Why Are There Different Notations for Scientific Symbols?

[Elbobo]

Couldn't find my answer on Google...

Often, I hear some character like a₀ pronounced ay-ZEE-ro, ay sub-ZEE-ro, or ay-NOT. Purely out of curiosity, where does this last name for a₀ come from? Origin? Actual spelling?

Second, I've seen the symbol for velocity written as both the normal letter v (as the Romantic languages are accustomed to), and the Greek letter \nu (nu). Which one is technically correct in the eyes of the professional science community (e.g., in journals, publications, reports, etc.)?

EDIT: Oh and last, DERIVATIVES. I've seen them written and typed dy/dx for example, but I've also seen cases where the d is a bit more stylized and somewhat resembles a backward "6." That's not any Greek letter that I know. Any clarification on usage there?

Sorry if these seem like frivolous questions, but I like knowing the proper way of things :) Semantics, pedantic, yeah yeah, I'm one of those.

 

[CompuChip]

It does sound a lot like "not", as a non-native speaker it took me a while to figure it out as well (professors from all over the world pronouncing it in broken English did not help either). But it is actually "nought" :-)

For velocity, the letter v is correct, in my opinion. It stands for "velocitas", as far as I am concerned. (Interestingly, the letter c for the speed of light is of similar origin. I think it was coined by Einstein, who used it as an abbreviation of "celeritas" - which basically also means speed in Latin).

There is actually a difference between something like \frac{df}{dx} and \frac{\partial f}{\partial x}. The \partial symbol looks like a Greek letter perhaps, but it is actually not (it's just a stylised d, as you say). People usually pronounce it "dau" ("dow") or "partial".
I don't know if you have seen any multi-variable calculus yet, but suppose you have a function f(x, y) = x y. Of course, it may be possible that y is itself a function of x (for example, in the simplest case y = x). In that case, the "partial" derivative treats the y as a constant, while the "total" derivative does not. So
\frac{\partial f}{\partial x} = y
while to the d/dx operator f(x, y) looks like x², and
\frac{df}{dx} = 2 x.
You can easily imagine an application in physics, where you have something depending on position and time explicitly, e.g.
f(x, t) = e^x + t².
However, usually the position x also varies with time, so actually x = x(t) is a function of t. Then it begins to matter which of the two you use, since e^x is just a constant, vanishing under the partial derivative operator, in one case, while it actually gives a non-trivial contribution of x'(t) e^x(t) in the other.

 

[jtbell]

ay-NOT

That's "a-naught". Look up the word "naught". It's hardly ever used in American English, but I understand the British use it more often.

(added: hah, I guess we Yanks use it more than I thought. The three usage examples shown in Google's dictionary are all quotes from Americans.)

 

[CompuChip]

By the way, I have the impression that some people actually write a little circle, more like the letter o than the figure 0.
In fact, I have even seen it used in typed documents: a_o or a_{\mathrm{o}} instead of a_0 (probably because the author(s) thought the 0 was too large or did not resemble the way they wrote it).

 

[jtbell]

Second, I've seen the symbol for velocity written as both the normal letter v (as the Romantic languages are accustomed to), and the Greek letter \nu (nu).

That thing that looks like a Greek \nu is actually an italic v (v). The difference is rather visible in LaTeX on my browser. In some books, they look a lot more alike.