Gravitational Theories in Higher Dimensions

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Discussion Overview

The discussion revolves around the concept of gravitational theories in higher dimensions, exploring how beings in lower dimensions might perceive gravity and the implications of higher dimensions for our understanding of gravity. Participants engage with theoretical ideas, including the nature of the fourth dimension and its relationship to gravity, as well as the validity of various theories such as M-Theory and string theory.

Discussion Character

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

Main Points Raised

  • One participant proposes that a creature in a 2D world would perceive a 3D hole as gravitational and a 3D mountain as anti-gravity, suggesting a parallel for humans in relation to the fourth dimension.
  • Another participant clarifies that the fourth dimension is typically understood as time, not as an additional spatial dimension.
  • A subsequent reply emphasizes that the fourth dimension could be considered as a geometrical axis, questioning whether 4D structures could create gravitational effects in 3D space.
  • One participant discusses gravity from a relativistic perspective, suggesting it can be viewed as the compression of space-time, while anti-gravity would correspond to decompression.
  • There is mention of M-Theory as a framework that attempts to unify gravity with quantum mechanics, although its correctness is debated.
  • Another participant expresses skepticism about the certainty of string theory and general relativity, noting that theories are considered valid until they encounter contradictions.
  • One participant argues that M-Theory could potentially explain phenomena across scales, but acknowledges the current limitations in mathematical tools to fully grasp it.

Areas of Agreement / Disagreement

Participants express differing views on the nature of the fourth dimension and its implications for gravity. There is no consensus on the validity of M-Theory or string theory, with some participants expressing skepticism about their correctness.

Contextual Notes

Participants highlight the limitations of current theories and the challenges in reconciling general relativity with quantum mechanics. The discussion reflects ongoing uncertainties in understanding higher-dimensional theories and their implications for gravity.

MentalManager
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Hello! I just had an stupid idea and i want to know what do you think of it. Let's say thers an creature who is living in 2d world. An 3d world hole in his 2d world plane would feel for this creature like gravitation. Wouldnt it? An 3d mountain would feel for him like ant-grav or somethink like this. Its because the creature doesn't know 3rd dimension.

The question. Would the 4D be for humans like gravitation? And 4D mountain like anti-grav. I have to say that I am only 17 years old and i don't know much physics. In my text can be mistakes.
 
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You often hear that we live in a 3-d world. Those 3 dimensions are our spatial dimensions (length, width, depth). Our 4th dimension is time, not gravity.
Paden Roder
 
I see that you didnt understand what i meant. I meant 4th dimension not as time but geometrical axis. I wanted to what do you think: can 4th dimension holes make in 3d some kind of barricade or gravitation.
 
a good Relativistic way to look at gravity would be through compression.

if you took a 3 diminutional chunk of Space-Time, gravity to us would be the compression of space-time toward a center...anti-gravity would be as if you decompressed space-time.

however, the relativistic way of looking at gravity is flawed since gravity has no ability to mesh with the Quantum world, which is why M-Theory is so nice.

check out "the elegant universe". it is a special on PBS...you can watch it on the web on PBS.org for free.

M-Theory though might be wrong...but hey...it explains things so well that it just has to be right :-)
 
I saw this "elegant universe" after i posted this question(or how do you called it) and i find this very interesting, but we cannot be sure that this string theory is right, we cannot be even sure the theory of relativity is right.
 
true, however, a theory that best reflects what we observe is considered to be right until we find a problem with it.

at the moment, GR and QM are the most right...however, we know that neither are totally right...the theory that explains the universe must explain from the very large to the infinitesimal.

M-Theory IMHO does this very well, and even though we cannot see strings today, we will be able to see hints of strings, we will have an idea that the theory is correct when we observe graviton's just before they move off our membrane, and when we observe Sparticles.

and as it said in the last hour, we should be able to see impressions left by strings from the time of the big bang.

I personally think that M-Theory does a good job of explaining things, but as Ed Witten says, he thinks we lack the mathematical tools today that will allow us to fully understand it.
 

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