Richard Clark wrote:
'The velocity of a point that contains no information nor energy."

The topic of "phase shift" relates to alternating electrical current,
that is volts and amps. These are essential to energy and they are
represented by symbols which are manipulated to solve our problems. A
sinusoidal wave is the symbol of the periodic variation of electrical
properties with time. Volts and amps taken in-phase represent real
energy.

All points on a sinusoidal traveling wave move with the same velocity
past a fixed point. So, to determine the velocity of the motion, choice
of a particular point on the wave, be it zero or peak value, no matter
where the wave travels, or how attenuated, is always the zero or peak
value of the alternation. For velocity, choice of the particular point
to use is immaterial.

The symbol of the wave contains the information. The wave itself
contains the energy.

Best regards, Richard Harrison, KB5WZI