Starship Asterisk*

bicyclebones wrote:Can the location of the most distant GRB tell us the direction of where the Big Bang occurred?

The BB didn't occur in any direction with respect to us. Essentially, it occurred everywhere; that is, any observer in the Universe sees himself at the apparent center.

harry wrote:

A couple of things. First, there was (and is) no leading edge to the Big Bang. Every point is expanding away from every other point, and the expansion rate increases with distance. There is no center, and no edge. Second, there is no limit on the rate of expansion- two points can even be separating from each other at faster than light. That's why the visible Universe (the part we can see because there has been enough time for its light to reach us) is actually more than 90 billion light years across, even though it's only existed for 13.7 billion year. The space between us and the GRB has expanded a lot since the event happened 13+ billion years ago.

Than how does redshift apply with this logic. The intrinsic properties wiuld shoot the data out of the roof.

In what way do you find [cosmological] redshift to be inconsistent with this description? We observe the redshift of the CMB to be over 1000, just as theory predicts.

What does "[t]he intrinsic properties wiuld shoot the data out of the roof" even mean?

Chris Peterson wrote:

bicyclebones wrote:Can the location of the most distant GRB tell us the direction of where the Big Bang occurred?

The BB didn't occur in any direction with respect to us. Essentially, it occurred everywhere; that is, any observer in the Universe sees himself at the apparent center.

Chris, I will never understand how you could imagine this unless you see the universe as infinite. If it is not infinite it will have borders. If it has borders it is probable there is a civilization within instrument's observation of the border nearest them. They will know they are not at the centre of the universe.

aristarchusinexile wrote:

Chris Peterson wrote:The BB didn't occur in any direction with respect to us. Essentially, it occurred everywhere; that is, any observer in the Universe sees himself at the apparent center.

Chris, I will never understand how you could imagine this unless you see the universe as infinite. If it is not infinite it will have borders. If it has borders it is probable there is a civilization within instrument's observation of the border nearest them. They will know they are not at the centre of the universe.

I have no firm opinion on whether the Universe is infinite. But I have no problem imagining a finite universe without borders, and I have no problem with the math that describes just that. If you're visual, however, it should be no harder to deal with than recognizing that the surface of a sphere is a 2D manifold that is finite (has finite area), yet is unbounded, has no edges, and has no center. Any point on that surface can be considered the center.

Chris Peterson wrote:

aristarchusinexile wrote:

Chris Peterson wrote:The BB didn't occur in any direction with respect to us. Essentially, it occurred everywhere; that is, any observer in the Universe sees himself at the apparent center.

Chris, I will never understand how you could imagine this unless you see the universe as infinite. If it is not infinite it will have borders. If it has borders it is probable there is a civilization within instrument's observation of the border nearest them. They will know they are not at the centre of the universe.

I have no firm opinion on whether the Universe is infinite. But I have no problem imagining a finite universe without borders, and I have no problem with the math that describes just that. If you're visual, however, it should be no harder to deal with than recognizing that the surface of a sphere is a 2D manifold that is finite (has finite area), yet is unbounded, has no edges, and has no center. Any point on that surface can be considered the center.

Any 2D piece of paper I've ever seen has borders .. and space is said to be flat .. and it has been said on apod a few times that the Big Bang is not like an expanding balloon .. and if the bang is like a balloon there is an interior, so it's 3D, and will have a centre, and the ballon will have borders, those borders being the surface, with a civilization living next to. Oh well .. on and on and around.

Chris Peterson wrote:

neufer wrote:Surely they mean more than 8.0 Gpc = 26.1 billion light-years. (ligth-years?)

Yes. Those pesky little decimal points and zeros seem to cause no end of problems in scientific stories that migrate to the popular press. Sometimes they're even messed up in the original press releases.

I still don't understand how this "event" can be more than 8.0 Gpc = 26.1 billion light-years away. The "event" is a point in space time that lies on a light-cone (which is, in fact, really more of "light-mandorla" whose apexes are us (now) and the big bang). The remnants of this "event" are now certainly more than 8.0 Gpc = 26.1 billion light-years away but NOT the "event" itself.

(Besides which...the de-ionization of the big bang plasma is the most distant event ever observed in actual "light-years" [though perhaps not in "parsecs"].)

neufer wrote:

Chris Peterson wrote:

neufer wrote:Surely they mean more than 8.0 Gpc = 26.1 billion light-years. (ligth-years?)

Yes. Those pesky little decimal points and zeros seem to cause no end of problems in scientific stories that migrate to the popular press. Sometimes they're even messed up in the original press releases.

I still don't understand how this "event" can be more than 8.0 Gpc = 26.1 billion light-years away. The "event" is a point in space time that lies on a light-cone (which is, in fact, really more of "light-mandorla" whose apexes are us (now) and the big bang). The remnants of this "event" are now certainly more than 8.0 Gpc = 26.1 billion light-years away but NOT the "event" itself.

(Besides which...the de-ionization of the big bang plasma is the most distant event ever observed in actual "light-years" [though perhaps not in "parsecs"].)

Since you can't understand it Neufer, I am led to listen carefully to my instincts wthin me telling me not to attempt understanding it.

aristarchusinexile wrote:Any 2D piece of paper I've ever seen has borders .. and space is said to be flat

No, it is not. It is said to be very close to flat; its actual geometry has not been determined.

I, too, am trying to get my head around this expansion thing. As I understand it, the space in which the GRB resides and the space in which we reside are separating at some horrendous high rate such that the radiation from the GRB has been playing catch-up for 13-or-so billion years and has only just reached us. OK so far? Suppose we have an object at z=4 along the same line of sight. It's separating from us at half the rate of the z=8 object and presumably from the z=8 object at the same rate. How is this gradation in expansion rate explained?

As for the Cosmic Background Radiation, it's here now. We're immersed in it and it's not coming from some great distance. Initially, the CBR was at some horrendous high temperature but since the universe is expanding at a horrendous high rate, the black-body temperature of the CBR has been red-shifted down into the microwave end of the spectrum. Measuring the CBR temperature today gives us a direct measure of the age of the universe and the Hubble Constant. Correct?

Does the CBR age set an upper limit on the expansion rate of the universe and suggest a value for its current size?

According to what I've read and heard, the number of objects found in the Hubble Deep field becomes smaller with increasing distance. Is this because the number is decreasing or because Hubble's sensitivity is petering out at those extreme distances? I think one of the first tasks for the Webb Space Telescope should be to revisit the Hubble Deep Field and verify the former. But what do we do if Webb sees more objects out beyond what Hubble could see? The GRB event suggests that more might be out there than we realize.

Hope this helps..

http://math.ucr.edu/home/baez/physics/R ... t/FTL.html
http://www.astronomynotes.com/cosmolgy/s2.htm <<------ READ ME, this site goes back way past the page i stopped it, very interesting...

Mark

zbvhs wrote:As for the Cosmic Background Radiation, it's here now. We're immersed in it and it's not coming from some great distance.

Everything we can observe is here right now. The point is, the source of the CMB is very close to the edge of the observable universe. Of all that we observe, it has come the greatest distance to reach us.

G'day from the land of ozzzzzzz


Chris said

Everything we can observe is here right now. The point is, the source of the CMB is very close to the edge of the observable universe. Of all that we observe, it has come the greatest distance to reach us.

The source is close to the dge of the universe? You have got to be joking. What crap?

Do you know what CMB is ?

Do you thick that other stellar objects such as supernovas and jets produce CMB?

harry wrote:Chris said

Everything we can observe is here right now. The point is, the source of the CMB is very close to the edge of the observable universe. Of all that we observe, it has come the greatest distance to reach us.

The source is close to the dge of the universe? You have got to be joking. What crap?

And why is that? Note I did not say the source was near the edge of the Universe, I said it was near the edge of the observable universe, which is a very different thing.

Do you know what CMB is ?

I do indeed. It is the highly redshifted radiation from the opaque hydrogen plasma that filled the Universe until it was a few hundred thousand years old. The source of the CMB radiation that we observe (that is, the material that produced it) is now at the edge of the visible universe, about 45 billion light years away.

Do you thick that other stellar objects such as supernovas and jets produce CMB?

No, why would you think I do?

I understand the CBR and agree. I mischaracterized the mechanism. Thanks.

I still don't understand why the universe looks like it does. I've read P. J. E. Peebles, Ned Wright, and others and I understand the basics of expansion. What I don't understand is why the universe is structured like it is. The z=8 GRB is the most distant object thus far seen. The Hubble Deep Field picture showed objects at larger and larger redshifts, say z=4 and z=6. With more sensitivity, we must expect that Hubble would have seen z=8 objects as well. The appearance is that the z=4 and z=6 objects are traveling slower relative to the z=8 objects than we are and haven't come as far as we have. Why does it look like this?

If you are on the sphere Chris talks about there is still a center of the sphere that is the center all points on the sphere.

bicyclebones wrote:If you are on the sphere Chris talks about there is still a center of the sphere that is the center all points on the sphere.

Yes, but it isn't part of the 2D surface of the sphere. In the same way, the center of our universe, the origin of the Big Bang, isn't to be found anywhere in our 3D volume. It is in the time direction.