More than 3 eigenvectors perpendicluar

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    Eigenvectors
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Discussion Overview

The discussion revolves around the concept of eigenvectors and their perpendicularity in various dimensional spaces. Participants explore the mathematical implications of having more than three mutually perpendicular eigenvectors, particularly in higher-dimensional vector spaces.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions how more than three eigenvectors can be perpendicular, suggesting a visualization of three axes as mutually perpendicular.
  • Another participant explains that in two-dimensional and three-dimensional spaces, only two and three mutually perpendicular axes exist, respectively, but higher-dimensional spaces can accommodate more axes.
  • A participant emphasizes the need for a definition of "perpendicular" that is not limited to visualizing 90-degree angles, especially in higher dimensions.
  • It is noted that while three mutually orthogonal vectors exist in three-dimensional space, the concept of vector spaces allows for any number of dimensions, including infinite-dimensional spaces.
  • One participant elaborates that in four-dimensional space, any two chosen axes can be considered perpendicular, and this reasoning extends to higher dimensions, where all axes can be mutually perpendicular.

Areas of Agreement / Disagreement

Participants express differing views on the nature of perpendicularity in higher dimensions. While some agree on the mathematical validity of having more than three mutually perpendicular vectors, others emphasize the limitations of visualization in lower dimensions.

Contextual Notes

There is an implicit assumption that the discussion is grounded in mathematical definitions of vector spaces, which may not align with physical interpretations of dimensions.

Who May Find This Useful

This discussion may be of interest to those studying linear algebra, vector spaces, or anyone curious about the properties of eigenvectors in higher-dimensional mathematics.

ss k
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all the eigenvectors of a matrix are perpendicular, ie. at right angles to each other, HOW?
I can imagine three eigenvectors as three perpendicular axes. How can be more than three axes are perpendicular with respect to each other?
 
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In a two-dimensional space such as the surface of a sheet of paper you can only have two mutually perpendicular axes. In a three-dimensional space you can have three. You cannot visualize a four-dimensional space, but mathematically it's a perfectly sensible concept - and how many axes do you need there?

You just need a definition of "perpendicular" that's not tied to your ability to visualize 90-degree angles.
 
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Nugatory said:
In a two-dimensional space such as the surface of a sheet of paper you can only have two mutually perpendicular axes. In a three-dimensional space you can have three. You cannot visualize a four-dimensional space, but mathematically it's a perfectly sensible concept - and how many axes do you need there?

You just need a definition of "perpendicular" that's not tied to your ability to visualize 90-degree angles.
Hi Nugatory,

Thanks usually there are n-vectors so n-axes and all are perpendicular with respect to each other. I don't want to plot them or see in some 3-d graphics programme but just wondering how they can even exist. Let's say I have 4 such axes (having values from -,0,+ and center orgin at 0) then axis 1,2,3 can be perpendicular with each other and how come the 4th axis will be perpendicular to any other axis.
 
What do you understand by "vectors"? It is possible to have a vector space of any dimension (even infinite dimensional vector spaces are used). You seem to be thinking of vectors in three dimensional space. If that is what you mean, then, yes, you cannot have more than three mutually orthogonal vectors. But that is dealing with physics, not mathematics.
 
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ss k said:
Hi Nugatory,

Thanks usually there are n-vectors so n-axes and all are perpendicular with respect to each other. I don't want to plot them or see in some 3-d graphics programme but just wondering how they can even exist. Let's say I have 4 such axes (having values from -,0,+ and center orgin at 0) then axis 1,2,3 can be perpendicular with each other and how come the 4th axis will be perpendicular to any other axis.
Consider the three dimensional case. Pick any two axis and ignore the third. Those two are in a 2 dimensional plane and the axes are at right angles.

But if we can ignore the third axis, we can go to more dimensions and ignore more axis.

In four dimensional space, pick any two dimensions. They form a two dimensional space and the axes are at right angles. Ignore the other axis. Since the two you picked were arbitrary, all the axis are perpendicular to all the others.

This works for any number of higher dimensions.
 
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Thanks all on PF. I think Factchecker replied exactly I was looking for.
 

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