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There's a weak connection, but to me it reads like clever marketing. Actually finding chirality in space would be extremely cool in that it would mean one of t

by dguest 2y ago

There's a weak connection, but to me it reads like clever marketing. Actually finding chirality in space would be extremely cool in that it would mean one of two things: - the panspermia hypothisis is correct, or - some non-biological process creates chiral molecules. Physics itself has plenty of chiral processes, but they only show up in the weak interaction. As the name implies, the weak interaction is really really weak and essentially doesn't exist on the energy scales of molecular interactions. So chirality would be a bit of a smoking gun for panspermia. On the other hand, not finding chirality just means we don't have a smoking gun. There might be another asteroid flying around that is 100% chiral, or maybe 50% of them and we were just unlucky. The briefing joins the point about chirality with evidence against panspermia, but really that might miss the point. Chiral or not, abundant amino acids in space means that one of the many steps to create life is relatively simple. If we could show that every subsequent step is simple that would be a big blow against panspermia. But in that case ruling out panspermia would be pretty cool, since it would suggest that life exists everywhere.

close04 2y ago
> the panspermia hypothisis is correct What I don't understand is why would chirality and panspermia be so tightly linked. The data right now still leaves every option on the table just because having any ratio of chiral molecules doesn't have to define how life evolves. It can't answer whether those molecules formed on Earth or hitched a ride on an asteroid, or life itself formed here or was brought here. We can assume that in a soup with balanced proportions of each chirality, the left handed molecules created a self replicating mechanism (some definition of "life") first or faster than right handed molecules, either accidentally or because some yet undiscovered advantage. Whether this happened on Earth, or was brought to Earth by one or more of the millions of asteroids is hard to prove.
- dguest 2y ago
  That's a good point. You also need consistency in the chirality on asteroids (also with earth). If we find one asteroid with chirality that doesn't match earth, it's good evidence that self replication just happens spontaneously rather than being seeded. If we find only one asteroid with one chiral molicule that does match earth, that supports panspermia very weakly: it still might just be random chance. But multiple matching molecules, on multiple asteroids, starts to seem like evidence for a common source. On the other hand: If we find multiple molecules with matching chirality, on multiple asteroids, and none of them match with earth... well, we should probably start preparing for the invasion.
marcosdumay 2y ago
> There might be another asteroid flying around that is 100% chiral, or maybe 50% of them and we were just unlucky. The more asteroids we look and not find any asymmetry, the more evidence we have that life never existed on any of them.
kjkjadksj 2y ago
The thing with panspermia is if you believe in emergent life you almost have to believe in the possibility of panspermia as well. It is why NASA uses clean rooms after all.

by dguest 2y ago

close04 2y ago

> the panspermia hypothisis is correct What I don't understand is why would chirality and panspermia be so tightly linked. The data right now still leaves every option on the table just because having any ratio of chiral molecules doesn't have to define how life evolves. It can't answer whether those molecules formed on Earth or hitched a ride on an asteroid, or life itself formed here or was brought here. We can assume that in a soup with balanced proportions of each chirality, the left handed molecules created a self replicating mechanism (some definition of "life") first or faster than right handed molecules, either accidentally or because some yet undiscovered advantage. Whether this happened on Earth, or was brought to Earth by one or more of the millions of asteroids is hard to prove.

dguest 2y ago
That's a good point. You also need consistency in the chirality on asteroids (also with earth). If we find one asteroid with chirality that doesn't match earth, it's good evidence that self replication just happens spontaneously rather than being seeded. If we find only one asteroid with one chiral molicule that does match earth, that supports panspermia very weakly: it still might just be random chance. But multiple matching molecules, on multiple asteroids, starts to seem like evidence for a common source. On the other hand: If we find multiple molecules with matching chirality, on multiple asteroids, and none of them match with earth... well, we should probably start preparing for the invasion.

marcosdumay 2y ago

> There might be another asteroid flying around that is 100% chiral, or maybe 50% of them and we were just unlucky. The more asteroids we look and not find any asymmetry, the more evidence we have that life never existed on any of them.

kjkjadksj 2y ago

The thing with panspermia is if you believe in emergent life you almost have to believe in the possibility of panspermia as well. It is why NASA uses clean rooms after all.