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Name: Bernie
Status: N/A
Age: 50s
Location: N/A
Country: N/A
Date: 1999 

Why is the concept of a defined universe i.e. 15 or so billion light years in size held to be the limit of the universe. I grapple with the idea of it all starting with a "Big Bang" and in my limited ability to grasp such concepts am comfortable with the explanations I've gleaned so far from persons such as LeMaitre; Einstein; Hubble; Hawkins and others, is it possible that something may exist 20, 30 50 or 100 billion light years distant, other "Big Bangs"?

Yup, and yup. We talk about what we know, can see, or can infer. We could talk about what's outside the inferable universe, but it would be a short conversation, because we don't have any information on which to base a conjecture or against which to test it.

...We have through history, always have had to make room for new conclusions i.e. Earth Centered, Sun centered universes is it possible that it goes on for ever in every direction and just because the light has not reached us and possibly never will that it does not exist? I have difficulty understanding the concept that nothing exists beyond those defined limits. "Nothing" is the absence of "Everything" including space, it seems to fly in the face of infinity.

Me too. The limit of knowledge is a very frustrating thing for humans, particularly when it sits there and thumbs its nose at you, as it does in this case. But if our ancestors weren't similarly frustrated by the limits of their understanding, we'd probably still be living in caves. Imagine what it must have been like really to believe that you personally could fall off the edge of the world if you simply took a long enough boat trip, and to have no clue into what you might fall.

Tim Mooney
Beamline Controls & Data Acquisition Group
Advanced Photon Source, Argonne National Lab

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