Irreducible Representations of EM-Tensor Under Spatial Rotations

In summary, the electric and magnetic fields, represented by vector fields ##\vec{E}## and ##\vec{B}##, respectively, are irreducible representations of the rotation group SO(3). However, under boosts, they transform into each other and are not irreducible under this action. The electromagnetic tensor F can be decomposed into the E and B fields under spatial rotations using the representation for the full proper orthochronous Lorentz group in terms of ##\mathrm{SO}(3,\mathbb{C})##. This means that a pure rotation-free boost will always mix the electric and magnetic field components.
  • #1
PreposterousUniverse
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Can we consider the E and B fields as being irreducible representations under the rotations group SO(3) even though they are part of the same (0,2) tensor? Of course under boosts they transform into each other are not irreducible under this action. I would like to know if there is in some way one could decompose the electromagnetic tensor F into the E and B under spatial rotations?
 
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  • #2
##\vec{E}## and ##\vec{B}## are vector fields in the sense of the usual rotation group SO(3). Each provides an irreducible representation of this group, because there's not proper subspace that stays invariant under the action of the group.

I'm not sure what you mean bye "decompose the electromagnetic tensor F into the E and B under spatial rotations". Maybe the most simple answer is to use the representation for the full proper orthochronous Lorentz group in terms of ##\mathrm{SO}(3,\mathbb{C})##. This is how the Riemann-Silberstein vector ##\vec{F}=\mathrm{E}+\mathrm{i} \vec{B}## transforms under proper orthochronous Lorentz transformations. The usual rotations are of course represented by the subgroup SO(3) of ##\mathrm{SO}(3,\mathbb{C})##. This means of course that ##\vec{E}## and ##\vec{B}## transform within each other by rotations. A pure rotation-free boost along a given direction is represented by the usual rotation matrix but with an purely imaginary angle, i.e., a boost always mixes electric and magnetic field components.
 

1. What are irreducible representations of EM-tensor under spatial rotations?

Irreducible representations of EM-tensor under spatial rotations refer to the different ways in which the electromagnetic tensor, a mathematical object used to describe the electromagnetic field, can transform under spatial rotations. These representations are important in understanding the symmetries of the electromagnetic field and its behavior under rotations.

2. Why are irreducible representations important in physics?

Irreducible representations are important in physics because they help us understand the symmetries and transformations of physical systems. In the case of EM-tensor, these representations can help us understand how the electromagnetic field behaves under rotations, which is crucial in many areas of physics such as quantum mechanics and electromagnetism.

3. How are irreducible representations of EM-tensor determined?

The irreducible representations of EM-tensor are determined using group theory, a mathematical tool that studies the symmetry properties of objects. In particular, the rotations of the electromagnetic field are described by the special unitary group SU(2), and the irreducible representations of this group can be used to determine the different ways in which the EM-tensor can transform under rotations.

4. What are some applications of irreducible representations of EM-tensor?

Irreducible representations of EM-tensor have many applications in physics, particularly in quantum mechanics and electromagnetism. They are used to study the symmetries of physical systems, such as atoms and molecules, and to understand the behavior of electromagnetic fields under rotations. They are also used in the development of new theories and models in physics.

5. Can irreducible representations of EM-tensor be extended to other symmetries?

Yes, the concept of irreducible representations can be extended to other symmetries besides spatial rotations. For example, in addition to rotations, the electromagnetic field also exhibits symmetries under translations and boosts. These symmetries can also be described using group theory and the corresponding irreducible representations can be used to understand the behavior of the EM-tensor under these transformations.

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