Can the cross product concept be completely replaced by the exterior product?

In summary, the exterior product is a more convenient tool that has every right to exist. However, it can be replaced with the cross product provided one does it correctly.
  • #1
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Do we really need concept of cross product at all? I always believed cross product to be sort of simplification of exterior product concept tailored for the 3D case. However, recently I encountered the following sentence «...but, unlike the cross product, the exterior product is associative». (https://en.wikipedia.org/wiki/Exterior_algebra) and it occurred to me that I might have been missing something.

Two remarks:
1) Clearly cross product is tied to 3D world and exterior product works for space of any dimension. Suppose we are considering 3D case only.
2) The cross product can be convenient tool. Being such it has every right to exist. But I am asking about whether it could be dropped entirely in favour of its exterior counterpart without losing anything in principle.
 
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  • #3
Thank you!
 
  • #4
if you write down the definition of the exterior product of two vectors in R^3, you will see that it has the same coordinates as their cross product. However if e1,e2,e3 is the standard basis of R^3, the cross product will be expanded in terms of that same basis, while the exterior product will be expanded in the basis e2^e3, e3^e1, e2^e3. The point is that both are aspects of the determinant, in particular both products are "alternating" and multilinear, and the only determinant is essentially the only such product.
 
  • #6
wrobel said:
Yes, cross product concept can be replaced with exterior product provided one does it correctly. But it would hardly simplify physics formulas
https://en.m.wikipedia.org/wiki/Hodge_star_operator
The exterior product is preferred in Geometric Algebra. Although there is a significant learning curve, GA is considered by its advocates to offer great simplifications.
 

1. Can the cross product and exterior product be used interchangeably?

No, the cross product and exterior product are two different mathematical operations with distinct properties and applications. The cross product is used in three-dimensional vector spaces to find a vector perpendicular to two given vectors, while the exterior product is used in higher-dimensional vector spaces to find a multivector that represents the oriented area of a parallelogram spanned by two given vectors.

2. Is one product more efficient than the other?

It depends on the context and the specific problem being solved. In some cases, the cross product may be more efficient as it only involves three-dimensional vectors, while the exterior product involves higher-dimensional vectors. However, in other cases, the exterior product may be more efficient as it can be generalized to higher dimensions and can handle more complex geometric calculations.

3. Can the cross product and exterior product be used in any vector space?

No, the cross product is only defined in three-dimensional vector spaces, while the exterior product is defined in any vector space with an inner product. However, the results of both operations can be extended to higher-dimensional vector spaces through the use of algebraic structures such as quaternions and multivectors.

4. Are there any real-world applications for the exterior product?

Yes, the exterior product has various real-world applications in fields such as physics, engineering, and computer graphics. It is used to calculate the magnetic field of a current-carrying wire, determine the torque of a rotating object, and model the lighting and shading of 3D objects in computer graphics.

5. Can the cross product concept be completely replaced by the exterior product?

No, while the exterior product can be used to solve some problems that the cross product can solve, it cannot completely replace the cross product. The cross product has unique properties and applications, such as finding a vector perpendicular to two given vectors, that cannot be replicated by the exterior product.

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