Timeline for Most harmful heuristic?
Current License: CC BY-SA 2.5
6 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 18, 2017 at 13:51 | comment | added | user21349 | The magnitude-and-direction definition doesn't even really work in physics. In relativity, you can't define a vector by its magnitude and direction, because a nonzero vector can have a zero magnitude. | |
| Oct 20, 2016 at 22:45 | comment | added | Gerry Myerson | I recently heard someone joke that a movie must be a vector, since it has both length and direction. | |
| Apr 17, 2013 at 20:47 | comment | added | Douglas Zare | If you are trying to say that $\mathbb R$ is a real vector space, do people really object that $-3$ and $+3$ only have magnitudes, and not directions? I prefer an actual definition over a misleading characterization, but I don't think this one leads to big problems. | |
| Aug 25, 2012 at 19:54 | comment | added | Todd Trimble | +1: it's just wrong for so many reasons. For one thing, it sounds sort of like a reduction of math to physics or something. For another, you need something like an inner product to make sense of it. But worst of all, it's totally ass-backwards when it comes to abstract mathematics, because "vector" has no independent meaning. Rather, a "vector" just means an element of some given vector space, which is a set equipped with ... so it's the concept of vector space which is primary, not vector! Paul Halmos had a similar rant in his automathography. | |
| Nov 19, 2011 at 7:06 | comment | added | Ryan Reich | My mother had an old "Advanced Calculus" book lying around when I was in high school. It mentioned this old chestnut and commented that it is a poor definition because some things are vectors but have neither magnitude nor direction (like scalars) and some things have both but are not vectors (like trains). | |
| Oct 3, 2010 at 3:28 | history | answered | Ross Churchley | CC BY-SA 2.5 |