Are imaginary numbers real?
Sunday, April 16th, 2006This blog entry isn’t really starting out well, is it? Even the title is inconsistent. It’s paradoxical. It’s illogical. It sounds downright counter intuitive. And this is a maths inspired blog entry as well. Oh no. How am I going to get through this? Maths, the bastian of logic, the pillar of consistency, the base of my rational mind, and it seems to be going down the path of the nonsensical and the absurd. Please hold me hand will you? And let’s soldier on together.
Are imaginary numbers real? Do imaginary numbers exist? English teachers, philosophers, heck, almost every human being on this planet (including a certain Mr. Rene Descartes) will say no. It’s obvious. After all, if they are imaginary, how can they possible exist? But evidently they do.
But for those of you who are feeling a bit lost, let’s start by defining our beloved imaginary number, i as :
More notably, i is the square root of minus one. And all of us who have been paying attention during our high school maths classes should know that you can’t have a square root of a negative number. No way. Squares always end up positive, so you can’t have square roots of negatives - they just don’t exist.
Of course, mathematicians, being the stubborn folk that they are, decided that they didn’t want to follow this simple logical argument. Hence the birth of our beloved imaginary friend i.
Funny thing is, it turns out that this number i not only exists, but it is also particularly useful. When combined with real numbers (called complex numbers), they can be used to express things like vectors and phasors (no, not the star trek phasor), which in turn is used in fields such as fluid mechanics, modern control systems, signal analysis (urgh!) and electronics. In fact, and this sounds cooler (This is cool? Timo you’re a big fat nerd) than it really is, in things like control systems and fluid mechanics, you can actually ‘transform’ real number problems into the ‘imaginary’ plane (let’s call it the imaginary world, just to make is sound sexy), play around with it there and solve the problem there with our imaginary tools, while sitting in our imaginary convertible with an imaginary voluptous female friend wearing a lovely, albeit imaginary, red dress (ok I am going overboard here); and then we can transform the solved problem back into the real plane. It’s like magic. In fact, without this ability to transform stuff into the imaginary plane, most airplanes now would crash. We wouldn’t have been able to send shuttles into space. Our DVD players won’t work. Hard drives won’t work. Hand phones won’t work. Lots of stuff won’t work. All because of imaginary numbers.
But if you are still not convinced about the existence of imaginary numbers, hear this one out : The 240V (or 120 volts is you come from the devil land, or Japan!) mains electrical supply that you are using at the moment to power your pc, is expressed as a combination of a real number (240 volts), and an imaginary number (god knows how many volts), and even if the real voltage drops from 240 volts to zero volts, you still can get a shock (and kill youself!) from the imaginary voltage! Figure that one out!
Now, if you are waiting for me to explain how imaginary numbers, work, or how they exist, you are going to be disappointed, because I haven’t the slightest clue (anti-climatic, I know, but you try making a topic like this dramatic!). I am nearly freaking out as it is.
But before I leave, I would like to show you one of the best formulas in the mathematical world, and one of my personal favourite, Euler’s Identity :
where e is Euler’s number (which is approximately 2.718….), i is our imaginary buddy, and pi is obviously pi. If you don’t know what pi is, you may as well stop reading right now. In fact stop reading 15 minutes ago.
Euler’s identity is particularly famous because it is very elegant, i.e., it is nice and simple. It also combines the most ‘important’ 5 constants of mathematics (0,1,pi,e and i), and it also combines all the major mathematical processes -multiplication, addition, equality, and exponentiation (power of … ).
Also, on a short side trip here, e and pi are also ‘irrational’ and ‘trancendental’. Irrational numbers are numbers that we can never ever fully determine, for example, for the case of pi = 3.14159…., the dot-dot-dot goes on forever. We can never ever fully calculate the value of pi. Trancendental numbers are numbers that are not solutions to non-zero polynomials, which basically mean that we can never find a polynomial equation (most common equations are polynomials) where the answer is pi, or e. So what does it mean for you and me? Nothing at all. Just thought it was interesting that the two most common numbers in nature, pi and e (e is found is many natural situations, most notably the growth of living populations), cannot be determined exactly, and can never be solutions to our equations. Makes you believe in God doesn’t it?
But to end, just as some take home work for you readers out there, if we take a look at Euler’s Identity again, how can it be that when you take an irrational and trancendental number (e), and exponentiate it by the product of another different irrational and trancendental number (pi) and an imaginary number (i), and add it to the first number of the universe (the number 1), it equals to zero, which is in fact not a number by itself, but an ABSENCE of a number. Work that one out!