Monday, December 22, 2008

Euler's identity



Euler's identity is said to be the most beautiful theorem in mathematics.

"It is absolutely paradoxical; we cannot understand it, and we don't know what it means, but we have proved it, and therefore we know it must be the truth."
- Benjamin Pierce

8 comentários:

joshyMinor said...

Wow, I thihnk you might actually be on to something here.

jess
www.privacy.de.tc

proee said...

eCalc is a free online calculator that supports complex numbers in both rectangular and polar formats. http://www.ecalc.com

meester-burns said...

All that equation (e**it = cos(t) + i sin(t)) says is that if your velocity is perpendicular-to and proportional-to a displacement from a central point (that is, i times the displacement vector in 2d), then you will move in a circle about the point at an angular velocity of 1 radian per time unit (say seconds). After pi radians you are 180 degrees from where you started, or -1 times your initial position. Obvious :)

Anonymous said...

My head hurts...

Anonymous said...

Meester-burns:
thats a physical result of the property of these numbers. The idea that 2 transcendental numbers behaving with such a simple relationship to form back to unity is incredible, from a number theory point of view. Physics just takes advantage of this fact by representing waves (cf circular motion in your case) with complex phases

J-P said...

Sorry guys, but the condition for the Maclaurin Series of e^x says that x must be a real number, and therefore, we cannot replace x by i∏ since i∏ is an imaginary number...

meester-burns said...

Anonymous: These numbers are intimately related to the 2-dimensional plane and circular motion. It is not a mere physical convenience and not just a formality of Taylor expansions. And e is not random transcendental. Ask yourself what e means. :) (Hint, in the complex plane, it comes up as the solution to the evolution equation df/dt = kf. Consider what that means for k positive, negative and imaginary - i.e. rate of change is +/- proportional to or perpendicular to displacement from 0, e is by any sane definition related to motion and continuous evolution.)

Alternately, you might think of the limit, so try to imagine what multiplying a number z by (1+ it/n) looks like for large n. This is gives you z plus a little component perpendicular to z. It is not shocking that doing that n-times might give you a rotation of the initial z (of course that's not a proof!)

My main point is that this still comes as such a shock to folks now mainly because complex numbers and e are taught way too formalistically.
and people don't understand what they are looking at.

Stefanos Nikolaou said...

J-P, study laurent series and you will understand