Common miscons (e.g. it exploded from a singularity) &why to check FAQ

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Discussion Overview

This thread explores common misconceptions related to cosmology and the Big Bang theory, encouraging participants to clarify misunderstandings and refer to the FAQ for detailed explanations.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants argue that a singularity is not a real entity in nature but rather a breakdown in mathematical theories, indicating a need for revised equations.
  • There is no consensus on whether time stops at the beginning of the universe's expansion; some models suggest it continues before expansion.
  • Participants note that the observable universe may not represent the entirety of the universe, which could be infinite.
  • Some argue that the universe does not require empty space to expand into, challenging the notion of an edge to the universe.
  • There is a suggestion that the universe may have been infinite at the start of expansion, but if it was finite, no estimates exist for its size.
  • Time behaves differently inside an event horizon compared to an outside observer's perspective, as it does not stop for an observer inside.
  • Hawking radiation is described as occurring outside an event horizon and is not faster than light.
  • Some participants emphasize that the Hubble redshift relationship does not definitively prove the Big Bang, referencing Hoyle's model as compatible with Hubble's observations.
  • There is a discussion about the implications of the cosmic microwave background (CMB) being a near-perfect black body and its significance for the Big Bang theory.
  • Participants discuss the special meaning of "nothing" in physics, noting that quantum effects can occur in regions described as "nothing."
  • Clarifications are made regarding the distinction between the steady state universe model and a static universe.

Areas of Agreement / Disagreement

Participants express multiple competing views on several topics, including the nature of singularities, the behavior of time at the universe's beginning, and the implications of various cosmological models. The discussion remains unresolved on many points.

Contextual Notes

Some claims depend on specific models or interpretations that are not universally accepted, and there are unresolved mathematical steps regarding the implications of finite versus infinite universe sizes.

marcus
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This is an idea for a thread. Might work or might not. Each post here should address a common misconception in 25 words or less.

You don't have to restate the common misconception, just respond to it. I think we're all familiar with the main ones that keep coming up. Your post (if you contribute one) could motivate a puzzled newcomer to consult the FAQ for lengthier discussion.
 
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A singularity is not thought of as a real thing in nature

Singularity means glitch or breakdown in a math theory. Not a thing in nature.
A symptom that the equations need fixing.
 
No evidence that time stops if you go back to start of expansion. Depends on which model. In some, it continues on back before expansion.
 
The currently observable portion of the universe is not the same as the universe ( the whole thing, which might be infinite, or might not.) Consult FAQ.
 
No reason to think universe surrounded by empty space. It doesn't need empty space to expand into. No reason to imagine an edge. Consult FAQ.
 
Universe may have been infinite at start of expansion. If finite size we don't yet have an estimate. AFAWK expansion isn't outwards from a point.
 
Time does not stop inside an event horizon. To an outside observer it does but not for an observer inside it moves normally
 
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hawkings radiation occurs outside an EH and is not faster than light
 
marcus said:
No evidence that time stops if you go back to start of expansion. Depends on which model. In some, it continues on back before expansion.
Which models? Please mention some names.
 
  • #10
marcus said:
No evidence that time stops if you go back to start of expansion. Depends on which model. In some, it continues on back before expansion.
aleemudasir said:
Which models? Please mention some names.

All of the first 50 papers on this keyword search list of research literature are about that kind of model:
http://inspirehep.net/search?ln=en&...2y=2013&sf=&so=a&rm=citation&rg=50&sc=0&of=hb

Probably the majority of the 400 or so other papers are too, but I didn't scan the list beyond the first 100. Research with models that match the observation data as well as the classic model but go back further in time has gotten very active. These are paper just since 2009.

We need a convention that if you have a question or want to discuss you start a new thread so this one can stay focused.
 
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  • #11
Hubble red shift relationship did not prove the big bang. Hoyle's model was developed after Hubbles's observaitons and was compatible with it. If I had to pick one obervation that showed the big bang (phase not singulatiry) then I would not pick Hubble. I think I would pick the fact the CMb is a near perfect balck body. If COBe had found it was not a black body that might have really thrown the cat amongst the pigeons.
 
  • #12
If the universe started out, or was ever at a finite size, then it must be of a finite size forever, yes?
 
  • #13
justwondering said:
If the universe started out, or was ever at a finite size, then it must be of a finite size forever, yes?

yes a finite cannot become infinite.

back to misconceptions. The word nothing has special meaning in physics. Quantum effects occur in regions often described as "nothing".
 
  • #14
skydivephil said:
Hubble red shift relationship did not prove the big bang. Hoyle's model was developed after Hubbles's observaitons and was compatible with it. If I had to pick one obervation that showed the big bang (phase not singulatiry) then I would not pick Hubble. I think I would pick the fact the CMb is a near perfect balck body. If COBe had found it was not a black body that might have really thrown the cat amongst the pigeons.

To add a related one-liner:

"The steady state universe model isn't the same thing as a static universe"
 
  • #15
sheaf said:
To add a related one-liner:

"The steady state universe model isn't the same thing as a static universe"

Yes I think that's a nice way to sum it up.
 

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