Differences between an axial vector, a pseudo vector and a bivector?

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Discussion Overview

The discussion revolves around the distinctions between axial vectors, pseudo-vectors, and bivectors, exploring their definitions and relationships in the context of vector mathematics and geometry. The scope includes conceptual clarifications and technical explanations related to these mathematical entities.

Discussion Character

  • Conceptual clarification
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that axial vectors and pseudo-vectors are synonymous and both are dual to bivectors.
  • One participant describes a bivector as a "directed area," analogous to how a vector represents a "directed length," and notes that in three dimensions, a directed area can be represented by its normal vector.
  • A participant proposes that if \(\vec{C} = \vec{A} \times \vec{B}\), then \(\vec{C}\) would be a pseudo-vector and also a bivector, as its magnitude corresponds to the area of the parallelogram formed by \(\vec{A}\) and \(\vec{B}\).
  • Another participant clarifies that \(\vec{A} \times \vec{B}\) is the (pseudo)vector dual to the bivector \(\vec{A} \wedge \vec{B}\), emphasizing that \(\vec{A} \times \vec{B}\) is a vector perpendicular to the oriented parallelogram defined by \(\vec{A}\) and \(\vec{B}\), while \(\vec{A} \wedge \vec{B}\) represents that oriented parallelogram more abstractly.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between pseudo-vectors and bivectors, with some suggesting they are equivalent while others clarify their distinct roles. The discussion remains unresolved regarding the precise definitions and implications of these terms.

Contextual Notes

The discussion includes assumptions about the dimensionality of the vectors and the nature of the operations involved, which may not be universally applicable. The relationships described may depend on specific mathematical contexts and definitions.

Swapnil
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What is the difference between an axial vector, a psudo vector and a bivector?
 
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Axial vector and pseudo-vector seem to mean the same thing, and are dual to bivectors.

A bivector is a "directed area". (similar to how a vector is a "directed length") In three dimensions, a directed area can be represented by its normal vector (i.e. it's "axis"): that's where pseudovectors come from.

Similarly, in three dimensions, a "directed volume" can be represented by a number: that's where pseudoscalars come from.
 
Last edited:
So, if
\vec{C} = \vec{A}\times\vec{B}

then C would be a psudo vector and it would also be a bivector since its magnitude is equal to the area of the parallogram spanned by A and B?
 
Almost: A \times B is the (pseudo)vector that is dual to the bivector A \wedge B.

A \times B is merely the properly oriented vector that is perpendicular to the oriented parallelogram with sides A and B. Roughly speaking, A \wedge B is that oriented parallelogram.

(But only roughly speaking -- the picture isn't quite that nice. For example, (A + B) \wedge B = A \wedge B)
 

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