The big idea: why relationships are the key to existence

The Q uantum theory is one of the most successful scientific ideas of all time. It has never been proven to be incorrect. Computers, lasers, and medical instruments are just a few of the technologies we've been able to build.

It's been a century since the birth of quantum theory. It doesn't tell us how physical systems work. Predicting the probability of a physical system affecting us is what it is. When an electron is fired from one side of a wall with two holes, quantum theory says nothing about where it will end up. If you do this now, the system will react in a similar way later. In between, what happens? The theory isn't telling us

Many scientists are happy with this. Some make hypotheses about hidden parts of nature or multiple universes that underpin the part of reality we see. Some people believe that science is only about what we can see and not what we think we know.

A new idea has begun to gain traction. Maybe there is no need to explain what quantum theory is all about. It may show us the deep structure of reality, where a property is not more than something that affects another. The effects of interactions may be exactly what this is. A good scientific theory should be about how things affect each other.

The winners in the long run are those who collaborate

The idea doesn't seem right. We are pushed to rethink reality in terms of relations. It was 25 years ago that the idea of quantum physics telling us about nature was first proposed. Several major philosophers picked it up and began discussing it. The idea of an interpretation of quantum mechanics is growing in popularity. What quantum phenomena are is evidence that all properties are related.

At the root of the western philosophy is a definition of existence. "Anything which possesses any sort of power to affect another, or to be affected by another, if only for a single moment, however trifling the cause and however slight the effect, has real existence."

Maybe this isn't such a radical idea after all. A chemical substance is defined by how it reacts, a biological species is defined by its niche in the biosphere, and what defines us as humans is our relationships. There is a blue teacup. The idea of a teacup is meaningless for an alien who doesn't know how to drink tea. If we take a longer view, we can see that it is just a fleeting aggregation of atoms. Are the atoms in reality? They are defined by their physical interactions with the rest of the world.

It's possible that quantum physics is the realization that reality continues all the way down to the elementary level. Reality is a network of processes.

I think it will come with a lesson. Think of reality in terms of interactions, not individuals. The interactions we are involved in allow us to exist. The winners in the long run are people who work together. Success is measured in terms of a single actor's fortune. It is both short-sighted and irrational. It misunderstands reality and ends up being self-destructive. We make this mistake all the time in international politics. It's a mistake to prioritise individual countries over the common good. It leads to the destruction of war and prevents us from addressing the real challenges that all of humankind is facing.

He is a professor of physics and the author of a book. Purchase a copy of the Guardian at guardianbookshop.com. There may be delivery charges.

Jim Al-Khalili wrote The World according to physics.

Theaetetus was written by Plato.

Karen Barad wrote Meeting the Universe Halfway about quantum physics and the interplay of matter and meaning.