What did Einstein say about quantum physics?

Hint: Two of the founding fathers of Quantum Theory, Niels Bohr and Max Planck, both earned the Nobel Prize in Physics for their work on quanta. Because he represented light as quanta in his theory of the Photoelectric Effect, for which he earned the Nobel Prize in 1921, Einstein is regarded as the third inventor of Quantum Theory.

Complete answer:
Quantum physics, Einstein thought, was a method to describe nature in terms of subatomic particles, but he questioned whether it was a good basis for explaining all of physics. Everything, he felt, is certain and can be calculated precisely. He was opposed to quantum theory's uncertainty. Light is made up of photons, which are energy packets, as stated by Einstein. The quantum theory of light described and demonstrated this notion. Light should be considered as both a wave and a particle, according to Einstein. Photons of light, he said, may act as both particles and waves at the same time (wave-particle duality). He demonstrated the duality of light.
Quantum Theory was seen by Einstein as a way to understand Nature on an atomic level, but he questioned whether it provided "a suitable basis for the whole of physics." He believed that accurately explaining reality necessitated making strong predictions and then making firsthand observations. Individual quantum interactions, on the other hand, cannot be witnessed directly, leaving quantum physicists with no alternative but to estimate the likelihood of occurrences occurring. Niels Bohr, a scientist, challenged Einstein and advocated for Quantum Theory. He claimed that simply indirectly seeing the atomic level alters quantum interactions' outcomes. Quantum predictions based on probability, according to Bohr, properly explain reality.

Note:
The general theory of relativity is a generalisation of Special Relativity and Newton's Law of Universal Gravitation, which describes gravity as a space-time characteristic. It is the geometric theory of gravity, which was first published in 1915. General relativity is another name for the General Theory of Relativity. In contemporary physics, the general theory of relativity provides the current account of gravity.