What is the Universe expanding into?

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Discussion Overview

The discussion revolves around the concept of what the universe is expanding into, exploring theoretical implications and the nature of cosmic expansion. Participants engage with ideas related to cosmology, the Big Bang, and the properties of space and matter in the context of the universe's expansion.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that the universe is expanding into "space," while others suggest it could be something else, like plasma.
  • One participant likens the expansion of the universe to being on the surface of a balloon, where distances between points increase as the balloon expands.
  • There is a notion that the universe's expansion could be in its early stages, with speculation about what might trigger another Big Bang and the balance between creation and destruction.
  • Another viewpoint compares the universe to a gas, noting that as it expands, its temperature decreases, similar to how gas behaves when allowed to expand into a larger volume.
  • Some participants express that discussions about forces or entities outside the universe are beyond the scope of scientific inquiry.
  • A participant asserts that the universe has no edge, contributing to the complexity of the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on what the universe is expanding into, with multiple competing views and ongoing debate about the implications of cosmic expansion and the nature of the universe.

Contextual Notes

Some discussions involve assumptions about the nature of space and time, the definitions of expansion, and the speculative nature of forces outside the universe, which remain unresolved.

johnveets
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All that is visible to the human eye is that which can be seen at the furthest limits of the Cosmos, which began with the Big Bang. So then, what could exist from that point on? What space or material is the expanding Universe encroaching into, and either pushing it away, or transforming it into something else? I know the best answer is probably Space, but could it be something else? Some kind of Plasma or something.
 
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Welcome to PF!

The short answer is we don't know.

You can read more about it here:

http://en.wikipedia.org/wiki/Metric_expansion_of_space

The expansion notion though is more like being on the 2D surface of a balloon and as the balloon expands distances between points on the balloon surface increase. We can't say the universe is expanding into anything, its simply that the distances between objects in the universe are increasing at an ever faster rate.
 
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This thread has been moved into the Cosmology forum, as that is a better fit for this topic we're more likely to find a knowledgeable expert there.

@johnveets you may want to search the cosmology forum for some of the other threads on what the big bang was and wasn't, and how the expansion of space-time works. The sticky "on the same page" thread at the top of this forum would be a good place to start.
 
jedishrfu said:
Welcome to PF!

The short answer is we don't know.

You can read more about it here:

http://en.wikipedia.org/wiki/Metric_expansion_of_space

The expansion notion though is more like being on the 2D surface of a balloon and as the balloon expands distances between points on the balloon surface increase. We can't say the universe is expanding into anything, its simply that the distances between objects in the universe are increasing at an ever faster rate.
For the moment they are expanding ever faster, could still be the early stages of the Cosmos. Am thinking though in terms of science fiction and applying the laws of expansion and contraction. When items cool they contract, and when heated expand. Let's say at one point before the birth of our Cosmos, the former Cosmos decreased in size into something infinitesimally small due to cooling and gravity. Gravity would continue to crush everything into the size of who knows what. What would then trigger another big bang? What force would be able to do that? As the Cosmos collapsed, then the force outside of the Cosmos (which we have no idea what it may be, and cannot see)? Would grow in size? The big bang would somehow trigger having the opposite effect. Expansion, and creation would then be reborn? Wouldn't this notion leave creation and contraction(destruction) in perfect balance?

[Mentor's note: Edited to remove a reply to a post that was moved to another thread: https://www.physicsforums.com/threads/questions-about-the-big-bang.800352/]
 
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johnveets said:
When items cool they contract, and when heated expand.

The universe is more like a gas. If you take a volume of gas and then allow it to expand into a greater volume, the temperature of the gas decreases. The universe works similarly. This is less apparent in the present universe, but the very early universe consisted of a high-density plasma which cooled as it expanded until it was cool enough to form a gas of hydrogen and helium (along with a trace amount of a few other elements).

johnveets said:
As the Cosmos collapsed, then the force outside of the Cosmos (which we have no idea what it may be, and cannot see)? Would grow in size? The big bang would somehow trigger having the opposite effect. Expansion, and creation would then be reborn? Wouldn't this notion leave creation and contraction(destruction) in perfect balance?

Any talk of something 'outside the universe' is beyond the scope of science, so we can't even begin to answer it.
 
Drakkith said:
The universe is more like a gas. If you take a volume of gas and then allow it to expand into a greater volume, the temperature of the gas decreases. The universe works similarly. This is less apparent in the present universe, but the very early universe consisted of a high-density plasma which cooled as it expanded until it was cool enough to form a gas of hydrogen and helium (along with a trace amount of a few other elements).
Any talk of something 'outside the universe' is beyond the scope of science, so we can't even begin to answer it.
Very well, thanks for your time.
 
That is the thing, the universe has no edge!
 

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