[shartshooter]

I read a comment on HN or Reddit a while back about how some molecules were found in a meteorite that were left-handed where every molecule on earth is right-handed or something to that extent.

If my memory serves it was as if molecules fit together like a lock and key except this molecule's key/lock combo was inverted.

Apologies if I'm bungling it up but it felt as though it was significant. As if the molecule found was unlike any molecule on earth due to its lock/key orientation.

[anorwell]

I think the homochirality of amino acids might be what you're referring to:

https://en.wikipedia.org/wiki/Chirality_(chemistry)#In_bioch...

"The origin of this homochirality in biology is the subject of much debate.[12] Most scientists believe that Earth life's "choice" of chirality was purely random, and that if carbon-based life forms exist elsewhere in the universe, their chemistry could theoretically have opposite chirality. However, there is some suggestion that early amino acids could have formed in comet dust. In this case, circularly polarised radiation (which makes up 17% of stellar radiation) could have caused the selective destruction of one chirality of amino acids, leading to a selection bias which ultimately resulted in all life on Earth being homochiral."

[dekhn]

I've also heard some scientists say that parity breaking could explain the origin of homochirality. Personally, I'm happier with the "random chance" hypothesis.

[jleahy]

You are talking about chirality. Biologically produced molecules are all of the same "handedness", but molecules produced by other means (normal chemical reactions) tend to have 50/50 chance to be either handedness (although selective reactions are possible).

So you'd expect to see both at a 50/50 ratio in a meteorite, if you see any at all. That's just chemistry.

[throwGuardian]

Why 50/50? It should take on the statistics of causations of chirality. And based on that, one might be able to guess the exact location and orientation of the meteorite when these chemicals were formed

[kens]

Interestingly, the protein described in the article is made out of glycine, the only amino acid that doesn't have handedness (i.e. it is achiral). So you can't tell if this protein is terrestrial or not based on its handedness.