The dimensions of elementary particles in quantum physics and string theory

Click For Summary

Discussion Overview

The discussion revolves around the dimensions of elementary particles as described in quantum physics and string theory. Participants explore the differences in dimensionality between point-like particles in quantum physics and one-dimensional strings in string theory, as well as implications in supersymmetric theories.

Discussion Character

  • Exploratory, Conceptual clarification, Debate/contested

Main Points Raised

  • Some participants note that in quantum physics, elementary particles are considered point-like with no dimensions, while in string theory, they are represented as one-dimensional objects.
  • Another participant suggests that the differences arise because the two theories operate at vastly different length scales.
  • One participant introduces the concept of "mass dimension" in the context of supersymmetric theories, discussing how the dimensions of various fields can be derived from the properties of supersymmetry generators.

Areas of Agreement / Disagreement

Participants express differing views on the implications of dimensionality in quantum physics versus string theory, and the discussion remains unresolved regarding the specific reasons for these differences.

Contextual Notes

There are assumptions about the definitions of dimensions and the context of the theories that are not fully explored, particularly regarding how dimensionality is treated in various theoretical frameworks.

T=0
Messages
10
Reaction score
0
I noticed that in quantum physics, an elementary particle has no dimensions, and is point like, but in string theory has one dimension. Why is this?
 
Physics news on Phys.org
T=0 said:
I noticed that in quantum physics, an elementary particle has no dimensions, and is point like, but in string theory has one dimension. Why is this?

This may sound silly, but basically it is because the theories are different. String theory is looking at things on a much smaller length scale than quantum theory.
 
Probably you mean "mass dimension"? In supersymmetric theories, the anticommutator of two susy generators Q is equal to the momentum P, which has mass dimension 1. From here, dimension of Q follows: it is 1/2. Similarly, by imposing that the action has 0 dim, you can find that a scalar field has dimension 1, a spinorial field 3/2, etc.
 
Thnx guys, great help.
 

Similar threads

Undergrad Unifying string theory and loop quantum gravity
  • · Replies 2 ·
Replies
2
Views
4K
Undergrad String theory vs Quantum field theory
  • · Replies 1 ·
Replies
1
Views
3K
High School String Theory & Elementary Particles: What's Real?
  • · Replies 12 ·
Replies
12
Views
3K
Undergrad Current theory of composite quarks and leptons
  • · Replies 6 ·
Replies
6
Views
3K
Graduate String theory and locality of small dimensions
  • · Replies 1 ·
Replies
1
Views
3K
Graduate Basic Scheme and Fundamental Equations of String Theory
  • · Replies 26 ·
Replies
26
Views
4K
Undergrad Strings 2025 Conference: Insights, Criticisms, and Key Highlights
  • · Replies 30 ·
2
Replies
30
Views
9K
Undergrad Trying To Conceptualize Two Dimensions Of Time
  • · Replies 2 ·
Replies
2
Views
5K
Undergrad Brane cosmology without string theory?
  • · Replies 1 ·
Replies
1
Views
2K
Graduate String Theory in N dimensions?
  • · Replies 1 ·
Replies
1
Views
2K