Is the universe right-left oriented

Answer 1

If our Universe were PERFECTLY symmetrical between left and right, that would mean no experiment could be performed that would distinguish between these two directions. This is called "chiral" symmetry.

Although sub-atomic particles do not actually spin, the terminology "left-handed" spin means particles that spin "clockwise" when viewed from the "top." Think of your left hand giving the "thumbs up" sign (my apologies if, in your culture, this gesture is obscene) -- your curled fingers would represent how the particle is spinning, while your thumb would represent the "top" of the particle.

Again, if our Universe had perfect chiral symmetry, then no interaction would have any preference for particles with left-handed spin or those with right-handed spin.

About fifty years ago, theory predicted -- and experiments showed -- that the weak interaction has, in some cases, a SMALL preference for left-handed spin.