The dimensions of elementary particles in quantum physics and string theory

In summary, quantum physics and string theory have different ways of looking at particles, which results in different dimensions being assigned to them. In string theory, particles have one dimension, while in quantum physics, they are considered to have no dimensions. This is due to the different theories and scales being studied.
  • #1
T=0
10
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?
 
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  • #2
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.
 
  • #3
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.
 
  • #4
Thnx guys, great help.
 

1. What are the dimensions of elementary particles in quantum physics and string theory?

In quantum physics, elementary particles are considered to be point-like with no measurable dimensions. However, in string theory, these particles are interpreted as tiny one-dimensional strings, which have a length on the order of the Planck scale (10^-33 cm).

2. How do these dimensions affect the behavior of elementary particles?

The dimensions of elementary particles affect their behavior in various ways. For example, the size of the strings in string theory can explain why particles have different masses and charges. Additionally, the extra dimensions proposed in string theory could potentially explain the existence of gravity and other fundamental forces.

3. Can we observe these dimensions experimentally?

Currently, there is no experimental evidence for the dimensions proposed in string theory. However, scientists are working on ways to test and potentially observe these dimensions through high-energy particle accelerators and other experimental techniques.

4. How do dimensions play a role in the unification of quantum mechanics and general relativity?

One of the main goals of string theory is to unify quantum mechanics and general relativity into a single, comprehensive theory. The dimensions of elementary particles in string theory play a crucial role in this unification by providing a framework for understanding the fundamental forces and particles that make up our universe.

5. Are there any other theories that propose dimensions beyond the three we experience?

Yes, there are several other theories that propose the existence of extra dimensions beyond the three spatial dimensions we experience. These include theories such as Kaluza-Klein theory, which suggests the existence of a fourth spatial dimension, and brane cosmology, which proposes the existence of multiple, parallel dimensions known as "branes". However, these theories are still highly speculative and have not been fully confirmed by experimental evidence.

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