You're reading the public-facing archive of the Category Theory Zulip server.
To join the server you need an invite. Anybody can get an invite by contacting Matteo Capucci at name dot surname at gmail dot com.
For all things related to this archive refer to the same person.
John Baez (Apr 05 2020 at 22:56):A thread on the historical roots of non-Euclidean geometry:
https://twitter.com/johncarlosbaez/status/1246834740893634562
People often say non-Euclidean geometry was discovered in the 1800s, but spherical geometry goes back to the ancient Greeks. It's important in astronomy, because the sky is a sphere! In spherical geometry, the parallel postulate breaks down. (1/n) https://twitter.com/johncarlosbaez/status/1246834740893634562/photo/1
- John Carlos Baez (@johncarlosbaez)
John Baez (Apr 05 2020 at 22:59):A rant on how logic fits into the duality between algebra and geometry:
https://twitter.com/johncarlosbaez/status/1246911691855552512
@Francis16833887 @mathemensch @CreeepyJoe @_julesh_ Fun questions! The basic reason why want to think of the sets of possible states of affairs as a topological space is that we need a way to think of one state as "close" to another, since our measurements are not perfectly precise. (1/n)
- John Carlos Baez (@johncarlosbaez)