Tag: Multiverse

Reading something shocking
I wonder if there is any major part of physics that has changed so fundamentally in the last thirty years as cosmology. Back in 1987 cosmology was more or less the last module we were taught as part of the astrophysics degree. But what we were taught then seems like basic arithmetic compared to today’s […]

Why isn’t the universe of infinite density?
Another speculation produced by Brian Greene’s The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos. Imagine the universe was infinite (along the “quilted multiverse” pattern – namely that it streched on and on and we could only see a part). That would imply, assuming that the “cosmological principle” that one bit of […]

Cosmologists’ problems with alephnull and the multiverse
This is another insight from Brian Greene’s book The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos – well worth reading. Alephnull () is the order (size) of the set of countably infinite objects. The counting numbers are the obvious example: one can start from one and keep on going. But any […]