All of the talk about finding a new distance record for farthest galaxy from us has fed my interest in the concept of universe expansion. I had three questions that hopefully someone here can help me understand.

First, because of the fact that all galaxies are moving away from each other, does that mean that some (those on the leading edge) galaxies are travelling faster than other galaxies?

Two, regarding the new farthest galaxy, is it further out than the center (at least the percieved center, but I'll get to that in my next question) from us or are astronomers looking back to the farther edge?

Finally, addressing the center of the universe - looking for information on this subject, I found this on the Bad Astronomy website
can someone help me understand how there is no center?

Sorry, if my questions seem silly, sometimes I have a hard time conceptualizing that which I cannot see.

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Some Scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that THAT is the basic building block of the universe- Frank Zappa

1) Galaxies are not moving, space is expanding and dragging the galxies with it.
2) Not the farthest edge, but the earliest edge.
3) There is no center in the same way that there is no center to the surface of the Earth.

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

[stupid question alert] I think I understand now how galaxies are not moving apart. The space is expanding in all directions making it appear from ANY given point that every other point is moving away from you. I've heard it said that this is over "large scale" distances as in those between galaxies. Does this expansion of space have a limit in terms of smaller distances? Is our galaxy itself expanding? Are the atoms in my desk slowly getting further apart?

If the amount of matter in the universe remains constant and the volume or space of the universe continues to expand, the average density of the universe is decreasing, right? Is the density of my desk also decreasing? If not, what is the limit where space ceases to be expanding?[/stupid question alert]

No...not yet! Maybe 30 billion years from now. Do a Google search for "big rip" for info on a possible "end of the universe" scenario.

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

So then is there some point between galaxies where space ceases to expand?

It's not that space ceases to expand, it's that gravity is stronger than the expansion. The mass of our galaxy is enough to prevent (currently) our galaxy from expanding along with space. For an intergalactic example, in the local group, gravity is strong enough to cause M31 and our galaxy to approch each other.

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Some try to tell me, thoughts they cannot defend,... - Moody Blues.

The universe is expanding in all directions, right? If so, isn't there a center, either with something or as a void?

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Some Scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that THAT is the basic building block of the universe- Frank Zappa

Well, technically there is a center, but it would be outside of our universe. Think of our universe as being spherical. In fact, think of it as a large, expanding balloon. Our universe has an extra dimension, so our 3 dimensional space is contained on the surface of the 4 dimensional sphere. It's basically like an ant on the baloon observing it's 2 dimensional movement capability (foreward, back, left, right) and seeing that the distance to the next ant on the baloon was increasing and concluding that this expansion had to have a center. It does, but it's no longer accessable. The center is not part of the baloon, it's inside it. Just as in this analogy, the center of the universe is not accessable to anybody in the universe, but technically there is a center. I cannot point to where the universe is, but I can tell you that if you go in one of two different directions perpendicular (spelling?) to all of our three, you will eventually hit the center of our universe. However, this would be impossible to do without some technology we haven't discovered yet.

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While I love to envision it this way myself, and was considering bringing up the example, is that true only of a closed topology universe? Or does an open universe have some way of having a center in higher dimensions as well? This is the kind of thing that gives me headaches whenever I hear more evidence mounting that the universe is negatively curved. #-o :P

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Thanks for the explanation, it makes a little more sense now. Kind of freaks me out to think about it though...

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Some Scientists claim that hydrogen, because it is so plentiful, is the basic building block of the universe. I dispute that. I say there is more stupidity than hydrogen, and that THAT is the basic building block of the universe- Frank Zappa

Uhh, what do you mean our universe has an “extra dimension”? You mean there is a “w” Cartesian coordinate of space, like in w, x, y, and z?

If you want to go that route, you're still a dimension short. You can't leave out time.

So space is “dragging” our own galaxy through... through what... space?

Does that mean that when I’m running away from a lamp post, I’m “moving”, but if someone puts me in a car, then the car “drags” me away from the post, but I’m not really “moving” relative to the post? The car is just “dragging” me along with it, but I’m “stationary”? What branch of physics is this?

Explain to us exactly how space “expands”. Do space particles get bigger, or what? Does “new space” fill in the gaps in the “old space”? Does the old space “stretch” or what?

You keep saying that “space expands”, but I want to know how space expands. What is the physical function of “space” that allows it to “expand”?

If we’ve got two rocks in front of us, and we move them apart, we see that the space between the rocks has “expanded”, but that’s because we moved the rocks. So how can the galaxies be moving away from us, thereby causing their light to redshift, yet you say they are “not moving”? Please explain in detail how that physically works.

here's a neato page i found on yahoo:
http://www.estfound.org/

Thanks for the good explanations. I pretty much have lost the ability to learn new things (or perform new tricks) so thanks for being patient. I think I learned more in the last two days about the universe from reading this and the other thread. I hope to be able to peruse some of the links as well.

As for your questions Sam5, I'm not your man, I have no idea how it works. Don't even know if I could comprehend it if explained.

I'm with you hickboy, kind of freaks me out too and hurts my head if I try to think about it too hard. :-s

Pi Man, that's only for a closed universe only, isn't it? Since our universe is flat, it's center would be somwhere inside of it, if it has one. Would it even have a center if it's infinite in extent? If it did, it wouldn't be impossible to tell if you were there.

I wish BA would send all these guys who say that space is expanding and that the galaxies are not moving to the "against the mainstream" board. That is such a stupid, ridiculous idea and misconception. If space is expanding to explain the red shift, then why does it expand so much more for radio waves than for x rays? A radio wave at z = 1 expands to twice its wavelength which is several meters, but an x-ray at z = 1 only expands a few nanometers. If the red shift is doppler, of course more distant galaxies are moving away faster than more nearby ones.

No! Several of us have tried (on several diferent threads that you have hijacked) until we were all blue in the face. I am sick and tired of banging my head against the wall of your obtuseness. I refuse to play your little game anymore.

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

HUH!! Your point is?

A one meter radio wave emitted at z=1 expands to two meters. A billion 1 nanometer waves of X-rays (1 meter) expands to two meters (one billion 2 nanometer waves). What's the problem? :roll:

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

I think I see the confussion. The question seems t be...If z is the same for all wavelengths from a given object, and, it is the space that is expanding, then, wouldn't space have to expand more for the longer wavelength light vs. the shorter. Analogy - place a 1" long rubber band parallel to a 2" long rubber band, expand the space by 1 inch (z=1 for the 1" rubber band) but the 2" rubber band has only a z of 0.5 even though both saw the same amount of [space] expansion.

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Lighten up! This is a stellar board! Author: duh.

"The Sun, with all the planets revolving around it, and depending on it, can still ripen a bunch of grapes as though it had nothing else in the universe to do..." Author: Galileo supposedly.