Looking at pictures of hubble's DSF (deep space field?) is throwing a big problem at me which i can't seem to find an answer for.
As we stare at millions of galaxies at the edge of our visible universe and as close to the big bang as we have been i cant help thinking we are looking at ourselves after all where else could we have been 15 Billion yrs ago other than in the middle of it? I saw someone say in this forum that only an un asked question is a stupid one so....

AND ANOTHER THING!!!! ever get the feeling you've asked such a dumb question it doesn't even deserve an answer?

Dear pleasurehead,
Your question really isn't a bad one at all as you said where else could we be? the only problem is we could well be looking at the big bang but how on earth could we see ourselves? it's just not possible

It's not a dumb question, it's an unclear one. What do you mean by this:

QUOTE: ...after all where else could we have been 15 Billion yrs ago other than in the middle of it?

P.S. Are you talking to yourself?

How can you say it's not possible? light can bend. A black hole can bend light up to 360 degrees. so if there was one near us it could happen

kkkzzz
If its the start of time our galaxy must be in there somewhere?

Yes i was talking to myself. Its bothering me

In order for us to see ourselves as a galaxy in ultra deep space, the light emanating from the Milky Way must travel all the way around the universe or get reflected back to us, as you suggest, by a twist in spacetime caused by a black hole or other massive object. In this case, there can be many reflections of us, just as there are many reflections of you in a hall of mirrors. Each mirror is like a celestial curvature in spacetime, and hence we might see not one but many reflections of us. But because the light is so weak, we are barely able to resolve any detail at all. We would not be able to positively identify ourselves.

On the first point (light traveling all the way around the universe), inflation theory probably rules out this possibility. If the fabric of spacetime is expanding faster than the speed of light, light that emanates from any point in space will never get back to its starting point.

but hey i'll carry on anyway
so what you are saying is, you rekon we could be looking at ourselves billions of years ago?

could it be possible that we may be moving away from the starting point so therefor doesn't have to reach it? could we cross the lights path?

See the thread "seeing into the past" by clicking here:

http://www.astronomy.com/asy/community/forum/topic.asp?TOPIC_ID=4980

When you hear people claim that the spacetime fabric is expanding, it means everything is moving away from everything else, but on a larger scale than the scale of a single galaxy or a conglomeration of galaxies within a supercluster. In these smaller scales, gravitational effects are pronounced, and these effects keep planets bound to stars, stars bound to their galaxies, and galaxies bound to the center of their supercluster. Galaxies will even collide with each other. But on larger scales, scales that are not dominated by local gravitational effects, everything is rushing away from everything else.

But here's an opposite question to the one you posed, based on SN1987A's message in the thread "galaxies receding":

QUOTE: Originally posted by SN1987A
The exact reason as to why this happens is unknown, but the galaxies and quasars seem to follow Hubble's Law which states that the velocity of the receeding object is proportional to it's distance from the observer

v = H x r

where v is the velocity, r the distance to the object and H is the Hubble's constant. The current value of H is somewhere around 72km/s per MPc i.e. if two galaxies,quasars or whatever are seperated by a distance of 1 Mega Parsec(3.26 million light years) then one of them observes the other to be moving away at a speed of 72km/s

So, if a quasar is at a distance of approximately 12 billion light years, it would be moving at 90% the speed of light.

This law ofcourse doesn't apply in places like the Local Group where gravity might play a significant role in bringing the galaxies together.
If spacetime is expanding at the rate of 72 kilometers per second per mega parsec, then galaxies at a distance of 12 billion light years will be receding at 90% of the speed of light.

What about galaxies at 14 billion light years distance? At some distance from us, spacetime may be expanding faster than the speed of light. So some galaxies that are just at the edge of our visible bubble should be disappearing. Over time we should be seeing fewer and fewer galaxies, not more and more (because beyond the visible bubble, spacetime may be expanding faster than light speed and, if true, then light from those galaxies will never reach us).

Have we noted any disappearing galaxies?

WOW! thank you. That has shed a little more (or maybe less) light on my confussion. I hadn't looked at it that way at all

KKKZZZ you have just revealed the fallibility of Hubbles law which should never have been called a law in the first place. It should have been called Hubbles highly educated guess. Because eventually the outer limits of the universe will be expanding faster than the light they emit. The only thing that expands faster WAS Hubbles ego.

Buckzumoff:

You are disregarding the effect that expanding spacetime has on the measurements themselves, the apparatus making the  measurements, and the time dilation due to expansion.

Hubble's Law is valid to a good approximation. The cosmological constant is variously interpreted, but we are approaching errors bars under 10 percent and are expected to improve upon that soon. When you are talking about cosmological factors, uncertainties of 10 percent are actually very good. Some of our measurements validate calculations very much better than that (the temperature of the CMB, for example).

 The calculations of the temperature of the CMB show that the CMB temp is "exactly" what it should be if the universe is @ 14 billion years old. If we were to, through observation, find that the universe is much older, then our "exact" temp of the CMB would become wrong. Let's hope the upcoming "Super Duper" Type Ia nova, detected at 20 billion light years distance, happens before we are all dead.

Cheers,

BQ 

That's not what I said. Let me rephrase: I'm talking about the precision of the measurements, not whether they are "correct."

When we make measurements in science, they are always accompanied by an accuracy factor. Let's say you define "one second" to a certain number of oscillations of an atom of an element at a given temperature, pressure, and ionization potential. There are potential inaccuracies in each of the factors you measure (isolating a single atom requires a certain amount of precision, reading the temperature another, and so on). When you add up the inaccuracies you arrive at a certain precision beyond which you can't discriminate, so you say the value of "one second" is "XYZ vibrations plus or minus 5%" or something like that.

So, taking your reply as an example, you could say something like "based on the currently accepted value of the temperature of the CMB, the equivalent age of the universe is 14By plus or minus X%.

That is what I meant.

 I get your point. My understanding is that the CMB is now one of the most recent observations that supports the BBT as the temp calculation is so close to the Hubble reverse expansion calculation. The Hubble reverse calculation is ok if we assume that the universe is a sphere with us near its center. If we are far far away from the center of this sphere then the age of the universe using this method becomes harder to calculate. The CMB temp squad stated that the CMB is at the exact temp it should be for a 14 Billion Year old universe. Perhaps our part of the universe is that old while other parts are at different ages? I'm not sure. However my point about an older universe making an exact temp calculation change remains. If the temp calc is not correct then it does not fully support current BBT.

BQ 

brooksquest, how can one state that the cmb temp is the same everywhere. How can they calculate the cmb temp 14 billion light years away NOW. The temp we receive is 14 b years old. In relative time the temp should be much cooler don't you think? Also please explain to me this, if the light that we see today is 14 B light years away the source emitting that light would have traveled( in time relative to us ) another 14 B years away from us. So according to calculations that source is traveling at a rate of 95%C  or another 13.6B light years( give or take a few million light years ) away from the point that we see it. So in our time is space twice as big in reality or was it one half the size when the light originally was emitted. Can you visualize what I'm getting at. If the light we see today is 14B light years away it then must be 14B years old. The position of the source has expanded away from us some 13 odd light years. So looking in on the universe from the outside ( impossible for us I know) it would actually be twice as big as we perceive it to be correct?Hypothetically speaking of course.

brooksquest, between you and chipdataJeff you make this forum lots of fun to read. You two never belittle me for my unanswerable and sometimes stupid questions. I hope to follow you both around these forums because you both seem well informed. Keep up the good work the both of you.

Thank you!

I think you would enjoy reading Wrinkles in Time, which chronicles the COBE project and explains the issues very well.

While I don't have the exact figures in mind at the moment, the COBE results simply astonished even the most knowledgeable scientists by presenting a very clear validation of the predictions of BBT redshift of the original BB afterglow. It was "lumpy" on local scales but isotropic to an amazing degree on cosmic scales. But there were errors due to the technology used and experimental physicists felt they could do better and perhaps resolve some of the questions.

Hence WMAP, which once again astonished even the researchers who had predicted some problems that BBT would have to overcome. This time not only were the results themselves  amazing, but their precision was even better than they'd dared hope. And, once again, the results verified BBT predictions.

There are many good explanations of these projects, but you won't be disappointed by starting out with George Smoot's Wrinkles in Time.

How the CMB studies fit in with overall expansion theory is explained very well in Patterns in the Void, by Sten Odenwald (The Astronomy Cafe, etc.).

And a good description of the balancing act that is measuring expansion at local, galactic-cluster, and cosmic scales is in Voyage to the Great Attractor, by Alan Dressler.