tholins- what are they?
AS far as I can make out no one knows what "tholins' are; it was coined from a greek root meaning 'muddy' and is simply any kind of reddish chemically intractable organic goop that might be found on the surface/atmosphere of a planet - originally it was just the crud that sticks to the glassware in a Miller-Urey experiment; and from this non-definition somehow life is supposed to emerge. Does anyone have a more rigorous definition?