Seeking clarification on singularity at genesis

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Discussion Overview

The discussion centers around the concept of singularities, particularly in the context of the universe's beginning and black holes. Participants explore the implications of singularities in cosmology and their relation to current physical theories, questioning the nature and understanding of these phenomena.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants note a discrepancy between Stephen Hawking's assertion that there was no singularity at the universe's beginning and the common belief that a singularity existed before the big bang.
  • It is suggested that extrapolating current evolutionary models into the past leads to a singularity, but this is deemed unphysical by many physicists.
  • Alternative theories exist that either do not include a singularity or do not address the very first moment of the universe's evolution.
  • Participants question whether the singularity before the big bang is analogous to the singularity beyond a black hole's event horizon, noting both involve issues with current physical theories.
  • There is a discussion about the implications of infinite density and whether it can be appropriately described as infinite mass, with some participants asserting that infinite density does not necessarily imply infinite mass.
  • Clarifications are sought regarding whether the characterization of singularities as infinitely dense reflects actual understanding or merely theoretical predictions.

Areas of Agreement / Disagreement

Participants express differing views on the existence and nature of singularities, with no consensus reached on whether they are analogous or how they should be characterized within current physical theories.

Contextual Notes

Limitations include the unresolved nature of singularities in physics, dependence on theoretical models, and the ambiguity surrounding the definitions of density and mass in this context.

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Seeking clarification on singularity at "genesis"

In Stephen Hawking's book, I read that there was no singularity in the beginning of the universe. However, practically every other source I come across seems to be under the impression that there was indeed a singularity before the big bang. I would really appreciate some clarification.

Thx
 
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It is unknown. If you just extrapolate the current evolution in the past, you get some singularity, but this is considered as unphysical by many physicists. Some other theories do not have a singularity, or do not consider the very first "moment" of the evolution of the universe at all.
 
mfb said:
It is unknown. If you just extrapolate the current evolution in the past, you get some singularity, but this is considered as unphysical by many physicists. Some other theories do not have a singularity, or do not consider the very first "moment" of the evolution of the universe at all.
Thank you very much for your reply. I have some follow-up questions which I will post below, but please do not feel obligated to respond at all if you don't want - these could be answered by anyone.

Is the singularity before the big bang analogous to the singularity beyond the event horizon of a black hole, or are they two different things? I've been under the impression that they're virtually the same thing, both being "infinitely" dense. I'm also under the impression that nothing can really be infinitely dense, and that there is a problem with our understanding and that it yields an infinite mass.
I'm very suspicious that I'm waist deep in misconceptions.
 
They share the problem that our current theories of physics cannot describe them properly.
 
mfb said:
They share the problem that our current theories of physics cannot describe them properly.
Is it appropriate to say that a singularity has infinite mass?
 
Infinite density does not imply infinite mass.
 
MikeyW said:
Infinite density does not imply infinite mass.
Uh huh. So you're saying it would be appropriate to say a singularity is infinitely dense? Is this what we actually think is going on in a singularity, or is that just what our theories predict?

Thank you
 

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