How can we be sure of a singularity?

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Discussion Overview

The discussion revolves around the nature of singularities, particularly in relation to the big bang and the state of the universe at or before t=0. Participants explore various hypotheses regarding the initiation of the universe, the concept of a singularity, and the implications of quantum mechanics on these ideas.

Discussion Character

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

Main Points Raised

  • Some participants question the evidence for a singularity being the initiation of the big bang, suggesting alternative scenarios where energy existed prior to this event.
  • There is mention of the state of the universe at t=0 being an open question, with many ideas but no current means to test them.
  • One participant proposes that the release of energy from sub-atomic particles could be significantly greater than that from splitting an atom, suggesting a mechanism for the big bang.
  • Others reference the work of Ashtekar and Bojowald, indicating that the question of a beginning to the universe may be transcended in quantum cosmology, where traditional notions of time may not apply.
  • Some participants discuss the relational nature of general relativity and the implications for defining time and observables in the early universe.
  • A participant proposes a model where the interaction between sub-atomic particles and a void leads to an explosion and expansion, suggesting a cyclical nature of universes.
  • Concerns are raised about the relevance of certain concepts, such as self-contained energy systems, and their connection to the discussion on singularities.
  • There is mention of the potential for resolving singularity issues through dynamical approaches in quantum gravity, though this remains a point of contention.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of singularities or the initiation of the universe. Multiple competing views and hypotheses are presented, with ongoing debate about the implications of quantum mechanics and general relativity.

Contextual Notes

Participants express uncertainty regarding the definitions and implications of singularities, the role of time in quantum cosmology, and the relationship between energy and the universe's state at t=0. The discussion reflects a range of interpretations and theoretical frameworks without resolution.

neonpotato
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I have often been told that at the start of our "universe" (I prefer "self-contained energy system" - SCES, myself) all energy was contained in a singularity. What is the evidence for this all-containing singularity being the initiation of the big bang?

Is it not reasonable that the extremely dense core of a shrinking SCES (or universe) could have exploded with energy already in existence around it?

Any illumination would be appreciated.

Please be aware my understanding of physics is limited.
 
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What the state of the universe at t=0 or t<0 (big bang starts time) is an open question. There are many ideas floating around, but there is (at the moment) no way to test them.
 
neonpotato said:
I have often been told that at the start of our "universe" (I prefer "self-contained energy system" - SCES, myself) all energy was contained in a singularity. What is the evidence for this all-containing singularity being the initiation of the big bang?

Is it not reasonable that the extremely dense core of a shrinking SCES (or universe) could have exploded with energy already in existence around it?

Any illumination would be appreciated.

Please be aware my understanding of physics is limited.

This has puzzled me as well. My take is this. When you split a rock, you might get a few sparks, perhaps a bit of radiation and some crumbs. When you split an atom you get quite a bit more energy released than from spliting a rock. By these two examples, in tandem, I would suggest that when a sub-atomic particle (wave) is either compressed by, or forced to dispense into a "void", a great deal more energy is released than what is released by splitting an atom... in fact probably 10 to the power of 9 more energy than is released than when an atom is split.

Then again, I've been wrong before.
 
baywax said:
... My take is this. When you split a rock, you might get a few sparks, perhaps a bit of radiation and some crumbs. When you split an atom you get quite a bit more energy released than from spliting a rock. By these two examples, in tandem, I would suggest that when a sub-atomic particle (wave) is either compressed by, or forced to dispense into a "void", a great deal more energy is released than what is released by splitting an atom... in fact probably 10 to the power of 9 more energy than is released than when an atom is split.

Then again, I've been wrong before.

I don't follow. How is this related to my question?
 
neonpotato said:
...
Is it not reasonable that the extremely dense core of a shrinking SCES (or universe) could have exploded with energy already in existence around it?
...

check out Einstein Online, an authoritative, mainstream, up-to-date website maintained as part of the Albert Einstein Institute's public outreach program.
http://www.einstein-online.info/en/spotlights/cosmology/index.html

it's great. Atyy (who posts here sometimes) told us about it.
It has a page that discusses what you are talking about
http://www.einstein-online.info/en/spotlights/avoiding_the_big_bang/index.html
and it also has useful page regarding singularitie and the different things people mean by "big bang" which can help us avoid confusion.
http://www.einstein-online.info/en/spotlights/big_bangs/index.html
 
Last edited by a moderator:
Ashtekar + bojowald state

"The question of whether the universe had a beginning at a finite time in the past is now `transcended'. At first, the answer seems to be `no' in the sense that the quantum evolution does not stop at the big-bang. However, since space-time geometry `dissolves' near the big-bang, there is no longer a notion of time, or of `before' or `after' in the familiar sense. Therefore strictly, the question is no longer meaniful. The paradigm has changed and meaningful questions must noe be phrased differently, without using notions tied to classical space-times"
 
GR is a relational theory in which you have to pick a dynamical observable to take on the role of a clock , but in the deep quantum mechaical region of the early universe there are no classical observables...
 
The 'big bang' is the sound of one hand clapping [in zen speak]. Since no classical observables existed at t=0, as Julian noted, using yardsticks and clocks to describe this realm is like trying to announce a a hockey game by weight and color.
 
julian said:
GR is a relational theory in which you have to pick a dynamical observable to take on the role of a clock...

that's right! Agrees with what I've read about the computer modeling of bounce at Penn State for instance. A dynamical observable, e.g. connected to a matter field, is included and serves as clock. The model is quantum rather than classical in this case. they don't have time as such, and choose one of the physical elements in the picture to use as a clock.

Have you read much about it? You sound as if you may have. Do you have any papers you want to give links to?
 
  • #10
neonpotato said:
I don't follow. How is this related to my question?

I'm trying to explain my thoughts concerning what caused the big bang. So, the wave or particle I mentioned that is compressed or dispersed and out of balance with the "void" (lack of time, space) is all of what's left of the old universe or "p-brane".

Today is is evident that the universe is expanding and that objects are getting further apart. I have extrapolated this motion to a point where even sub-atomic particles have separated by great distance until space and time collapse, leaving only isolated sub-atomic particles surrounded by a void. At this point I am proposing that some sort of interaction between the sub-atomic particle and the void causes a rather large explosion and expansion. Then there is another universe developing.

Make me wrong!
 
  • #11
The note I made was cautionary - my understanding isn't detailed. Tied with the notion of time is energy - so I was unsure of the relavence of SC(Energy)S. I wish to understand these things better myself.

Something that confuses me: The results about singularity avoidance so far pertain to the kinematic level (I think) - but things can change dramatically at the physical (dynamical level). Thiemann has written a paper in which he describes the reduced pahse space quantization of GR (which explicitly operates at the physical level) and proclaims it may resolve the singularity problem dynamically. The thing is, it is an essential feature of the RPSQ that the dynamical time variable is described classically, which is at odds with what I said before!

ian
 
  • #12
I will try to bring together the list of references that contribute to my "understanding" of the issue
ian
 

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