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ChromeStar
2005-Feb-13, 10:52 AM
This idea stems from One of the other stories in Story Comments



Aqualung - Posted: Feb 9 2005, 07:48 AM

If our galaxy was close enough to the 'edge' of the universe for this star to reach the edge of the universe. Then wouldn't the universe just bulge to accomodate the star, therefore keeping it in the current universe.


Ok lets asume for a second the Universe is expanding slow enough for the star to reach the Universe's limits, what now does he star diappear? or just expand @ the same pace? does it.... ?

Nyrath
2005-Feb-13, 02:07 PM
Well, current theory holds that there really isn't an "edge to the unvierse", for the same reason that there isn't an "edge to the earth". If you started travelling on earth in one direction, you would not reach any edge. What would happen is that you'd eventually come back to your starting point.

In this analogy, the expanding universe would be as if the earth was inflating like a balloon. Things would get farther apart, but there would be no edge.

There is an edge to the "observable" universe. Any galaxy or star farther from us than a certain distance will never be observed, as the light will never catch up with us. There is an article about this in the current issue of Scientific American.

nomadicdemon
2005-Feb-13, 11:46 PM
Well, Nyrath has a point, there could be no edge of the universe, but then again, who knows, maybe there is, there's so much we just don't know....I doubt there is an edge, but maybe there is.....I highly doubt it....but again, who knows......

ChromeStar
2005-Feb-15, 05:59 PM
Thats all true and thanx, :) but it doesn't quiet cover my question.

Lets say the point is where the universe ends, kind of like the end of earth - its atmosphere. So what would happen? :huh:

antoniseb
2005-Feb-15, 08:55 PM
It is important to think of the "edge" of the universe as something that is racing away from us [and everything else in the universe] AT the speed of light in a vacuum. NOTHING that isn't at the edge can catch the edge. Anything already at the edge, is time dilated so much that it is still experiencing the first moments of the existance of the universe.

Hen3ry
2005-Feb-15, 11:05 PM
It is entirely possible that it is impossible for humans to imagine infinity.
Space has no edge, no end, no center, or side.
Big doesn't begin to cover it.

Svemir
2005-Feb-18, 11:46 AM
Let me try with an analogy.
Imagine a circle, this is your universe, and you are a dot on that circular line.
The line is only thing that exists.
If you try to rich out in a direction of the center, out of the center or up/down in dimensions which you are not aware of and you don't exist in, your hand will follow the line of the circle. This involves motion and velocity expressed as ds/dt.
You expirience your universe as 2-dimensional with 1 space and 1 time dimension.
Any atempt to rich the third dimension (the plane, second space dimension) fails.
You can say you are at the edge of the universe.
That means that you and me, we are at the "edge" of our Universe right now, reaching out of the edge means trying to move into 5th dimension(4th space dimension).
If it was possible it will give raise to the weirdest lifeforms, some of us will be uglier and some will be more beautiful. End of the golden age of plastic surgery. You could do it of your own. <_<

There is no need to travell somewhere to "see" or "feel" some "edge".

Now, we gonna expand our one-line universe with circular (closed) curvative, to draw analogy to the current Bing Bang view of an expanding universe. It has much in common with the famous ballon show.
How do we do that?
Suppose we start with a universe of 1 cm in radius(d).
For every second we make the radius 1 mm longer.
What is happening to our universe?
It&#39;s being 2*PI * 1 mm BIGGER (since it&#39;s only a line, this means longer) every second.
Where is the center of our universe?
Our universe has no center or you can regard it as it is in some dimension unreachable to us.
What can you see?
You can see the visible universe, that becomes bigger with the expansion.
Expanding our circle very, very big, we will be able to see the entire universe as it will appear FLAT (= straight line).
Analogy with Earth: Earth appears to be flat to us because of it&#39;s big radius.
What if you travell at some velocity in one direction?
It&#39;s the same thing like travelling to your parents for Thanksgiving, you move through space and expirense time passing by. When you get back it&#39;s like travel in the oposite direction.
What if you travel at the speed of light i one direction, where speed of light in our universe is 2*PI*1 mm/s?
This is a tricky one.
You actually catch up the expansion of the universe (this is what Antoniseb reffers to) and you can regard this as being at the "edge" of the Universe.
Hence, every photon in our real world is on the "edge" of Universe.
Wait a minute, you say, does this mean that time stands still for a photon?
Actually, time is undefined for photon, according to Einstein.
Like a result of division with zero in mathematics.

to be continued....

StarLab
2005-Feb-18, 07:00 PM
I&#39;d like to add, Moestar, that stars really don&#39;t have acceleration or inertia or velocity. When two stars (or any form of celestial body) are near enough to each other, each is caught in the other&#39;s gravitomagnetic pull...besides, it is spacetime that expands outward as the star has no motion. Because of that, a star can&#39;t really accelerate past the edge of the universe (assuming such an edge exists). :unsure: