The original version of this story appeared in Quanta Magazine.
After her adventures in Wonderland, the fictional Alice stepped through the mirror above her fireplace in Lewis Carroll’s 1871 novel Through the Looking-Glass to discover how the reflected realm differed from her own. She found that the books were all written in reverse, and the people were “living backwards,” navigating a world where effects preceded their causes.
When objects appear different in the mirror, scientists call them chiral. Hands, for instance, are chiral. Imagine Alice trying to shake hands with her reflection. A right hand in mirror-world becomes a left hand, and there’s no way to align the two perfectly for