Really dumb question: why do we use e_i for unit vectors?

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Discussion Overview

The discussion revolves around the historical reasons for the notation of unit vectors, specifically the use of \(\mathbf{e}_i\) instead of other potential notations like "u" for unit. Participants explore possible linguistic origins and the implications of such conventions.

Discussion Character

  • Exploratory
  • Debate/contested
  • Meta-discussion

Main Points Raised

  • One participant inquires about the history behind the notation \(\mathbf{e}_i\) for unit vectors, suggesting it may originate from another language.
  • Another participant proposes that the notation could come from the German word "ein," meaning one or unit.
  • A different viewpoint suggests that "e" might stand for "element," indicating a possible alternative origin.
  • Some participants express skepticism about the reliability of information provided by math teachers, referencing a paradox related to verification of truth.
  • There is mention of Epimenides' paradox, with participants discussing its implications and relevance to the conversation.
  • One participant finds the discussion informative and defends the value of asking about historical notation.
  • Another participant expresses frustration about the thread's relevance, questioning its purpose.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the origin of the notation for unit vectors, with multiple competing views presented regarding its linguistic roots and the reliability of information from educators.

Contextual Notes

Participants reference various interpretations of the notation's origin, but the discussion lacks definitive conclusions or established facts regarding the historical context.

Peeter
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Anybody know the history of why something like \mathbf{e}_i is conventionally used for unit vectors (as opposed to u for Unit which is less common).

I assume this originates from another language? If so I'm curious what language and what word.
 
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German, I suspect - ein.
 
Ah. One (unit). Thanks!
 
I'd always been told it was short for "element."
 
quadraphonics said:
I'd always been told it was short for "element."
Never believe what a math teacher tells you!
 
D H said:
German, I suspect - ein.

I agree, "e" for "Einheitsvektor" meaning unit vector.

Might also be derived from Euclidean though..who knows for sure..:smile:
 
HallsofIvy said:
Never believe what a math teacher tells you!

How come?
 
sutupidmath said:
How come?
He's a math teacher trying to revive Epimenides paradox. Follow his advice: Don't believe anything he says.
 
I am assuming he is implying with this, that we, students, must check everything out on our own, no matter who tells us that sth is true or not. We have to verify everything on our own, right, is this what halls is saying, right?

Ok, i am going to check the meaning of that paradox on wiki.
 
Last edited:
  • #10
whats Epimenides paradox??
 
  • #11
transgalactic said:
whats Epimenides paradox??

google it!
 
  • #12
aaahhh i know that from the "SAT" exam

the lier paradox

those logic questions took a decade from my life
 
Last edited:
  • #13
I actually found this discussion to be fairly informative. I never think that asking for historical reasons for notation is a stupid question.
 
  • #14
I should have labelled the post "non-technical question: ..." ;)
 
  • #15
why does this nonsense thread receive space? mindless relief?
 
  • #16
mathwonk said:
why does this nonsense thread receive space? mindless relief?
Would there be something wrong with that?
 
  • #17
Epimedes' paradox was to say that "All Cretan's are liars". Of course, Epimedes was himself a Cretan. There is, in fact, a place in the Bible (New Testament. I've forgotten exactly where but may be in Paul's epistle to the Corinthians) in which we are warned to beware of Cretans- "they say of themselves that they are liars"!
 

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