Hi, I’m John Skieswanne, and this post is part 1 of a series on physics. In this series I will explain a few pillars of modern physics. I won't be
using any complex maths. It is my hope that this series will introduce some of you brilliant, curious-minded laymen out there to the inner circles of
So, sit back and enjoy.
the Uncertainty Principle.
In the quantum model, once you reach the subatomic level, nothing is certain anymore. In fact, one of the major pillars of the Quantum Model (QM, for
short) is actually named the "Uncertainty Principle".
When we measure the position of "large" objects, their position doesn't get much disturbed. This applies for galaxies, for stellar objects, and for
small objects such as watches and T-shirts and tennis balls. This even works for most atoms. But one thing Werner Heisenberg discovered in 1927: there
is a lower limit to this process. Past a certain point, there is no way to know for sure where a subatomic particle is located anymore. At such a
small scale, we can only say these particles have a probable
Here's an analogy to illustrate Heisenberg's argument:
Imagine an electron (the target particle) as a lonely pin on a very, very dark bowling lane. You can't see the pin, you can only guess where it is.
Since you don't know yet the position of the pin on the lane, you may think of the pin as being smudged all over the lane as a probability amplitude
- meaning it can be nearly everywhere inside this wave-like function of possibilities, but at some places more likely than others:
Heisenberg pointed out that to figure out where the electron (our bowling pin) is, you have to send some kind of signal onto it, like a light or
something (you can't know its position if you don't detect it in the first place).
Now light rays are made of particles, called photons.
Imagine you have a bowling ball - a glow-in-the-dark bowling ball. This ball represents the photon - the particle of light. Now imagine you throw the
bowling ball onto the lane, at the pin somewhere in the dark. Luckily, you hit the pin with the very first shot - and at the point of impact, you see
your bowling ball deviate. Now, you know where the pin is, right? - It is located at the point where your bowling ball got deviated.
Because of the impact itself
, the pin has been kicked back at some other, random direction. Thus although its position may be known at the
moment of impact, its momentum (and momentum direction) is not known with certainty anymore.
Thus, Heisenberg concluded that at the subatomic level, no machines can accurately pinpoint the exact position of a particle without compromising its
momentum, and vice-versa. That's basically because the target particles are so small, that any measurements, such as those performed by sending a
photon at them, would upset their state (by distributing energy to them).
That is why in the Quantum Model the properties (such as position, momentum, etc) of a particle are represented using probabilities. Since we just
don't know, we assign this probability wave function to a particle. Once you know one property of the particle for certain, then you may say that you
"collapsed the particle's wave function" - this basically means that you've eliminated all other possibilities but one (for this specific
property) down to zero.
A common mistake, especially in New Age, is to confuse "subatomic measurement" with "human eye". These are two different kind of "observations".
In physics, "observation" really means "measurement" - not necessarily organic, visual or spiritual, but actually physical.
You can stare in the dark for eons - this will not change the wave functions of the particles there. To collapse the wave function you actually have
to send something at it, you have to interfere with it in some way, otherwise it can't "know" if you're measuring it or not in the first place.
Additionally, Heisenberg's Uncertainty vanishes astronomically as soon as the target object becomes large enough to sustain measurement without
getting kicked to some random direction. So far, galaxies, planets and even humans do not receive that much of a kick from the Reception of One
Photon. Accordingly, these larger objects are dominated by very tangible laws ("classical" laws of physics) discovered by Newton and Einstein ages
I hope you enjoyed this read; Part 2 will be coming soon, and will deal about Einstein's Special Relativity - a very popular aspect of modern