The Universe-Neraton Land

Some theorists extend their model
of "all of space-time" beyond a single connected space-time to a set of disconnected space-times, or multiverse. In order to clarify the terminology, George Ellis, U. Kirchner and W.R. Stoeger recommend using the term the Universe for the theoretical model of all of the connected space-time in which we live, universe domain for the observable universe or a similar part of the same space-time, universe for a general space-time (either our own Universe or another one disconnected from our own), "multiverse" for a set of disconnected space-times, and "multi-domain universe" to refer to a model of the whole of a single connected space-time in the sense of chaotic inflation models.

For example, matter that falls into a black hole
in our universe could emerge as a Big Bang, starting another universe. However, all such ideas are currently untestable and cannot be regarded as anything more than speculation. The concept of parallel universes is understood only when related to string theory. String theorist Michio Kaku offered several explanations to possible parallel universe phenomena.

Physicist David Deutsch suggests that a multiverse
is a consequence of the many-worlds interpretation, which he considers to be the best alternative explanation to the Copenhagen explanations of Quantum theory first presented by Niels Bohr, over half a century ago.


Theoretical and observational cosmologists vary in their usage of the term Universe to mean either this whole system or just a part of this system. As used by observational cosmologists, the Universe (upper case "U") most frequently refers to the finite part of space-time which is directly observable by making observations using telescopes and other detectors and using the methods of theoretical and empirical physics for studying the basic components of the Universe and their interactions. Physical cosmologists assume that the observable part of (comoving) space (also called: "our universe") corresponds to a part of a model of the whole of space, and usually not to the whole space. They frequently use the term the Universe to mean either the observable part of space, the observable part of space-time or the entire space-time A majority of cosmologists believe that the observable universe is an extremely tiny part of the "whole" (theoretical) Universe and that it is impossible to observe the whole of comoving space. It is presently unknown whether or not this is correct, since according to studies of the shape of the Universe, it is possible that the observable universe is of nearly the same size as the whole of space, but the question remains under debate. If a version of the cosmic inflation scenario is correct, then there is no known way to determine whether the (theoretical) universe is finite or infinite, in which case the observable Universe is just a tiny speck of the (theoretical) universe.


	The Universe is defined as the summation of all mass energy that exist and the space-time in which all events occur. Based on observations of the portion of the universe that is observable, physicists attempt to describe the whole of space-time, including all matter and energy and events which occur, as a single system corresponding to a mathematical model.

The currently accepted theory of the universe's formation is the Big Bang model, which describes the expansion of space-time from a gravitational singularity. The universe underwent a rapid period of cosmic inflation that flattened out nearly all initial irregularities. Thereafter the universe expanded and became steadily cooler and less dense. Minor variations in the distribution of mass resulted in fractal segregation into features that are found in the current universe; such as clusters of galaxies.


Theoretical cosmologists study models of the whole of space-time which is connected together, and search for models which are consistent with physical cosmologists' model of space-time on the scale of the observable universe Their models are speculative but use the methods of theoretical physics. These models are usually referred to using the term universe (lower case "u"). Sometimes theorists use the Universe (upper case "U") to refer to the whole of the specific space-time in which we live


Information

	Mercury


	Venus


	Earth


	Mars


	Jupiter


	Saturn


	Uranus


	Neptune