In string theory one studies strings moving in a fixed classical space — Lee Smolin

"I was joined by Carlo Rovelli, and we were able to make a full-fledged quantum theory of gravity... This became loop quantum gravity."

"Since the 1960s, particle theory had been split into two groups: those following the atomism of the quark theory and those who had followed the anti-atomism of that had led from the bootstrap program to the string theory. What happened in 1984 was that it was realised that string theory could combine and satisfy the aspirations of both approaches to fundamental physics. Thus, the community of gauge theorists, driven by the failure of the proton decay experiments to search for new ideas that could unify physics, all of a sudden encountered their old friends, the string theorists, in the middle of what might be called a desert of disappointed expectations."

"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."

"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."

"The landscape problem represents a serious problem in the development of science. Its solution requires... the construction of speculative cosmological scenarios, which posit regions or epochs of our universe for which we presently have no observable evidence. Nonetheless we must insist on taking seriously only scenarios and hypotheses that make falsifiable or strongly verifiable predictions, otherwise people can just make stuff up and the distinction between science and mythology becomes porous. ...there are already candidate solutions that make real, falsifiable predictions."

"Rule I: Except during a measurement, the wave evolves smoothly and deterministically, like a wave on water. ... Rule II: During a measurement of position, the wave collapses around the position where it is seen, with a probability proportional to the square of the height of the wave, before the collapse. ... In fact the two rules seem to contradict each other."