[spiritbear14]

what Crick means, I believe, is that since multiple codons can code for a single amino acid the information or entropy in that set of codons is larger than the information transferred to the protein creating a many-to-one interaction. This means that you could, in principle, create an RNA sequence 'A' that codes for the same protein as another sequence 'B', but they are discretely different implying that this difference could be exploited to send different information back from proteins to this different RNA sequence. Kinda a reach in my opinion and not really important as proving you could do that doesn't bring us any closer to understanding what nature actually does. I guess the most interesting result with this research is analyzing the thermodynamics of this reverse interaction as an argument as to why nature has not evolved a way to do this.

[robwwilliams]

Codons for the same amino acid can have very different efficiencies due to use of different tRNAs. And tRNA abundance varies across organelles (mitochondria), cells, and organs. It is not just protein sequence but also protein abundance and translational progressivity/speed/efficiency and completeness. Reverse translation would not recover these aspects.