left, right and wrong

Painting: by René Magritte

"Flash back three or four billion years -- Earth is a hot, dry and lifeless place. All is still. Without warning, a meteor slams into the desert plains at over ten thousand miles per hour. With it, this violent collision may have planted the chemical seeds of life on Earth. [...] 'These meteorites were bringing in what I call the "seeds of chirality,"' stated Breslow. 'If you have a universe that was just the mirror image of the one we know about, then in fact, presumably it would have right-handed amino acids. That's why I'm only half kidding when I say there is a guy on the other side of the universe with his heart on the right hand side.'" — Science Daily
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"Biochemistry is the story of shapes, and this is its strange plot twist. Lots of molecules come in multiple conformations -- sticking together the same atoms can sometimes yield different three-dimensional structures that are mirror images of each other, a property called chirality. Indeed, most of the basic molecules of life, from the nucleic acids of the genome to the amino acids of the proteins, have mirror-image versions. And all cells have enzymes called isomerases, which flip certain molecules into their mirror versions. But for some reason, in the machinery of living things on Earth, one side of the mirror remains almost wholly unused.
"[...] create a life-form that runs on an operating system different from our own, based on mirror-image versions of Earthly proteins and DNA. Let these alien cells grow and mutate, and see how they survive. If it worked, those new cells — Church called them 'mirror life' — could answer one of the deepest questions about the origin of life, not just here on Earth but everywhere in the universe." — John Bohannon, Wired UK
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