Mapping the Universe?

[baumer]

Recently, I've been thinking about the mapping of the universe (http://www.sdss.org/background/).

I cannot see how it's possible to have an accurate map of the universe, or a significant portion of it for that matter.

The information recorded with telescopes is only travelling at the speed of light, whereas most of the distant objects in the universe are several million light years away. This information is outdated, simply because it has to travel for millions of years to reach us.
Meaning that the actual location of these objects at this moment in time would have to be calculated if it was going to be mapped (Probably not that reliably).

As you look further into the universe, you look further back in time, and thus the inaccuracy of the map would be proportional to the distance from earth (because that is where the information was gathered).

An implication of relativity, I guess, but I still don't see a use for an inaccurate map. Perhaps I am missing something.

You are right that the further out we look into the Universe, the further back in time we look. And this is a very interesting part of the picture to may astronomers because it allows us to develop models as to the history of the Universe. The current mainstream theory as I understand it is that the Universe is Homogeneous on a very large scale. But if you look at the smaller scale there are clusters of galaxies. What percentage of the mass of the Universe is "dark matter" and how this effects the clustering is still an open question. Also, some have suggested there may be fractal patterns within the Universe. So a good map helps us understand the history of the Universe - it may help to verify some ideas about the Big Bang Theory or perhaps point us in other directions.

[atrifix]

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An implication of relativity, I guess, but I still don't see a use for an inaccurate map. Perhaps I am missing something.

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Besides the thought-concept that you could somehow deduce the current state of the universe based on what you know about the past (which is technically unfeasible), having a map of the universe is just useful for physicists and those otherwise interested in the universe. They aren't using these maps in order to navigate rocket ships, after all.

The WMAP (Wilkinson microwave anisotropsy probe) map shows the universe as it was when it was only 380,000 years old. It confirmed the predicted background radiation that would be left after a "big bang". The picture just looks like a bunch of dots, but these dots represent fluctuations in the original cataclysm of the big bang shortly after the universe was created. By measuring the distribution of these fluctuations, scientists can see the origin of galactic clusters.
I'm not an astronomer. My source here is: Michio Kaku - "Parallel Worlds"

[baumer]

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having a map of the universe is just useful for physicists and those otherwise interested in the universe. They aren't using these maps in order to navigate rocket ships, after all.

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What do they use the maps for? I could see them looking into the past to see what the universe was like a long time ago.

But that isn't using the map of the universe, it's just gathering information from that one spot in one particalur state at one particular time.

All the data, if mapped, would be of no more use together as it is separate (on a certain scale).

[baumer]

Perhaps my stance on the mapping of the universe was in error before I even read anything about it.
The thing physicists probably do care about is the past structure of the universe, and seeing further back in time is more important than seeing the "present".