First a little context about what Advaita Vedanta is.
It is a philosophical and spiritual tradition within Hinduism, but it is not one of the Vedas or Upanishads. The Upanishads are a collection of ancient Indian texts that are considered the concluding part of the Vedas.
The Upanishads explore various philosophical and metaphysical concepts and are a significant source of spiritual knowledge in Hinduism.
Advaita Vedanta, on the other hand, is a specific school of Vedanta philosophy that was founded by Adi Shankaracharya in the early medieval period. It is based on the interpretation of the Upanishads and other Hindu scriptures.
Advaita means non-dual, not two.
Advaita Vedanta said that this world is ‘Maya’ or an illusion or not real. It is because of our ‘Avidya’ or ignorance that we mistake this world for real. It is due to the inability of our senses to see beyond this material world that we mistake this world for real.
Now how are Quantum Physics and Advaita Vedanta similar?
Unity and Interconnectedness: Both quantum mechanics and Indian philosophy emphasize the interconnectedness of all things. In quantum mechanics, the concept of entanglement illustrates how particles can become correlated and interdependent, regardless of the distance separating them.
In Indian philosophy, the idea of the interconnectedness of all beings and the oneness of the ultimate reality (Brahman) reflects a similar notion.
Non-Duality and Superposition: The principle of superposition in quantum mechanics, where quantum systems can exist in multiple states simultaneously, shares some similarities with the non-dualistic philosophy found in Indian thought. To exist in multiple states is an illusion.
In both cases, the fundamental reality is seen as singular, and the apparent multiplicity or duality is considered illusory.
Unity of Consciousness: Some interpretations of quantum mechanics suggest that consciousness may play a fundamental role in the nature of reality.
Erwin Schrodinger, in his book “My view of the world”, wrote
"In all the world, there is no kind of framework within which we can find consciousness in the plural; this is simply something we construct because of the temporal plurality of individuals, but it is a false construction”
Advaita Vedanta emphasizes this idea of a singular, universal consciousness (Atman/Brahman) that underlies all individual consciousness.
Observer Effect: The Double-Slit experiment proved that an electron/photon can behave both like a particle and a wave. It behaves like a particle when observed and as a wave when not observed.
And look at what Advaita Vedanta says: It is the observer that brings the universe into existence otherwise universe does not exist as we know it.
For eg. when a person dreams then it is due to the dreamer that the dream exists, if there is no dreamer then the dream vanishes.
It's important to note, however, that the parallels between quantum mechanics and Indian philosophy are not exact, and there is ongoing debate about the philosophical implications of quantum theory. The connections are a matter of interpretation.
But one thing is for certain in my mind. Science may take years to prove what had been written or said in the Indian Philosophy. But both will surely merge at a mutually agreed conclusion.