Wednesday, November 12, 2008

Rerun: Heisenberg Uncertainty Principle

I've got a thing or two to write about, but they'll take time. So, since I have a bunch of new readers, I'm reposting an entry from September 2007 instead.

I am a geek of all trades. Among the many kinds of geek that I am, I am a sci-fi geek. The best kind of sci-fi are the kinds where the science is based on real science. An understanding of the fundamentals is key to appreciating some books. So I'm going to give some simple lessons in areas of physics that most people aren't likely to have dealt with.

Let me start by insulting your intelligence and work up to more complicated issues.

Things that you can touch are called "matter". If you smash up matter into little bitty pieces and then smash it up some more you get what are known as molecules. Break down the molecules and you get atoms. Atoms break down into neutrons, positrons, and electrons. In charts of atoms you get a picture that reminds many people of the Solar System picture. That is a big thing in the middle with smaller things going around it. In an atom the thing going around is called an electron. But instead of having a nice orbit where you can point at the electron and say "there it is" the best you can do is point to an area around the nucleus (the big thing in the middle) and say it's in here somewhere. You can chart the probability of where it is, but if you actually measure it then you've changed it.

At the subatomic level - I mean when working with the electrons, neutrons, and positrons - there's all kinds of weirdness.

Watch this film that explains the double slit test.

Dr. Quantum Explains Double Slit Experiment

Posted Jun 07, 2007

This is the strongest experimental proof of alternative universes.

Remember what I said about not being able to know where the electron was around the nucleus? Just where it PROBABLY is. Similarly, in the experiment you just watched you only get to know where the electron you're firing PROBABLY is. Some scientists think that the electron is in all the locations it could be but in parallel universes. So even when firing just the one electron at a time all the possible electrons in all the possible universes interfere with each other and make the pattern on the wall. BUT when you put up something to see which slit the electron goes through you force one of the universes to become OUR universe. This is what Doc Quantum meant when he said that it "collapsed the wave form". All the possible universes collapsed once observed.

Think of "Back to the Future". By going back in time they changed things and reality split into two alternative time lines. So Marty had to go back and fix things so that the two realities collapsed back into one. It's fun to think about alternate realities where Hitler died in that WWI gas attack and what not. But what about that reality where the only difference is you wore a green shirt one day instead of the blue one. The color of your shirt didn't change anything so those two realities collapsed back into one once two versions of you take the shirts off. Similarly, all those parallel and interfering universes with the electrons collapse into one. When they collapse depends on when they're observed. If observed before going through the slit only one hits the wall. If you wait to observe until after it hits the wall then all the other universes have messed with it. Only one of the many possible electrons in the many possible universes gets to hit the wall. But all the possibilities influence the path it takes.

I know, freaky, huh?

We have nothing but science fiction writers to allude to multiple universes on a super-atomic scale. It's just a helpful allegory to help understand the weirdness of the double slit experiment. And it's a fun "what if" thought experiment.


Malaise Inc said...

Things that you can touch are called "matter"

Well, strictly speaking you can't touch anything because of gravity, but I am just being pedantic. And thanks, I never really did understand the Heisenberg Uncertainty Principle before and I took a year of college physics.

Ibid said...

Woo! That's what I like to hear.