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Relativity with regard to CMBR and galaxy types


MarkE

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1 hour ago, MarkE said:

Then the graph wasn't what I asked for.

I asked whether anyone could draw the shape of the universe on a piece of paper (or explain that drawing in words, which would also suffice).

The "shape" is often interpreted as the curvature of the universe, so in a sense, it is what you asked for, even if you did not realize it.

Perhaps you need to clarify what you mean by the shape. As I said before, a volume is 3D, and you aren't going to be able to put that onto a 2D map. The best you can do is a projection, or, alternatively, you could represent the components at some value of R on a map. Much like a map of the earth's surface is at some rough, nominal value of R. You can also have a map of the ocean bottom. But it would be difficult to map both the surface and what it looks like 5km below the surface on the same static map.

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If you can draw the Solar System, and the Milky Way, or the Local Group, it must be possible to make a drawing of the entire universe.

Did you miss where I explained why these are not equivalent? (things that are close to 2D and others are 3D, and how many items are in the image))

 

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I'm not saying that I have a clear indication of what the shape of the universe must be, I just think that, if nobody is able to draw it on a piece of paper, there's no leading, widely accepted shape that's more plausible than any other shape. Therefore it could be spherical, like a globular cluster (which would make the most sense to me).

It sounds like you want a 3D spatial map of the objects in the universe. How do you represent objects that could be 10 LY away from us, and 20 LY, and 30 LY etc., etc. (as you would have if you look in the direction of the Milky Way for the first 60k LY or thereabouts) out to 45 billion LY, that all might be along a line of sight?

IOW you're standing in a dense forest and you want a picture of the whole forest - all the trees. Can you do that from that perspective?

One thing you might look at for deep space, in certain directions, would be Hubble deep-space pictures. But it won't tell you the actual depth of the image; it's just a projection onto a plane.
 

 

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6 hours ago, swansont said:

One thing you might look at for deep space, in certain directions, would be Hubble deep-space pictures. But it won't tell you the actual depth of the image; it's just a projection onto a plane.

One of my favourite/s illustrative photos of space, and the history of the universe.

Hubble Ultra Deep Field

This view of nearly 10,000 galaxies is called the Hubble Ultra Deep Field. The snapshot includes galaxies of various ages, sizes, shapes, and colours. The smallest, reddest galaxies, about 100, may be among the most distant known, existing when the universe was just 800 million years old. The nearest galaxies - the larger, brighter, well-defined spirals and ellipticals - thrived about 1 billion years ago, when the cosmos was 13 billion years old.

The image required 800 exposures taken over the course of 400 Hubble orbits around Earth. The total amount of exposure time was 11.3 days, taken between Sept. 24, 2003 and Jan. 16, 2004.

 

Credit:

NASA, ESA, and S. Beckwith (STScI) and the HUDF Team

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