Why is the universe shaped like a pebble?

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Discussion Overview

The discussion revolves around the shape of the universe, specifically addressing the notion of it being "pebble-shaped." Participants explore various models and interpretations of the universe's geometry, referencing the Cosmic Microwave Background and the implications of observational limitations. The conversation includes theoretical considerations, visual representations, and speculative ideas about the universe's structure.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • Some participants question why the universe appears pebble-shaped rather than round, suggesting it may be a "pebble in a greater universe."
  • One participant argues that the diagram representing the universe's shape is misleading, comparing it to a 2D map of the Earth that cannot fully capture its 3D nature.
  • Another participant introduces the idea that the Cosmic Microwave Background (CMB) is not the universe itself but radiation from the Big Bang, emphasizing the lack of a definitive shape for the universe.
  • There is a discussion about the apparent features of the CMB, such as the "equator" and "polar caps," with some participants expressing confusion about their significance.
  • One participant asserts that current research indicates the universe is flat, while another highlights the limitations of observational data, suggesting the universe could have various curvatures beyond what is currently perceived.
  • Another participant notes that the pebble shape may result from the flat map projection used to represent the universe in 2D.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the shape of the universe, with some asserting it is flat while others suggest it may have different curvatures. The discussion remains unresolved, with no consensus reached on the universe's shape.

Contextual Notes

Participants acknowledge the limitations of their observations and the dependence on how the universe is represented in 2D, which may not accurately reflect its true geometry. There is also mention of unresolved mathematical and theoretical aspects related to the universe's shape.

alice22
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http://news.bbc.co.uk/1/hi/science_and_environment/10501154.stm
1galactic_regions_786.gif

Pebble.
Gray---Pebble-shaped-paper-wei-5824275.jpg

Universe.I would have expected it to be rounder.

So why is it pebble shaped?

Could it be our universe is merely a pebble in a greater universe?
 
Astronomy news on Phys.org
That diagram doesn't represent the apparent shape of the Universe. Imagine an Atlas of the Earth, In order to represent all geographical anomalies, such being the continents and oceans, it is impossible to display it 2-dimensionally when the Earth is 3-dimensional. Similar to this Atlas: http://skywalker.cochise.edu/wellerr/students/pleistocene-extinction/extinct_files/image008.jpg
The photo is essentially a mapping of the 3-dimensional Cosmic Microwave Background but stretched onto a 2-dimensional surface which shows it's curvature, you can try to attach the ends of the mapping and you'll create a sphere. There is no conclusive shape of the Universe but since we are surveying the sky from a single location and light sources emitted come from every direction converge at the specific point (Earth) the Universe appears to be spherical

http://en.wikipedia.org/wiki/Robinson_projection
 
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So what is that white line in the middle like an equator?Why does it appear to have red polar caps?

Universal warming perhaps?
 
No in fact the telescope (Planck telescope) used to measure the Cosmic Microwave Background Radiation measures precisely (supposedly) the excess radiation from the Big Bang. When the Universe went through a process of rapid expansion (inflation) it cooled enough for stable atoms to form - the left over photons that weren't absorbed have been propagating through space and have been transformed to Microwaves because of Universal Expansion. The temperature of the Cosmic Microwave Background is 2.725 K which puts it in the Microwave Range of 160.2 GHz. What I stated before is this isn't the Universe. This is radiation that is found in the Universe which originated during the Big Bang. To imagine the Universe to be spherical is rather naive because there is no experimental description of the Universe's Shape : http://en.wikipedia.org/wiki/Shape_of_the_Universe
The irregularity in the Cosmic Microwave Background: Poles and equator, is due to anisotropies or variances which is dependent on the size of the observed region. Experimental and theoretical research correlate this effect to thermal variations caused by quantum fluctuations of matter in a very tiny space (the early universe). Therefore during the Big Bang when radiation was more prominent than matter and the Universe was extraordinarily small there were quantum fluctuations that occurred and when the Universe cooled these dynamics are visualized in the apparent non-uniform display in the Cosmic Microwave Background.

- Kevin
 
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alice22 said:
So what is that white line in the middle like an equator?
From the article, that's the Milky Way Galaxy:
The bright horizontal line running the full length of the image is the galaxy's main disc - the plane in which the Sun and the Earth also reside.
Why does it appear to have red polar caps?
Um...are you serious?

Did you read any of the article? Please read all of it.
 
You're absolutely correct, I didn't read the article it just seemed to look like the the Milky Way but I was convinced otherwise. But the object being described isn't really in accordance with his question - which I already answered. It's just the way it is being projected, it's similar to putting the Geography of the Earth on a 2-dimensional surface as I stated above.
 
Thanks for posting the article, Alice :)
_46395713_09feb2009-3108_h.jpg

^^This is cool!
And I cannot believe this :
This ancient light's origins date to 380,000 years after the Big Bang
:eek:
 
The Universe, in fact, is flat :).
 
Current research and experimental testing states tangentially that the Universe is flat. The immediate paradox is that our observations are greatly limited. The Universe way possibly be a manifold of negative or positive curvature yet our ocular limitations only allow us to percieve the Euclidean Space which is observed at small distances which is our Observable Universe. The question is still unanswered, physics is based off observation and if a flat universe is what we discover than that's what will be said as of today.
 
  • #10
The pebble shape is due to flat map projection - same as that used to portray a map of the Earth in 2D.
 

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