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Fig 1: Light goes through both holes,Fig 2: Interference Pattern,Fig 3: Light behaves like a wave


In 1927, Heisenberg was trying to figure out 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 is going – Say what?


Let us 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 represents how high the wave is when you measure it.


So let us say you see a wave you like and decide to surf on it, what will be its frequency then? Well, it is not that easy! Since this wave is isolated – like a pulse in an electrocardiogram – we cannot possibly measure the frequency of the wave.


Has your brain exploded yet? Well check this out then because that is the Uncertainty Principle in a nutshell: you can either know where the wave is or where it is going to be but not both at the same time. It is because it exists as both a particle and a wave #holdonasecond


This is based on the wave-particle duality property explained by the Double Slit experiment that we are going through in a minute.


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 three pencil- leads.


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


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

Guess what? That is not what is happening!

Instead, when we check the wall where the light was captured, we see is a multitude of lines on the wall, looking like Figure 2


Now, think about what it looks like.


Got it?


Yes! It does look like we have just blasted a wave through the holes as it creates the same pattern on the wall– called the interference pattern – Figure 3


Now the physicists were baffled by this discovery so they decide to shoot the photons of the laser beam 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.


Wrong again! It was exact same thing.

The only conclusion was that the photon leaves the machine as a particle, then becomes a wave before going through both holes and interferes 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 only going through one hole – meaning that only 2 lines should appear on the wall! Like we previously hypothesized #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 into one possibility and the outcome changes for every observation– same conclusion as the Schrödinger’s cat experiment.


Down the Quantum Hole

Fig 2: Interference Pattern
Fig 3: Light behaves like a wave