Did the Big Bang create space and time?

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Discussion Overview

The discussion revolves around the implications of the Big Bang theory, particularly whether it suggests that space and time were created at the moment of the Big Bang. Participants explore the relationship between the expansion of the universe, singularities, and the nature of spacetime, touching on both scientific and philosophical aspects of the topic.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants note that Georges Lemaître's formulation of the Big Bang theory was based on the observation of an expanding universe, leading to questions about the nature of singularities and the beginning of the universe.
  • It is mentioned that the Big Bang theory does not provide information about events prior to the Inflation Era, leading to uncertainty about the creation of space and time.
  • Some argue that while the formal Big Bang theory does not assert that space and time were created, there is speculation regarding the conditions at the moment of the Big Bang.
  • Others suggest that the connection between space and time, as described by relativity, implies that time also begins at the moment of the Big Bang, although this is characterized as speculation rather than a definitive claim of the theory.
  • A participant raises the question of whether interpretations asserting the creation of space and time make testable predictions that differ from those that do not, suggesting that without such predictions, these interpretations may not qualify as scientific.
  • It is pointed out that the current cosmological models do not necessarily include an initial singularity as part of their framework, indicating a shift in understanding from Lemaître's original model.
  • Some participants clarify that in the idealized model with an initial singularity, space and time would be considered created at that point, but this model is not representative of current cosmological theories.

Areas of Agreement / Disagreement

Participants express differing views on whether the Big Bang created space and time, with some asserting that it does not, while others infer that it does based on the implications of relativity. The discussion remains unresolved, with multiple competing interpretations present.

Contextual Notes

There are limitations in the discussion regarding the definitions of terms like "initial singularity" and the implications of current cosmological models, which may not align with earlier interpretations of the Big Bang theory.

Lunct
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As I understand it Georges Lemaître, upon learning about Hubble's discovery that space is expanding, came up with the big bang theory. He thought that if space is getting bigger, then it must have been smaller at one point, and if you go back far enough you get an extremely dense singularity. From this, all we would know is that the universe was once in a singularity, then expanded into the universe as we know it. So then why do people say that the big bang created space and time? How would we know this? And wouldn't this also imply that it created all matter and energy, because how could they exist with no space and time, unless they are in some other dimension separate from space and time? So did the Big Bang create energy and matter?

I understand that this question is probably breaking the bounds of physics, and entering into the territory of broader philosophy.
 
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The "Big Bang Theory" is silent on what happened at the point you get to if you extrapolate time backwards, and only starts after the Inflation Era.
 
phinds said:
The "Big Bang Theory" is silent on what happened at the point you get to if you extrapolate time backwards, and only starts after the Inflation Era.
So it would not assert that space and time were created?
 
Lunct said:
So it would not assert that space and time were created?
The formal BB Theory does not, no, but there is great speculation as to just what was going on, just no evidence to support any theory.
 
phinds said:
The formal BB Theory does not, no, but there is great speculation as to just what was going on, just no evidence to support any theory.
okay thanks that makes sense
 
The expansion of the universe implies that there was a point at which space began, as you point out. Since space and time are connected, as relativity shows, into spacetime, it's inferred that time also begins at the moment of the big bang.
 
alantheastronomer said:
The expansion of the universe implies that there was a point at which space began, as you point out. Since space and time are connected, as relativity shows, into spacetime, it's inferred that time also begins at the moment of the big bang.
That's just speculation and is not part of the Big Bang Theory.
 
Do interpretations that space and time were created at the instant of the Big Bang make testable predictions that are different from interpretations that they were not created?

If not, these interpretations are not really science - just speculation. Real science assertions need to make testable predictions that are different from competing or opposing assertions.
 
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Lunct said:
if you go back far enough you get an extremely dense singularity. From this, all we would know is that the universe was once in a singularity

It's important to realize that Lemaitre's original model, which had an "initial singularity" in it, is not the current model that cosmologists actually use. It's not just that refinements have been added as to the detailed expansion history of the universe; it's that the presence of the initial singularity is now viewed as an indication that the model is just an idealization, and stops being valid at some point as you go back in time. Our best current model uses the term "Big Bang" to denote, not the idealized "initial singularity", but the hot, dense, rapidly expanding state that is th earliest state of the universe for which we have good evidence. In models that include an inflation phase, the "Big Bang" state is the state at the end of inflation.

Lunct said:
why do people say that the big bang created space and time?

In the idealized model in which there is an initial singularity, there is no space or time before that; so in that sense, in the idealized model, space and time are "created" at the initial singularity. But people who refer to this probably don't realize that that idealized model is not the one that cosmologists actually use.
 
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Thank you for all the replies, you have cleared things up.
 

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