The expansion of the universe, evidence of a 4th spatial dimension?

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Discussion Overview

The discussion revolves around the concept of the expansion of the universe and whether it could be indicative of a fourth spatial dimension. Participants explore analogies, particularly the balloon analogy, to understand the nature of this expansion and its implications.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • One participant suggests that the expansion of the 2-D surface of a balloon in the third dimension could imply the existence of a fourth spatial dimension in the context of the universe's expansion.
  • Another participant emphasizes that the balloon analogy is limited and that one can conceptualize curvature without invoking an extra dimension, suggesting that the balloon surface represents the entirety of space.
  • Several participants express interest in additional resources to better understand the topic, indicating a desire for concise explanations.
  • A participant questions whether the increase in distance between specific points on a toy model can be analogically related to the expansion of space, noting the appearance of metric expansion.

Areas of Agreement / Disagreement

Participants express differing views on the validity and implications of the balloon analogy, with some supporting the idea of a fourth spatial dimension and others challenging that notion. The discussion remains unresolved regarding the interpretation of the expansion of space.

Contextual Notes

Participants acknowledge the limitations of analogies used to describe complex concepts, and there are references to external threads and resources that may contain additional insights or differing perspectives.

pondzo
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in order to explain the big bang theory and the expansion of space itself, people often draw upon the analogy of blowing air into a balloon and the 2 dimensional surface of the balloon expanding. isn't the 2-D balloon surface expanding in the third dimension, since the volume of the balloon is increasing. so in the same way couldn't the expansion of three dimensional space be indicative of the existence of a 4th spatial dimension (not temporal ) ?
 
Space news on Phys.org
See https://www.physicsforums.com/showthread.php?t=261161#post1899468

4. to understand that something can be curved without there being an extra dimension---part of the mental exercise is to picture the balloon surface as all there is, there is no inside the balloon and there is no outside---only the balloon surface exists.

The balloon analogy is just that- an analogy. It's not perfect and has limitations. The entire thread is worth perusing.
 
thanks for the link jimmy, ill try and get through the thread, but it is quite lengthy!
 
pondzo said:
thanks for the link jimmy, ill try and get through the thread, but it is quite lengthy!

Try the link in my signature
 
Thanks, phinds. I wish I would have remembered your page. Much more concise than that long thread. :thumbs:
 
Thank you for the link phinds, much quicker than the other thread, although the other thread has some interesting content.

i have had this toy for a while exactly the same as this:
is the increase of the distance between the (inside layer) orange dots at all analogical to the expansion of space?
 
Last edited by a moderator:
pondzo said:
Thank you for the link phinds, much quicker than the other thread, although the other thread has some interesting content.

i have had this toy for a while exactly the same as this:
is the increase of the distance between the (inside layer) orange dots at all analogical to the expansion of space?


I can't see it very well, it all moves so fast, but yeah, it does look like metric expansion if you consider only the dots.
 
Last edited by a moderator:

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