lördag 25 maj 2013

Completely random

I thought a post on random would be a suitable topic for a first post as my thought and interests may strike you as fairly random. However they aren't or at least i don't think so. I did think of writing some kind of blog statement but i hope it'll become obvious the more i write. You shouldn't talk about what you're going to do,you should talk about what you've done. Encourages action.

You've all seen this one,right ? If you haven't, go to xkcd.com and immerse yourself in his wonderful world of geekiness.

That's the funniest joke i've seen but as often (always?) with xkcd there's something deeper beneath the surface. What is random ? A sequence of 4:s is just as random as any other sequence. You could argue that random should be impossible to predict but unless you've seen the code you can't be absolute certain the next number is going to be a 4 even though all the previous ones has been. On the other hand a true random algorithm should be able to generate all possible permutations of valid numbers which clearly this one doesn't  (unless 4 is the only valid output but then there's no need for a random algorithm,is there?).

You often see random in situations where it isn't actually what you want. If you ask a 100 persons for a random number between 1-100 very few is going answer 1,50 or 100. 47 somehow feels more random than 50. Funny that, no ?

In acoustics there's a device called a diffuser which scatters sounds in "random" directions and in "random" phases. Does this mean you can just construct one any which way ? Of course not, there's a clearly defined maths behind it and the outcome is entirely predictable. It may look like you could just glue a bunch of random length wooden pieces together but that wouldn't work. It wouldn't work as expected.

If you imagine the diffuser being a reflective surface and then imagine a single ray of light hitting it,it would reflect back in a "random" angle and at a "random" time (due to the depths being different). If you move the ray slightly it would reflect back at a completely different angle and time,so is it random ?

Not really as it is completely predictable. On the other hand for it to be truly random it would have to move and we clearly don't want that.

So what is random ? Not as easy as one would imagine,huh ?

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