Updated: Feb 4, 2022
The building block, for our physical reality, some time back, was atoms. Then we smashed atoms together and found much smaller subatomic particles. We even came up with the bottom-up approach and assumed the building block of our world to be strings (Kaku's string field), consciousness (Hoffman's conscious realism), etc. I studied them and realize they all have one assumption in common. They tend to ignore the protagonist of their inventors'
lives. They tend to divide reality into different areas of study and assume that they are independent. Physics, biology, philosophy, language, etc. I mean think about it, are they really independent? Imagine if you lose the ability of language processing, can you really observe something and process the information the way you do now? If you lose your philosophical sense, can you really be curious enough about the world? For me, it's highly unlikely. Whatever I understand about anything has multiple layers of filters and modifiers created by my biological, philosophical, and linguistic characteristics.
For example, we may feel like we are the perfect observer but there will always be biological limitations because we are humans. A dog, for example, will have a completely different theory for the same observation. I saw similar things with people with different languages and philosophical senses. They are all curious about very different things and have very different approaches when encountered with the same philosophical problem. So I think, if I made a theory about an observation it will be more about myself than about the physical world. In my opinion, we can spend years in college studying various theories and live in an illusion that our understanding of the world is increasing, but, in fact, what we are doing is altering our characteristics to align with that of the people who made those theories.
I can relate to it myself. In my school years, when I first learned about the life of Albert Einstein, I was very disappointed. His social life was terrible, he divorced once and then went on to cheat on the second wife. The way he handled almost everything apart from physics was very disheartening for someone like me who wanted to learn physics. But as I learned more about his theories and started to understand what was going on in his mind, that disappointment became smaller and smaller. Now everything is fine. It doesn't matter if he ruined more than half a dozen people's life. After all, he was a human, and humans make mistakes, right!
So, why am I saying this? How is it related to the building block of our reality? Why am I even calling it 'building block of our reality and not 'building block of our universe'? This is because the universe is just an idea. An idea that came to someone while watching the night sky. I mean, just think about it, everything we have ever known about this world including the vastness of our universe is an idea that came to us after an experience. It's all just an attempt to explain an experience. Light from around the world coming into our eyes is not our reality, the processes* giving rise to this experience that we are experiencing is. (* It can be the chemicals getting activated in our brain as a result of those lights (current scientific view). Or conscious agents interacting with each other ( Hoffman's conscious realism) or any one of the infinite possible theories trying to explain our experiences.) Me reading a new theory about a recent finding and wondering about the world is an experience and that is my reality. Whatever I deduce from that theory is an idea, which will lead me to another experience.
So what causes this experience? My answer to this question is another question, i.e, Why should everything must have a cause-effect relationship? Cause-effect relation is a property of the ideas as we know them. Experience on the other hand is not that simple. Experience is very different from the "Idea of Experience". The moment we try to think about our experience at any given point in time, it becomes an idea. Only then we can try to establish a cause-effect relationship to our experiences.
Then, does that mean that experiences are the building block of our reality? No, probably not. But, it's the only clue we got that is definitely true.