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The Double Slit Experiment is one of the most famous experiments in physics. It gives a different insight into how reality works. The experiment shows that seemingly solid particles act as waves until observed by consciousness. The act of observing particles directly effects their behaviour.

## The Double Slit Experiment Diagram Explanation

To explain this, lets refer to this image:

In summary, when waves that pass through two narrow, parallel slits, they form an interference pattern on a screen behind the slits (as shown in (b)). This holds true for all types waves; light waves, water waves, sound waves and so on.

When using solid particles (photons or electrons), logically, we would expect them to leave two lines as they pass through the two slits (as shown in (a)). However, when these particles pass through the slits, an interference/wave pattern is still formed (as shown in (d)). Even if only one particle passes through, it still forms an interference/wave pattern. It’s as if the particle travels through both slits at the same time.

Furthermore, even if these particles are sent through the slits one at a time, the interference/wave pattern is still formed (as shown in (d)). The wave is a wave of probability, as the experiment is set up so that the scientists don’t know which of the two slits any individual particle will pass through.

To observe what happens, scientists set up detectors in front of each slit to determine which slit the particle actually goes through. However, when trying to observe what happens, the particles act differently, forming two straight lines on the screen (as shown in (a)) as opposed to the interference/wave pattern (shown in (d)). This is true even when setting up the detectors behind the slits. No matter what the scientists do, if they try anything to observe the particles, the interference pattern does not show.

As such, the act of observation makes these particles act as we would expect (as solid matter as shown in (a)), but when not directly observed, the particles act as waves (as shown in (d)). ‘It seems that our consciousness converts wave information into the seemingly solid world we see’.

## The Delayed Choice Experiment

Following on from this, scientists tried a variation on the ‘Double Slit Experiment’ (the ‘Delayed Choice Experiment’). The scientists placed a particular crystal at each slit. These crystals split incoming particles into a pair of identical particles. The idea being that one particle from the pair should create the standard interference/wave pattern, whilst the other travels to a detector.

However, this still doesn’t work and to make things more strange, it doesn’t work regardless of when that detection happens. For example, if the second particle is detected after the first particle hits the screen, it still ruins the interference/wave pattern. This means that observing a particle can change events that have already happened.

‘This is still one of the greatest mysteries of quantum mechanics.’

## The Double Slit Experiment Video Explanations

Below are some videos explaining the ‘Double Slit Experiment’. Note also that the Holographic Universe is often referred to when talking about the ‘Double Slit Experiment’. You can check out our post on the Holographic Universe here.

The Double Slit Experiment is often used to back up the Holographic Universe, an idea favoured by leading physicists in the World Science Festival. Former NASA physicist Tom Campbell refers to the Double Slit Experiment in the video below, where he also favours that consciousness is the primary source of reality and matter is dependant on consciousness.

You can read more on the Double Slit Experiment here and the Holographic Universe here.

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