Showing posts with label probability. Show all posts
Showing posts with label probability. Show all posts

Saturday, April 14, 2018

Boffon's Needle



Boffon's Needle


This experiment used integrals to calculate the probability of a needle being dropped on a sheet of paper with lines drawn on it landing on a line. I don't care about that, except that in 1777 The Comte De Buffon (Georges-Louis Leclerc) figured that the probability of a needle landing on a line is two divided by Pi.

So here's what I did: I found a box of needles (pins) that were 3/4" long. Then I drew lines on a piece of paper spaced at 3/4" from each other. This makes the needle and the space both 3/4" and thus they have a scale of "1". 

I dropped 11 needles and got 7 hits.

So:  2 x needle unit 1 x 11 drops divided by 7 hits = 3.14285

2(1)(11)/7 = 3.14285

Pi is = 3.141592...




This was the first (and only) drop I did. By the way, if you take a ruler and continue the lines every 3/4" the 3 needles that fell towards the bottom wouldn't have hit any lines...had I bothered to draw them in. The lowest needle would have been close though.

Let's take that scenario:  2(1)(11)/8 = 2.75

Yeah, I'll fudge a little and keep my nice 7 hits instead of 8.

So, eventually when I post my RF and AF probe builds they'll probably have something about sine waves (which are 2 pi in proportion...I think).


Saturday, May 23, 2015

Probability is really just plain old chance




“Probability is really just plain old chance.”        -Michael Logusz

"Gefühl ist alles name ist schall und rauch."-Goethe's Faust



This ties in with my last post about 1 = 0.99... and "common sense", "normal thinking", etc. versus mathematical theory and terminology. 


Probability merely studies abstract models and not real life! Probability is better understood sometimes as “possibly” or “more than likely” or “usually”. Chance!


Games of chance (gambling). The probability that I would never win at the slot machine approaches zero. Am I (and every other tourist in Vegas) a guaranteed winner? Nope, but the way some people approach probability in mathematics would make it seem so.


If you flip a coin the chances of heads/tails if 50/50.


If you flip a coin 99 times and get heads 99 times, the chances that the next time you flip the coin it will also be heads is still 50/50. Math deals with ideas, not necessarily the real world. 


My "monster toned" 1922 penny that I recently bought (with free shipping!). It sure is a beaut! If I it the "chances" are that it'll land on heads is 50% theoretically speaking. I just flipped it three times and got three tails in a row :(




For instance mathematicians deal with lines a lot. Their lines have no depth, breadth, width, etc. Engineers deal with lines in the real world: if you make a 1” hole in something and try to put a 1” peg in it, it will NOT fit! Engineers need to make the peg slightly smaller than the 1” hole to get it inside.


A common problem with CAD/CAM design is that people design things the ‘math way’ and do not take into consideration the width of the line they drew with a pencil—or with the computer. The result: parts are too tight and can’t go together.

So if (as discussed in the last post) infinities of nothing can still add up to something is there something analogous with chances? Yes: quantum tunneling. In many of my posts I reference radioactive alpha emitters, usually AM-241. According to "regular" physics it's impossible for a slow/weak alpha particle to break past it's barrier and be emitted. Impossible. Hmmm...according to quantum physics it's insanely rare. An alpha particle would have to bounce around three times ten to the thirty-first power! Almost no chance but still a nontrivial possibility. Schroedin and Heisenberg came up with the answers, alternating fixed time or the basis on their related equations...but that doesn't matter because of you read my other posts you'll see that I have a tiny piece of Americium-241 that blasts out so many "ultra-rare" particles every second of enough to irradiate old silver dimes and cause an amazing display in a radioscope (see later post "So you wanna see atomic particles with your own eyes huh? Part II").

Yes, something so rare it's impossible in regular physics but can easily be seen with some zinc-sulfide smeared on an eyepiece (radioscope / spinthariscope). Don't believe your eyes? Irradiate an old silver dime with AM-241 wrapped in aluminum foil: your Geiger counter will let you know you've done " The Improbable " a few zillion times over.