# The Uncertainty Principle

In 1927, Heisenberg was trying to figured out with Maths how to determine the exact position of an electron orbiting its nucleus.

The results he found were pretty shocking, he discovered that the better we know where a particle is, the less we know how fast it’s going – Say what?

Let’s take a wave for example – the ones you surf on – the frequency will represent how close the waves are to each other, the closer the waves are the higher you can surf; its position is where the wave is when you measure it.

So let’s say you see a wave you like and decide to surf on it, what will be its frequency then?

Well, it’s not that easy! Since this wave is isolated – like a pulse in a electrocardiogram – we can’t possibly measure the frequency of the wave.

Has your brain exploded yet? Well check this out then because that’s the Uncertainty Principle in a nutshell: you can either know where the wave is or where its going to be but not both at the same time.

This is probably because particles exist both as particles and as wave based on the wave-particle duality property explained by the Double Slit experiment that I’m going to explain, well, right now.

The Double Slit Experiment

The experiment was made with a laser, a metallic plate with 2 holes in it and a wall behind the plate.

However you can actually try this yourself at home with a laser pointer and 3 pencil leads.

If we shine the light through the holes what should we see behind the wall?

Well since the light is going through 2 holes and we know that light as a particle like behaviour we should see 2 lines on the wall – Figure 1

Well guess what? That’s not what’s happening!

Instead, what we see is a multitude of lines on the wall, looking like this.

Now, think about what what does it look like.

Got it?

Yes! it does look like we’ve just blasted a wave through the holes as it creates the same pattern – called the interference pattern – Like this:

Now the physicists were baffled so they decide to shoot the photons one by one like a baseball pitching machine for an hour, since it was one by one, there was no way it would have the same interference pattern as above.

Well wrong again!

The only conclusion was that the photon is leaving the machine as a particle, becomes a wave before going through the holes and interfere with itself to hit the wall.

To make sure of this they decided to have a closer look at what’s going on before the particle goes through the hole by using a detector, however they ended up being even more confused when they realized that the particle was going through only one hole – meaning that only 2 lines should appear on the wall #braingoesboom

It looks like the particle knew it was being observed and change its own pattern. The simple fact of observing the particle make the wave function collapse – same conclusion as the Schrödinger’s cat experiment.