Is the Big Bang Similar to a Black Hole?

In summary, the conversation discusses the differences between the big bang singularity and a black hole as possible beginnings of the universe. One major distinction is that the black hole singularity lies on the future light cone, while the hot big bang is observed in the past. It is also mentioned that the big bang is able to expand rapidly and slow down, allowing for a flat space even when spacetime is not. The conversation also explores the temperature difference between the two, with less than 3 degrees K for black holes and 1028 degrees K for the big bang. It is questioned whether this temperature difference is related to the differences in the curvature of time and space between the two. The possibility of quantum insights is also mentioned, with the example
  • #1
Naty1
5,606
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In this FAQ at the Baez website, the big bang singularity is contrasted with a black and white hole as a possible beginning of our universe.

Is the Big Bang a black hole?
http://math.ucr.edu/home/baez/physics/Relativity/BlackHoles/universe.html

[I'm not interested in answering the title question,which is NO, but rather exploring the differences.]

A few major differences are outlined:
The black hole singularity always lies on the future light cone, whereas astronomical observations clearly indicate a hot Big Bang in the past...

The short answer is that the Big Bang gets away with it because it is expanding rapidly near the beginning and the rate of expansion is slowing down. Space can be flat even when spacetime is not. Spacetime's curvature can come from the temporal parts of the spacetime metric which measures the deceleration of the expansion of the universe. So the total curvature of spacetime is related to the density of matter, but there is a contribution to curvature from the expansion as well as from any curvature of space...

So, the first sentence appears to be a major distinction between a BB and a BH. ok.

Three questions:

what about the temperature difference between the two...less than 3 degrees K for many black holes and 1028 degrees K for the big bang...Does this manifest in the differences or is temperature relatively unimportant?

Also, Is SPACE hardly curved at the big bang, just time, while for a black hole both space and time are severely curved?? If so, does the extreme curvature of time relate to the temperature difference? to the initial expansion/repulsion?

Do we have any quantum insights yet that support, contradict or offer other insights?

edit: from another thread, I saved this partial insight:

Pervect: "Because the stress-energy tensor for expanding matter is different from the stress-energy tensor of non-expanding matter, you can have compact, dense, expanding objects that are not black holes." ok.
 
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  • #2
I posted this elsewhere:
Is Spacetime Quantized? Loop quantum gravity even makes precise predictions about the geometry of spacetime at the Planck scale.
Sounds interesting, but I do not have any of those predictions.

http://www.knowledgerush.com/kr/encyclopedia/Spacetime/

I checked Lee Smolin's THREE ROADS TO QUANTUM GRAVITY [year 2000] and he discusses LQG
in terms of evolving [Penrose] spin networks in some detail, and has done research himself, but says nothing about the geometry relative to BH and BB...
 

1. What is the difference between the big bang and a black hole?

The big bang refers to the event that is believed to have started the expansion of the universe, while a black hole is a region of space with such a strong gravitational pull that nothing, including light, can escape from it.

2. Can a black hole lead to another big bang?

There is currently no evidence to suggest that a black hole can lead to another big bang. The big bang is a unique event that is thought to have occurred only once.

3. Does the big bang theory explain the formation of black holes?

No, the big bang theory does not explain the formation of black holes. Black holes are formed through the collapse of massive stars, not through the expansion of the universe.

4. How are the big bang and black holes related?

The big bang and black holes are both related to the concept of gravity. The big bang theory suggests that the universe began with a singularity, a point of infinite density and gravity. Black holes also have a singularity at their center with a strong gravitational pull.

5. Can the big bang and black holes coexist?

Yes, the big bang and black holes can coexist. In fact, black holes are thought to exist in many galaxies, including our own, which formed after the big bang. However, black holes do not play a significant role in the expansion of the universe as predicted by the big bang theory.

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