Energy of the waves during interference
Consider two forces F1 and F2 of equal magnitudes and opposite directions acting on a point. The combined effect (vector sum) of the forces on the point is zero.
Consider two waves y1 and y2 of equal amplitudes and opposite directions, passing through a point. The combined effect (vector sum) of the waves on the point is zero.
Is there something different?
Yes, one thing is different.
The forces are applied by two material bodies, for example our hands.