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Introduction and crazy question...
Posted: Wed Jan 27, 2010 12:46 am
by Mdub
Hi everyone,
Space cadet Mike here.
What a great time to be alive!
I can remember when all the things we are doing and learning now was the stuff of science fiction!
My question , after many
's, is:
Is it possible, when looking at the Hubble Deep Field Exposure, that one of those tiny red blobs could be the Milky Way as it was ~13 billion years ago?
Can we track objects/galaxies through time?
It
seems possible
Re: Introduction and crazy question...
Posted: Wed Jan 27, 2010 2:35 am
by neufer
Space cadet Mike wrote:Is it possible, when looking at the Hubble Deep Field Exposure,
that one of those tiny red blobs could be the Milky Way as it was ~13 billion years ago?
Probably not.
Space cadet Mike wrote:Can we track objects/galaxies through time?
It
seems possible
Not the same objects/galaxies:
http://en.wikipedia.org/wiki/Observable_universe wrote:
<<78 billion light-years... is a lower bound for the size of the whole Universe, based on the estimated current distance between points that we can see on opposite sides of the cosmic microwave background radiation (CMBR). If the whole Universe is smaller than this sphere, then light has had time to circumnavigate it since the big bang,
producing multiple images of distant points in the CMBR, which would show up as patterns of repeating circles. Cornish et al. looked for such an effect at scales of up to 24 gigaparsecs (78 billion light years) and failed to find it, and suggested that if they could extend their search to all possible orientations, they would then "be able to exclude the possibility that we live in a Universe smaller than 24 Gpc in diameter". The authors also estimated that with "lower noise and higher resolution CMB maps (from WMAP's extended mission and from Planck), we will be able to search for smaller circles and extend the limit to ~28 Gpc." This estimate of the maximum diameter of the CMBR sphere that will be visible in planned experiments corresponds to a radius of 14 gigaparsecs, the same number given in the previous section.>>
Re: Introduction and crazy question...
Posted: Wed Jan 27, 2010 5:08 am
by Chris Peterson
Mdub wrote:Is it possible, when looking at the Hubble Deep Field Exposure, that one of those tiny red blobs could be the Milky Way as it was ~13 billion years ago?
No. Aside from the difficulty with coming up with a plausible geometry for that observation, there's the simple fact that the Hubble Deep Field doesn't show the Universe as it was 13 billion years ago. It shows about 3000 galaxies that are seen over a range of 12 billion years ago to recent. All those little red blobs have different redshifts, meaning different distances.
Can we track objects/galaxies through time?
Any individual object we examine we see only at one particular time, dictated by its distance. We can only track it through time by observing it at different times; for the vast majority of objects we haven't been able to observe long enough to see any kind of change.