Talk:Observable universe

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Shape

How can we say that the observable universe is ball-shaped if we can't tell exactly what shape is the Universe? 79.186.242.134 (talk) 12:29, 30 April 2024 (UTC)[reply]

If you point your finger in the sky, look up and focus on your finger nail, then start moving your head slowly and stare straight, eventually, your vision forms a ball⚽ 120.16.2.76 (talk) 10:17, 5 July 2024 (UTC)[reply]

Shouldn't Universe be Capitalized?

If astronomical bodies are capitalized, and the monotheistic God is capitalized, something that could be described as both should also be capitalized, right? Octaazacubane (talk) 14:56, 20 September 2024 (UTC)[reply]

Isn't the first sentence misleading?

The article starts with

The observable universe is a spherical region of the universe consisting of all matter that can be observed from Earth;

A plain and simple reading of this sentence contradicts reality. It implies an agency for observers that physics denys us. The matter at 45.7 billion light-years cannot be observed "now", we can only observe the light from matter that would have been emitted 13 Gya. I think a clearer starting sentence would be

The observable universe is a spherical region of the universe consisting of all light that has ever been emitted since the Big Bang.

This includes the critical issue of time and is more consistent with particle horizon. Johnjbarton (talk) 19:15, 10 April 2025 (UTC)[reply]

I agree that the current first sentence has issues, but your proposal does not seem to be correct. Suppose for example that the full universe is infinite and the Big Bang happened everywhere at once; then your sentence would imply that the observable universe is the full universe, which is not true. --Trovatore (talk) 20:15, 10 April 2025 (UTC)[reply]

Of course you are right. How about:

The observable universe is a spherical region of the universe consisting of all light emitted since the Big Bang that arrives on Earth at one time.

Johnjbarton (talk) 21:35, 10 April 2025 (UTC)[reply]

Universe or "Observable universe"?

The term "observable universe" has a specific meaning. It is not a synonym for the universe. So some of the content seems off topic. I think most of the composition and structure content does not belong here, other than as a summary. Johnjbarton (talk) 23:46, 10 April 2025 (UTC)[reply]