Re:Three Super-Massive Black Holes Merging Together in Our N...
by stan_rogers on Sunday August 29, 2021 @01:23PM
(#28348603)
Just an unnecessarily pendantic note: the visible (observable) universe would be defined as anything that emitted radiation that would have reached us, and in an expanding universe that means it's considerably larger than 14-ish billion light years radius. Conveniently, it works out to about 14 billion parsecs, so nobody needs to remember another number, they just need to do the conversion.
It's a question of definitions. He makes the argument that defining "universe" to mean "our visible universe", that is, a radius of around 14B ly, is the most useful; if you assume infinite space and infinite matter (which seem to follow from the theory of inflation, which has provided explanations and predictions elsewhere), there are likely infinitely many universes all around following this definition (for other visibility scopes).