Before we begin we need to be very clear about something that I touched on before. Whenever we use the term “observation” when it comes to particles we have to understand that we can’t actually observe them directly. They are so far below are normal scale that we can’t possible “see” them in that way. Rather we can utilize various techniques and experiments and given the results of those experiments amplify those results in such a way that we can observe their effects.
While a very different concept, the idea is something along the lines of CO2. You can’t see CO2 since it’s a clear gas. If in the center of the room you see an empty fish tank. I can tell you that the tank is full of CO2 but you have no way of actually observing it directly. So how can I prove to you that the tank is full of CO2? There are numerous ways, but one way would be to simply blow some bubbles into the tank. You would see the bubbles stop falling at the level of the CO2. They would sit on top of it because CO2 is more dense than air. By “seeing” the effect you could now “observe” the CO2 in the tank.
In this world of quanta we have to do much the same, we have to observe particles by “seeing” the effects or amplified signals when these particles interact with other things, much like the CO2 interacted with the bubbles.
In the double-slit experiment we saw what effect observing the particles seemed to have. We saw that the act of observing (or knowing which-path information) collapsed the wave functions and created different results on our screen versus when we didn’t observe them.
So let’s talk about a different experiment that correlates in much the same way.
For the purposes of this example we’ll deal with an electron. Here’s a video I made to help explain this:
So again we touch upon this idea of superposition. When an electron goes into our color detector it is in a superposition of being both black and white. When thinking about this example initially we are trying to think of the electron as a single small tiny “thing”, and admittedly I purposefully lead you in this direction of thinking in the video. Still it’s just a natural way for us to think. Instead we have to stop thinking like that. We have to consider the fact that when we aren’t observing the electron only exists as a wave function, meaning a superposition of all the possible states that electron could be in if it was observed. This means it’s both black and white. But as long as we don’t measure rather it is black or white (which would force a collapse of the wave function) then it is undisturbed.
Make no mistake about it, there are some physicists out there who would cringe after watching this. Why? Because of my use of one word. “Knowledge” I can’t blame them at all because you see, physicists want to believe the world we live in is real and independent. They grasp on with dear life to the idea that everything else is “out there” and that even if all the life in the universe was somehow completely wiped out our universe would continue on. To accept the idea that our consciousness can change the physical world around us in some way is quite frightening. To accept the idea that the entire universe only exists because there is a consciousness here to observe it is down right terrifying.
Yet so many experiments have been run, and many of these have tried to prove that our knowledge of a system doesn’t change it. Yet there just hasn’t been any results that have supported that notion. It’s hotly debated to be sure.
For me personally, I have no problem accepting that our consciousness can collapse wave functions into reality. That it’s our knowledge of one area of a system that provides uncertainty in another. That if we choose to measure the momentum of a particle we can’t possibly know it’s position and likewise if we choose to measure the position of a particle we can’t possible know it’s momentum. That for as long as we don’t “look” there is nothing but a superposition of states with absolutely no real “substance” at all, and that the mere act of “looking” causes decoherence into one finite state or “reality.”
Now I made a promise in the beginning that I was going to keep things as simple as I could and therefore try to leave most of the maths out of it. There are a few things though where I believe it could be beneficial to know at least some of the basics. So soon I will introduce a couple of key elements. If you’re brushed up on your calculus it’ll be a breeze, if not it shouldn’t be hard to follow along and at least have a general understanding of what is going on. For now, no worries, I just wanted to give you a fair warning in advance that you might see more maths starting to pop up a little here and there.
In fact lets get a couple of fundamentals out of the way now.