to remember exactly and I can't be bothered to look it up on Wiki), some very clever people discovered particles (the k muon was IIRC the first) which, when they decay, chuck out one of the particles they decay into in one direction rather than the other, and that gives us a basis for defining left and right. We tell our aliens over the phone to observe the decay of k muons, and that direction is what we call
Left. In the jargon again, that is called breaking (or violation) of the combined charge and parity symmetry, or CP violation.
Disclaimer: I last did this stuff as second year undergraduate physics thirty years ago, the physics I do now is different, and I may have got this all wrong. But who cares?
