Three Roads to Quantum Gravity

Time is described only in terms of change in the network of relationships that describes space.

There is no time apart from change. There is no such thing as a clock outside the network of changing relationships. ...one can only compare how fast one thing is happening with the rate of some other process.

We are the result of processes much more complicated than the small aspects of our lives and societies over which we have some control.

There are unfortunately not a few good professional physicists who still think about the world as if space and time had an absolute meaning.

I believe that the main lesson of relativity and quantum theory is that the world is nothing but an evolving network of relationships.

The geometry of space changes when things in the universe change their relationships to one another.

There is nothing beyond the world except what we see, no background to it except its particular history.

There is no fixed, eternal frame to the universe to define what may or may not exist.

There is no meaning to space that is independent of the relationships among real things of the world. ...Space is nothing apart from the things that exist. ...If we take out all the words we are not left with an empty sentence, we are left with nothing.

It is absurd in general relativity to speak of a universe in which nothing happens.

In the theory of electric fields it is assumed that points have meaning. ...Physicists using general relativity... cannot speak of a point, except by naming some features of the field lines that will uniquely distinguish that point. ...the network of relationships evolve with time... constantly changing.

Neither space nor time has any existence outside the system of evolving relationships that comprises the universe. Physicists refer to this feature of general relativity as background independence.

The relational picture of space and time has implications that are as radical as those of natural selection, not only for science but for our perspective on who we are and how we came to exist in this evolving universe of relations.

We have known since the middle of the nineteenth century that the world is not composed only of particles. ...the world is also composed of fields. ...General relativity is a theory of... the gravitational field. ...Because there are three sets of field lines, the gravitational field defines a network of relationships having to do with how the... lines link with one another. ...This is why we call relativity a relational theory.

The first principle of cosmology must be 'There is nothing outside the universe'. This is not to exclude religion or mysticism... But if it is knowledge that we desire... we need to seek answers to questions about the things we can see... only things that exist in the universe.