Astronomy/infinity & the universe
QUESTION: when i say the universe is this understood to be an infinite propitiation ( no beginning, no middle, no end) or is there an understanding that it resides within something else !
In current standards of astronomical parlance when one uses the term "universe" it refers to a single entity which may be infinite or not. Here, I refer to extent not duration. So far as our current information, this entity did have a beginning - in the Big Bang - but will continue expanding forever owing to the agency of dark energy. Further, this expansion - based on current observations is accelerating.
The notion of residing in something else (i.e. a "multiverse") is purely speculative as there are no observations to support it. While some exotic theories have proposed a multiverse we still have no evidence that such a thing exists and hence, the postulation remains conjecture not fact.
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QUESTION: The big bang happened however it did occurred at a given point that point had a place to be. Is this point infinite, as the assumption that the known universe will expand (forever) would suggest that has a start point but no end.Given that the big bang happened this surely shows that infinity is just that and the universe as we observe it is a single event in a single infinity. Or am I missing some thing please can you point me to some literature that may in simple terms explain this .
Yours with great interest Steven
THe Big Bang, according to existing theory, originated from a point roughly the size of an atomic diameter, or about 10^-15 m across. Hence, originating from a super dense state and likely triggered via a large negative energy. However, it is not true to say "that point had a place to be". No, it did not. Given the ensuing expansion was one of space as well as time.
Given this, the expansion itself can have no defined locus. Think of raisins expanding on a loaf of bread pudding, or ink dots on an inflating balloon. No single raisin (or dot)
enjoys a privileged position of "center" to the particular expansion. All expand outward in relation to every other. Or, if you prefer, no specific locus of origin can be traced backward to a specific location in the universe.
Thus, yes, there was a start "point" but its exact location can't be known since we are talking of an original "explosion" in space as well as time. This is a difficult concept to grasp which is why a couple of books may help:
The first is Steven Weinberg's, "The First Three Minutes" - published in 1977, I believe. It goes through every point of the process including who first originated it (George Gamow) and how the first evidence for the Big Bang was found (using a radiotelescope at Bell Labs, in 1965 - which detected a uniformly directional microwave signal)
The book also contains an Appendix that is excellent, and takes the reader through the basic physics, extrapolating back to the early temperatures and showing exactly how and why observations point to the cosmos' originating in a Big Bang.
Another book, which can be used profitably with these, is Alan Lightman's (1991 effort, "Ancient Light - Our Changing View of the Universe", Harvard Univ. Press, which takes a survey approach - but still at the basic, understandable level.
The "no end" part - as you will infer from reading any or all the above - is traced to the expansion itself going on with no termination point.
Your other statement:
"Given that the big bang happened this surely shows that infinity is just that and the universe as we observe it is a single event in a single infinity."
Is a non sequitur and also misrepresents what we mean by "infinity". (See my previous response).
Yes, I suppose one might assert or say the original (primeval) cosmic "atom" represented an "infinity" - but with its "explosion" and subsequent expansion that "infinity" ceased to exist. It has now become mass-energy expanding in space and time. Hence, there is no longer any "single infinity", i.e. which is fixed.
Again, the books I referenced can help clarify this, as well as Lawrence Krauss' book, 'A Universe From Nothing'.
I believe if you can access the preceding books a lot will be made more clear, but again, given this is a difficult area by its nature, bear in mind "simplicity" is relative! Yes, by comparison with other works these books are relatively "simple" but a reader without physics background may still not find them *that* simple!
Hope this helps!