Einstein's Clocks, Poincare's Maps

I'm reading Einstein's Clocks, Poincare's Maps: Empires of Time by Peter Galison.  It's about the preludes to the theory of relativity.  I won't blog the book in detail, but I want to record a few observations so I remember what I read.

Time and space measurements were a big deal in the 19th century.  Telegraphs enabled people to communicate rapidly, which both meant that people could exchange clock readings and that they'd want to (so that they could time-stamp communications).  Trains needed precise timing, so that if a schedule said you'd arrive at noon you knew if that meant when the sun was overhead at the arrival station or at some central hub where the schedules were being set.  And longitude measurements (which required determining the time when you observed a celestial object at a particular position in the sky) were crucial for navigation and also for treaties between colonial empires.  As a result, mathematician Henri Poincare (who was also an engineer involved in a lot of issues of timing and longitude) put a lot of thought into the notion of times and distances being the products of defined human procedures rather than immutable and absolute features of the universe.

On page 200 I learned that Poincare delivered a presentation at a 1900 philosophy conference and questioned whether the science of mechanics needs reformulation.  He questioned absolute time, absolute position, simultaneity, and even whether Euclidean geometry was just a linguistic convention.  As strange as the last one sounds, he was heavily involved with geometry on spherical surfaces (navigation and surveying) so he was used to the idea of very real problems of a very real world requiring geometry on curved surfaces.

Furthermore, he was in dialogues with Lorentz and others, who were questioning whether electromagnetism could be fixed by redefining space and time.  The Lorentz transformations were known before Einstein, but people used these formulas in a conceptual framework that distinguished between absolute time and the timing of things relative to the ether.  Einstein's leap was to do away with ether, not to invent these formulas de novo.  I was aware of this part previously, but the book fleshes out some of the timeline and correspondence.

There's also a lot of geopolitics that I can't bring myself to care about.