Lee Smolin: Relative

“Combine general relativity and quantum theory into a single theory that can claim to be the complete theory of nature. This is called the problem of quantum gravity.”

Lee Smolin

The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next (2007)

Nature , Problem

“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.”

Lee Smolin book Three Roads to Quantum Gravity

Three Roads to Quantum Gravity (2000)

Universe , Time

“Some of the effects predicted by the theory [of loop quantum gravity] appear to be in conflict with one of the principles of Einstein's special theory of relativity… that the speed of light is a universal constant. …Photons of higher energy travel slightly slower than low-energy photons. …the principle of [general] relativity is preserved but Einstein's special theory of relativity requires modification. …A photon can have an energy-dependent speed without violating the principle of [general] relativity!”

Lee Smolin

"Loop Quantum Gravity," The New Humanists: Science at the Edge (2003)

Travel , Light , Universe , Appearance

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

Lee Smolin book Three Roads to Quantum Gravity

Three Roads to Quantum Gravity (2000)

Universe

“Relativity and… quantum… remain incomplete…. the main reason each is incomplete is the existence of the other. The mind calls for a third theory to unify all of physics, and for a simple reason. Nature is… "unified." …interconnected, in that everything interacts with everything else.”

Lee Smolin

The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next (2007)

Nature

“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.”

Lee Smolin book Three Roads to Quantum Gravity

Three Roads to Quantum Gravity (2000)

World

“One of the evident facts about the world is the stability of empty space-time. In classical general relativity we can explain this as a consequence of the positive energy theorem… the positive energy theorem must extend in some suitable form to any viable quantum theory of gravity.”

Lee Smolin

"Positive energy in quantum gravity" arXiv (Jun 10, 2014)

World , Time

“In both quantum theory and general relativity, we encounter predictions of physically sensible quantities becoming infinite. This is likely the way that nature punishes impudent theorists who dare to break her unity. …If infinities are signs of missing unification, a unified theory will have none. It will be what we call a finite theory.”

Lee Smolin

The Trouble With Physics: The Rise of String Theory, The Fall of a Science, and What Comes Next (2007)

Way , Nature

“In string theory one studies strings moving in a fixed classical spacetime. …what we call a background-dependent approach. …One of the fundamental discoveries of Einstein is that there is no fixed background. The very geometry of space and time is a dynamical system that evolves in time. The experimental observations that energy leaks from binary pulsars in the form of gravitational waves—at the rate predicted by general relativity to the… accuracy of eleven decimal places—tell us that there is no more a fixed background of spacetime geometry than there are fixed crystal spheres holding the planets up.”

Lee Smolin

"Loop Quantum Gravity," The New Humanists: Science at the Edge (2003)

Study , Time , Dependency

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

Lee Smolin book Three Roads to Quantum Gravity

Three Roads to Quantum Gravity (2000)

World

“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.”

Lee Smolin book Three Roads to Quantum Gravity

Three Roads to Quantum Gravity (2000)

Change , Time

“While most people… were seeking to modify the principles of either relativity or quantum theory, we surprised ourselves (and many other people) by succeeding in putting them together without modifying their principles.”

Lee Smolin

"Loop Quantum Gravity," The New Humanists: Science at the Edge (2003)

People

“The suggestion was that a positive energy proof for general relativity could be gotten by restricting supergravity to its bosonic sector, which is general relativity.”

Lee Smolin

"Positive energy in quantum gravity" arXiv (Jun 10, 2014)