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The Question

(Submitted October 21, 2001)

As a Philosophy student, I have linguistic tools to deal with space and time. These are bound intimately with consciousness. Having minimal experience with the astronomer's conception of space, and having only an amazed onlooker's idea of the "space" of the space of the universe, and having a child's wonder of the idea that the universe may be expanding unstoppably onward, then I ask a child's question: what is the universe expanding into? What "space" exists that allows us to say: this is big, and growing bigger into WHAT? Into what "space" is the universe expanding? And I am familiar with the idea that "expansion" and "growth" only happen within space/time parameters- philosophically speaking, reality is only apparent under the conditions that we "appear"... so I have read that the "edge" of the "edge of the universe" idea really does not not hold true when one "does the math." I would like to know more about this math, that conditions a movement that expands, but expands not "into" not "out" or "toward" -anything else...

The Answer

Thank you for your question. Perhaps the simplest way to look at these questions is the following: if the universe includes, by definition, everything -- all of space, time, matter, energy -- than there can be nothing outside of it (and hence no edge), nothing for it to expand into. Its true that this is contrary to our everyday experience, as is much else in physics and astronomy; but of course our everyday experience does not extend to the entire universe. In some ways this line of argument parallels those in refutations of the "argument by design" for the existence of God.

Another way to look at it: if there were a higher-dimensional space in which the universe were embedded and into which it expands (like a two-dimensional balloon expanding into three-dimensional space), we could have no way of ever measuring the existence or characteristics of such a space. Whether such an unobservable space can truly be said to exist at all is a question best addressed by philosophers such as yourself!

Here is an additional reference you may find helpful:

-- Michael Loewenstein and Amy Fredericks for "Ask an Astrophysicist"

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