It is not accurate to say that Albert Einstein was completely against quantum physics. While he did have certain reservations and concerns about some aspects of quantum theory, it is more appropriate to describe his position as being skeptical or critical rather than outright opposition. Einstein played a crucial role in the development of quantum theory, and his contributions were significant, particularly in the field of the photoelectric effect, for which he was awarded the Nobel Prize in Physics in 1921.
However, Einstein did have philosophical and conceptual disagreements with certain interpretations of quantum mechanics, particularly the indeterministic nature of the theory. He is famously known for his statement, "God does not play dice with the universe," expressing his discomfort with the probabilistic nature of quantum theory.
Einstein's skepticism was primarily directed at the Copenhagen interpretation of quantum mechanics, which was the prevailing view at the time. This interpretation, developed by Niels Bohr and his colleagues, emphasized the probabilistic nature of quantum phenomena and the idea that the act of observation or measurement plays a fundamental role in determining the outcome of an event. Einstein, on the other hand, favored a more deterministic worldview, where physical properties have definite values independent of measurement.
Einstein, along with Boris Podolsky and Nathan Rosen, formulated a thought experiment known as the EPR paradox in 1935. This paradox aimed to illustrate what they perceived as a fundamental flaw in the completeness and local realism of quantum mechanics. The thought experiment suggested that quantum mechanics might involve "spooky action at a distance," where information could be transmitted faster than the speed of light, violating the principles of special relativity.
Despite his reservations about certain aspects of quantum theory, it is worth noting that Einstein's criticisms did not lead to the rejection of quantum mechanics. The Copenhagen interpretation and other interpretations of quantum mechanics have been widely accepted and successfully applied in numerous experiments. Einstein's views stimulated important debates and discussions, contributing to the development of our understanding of the quantum world.