Part 2

# Wave-Particle Duality

Matter presents the particularity of having a wave and particle behavior. This phenomenon is known as the wave-particle duality, or complementarity. However, since the 1900s, this enigma has still not been solved.

This webpage proposes a rational and logical explanation to the wave-particle duality.

## Current Definition ofthe Wave-Particle Duality

It is generally accepted that the wave-particle duality is two different visions of a single object. Usually, we take a cylinder to explain duality. We observe either a rectangle or a circle depending on where we stand.

This metaphor is very interesting but it does not explain anything. More precisely, it does not explain what really occurs on the particle level.

Physicists do not need a philosophical approach to the wave-particle duality but a scientific explanation. This is why this webpage has been created.

## Logical Explanation ofthe Wave-Particle Duality

It might be objected that an elementary particle is different to a drop of water. Einstein also used many examples such as the train or the lift to explain Relativity. In the same line of thought, examples in this webpage are provided only to make clear the wave-particle duality principle.

## More Examples of theWave-Particle Duality

#### Swimming Pool

A toy boat is in the middle of a swimming pool. If you want to capsize it, you have two possibilities: to launch stones (particle concept) or to make waves (waves concept).

Let's replace stones by a high-pressure water cleaner like a "Karcher". The water that flows out of the Karcher can be considered as a particle and has all of its characteristics. In fact, we can capsize the small boat by pointing the Karcher towards it.

Now let's put the end of the gun in the water of the swimming pool. The water from the Karcher, which was like a particle in the air, will also be like a particle in the water. This operation does not change the corpuscular nature of the water that flows out of the lance.

We can then observe that the water, therefore like a particle, is transformed gradually into waves.

If, moreover, we actuate the Karcher for a short time, comparable to the action time of a particle, we can see that the small jet of water coming out from the gun becomes a single wave.

#### Niagara Falls

Nature offers us identical situations: the water of Niagara Falls has a particle behavior during its fall and, once it has reached the river down below, the particles become "eddies", like waves.

#### Opposite situation

The opposite situation also exists: let's take the example of an almost empty swimming pool. If we make only one wave in the residual water, some amount of water will spill out of the evacuation valve. Thus, the wave is transformed into a short filament of water, or "particle". The water that comes out from the evacuation valve is obviously not a wave. Yet, it is the same water that, a few seconds ago, was a wave.

In our examples, the transformation particle to wave and conversely is possible only if the medium is also water. In other words, the medium must also be in the same composition as the particle and the wave. It is a necessity.

## Law #1

The Wave-Particle Duality appears
only in this particular situation where:

• the particle,
• the wave,
• the medium

. . . have the same constitution.

## Law #2

As we saw in the preceding example of the pressure washer, the wave state appears only if the particle, i.e. the piece of water, is moving. Otherwise, if the particle (here the piece of water) is motionless, it keeps its corpuscular state. Hence:

When the particle is moving,
it becomes a wave

This law is very important since it solves many enigmas of modern physics. For example, electromagnetism only appears when the charged particle is moving. If the particle is at rest, electromagnetism does not exist.

## Law #3

In the swimming pool example, the water of the pressure washer is transformed gradually, in intermediate phases, from a particle state into a wave state. Obviously, all these states of transition between particle and wave cannot coexist. It is either one or the other but not several states together.

Experimentations confirm that the particle and wave states never appear simultaneously. So, resulting from experimentation, we can say:

Particles can exclusively take one, and
only one, of the three following states:

• Particle state, when it is motionless,
• Wave state, when it is moving,
• Halfway state, between wave and
particle during the transition.

## Young Slits

Contrary to preconceived ideas, the Young Slits enigma is only 20% concerned by the wave-particle duality. The remaining 80% are solved by the nature of electromagnetic waves. Therefore, the Young Slits is explained later, in Part 4 "Electromagnetism".

## Confirmation

In modern Physics, we have at least three indications confirming this explanation of the wave-particle duality:

1. The three laws stated above, issued from simple observations, are exactly what we see in physics. In particular, experimentations show that the particle and wave never appear simultaneously, like the drop and waves of water in the above examples.
2. As we know, electromagnetism appears only when the particle is moving. Our examples show that if the particle does not move, the wave does not exist. Here also we see a perfect match between our above explanation and scientific experimentations.
3. These three laws explain several enigmas in physics, such as the two slits experimentation, EPR, photon intrications (quantum teledeportation)...

It must be also noted that, to date, no one has given a better explanation of the wave-particle duality.