Is our 3D universe a shadow of a 4D Universe?

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Discussion Overview

The discussion explores the concept of whether our 3D universe could be a shadow or projection of a higher-dimensional reality, particularly a 4D universe. Participants examine implications of dimensionality on perception and understanding, referencing theories such as the block universe and the growing block universe, while also addressing the nature of evidence in scientific discourse.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • Some participants propose that our 3D universe may be a shadow of a higher-dimensional reality, drawing analogies to how 2D beings perceive 3D objects.
  • Others argue that the notion of a shadow is imprecise, suggesting that a 3D slice of 4D spacetime does not equate to a shadow, comparing it instead to a slice of ham versus a pig.
  • One participant mentions the block universe theory, which posits that all of spacetime exists simultaneously, challenging the idea of a universe that grows over time.
  • Another participant emphasizes the importance of evidence in scientific discussions, stating that claims without falsifiable predictions and experimental tests may not be valid topics for discussion.
  • Some participants express skepticism about the existence of higher-dimensional objects due to the lack of evidence, while others maintain that absence of evidence does not imply absence of existence.
  • There is a reiteration of the need for peer-reviewed references to support claims made in the discussion.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nature of the universe or the validity of the claims regarding higher dimensions. Multiple competing views remain, particularly regarding the interpretation of the block universe and the necessity of evidence in scientific discourse.

Contextual Notes

Limitations include the lack of clear definitions for terms like "shadow" in the context of dimensionality, and unresolved questions about the implications of the block universe versus the growing block universe theories.

Zdravko
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Is it possible that our 3D universe is just a shadow in 3D space of 4D or higher dimensional reality? And we are limited in our perception of it by our 3-dimensionality. In other words like Flatlanders would just see s square of a cube sitting on the plane or passing through the plane. Actually they would see a line, but they could deduce that this line represents a square by the number and type of corners (angles) they could feel by going around the line? Similarly we deduce a lot of things by studying nature. But all of the results are limited by our 3-dimensionality?
 
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Sure. It's also possible that unicorns actually exist but I'm not holding my breath since there's no evidence for either one.
 
Is this just the block universe, stated rather imprecisely? "The universe now" is a 3d spacelike slice through 4d spacetime. Even viewed like this, though, the universe isn't a shadow of spacetime any more than a slice of ham is a shadow of a pig. So it's possible I'm searching too hard for meaning here.

OP - look up "block universe". If that's what you meant, then yes. If you meant something like Plato's cave then there is nothing like that in modern physics that I'm aware of.
 
If phinds can not find evidence, it does not mean things do not exist.
 
Zdravko said:
If phinds can not find evidence, it does not mean things do not exist.
That is not how science works. You need falsifiable predictions and then experimental tests of them - what phinds sums up as "evidence".

If you meant the block universe then that's a way of conceptualising relativity theory, which has tons of predictions and tests of it, and is science. If you meant something else then it's almost certainly something with no evidence for it, and probably no possibility of evidence. That's not science, and therefore not a valid topic of discussion here (i.e. unless you can provide peer-reviewed papers supporting whatever it is you are getting at the thread will probably get locked).
 
Zdravko said:
If phinds can not find evidence, it does not mean things do not exist.
I agree. Absence of evidence is not evidence of absence. I still don't believe in unicorns or in what you are suggesting and my statement was NOT that *I* can't find evidence but that (as far as I know) there IS no evidence. I feel confident that if there WERE any evidence it would be a big deal and I would have heard of it.
 
From what I understand growing block universe theory of time is different in that more and more spacetime is coming into being, Here we are talking about 4 D objects passing through a 3D space. For example if a cube (3D object) is passing through a plane (2 D space), some hypothetical 2 D beings, living on that plane would "see" it as a line that exists in their space for the duration of the passage, and then it is gone. They would not have the ability to comprehend what is the real nature of the object (cube), due to their 2D space limitations.
 
Zdravko said:
From what I understand growing block universe theory of time is different in that more and more spacetime is coming into being, Here we are talking about 4 D objects passing through a 3D space. For example if a cube (3D object) is passing through a plane (2 D space), some hypothetical 2 D beings, living on that plane would "see" it as a line that exists in their space for the duration of the passage, and then it is gone. They would not have the ability to comprehend what is the real nature of the object (cube), due to their 2D space limitations.
Yes, I've read Flatland and it's a wonderful and very clever book but I think extrapolating it to the real 3D world is a waste of time.
 
The block universe asserts that all of spacetime always exists in some sense. No growth is needed. What you call "the universe now" is a 3d slice through that.

If you mean something other than that, I'll repeat: do you have a textbook or peer reviewed journal article reference for what you want to discuss? If not, this thread is going to get locked because PF rules require that as a minimum standard for discussions.
 
  • #10
Ibix said:
The block universe asserts that all of spacetime always exists in some sense. No growth is needed. What you call "the universe now" is a 3d slice through that.

If you mean something other than that, I'll repeat: do you have a textbook or peer reviewed journal article reference for what you want to discuss? If not, this thread is going to get locked because PF rules require that as a minimum standard for discussions.
Thanks @Ibix -- this is a good place to close the thread for a bit.

@Zdravko -- If you have such references, please send them to me via Private Message (click my Avatar and Start a Conversation). Thank you.
 

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