The Edge of 'The Universe'

The Edge of 'The Universe', or thoughts about "meta-verses" and "multi-verses" --

Aside from the fact that these silly concepts are dishonest equivocations -- for these and all similar concepts are but attempts to redefine the term 'universe' (*) without giving notice -- in seeking to demote the concept "the universe" from referring to *all* physical things to referring *some* physical things, the equivocators are also asserting that there is such a thing as "the edge of the universe". Yet, according to modern physics (and do not these persons *always* assert that their assertions are grounded in science?), the very idea of an edge of the universe is incoherent.

Let's explore these ideas ...
(*) The term, and the concept, 'the universe' has always referred to "all things existing in physical space-time". The specific material and physical entities and relationships to which the term and concept is applied have changed -- expanded -- over the centuries, as human understanding of the physical world has increased. But, all such change in application is wholly consistent with the unchanging content of the concept.

For example, in ancient times, when "the fixed stars" (and for that matter, also "the wandering stars", and the sun and moon) and the galaxy were thought to be lights and objects affixed to or embedded in crystal spheres of immense size surrounding the earth in concentric circles, the meaning of 'the universe' didn't stop with the earth or the moon; the "fixed stars", believed to be so distant that in relation the earth was as a mathematic point, were also included in 'the universe'.

Later, when it was understood that "the fixed stars" were like the sun (or, alternately, that the sun was another star), and that the galaxy was not one object, but was rather innumerable stars so distant that they appearto us as a mist, rather than as discrete points of light as "the fixed stars" do, 'the universe' was understood to refer to all that, too.

Later, when it was understood that certain nebulae were not simply gas-clouds or "fuzzy stars", but were actually masses of stars at vast distances from other masses of stars, 'the universe' was understood to refer to all that, too. For a time, these galaxies (as we now call them) were referred to as "island universes"; but that was a poetic or metaphorical usage, it was no more to be taken literally than referring to the Western Hemisphere as "the New World" was ever meant to be taken literally.

Many Worlds
Now, in these days, there are many persons asserting that the may be, or even that there are, "other universes", perhaps even infinitely many. Some of these persons even assert that their claims are scientific -- yet, definitionally, no such claim, nor argument for such a claim, can ever be scientific. For, definitionally, science deals with empirical evidence, and, definitionally, any empirical evidence asserted for any purported "other universe" shows simply that the so-called "other universe" is really just a previously unknown part of this universe. It's like "the Old World" and "the New World" in this regard.

So, What About This 'Edge' of 'The Universe'?
The Solar system has an 'edge', a limit-in-space; the Galaxy has an 'edge', a limit-in-space; the universe does not. Now, to be sure, the 'edge' of a solar system, or of a galaxy, is quite imprecise; setting exactly where it lies is wholly arbitrary. Nevertheless, one can in honesty say of *this* volume of space, "This is the Solar system" or "This is the Galaxy", and of the remaining volume of space, "but that is not". One cannot say the same about 'the universe': it has no 'edge'; there is no volume of space "out there" which is "outside" 'the universe'; there is no place one might theoretically go such that to one's back is 'the universe' and before one is 'not-the-universe'.

But, when one claims that there are, or simply claims that there may be, "other universes" or "a meta-universe" containing a multiplicity of "universes", then one is precisely claiming, or implying, that there is a physical "outside" of 'the universe' -- that is, that it has a limit-in-space, an edge (**). One is likening "the universe" to a specific raisin nestled in a raisin pudding.

Now, if one were to claim or argue that the present-day conception of 'the universe' is too small -- in the same way that previous conceptions were too small -- that would a very different thing from asserting that there are "other universes".

At one time, we thought that The Galaxy was the full extent of The Universe; then we discovered Other Galaxies and realized that the concept 'the universe' refers to far more than we had previously thought -- in effect, galaxies are like individual raisins in the raisin pudding (of which there is no "outside").

But, as that 'the universe' refers to "*all* things existing in physical space-time", to claim that there are "other universes" is exactly analogous to calling the other galaxies "Island Universes", or calling the Americas "the New World", and insisting upon meaning either literally, rather than as poetic metaphor. In asserting that there are "other universes", one is saying that "the universe" is a discrete raisin pudding contained within a pudding of other discrete puddings (which are not necessarily raisin puddings).


(**) This is quite a different thing from metaphorically speaking of God as being "outside" of time-and-space.


Edit (2011/09/28):
The reason I keep writing "the universe" in quotes is that there is no such entity. The term 'the universe' is a concept, and it is a meaningful and useful concept, at any rate, when it isn't muddled with equivocations; but the word and concept don't actually refer to a physically existing thing. The concept 'the universe' is analogous to the mathematical concept "the set of all sets".