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

[Peeter]

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.

 

[D H]

German, I suspect - ein.

 

[Peeter]

Ah. One (unit). Thanks!

 

[quadraphonics]

I'd always been told it was short for "element."

 

[HallsofIvy]

I'd always been told it was short for "element."

Never believe what a math teacher tells you!

 

[Pere Callahan]

German, I suspect - ein.

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

Might also be derived from Euclidean though..who knows for sure..

 

[sutupidmath]

Never believe what a math teacher tells you!

How come?

 

[D H]

How come?

He's a math teacher trying to revive Epimenides paradox. Follow his advice: Don't believe anything he says.

 

[sutupidmath]

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.

 

[transgalactic]

whats Epimenides paradox??

 

[sutupidmath]

whats Epimenides paradox??

google it!

 

[transgalactic]

aaahhh i know that from the "SAT" exam

the lier paradox

those logic questions took a decade from my life

 

[LukeD]

I actually found this discussion to be fairly informative. I never think that asking for historical reasons for notation is a stupid question.

 

[Peeter]

I should have labelled the post "non-technical question: ..." ;)

 

[mathwonk]

why does this nonsense thread receive space? mindless relief?

 

[LukeD]

why does this nonsense thread receive space? mindless relief?

Would there be something wrong with that?

 

[HallsofIvy]

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"!