Einstein's understanding that the speed of light is constant and independent of the observer is not directly related to the observer effect in quantum mechanics. These are two separate concepts in physics.
Einstein's theory of special relativity, developed in 1905, proposed that the laws of physics are the same in all inertial reference frames and that the speed of light in a vacuum is constant for all observers, regardless of their relative motion. This theory revolutionized our understanding of space, time, and motion.
On the other hand, the observer effect, also known as the measurement effect, refers to the idea that the act of observing or measuring a quantum system can disturb or alter the system being observed. This effect is specific to the microscopic world of quantum mechanics and is not directly related to the macroscopic world described by special relativity.
The observer effect in quantum mechanics arises from the fundamental nature of quantum systems, where the act of measurement necessarily involves interaction with the system, leading to a change in its state. This effect is a consequence of the wave-particle duality and the probabilistic nature of quantum mechanics.
While both concepts involve the role of the observer, they address different phenomena in different domains of physics. Einstein's understanding of the relativity of the speed of light is a valid and well-established description of the behavior of light and other objects with respect to different observers in the framework of special relativity. The observer effect, on the other hand, pertains to the peculiarities of quantum systems and their measurement.