It wasn't so long ago we thought space and time were the absolute and unchanging scaffolding of the universe. Then along came Albert Einstein, who showed that different observers can disagree about the length of objects and the timing of events. His theory of relativity unified space and time into a single entity - space-time. It meant the way we thought about the fabric of reality would never be the same again. "Henceforth space by itself, and time by itself, are doomed to fade into mere shadows," declared mathematician Hermann Minkowski. "Only a kind of union of the two will preserve an independent reality."No, Einstein did not show those things. FitzGerald published his theory that motion affects lengths of objects in 1889, and Lorentz showed that time was also affected in 1892. Einstein did not write his first paper on the subject until 1905. When Minkowski published the above quote in 1908, Einstein denounced it. I document this in How Einstein Ruined Physics.
But did Einstein's revolution go far enough?
The reasons for combining space and time are the spacetime geometry and the electromagnetic covariance. These were published by Poincare in 1905 and Minkowski in 1908, and not by Einstein. Einstein did not even understand these concepts until about 10 years later.
The new paper by Lee Smolin and others says:
The idea that we live in a spacetime is constructed by inference from our measurements of momenta and energy. This was vividly illustrated by Einstein’s procedure to give space-time coordinates to distant events by exchanges of light signals .The reference is to Einstein's famous 1905 paper. That 1905 procedure was published first by Poincare in 1900.
Formulations of physics in terms of phase space are not new, and go back a couple of centuries. This new paper has some speculative ideas that are probably useless, but they are clearly labeled speculation and I have no problem with that. You can see how speculative it is by these claims about what you would have to do to observe the new ideas:
Relative locality would deal a huge blow to our picture of reality. ... Let's say you were patient enough to wait around while a black hole evaporated, a process that could take billions of years. Once it had vanished, you could ask what happened to, say, an elephant that once succumbed to its gravitational grip. But as you look back to the time at which you thought the elephant had fallen in, you would find that locations in space-time had grown so fuzzy and uncertain that there would be no way to tell whether the elephant actually fell into the black hole or narrowly missed it. The information-loss paradox dissolves.My point is to note how much modern physicists emulate an entirely false notion of an Einsteinian revolution. The pattern is (1) tell some false Einstein story, (2) claim a paradigm shift, (3) argue for the completion of some Einsteinian revolution, (4) question reality, and (5) make some completely untestable prediction.