Reality would be a game of quantum mirrors because all known objects do not have their own existence, but form a network of existential relationships that gives them a physical appearance.
Imagine that you sit down and grab your favorite book. You look at the cover image, run your fingers over the soft cover of the book, and smell that familiar book smell as you flip through the pages. For you, the book is made up of a variety of sensory aspects.
But you also hope that the book has its own independent existence behind those appearances. So when you put the book on the coffee table and walk into the kitchen, or leave your house to go to work, you expect the book to look, feel, and smell the same as when you held it.
Expecting objects to have their own independent existence, apart from us and any other object, is actually a deeply ingrained assumption we make about the world.
This assumption has its origin in the scientific revolution of the seventeenth century and is part of what we call the mechanistic worldview .
In this view, the world is like a gigantic clockwork machine whose parts are governed by established laws of motion. This worldview is responsible for much of our scientific advancement since the 17th century.
But as Italian physicist Carlo Rovelli argues in his new book Helgoland, quantum theory, the physical theory that describes the universe on the smallest scales, shows almost certainly that this worldview is false. For this reason, Rovelli argues that we should adopt a "relational" worldview.
What does it mean to be relational?
During the Scientific Revolution, the English pioneer of physics Isaac Newton and his German counterpart Gottfried Leibniz disagreed about the nature of space and time.
Newton claimed that space and time act as a "container" for the content of the universe. That is, if we could eliminate the content of the universe, all the planets, stars and galaxies, we would be left with empty space and time. This is the "absolute" view of space and time.
Leibniz, on the other hand, claimed that space and time were nothing more than the sum total of distances and durations between all objects and events in the world. If we eliminated the content of the universe, we would also eliminate space and time.
This is the "relational" view of space and time: they are nothing more than spatial and temporal relationships between objects and events. This relational view of space and time was a key inspiration for Einstein when he developed general relativity.
Rovelli makes use of this idea to understand quantum mechanics. He asserts that the objects of quantum theory, such as a photon, electron, or other fundamental particle, are nothing more than the properties that they exhibit when they interact with, in relation to , other objects.
These properties of a quantum object are determined through experiments and include things like the object's position, momentum, and energy. Together they form the state of an object.
According to Rovelli's relational interpretation, these properties are all there is to the object: there is no underlying individual substance that "has" properties.
So how does this help us understand quantum theory?
Consider the well-known quantum puzzle of Schrödinger's cat. We put a cat in a box with some lethal agent (like a flask of poisonous gas) triggered by a quantum process (like the decay of a radioactive atom) and we close the lid.
The quantum process is a random event. There is no way to predict it, but we can describe it in a way that tells us the different possibilities that the atom will decompose or not in some period of time.
Because the decomposition will lead to the opening of the poison gas vial and thus the death of the cat, the life or death of the cat is also a purely chance event.
According to orthodox quantum theory, the cat is neither alive nor dead until we open the box and observe the system. There remains an enigma about what it would be like for the cat, exactly, to be neither dead nor alive.
But according to the relational interpretation, the state of any system is always in relation to some other system. So the quantum process that unfolds in the box could have an indefinite result in relation to us , but at the same time have a definite result for the cat .
Therefore, it is perfectly reasonable that the cat is neither alive nor dead to us and, at the same time, is definitely alive or dead . A fact is real to us in one way, and the same fact is real to the cat in another way.
When we open the box, the state of the cat becomes definitive for us, but the cat was never really in an undefined state by itself.
In relational interpretation, there is no global vision of reality or "God's eye ."
What does this tell us about reality?
Rovelli argues that since our world is ultimately quantum, we must heed these lessons. In particular, objects, like your favorite book, may only have their properties relative to other objects, including yourself.
Fortunately, that includes all the other objects too, like your coffee table. So when you go to work, your favorite book keeps popping up like it did when you were holding it. Still, this is a dramatic rethinking of the nature of reality.
From this point of view, the world is an intricate network of interrelations, so that objects no longer have their own individual existence independent of other objects, like an endless game of quantum mirrors.
Furthermore, it is quite possible that there is no independent "metaphysical" substance that constitutes our reality and that underlies this network.
As Rovelli says:
We are nothing more than images of images. Reality, including ourselves, is nothing more than a thin and fragile veil, beyond which… there is nothing.
This article originally appeared on The Conversation.