Quote (Azrad @ May 3 2013 12:22pm)
That is pretty much it. It is a cool and useful identity (a true statement). No more so than Cos(x)^2 + Sin(x)^2 = 1 (imo).
The easiest way I know to derive it is to calculate the Maclaurin series of:
e^(ix)
sin(x)
cos(x)
and then Euler's formula will become obvious. Substitute x = pi and you get the identity quoted above. Of course as brmv eluded too, if you don't know what any of that means, well then you've got some work ahead of you.
It's not appropriate for Ylem to expect a real-world example of every little fact in mathematics as is possible in relatively basic physics (not that it wasn't groundbreaking at the time, but it's taught to first year undergrads). It's a little involved to understand all the characters involved and their significance. I suppose the significance of the exponential function is the first stumbling block, basically it's important because it's rate of change is equal to itself, so here's one example:
Suppose something changes at a rate proportional to itself, for example, with continuously compounded interest, the amount of interest you get per time unit is proportional to the amount of money you have at that time -- so say you had $10,000 at 5% continuous interest -- in 10 units of time, it can be shown you will have $(10,000*exp(.05*10)).
We could equally well talk about radioactive decay, which is essentially the same, but with a negative rate -- the math doesn't care what it's talking about, it works for phenomena that works similarly, and the number e comes up in tremendously many other mathematical applications. It's important to realize math is not applied to anything in particular, its strength comes from its generality.
Most people probably understand the what pi, sin, cos, and i are and some things they're good for, and so the end of the story is that this formula reveals a way to turn a problem about e into a problem about sin, cos, and i which we have some good tools to deal with. Otherwise, we can turn a problem about i, sin, and cos into a problem about e, which gives us access to another set of tools. Sometimes one or the other form is more convenient, that's the extent of its value. Mathematics is simply more underwhelming to the casual observer than the sciences.
This post was edited by N1ccolo on May 5 2013 01:43am