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Expanding Universe: From Where?
Name: Mario
Status: other
Grade: other
Location: NY
Country: USA
Date: May 2, 2011
Question:
In astronomy they say that the universe is expanding,
From what location? Is it expanding from the big bang out? Where is
our galaxy locates in relation to center? are there possible answers
for my questions? Thank you Still searching at 85.
Replies:
Mario,
Try this: take a balloon that is inflated enough so that it maintains
its form but is not yet fully inflated. Mark several spots on the
balloon (I like forming a cross-pattern marking the center of the cross
as "0" and then at equal intervals "1", "2", and so on).
Now inflate the balloon slowly. What you should see is that the
distance between marks are getting larger and larger. Moreover, the
farther two marks were to begin with, the faster those two marks get
farther away from each other ("1" and "2" may be getting farther apart,
but "1" and "4" are getting farther away faster).
Now think of the universe as the surface of this balloon, and the marks
you made the galaxies in the universe. This is exactly what we observe.
Objects that are farther from us, tend to be receding faster (having a
higher red shift) than objects that are closer.
But where is the "center" or "origin" of the expansion? We could ask
the same thing of our balloon. Since we defined the surface of the
balloon as the universe (the entirety of everything), then it is
impossible to mark any spot on the surface of the balloon as the origin
of the expansion since all points are getting farther away from each
other. ( ... we could theorize that if the 2D beings on the surface of
the balloon could imagine a 3rd dimension, then they could imagine that
the "origin" was somewhere beyond their 2D world
- and then extrapolate that to our situation and say that we 3D beings
have to imagine a 4th dimension to get to the "origin" - but that would
be pointless since we cannot access the 4th dimension, cannot gather
data about it, and it would not be science.)
Greg (Roberto Gregorius)
Canisius College
Dear Mario,
Very good question. From everywhere in the Universe, like a balloon
blowing up, specks on its surface appear to move apart no matter where
you are on the balloon. Our galaxy is very far from the "center" if we
even know where it is.
Keep searching!
Sincerely
David H. Levy
When considering the expansion of the Universe, you have to toss out "common sense" and "intuition". First, we may not be "seeing" all of the Universe. We can only observe the Universe as far as the speed of light (299,792,458 meters/sec.) multiplied by the age of the Universe (13.75 billion years). If there is anything further out there than that, the light (or other electromagnetic radiation) has not reached us yet. Second, until recently it appeared that the Universe was slowing down the older the source of the radiation. Now however, the oldest (and furthest galaxies seem to be speeding up). Presently no one knows why. Third, now for your question. The Universe is expanding, not from one reference point (like the Earth, or like the "big bang", but everything is getting further away from everything else.
A rough analogy would be the distance between spots on a balloon that you blow up. As the balloon expands the spots get further apart from all the other spots. There is no point of reference. This is a little weird because it means our galaxy is located in relation to the center. There is no center.
Vince Calder
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