View Single Post
Old 04-17-2017, 06:04 PM
Chronos Chronos is offline
Charter Member
Join Date: Jan 2000
Location: The Land of Cleves
Posts: 75,144
Some probability problems are well-defined when dealing with infinities, and some are not. Some seem well-defined, but turn out not to be once one looks at them with enough rigor. And some problems which lack sufficient rigor can have that rigor applied in multiple different ways, which lead to different answers. Which one applies here depends on just exactly how the multiverse is structured.

Quoth Stranger on a Train:

As to the concept of other universes, it should be recognized that there are two separate concepts here. One comes from the quantum mechanical notion of simultaneous superposition of possibilities at the quantum level, derived from Hugh Everett's "relative state" interpretation (note that Everett did not promote the idea that there was a literal "multiverse"; just that we're experiencing one of a multitude of simultaneous possibilities). In this multiverse, all the laws of physics are the same but the resolutions of individual states fill all possible options, and share the same mass-energy matrix in a state of superposition.
There's a third possibility, also: Bubble universes in the eternal inflation model. In these, you could in principle point with your finger in the direction towards some other universe, but the bubbles are receding from each other at such great speed that causal connection between them is impossible. Such bubbles might or might not show variation in fundamental constants: I don't think that question is actually resolved.

The other is from brane cosmology that there are separate, unconnected physical universes formed from an initial singularity of energy and which deconstructed into different balances of dimensions and physical parameters. In this case, each universe has its own separate mass and energy (which may or may not be infinite in extent) and are in no way causally connected with one another.
In most braneworld models, the branes are in fact causally connected, just not easily. Electromagnetism, the strong force, and the weak force are confined to the branes, but gravitational effects can still bridge the gap.