Re: "A diagram of C23 basic types"

On Mon, 14 Apr 2025 18:46:22 -0700, Chris M. Thomasson wrote:

Humm... Is the "Big Bang' nothing more than a hyper large and rather
local explosion?

No, as cosmology is currently understood, it is meaningless to talk
about space or time before the Big Bang. The Big Bang is the event that
starts both time and space. That makes it very different from any normal
explosion. At the moment of the Big Bang, the entire universe was
infinitely small, so literally everything was "local".

An analogy I like is to think of the surface of a sphere, with space
corresponding to longitude, and time corresponding to latitude. Asking
about what happened before the Big Bang is a meaningful as asking what's
south of 90S latitude.
This analogy implies a universe that ends at the equivalent of latitude
90N, but you could just as well use a hyperboloid of revolution as an
analogy to a universe that starts but never ends. I think spheres are
easier for most people to think about.