@Firefly said in What is reality ?: it's a philosophical aspect* of Theoretical physics. However, there is a difference in perspectives and theoretical Physics leads to many philosophic inquiries which are mostly spurious or misleading. Some of you may not agree, but this is what I think. Can't argue further. Peace out. Yay, my first flamewar! I know the better man steps back first, so I will give you the honor of being the greater man among us today. However if you give it back to me I will keep it this time. The question what reality is, if it is objective, if our senses can tell us something about this objective reality, or if reality is a dream and wether our experience is more real than the world itself has been asked by philosophers since thousands of years. Platon, and aristotle have made it a topic and so have the great gurus of the east, Buddha himself not the least. It has been a thing long before theoretical physics was even a thing. What makes this topic uniquely philosophical however is the fact, that theoretical physics deals with the physical world. It could never answer the question why there is anything at all. Thus the question what reality is cleary oversteps the boundaries of theoretical physics. Especially since, from the perspective of theoretical physics, it is impossible to gain any knowledge over a spiritual world (if such a thing exists). However it is very important to include the question of spirituality when wondering about what reality really is. To be completely exact: this an ontological question, ontology being a subdiscipline of philosophy. But I do very much appreciate your insight, because indeed as you said theoretical physics adds very interesting aspects to the discussion!