[FOM] Directions for Computability Theory Beyond the PureMathematical
joeshipman@aol.com
joeshipman at aol.com
Wed May 17 17:50:36 EDT 2006
There is nothing to prevent a more general physical theory than we
currently have entailing that certain physically measurable
dimensionless constants (such as the fine-structure constant, or lepton
mass ratios) are DEFINABLE but NONRECURSIVE real numbers. If sich a
theory were correct, one form of Church's thesis would be false and we
could, by an effective procedure, obtain a nonrecursive sequence (and
thereby gain physical knowledge of mathematical facts which ZFC cannot
prove, since any nonrecursive definable sequence has elements whose
value ZFC does not settle).
The evidence for such "knowledge" would not be mathematical but
physical, we would believe those mathematical facts for the same reaosn
we believe physical theories to be correct. Godel envisioned this
possibility.
-- JS
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