RUTA
Science Advisor
- 1,492
- 531
Planck's constant h appears in Planck's radiation law, the Planck-Einstein relationship, and Einstein's photoelectric equation, for example. In that sense, it is a fundamental constant of Nature. As Weinberg points out, measuring an electron's spin "is a measurement of a universal constant of Nature, h." Thus, Information Invariance & Continuity applied to the electron spin measurement (a qubit) means everyone must measure the same value of h, regardless of their relative Stern-Gerlach magnet orientations. Reads just like the light postulate and is justified the same way, too.vanhees71 said:Of course, QT must be compatible with the spacetime model you use and that's why you come to unitary ray representations of the Galilei or Poincare group for the Newtonian and special-relativistic spacetime model, and ##\hbar## is a scalar parameter, because it's just an arbitrary conversion factor to define the SI units.