If only dimensionless constants are physically meaningful, and both Planck's constant, $h$, and the speed of light, $c$, are in the denominator of the expression for the fine structure constant, $\alpha$, then is there any way of distinguishing, by measurements or experiments, between an increase of $h$ and an increase of $c$ (assuming a definition of $c$ in terms of a meter rod, rather than itself)?
Answer
What Duff says makes sense. Only a change in a dimensionless combination of units can be detected.
The argument seems to be that every physical constant (unit) must be defined and measured in terms of others. So we cannot tell if a change is in the unit being tested or one of the units which we assume to be constant. Which set of units could have changed depends on how the unit in question is defined.
No comments:
Post a Comment