What is a quantum laser micrometer? Very simply, a micrometer is a device to measure the width of a very small object. Usually, small widths are measured mechanically or electronically. With a laser quantum micrometer, nano-distances can be measured with a greater accuracy than can be measured by other means, and you can make one cheaply at home!
In this simple but detailed instructable I’m going to show you how to reconstruct my spin on the famous “double slit” experiment at home to illustrate some freaky quantum mechanical effects and how they work, find the width of a human hair, have stuff be in two spots at once, and “erase” information from the universe, showing that sometimes stuff acts like it is in two spots at the same time, but changes back to being at one spot once you interact with it. After completing this instructable, you will hopefully have a more complete understanding of quantum mechanics, what it means, why it is relevant, and how to creatively use it.
What people do not realize is that it is possible to reconstruct the very experiment that sparked the field of quantum physics right at home using only household materials. After one chemistry lecture in which one of my professors was explaining quantum mechanics, I bet one friend that I could perform the “double slit experiment” using only a human hair, a laser pointer, a string, a measuring tape, along with tape and some other common materials. What resulted from this is a new device that can be used to measure nano-distances right at home at a cost of around only a few dollars: the quantum laser micrometer (or Nestor's micrometer if you are feeling like giving an honorable mention).
Quantum Physics is a relatively new field of physics. Just as Sir Isaac Newton’s theories explained the actions of the very large, quantum mechanics focuses on the mysterious world of the very small, and has made several startling claims. Quantum Physics was founded on the notion that matter behaves like particles (solid) when it is a part of a large object because it has a larger influence on its environment, but behaves more like a wave (in many possible places at once, like a cloud or a “wave of potentials” that radiates outward) when it is smaller and interacts less with its environment. In fact, the notion of particles themselves is not as "solid" as one might initially think, but can be thought of distributions of energy (such as light) at discrete quantities ("quanta"). This is initially a difficult concept to grasp, but essentially the wave/particle duality means that matter (stuff) is in no one definite spot at once until the universe records its presence there by interacting with it (such as when it bumps into something or light hits it); thus smaller particles are more likely to behave more “wavelike” and larger pieces or matter behave more “solid.” I’ll talk about this more later.
Step 1: Understanding the Experiment
Since we know that matter (things) should only be in one place at once, not two, the instant that one of the ripples hits another object, thus “interacting” with the universe, the wavelike behavior of the blob of matter disappears and begins to act like it’s in one spot (“solid”) again. So in other words if the ripple bumps into something or we try to see the blob acting like it’s in many spots at the same time the blob says to itself “oh no! They’re catching on to me… I’m going to act like I’m in one spot again.”
Even though stuff acts like this, we can still catch it behaving like it’s in many spots at the same time and acting like a wave. The “double slit” experiment is how we do this. If we pass blobs of stuff through two slits and it creates a pattern of two bands of hits on the back of the wall we know that it’s acting like a solid particle. If it makes a pattern with many bands of hits on the back of the wall we know that it’s acting wavelike.