Branes and LQG: A Simplified Explanation

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Discussion Overview

The discussion centers around the concepts of branes and Loop Quantum Gravity (LQG), with participants seeking simplified explanations of these advanced topics in theoretical physics. The scope includes conceptual clarification and exploratory reasoning related to string theory and quantum gravity.

Discussion Character

  • Exploratory
  • Conceptual clarification

Main Points Raised

  • One participant requests a simple explanation of branes and LQG, expressing a desire for clarity due to their limited background in physics.
  • Another participant describes branes as features of string theory, likening them to membranes in higher dimensions and explaining their role in the context of strings.
  • The same participant introduces LQG as a candidate for quantizing gravity, explaining its origins in the study of Wilson loops and the transition to networks.
  • A follow-up post seeks further clarification on the dimensionality of branes, questioning whether a single brane can exist in one or multiple dimensions.
  • Another participant references Michio Kaku's description of branes as slices of an 11-dimensional bulk space, drawing parallels to geometric constructs in lower dimensions.
  • A later post indicates that one participant feels they have gained a better understanding of the topics discussed.

Areas of Agreement / Disagreement

Participants express varying levels of understanding regarding branes, with some seeking more information while others provide different perspectives on their nature and dimensionality. The discussion remains unresolved regarding the complete understanding of branes.

Contextual Notes

Participants express uncertainty about the concepts, particularly regarding the nature of branes and their dimensionality. There is a reliance on simplified analogies that may not fully capture the complexities of the topics.

DarkAnt
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I'm a very ignorant person. Could someone please explain to me what branes and LQG are? I know what a string is (or at least i think i do). I am a firm believer of K.I.S.S. so try to keep it simple for me because I'm just in 11th grade.
 
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A brane is a feature of more advanced string theory, its a piece of spacetime of some number of dimensions (almost any number). The word brane comes from "membrane", and the idea is "Like that but in several dimensions" Originally branes and strings were more or less on an equal footing, and branes were where strings stuck their end points (if I may be so over colorful). In later work it's branes on branes, and crossed branes, and all sorts of variations.

LQG stands for Loop Quantum Gravity. About 20 years ago it was found that you can do interesting things with "Wilson loops" that were sort of physics around a loop in space. Then it was found they didn't have to be loops (but the name stuck) and they started using networks. The idea is to use these networks to build quantum gravity of spacetime. The traditional way of quantizing gravity, they way they had quantized the other forces, didn't work.

Now both advanced string physics, with branes, and Loop Quantum Gravity, without loops, are candidates for quantizing gravity. May the best theory win. And by "best" I mean the one that actually gets the job completely done. If they both do, even better.
 
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Thank you selfAdjoint.

I still don't understand branes all that well but I now know what LQG is. A little more explanation is needed on the whole branes thing.
Does a single brane exist in just one dimension, exist on many dimensions or can it do both?
ok, a lot more explanation is needed on branes because in my mind I see them as the connector pieces in a K'nex set that the pegs fit into which I'm guessing is far from being correct. Keep in mind I know almost nothing about anything.

Why do questions always lead to more questions?
 
Michio Kaku has described branes as simply a way of slicing up an 11D bulk space. The same way in normal Euclidean geometry you can have lines, planes and solids, you can have branes of any dimension sliced from 11D space as a whole.
 
I understand now, thank you :smile:
 

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