"The two slit experiment contains the only mystery. We cannot make the mystery go away by 'explaining' how it works ... In telling you how it works we will have told you about the basic peculiarities of all quantum mechanics."
- Richard Feynman
The Double Slit experiment is a simple idea to get your head around, however it's application to Quantum Mechanics is not. In this case, particles travel towards a barrier which has two slits through which they can travel. On the other side of the barrier is a screen which measures where they hit. When the particles hit the screen, they do not do so randomly, but instead form an interference pattern. That is, their journey to the screen follows a path that can only be explained by wave-like proprieties created from passing through both the slits.
The revelation of the double slit experiment is that even when only a single particle is present, it will follow an interference path to the screen. It's not just that a large number of particles together act like a wave, a single particle also has wave-like properties. Hence the application to quantum mechanics.
The classical and most widely accepted explanation for this effect is known as the Copenhagen Interpretation. It was first introduced by Neils Bohr and Werner Heisenberg in 1925 and states that all particles have a wave particle duality, and therefore in the experiment, all particles travel through both slits. It's not until we try and measure their position (on the screen) that the particle like nature is discovered.
It's poor cousin in the theoretical physics world is Pilot Wave theory. It was described by Louis de Broglie and improved upon by David Bohm, and states that particles actually only travel through one slit, but their movement is dictated by a wave in which the particle travels. The reason why this theory is less accepted is because the presence of the wave itself. It is seen as a theoretical construct that requires "hidden variables" for it's explanation.
Classical quantum mechanics doesn't suffer from the hidden variable problem, but none the less has it's own problems to deal with. As I said earlier, only when a particle hits the screen does it cease to display wave like properties. This is called the wave function collapse and it is intricately linked to our own consciousness. This is because the collapse to a discreet, measurable position requires an observer. This leads to further theories that need to be accepted such as the many worlds theory, where all measurements lead to multiple outcomes in alternate realities.
But what if we accept the hidden variable associated with Pilot Wave theory? That would mean to try and understand the wave itself. If the movement of any particle is decided by a wave that is external to it, yet bound to it, then surely we can understand something of the nature of this wave?
The Double Slit experiment provides the simplest case of interaction for us, so that we can look at what properties the wave might have. The wave a particle travels on displays classical interference patterns, that is it interacts with the world of particles that pass through it, and it therefore contains information about those events that it reacts to. This is either true, or their is no separate wave function to speak of. This is referred to as the non-locality principal, which the Pilot Wave theory relies on. The calculations behind the theory show that the wave function is a universal phenomenon.
The wave function can be described as the movement we see in an information field. This field is a continuum inhabiting all space, and imparts some of it's knowledge on particles travelling through it. It also receives information from those particles. In this way, their appears to be a universal knowledge layer underpinning all matter. It seems to interact with the energy levels of everything in it.
What are other ways to think of this information field, with it's ability to store and impart knowledge on the world around it. I would like to think of this as consciousness itself. It is the information store that grounds all matter. In this way, it can be said that everything is conscious, because it inhabits this field. The universe is conscious.
It also explains our own consciousness. We don't have a consciousness that is separate from the world around us, as their is only one consciousness that encompasses the universe. What we have as individuals is self awareness. All animals have this to some extent, ours is merely the most expressive, thanks to our higher levels of cognition. That higher cognitive function also allows us to interact with universal consciousness at a higher level. There is a feedback loop that allows our own self awareness to become more integrated with that consciousness. The more we think, feel and understand, the stronger this process becomes.
After writing this, I read some great articles on Nautilus that led me further down the rabbit hole, they're worth a read:Â http://nautil.us/issue/47/consciousness/is-matter-conscious and http://nautil.us/issue/47/consciousness/roger-penrose-on-why-consciousness-does-not-compute