[Correspondence]

Date:
1972-1973
Reference:
PP/CRI/H/5/7/2
Catalogue details

Licence: In copyright

Credit: [Correspondence]. Source: Wellcome Collection.

    1/31
    October 5, 1973 Dr. Carl Sagan ICARUS Center for Radiophysics and Space Research Cornell University Ithaca, New York 14850 Dear Carl: The letter from Frieden like the paper that you sent me con tains two points—one perhaps valid and the other mistaken. Perhaps I should spell out for you in more detail the argument about sea water. In the presence of free oxygen, molybdenum is oxidized to the hexavalent state as molybdate. The molybdates are water soluble and could easily be weathered out of rock, and hence accumulate in the oceans. It is my impression, although I am not an expert, that in a reducing environment molybdenum would have been present as a highly insoluble sulphide or lower oxide. Under such conditions there is no particular reason why it should have accumulated in the oceans to any greater extent than nickel or chromium. If the atmo sphere of the Earth was reducing when life evolved, it is not at all clear to me that molybdenum would have been abundant, as your various authors claim. However, I think their argument is valid, and deserves to be published with these reservations. Frieden has completely missed the point in his second comment. Our argument is that the code would not be universal at the site of the primary origin of life, but would become universal if all organisms at a secondary site were derived from a single advanced organism trans» ported from the primary site. Yours sincerely, Leslie E. Orgel Post Office Box 1809, San Diego. California 92112 • Telephone (714) 453-4100