"Jeff Wisnia" wrote

My inquiring mind just asked me why the preponderance of threaded
fasteners, jar lids and stuff have right hand threads. (Both above and
below the earth's equator. G)


The advantage to making most threads in the world have the _same_ handedness is
obvious. The reason we _call_ the predominant type "right-handed" is probably
because most people are right-handed. I mean, think about it: what is it about
the actual geometry of the helix that screams "right" or "left"?

Ben Franklin had a 50/50 chance to designate "positive" and "negative" in such a
way that the electron, the thing that usually moves when current flows, would be
_called_ "positive" a century later. He guessed "wrong", and we ended up with
some extra minus signs in the equations of physics. Likewise, the form of helix
we commonly use for screws could have been _called_ either "right" or "left".
Since the universe turns out to be weakly "left-handed" by the definition we
chose for _screws_, you could say that whoever named screws got it "wrong" too
:-)

-- Tony P.