What Came Before the Big Bang? Exploring Pre-Universe Matter and Energy

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Discussion Overview

The discussion revolves around the concept of what existed before the Big Bang, exploring theories and ideas regarding pre-universe matter and energy. Participants engage in a philosophical and theoretical examination of the implications of a singularity and the nature of existence prior to the Big Bang, touching on various cosmological models and analogies.

Discussion Character

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

Main Points Raised

  • Some participants argue that all matter and energy could not have simply appeared from a singularity, suggesting it must have existed in a different form prior to the Big Bang.
  • Others question the reasoning behind the assertion that something cannot come from nothing, proposing that there may be deeper truths about the universe that necessitate a cause for the Big Bang.
  • A comparison is made between the creation of the universe and the development of self-awareness in children, suggesting that properties may exist in a latent form before they become apparent.
  • Some participants challenge the analogy of self-awareness and energy conservation, arguing that self-awareness is a result of a complex nervous system and is not analogous to the creation of the universe.
  • Various cosmological theories are mentioned, including the Hartle-Hawking no-boundary proposal, Loop Quantum Cosmology, and ideas of universes being born from others, though participants express uncertainty about their validity and evidence.
  • One participant notes that while many physicists agree that something must have existed before the singularity, there is a wide variety of ideas about what that might be, with no consensus on a definitive model.

Areas of Agreement / Disagreement

Participants generally agree that the concept of a singularity is problematic and that something must have existed prior to the Big Bang. However, there are multiple competing views regarding what that might entail, and the discussion remains unresolved with no consensus on a definitive explanation.

Contextual Notes

Participants express uncertainty about the implications of various cosmological models and the nature of existence prior to the Big Bang. The discussion highlights limitations in current understanding and the speculative nature of proposed theories.

  • #31
Drakkith said:
Care to elaborate? I don't know why you wouldn't use something like potential energy in this situation.
Well, since you'd usually use Newtonian gravity in this situation, you probably would. But my point is that when you work with General Relativity, there simply isn't any potential energy term there, and furthermore there is not even any good way to define one in general.
 
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  • #32
Chalnoth said:
Well, since you'd usually use Newtonian gravity in this situation, you probably would. But my point is that when you work with General Relativity, there simply isn't any potential energy term there, and furthermore there is not even any good way to define one in general.

Alright, then is this even an issue in GR?

And is GR the only thing to look at here in regards to conservation of energy?
 
  • #33
Drakkith said:
Alright, then is this even an issue in GR?

And is GR the only thing to look at here in regards to conservation of energy?
Well, it's a conceptual issue, to be sure, as many people have a hard time understanding that conservation of energy is only an approximate, local law, one that simply does not hold globally.

The main issue here is that conservation of energy stems from invariance in time. That is, if you can take a system and examine it at two different times and the system remains the same in some specific mathematical sense for those two times, then energy is necessarily conserved between those two times.

Most of the physical laws we know and love, whether they be Newtonian physics, or electricity and magnetism, or quantum mechanics all are unchanged in time, and so they all follow energy conservation. General Relativity throws a wrench into this whole thing because it makes the time coordinate arbitrary: if you can change your very definition of what you mean by "time", then the very idea of "time invariance" ceases to have meaning, and so while you might be able to write down a specific system where energy conservation holds, in general it just won't.
 

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