Here we propose a scenario using the attractive and annihilation forces seen in the preceding webpage.
We will try to imagine what occurs when two areas of opposite density of spacetime are put together.

For the moment, we do not know the nature of this interaction.
In the previous webpages, we have shown that EM waves are vibrations in spacetime but we do not know anything about
the sub-structure of spacetime.
Part 3 covers this subject but, for the moment, we try to describe the phenomenon and compare it to something known.

Background about antiparticles (Part 3)
Each particle has its counterpart antiparticle which has the same mass ("closed volume" more exactly,
see www.mass-gravity.com), but an opposite charge.
The positron, or "positive electron", is the antiparticle of the electron, which is negative.
Therefore, its charge is +1 instead of -1.
Another example is the antiproton, which is nothing but a proton with a charge of -1 instead of +1.

This webpage is the 4th part of the website
http://www.what-is-matter.com
It is strongly suggested to also read the three previous parts.

Scenario

Let's consider two areas of the same dimension, A and B, taken from an EM wave, i.e. a polarized
vibration in spacetime.
These two pieces are made of high and low density of spacetime respectively.
Area A comes from a positive half-period and B from a negative one.

As we can imagine, these two area will annihilate each other since they have opposite polarities.
This annihilation produces movements in the surrounding spacetime.
An identical phenomenon exists when an anticyclone comes into contact with a depression.
The annihilation always produces wind, sometimes storms, and disturbances in the surrounding space.

Thus, in our example:

Two areas A and B (yellow points) are extracted from an EM wave by a thought experiment,

The surrounding space is the global spacetime of the universe,

The two areas will annihilate each other (red interaction in the figure),

Two little waves (in red on the figure) are produced by the annihilation,

These two waves are emitted in 180^{o} to preserve the momentum,

Finally, these two waves are EM waves which are also made of spacetime.

Thus, the loop is closed in accordance with our Wave-Particle Duality definition:

The two "pieces" of an EM wave, areas A and B, are annihilated,

... that produce movements in spacetime,

... which are nothing but new EM waves.

Different volumes

Let's suppose now that one of the areas has a volume of 0.1% superior to the other (not represented in the figure).
What would occur?

It is simple: the excess 0.1% will not be annihilated.

For example, let's take an area of a volume equivalent to 511 KeV, and the other 509 KeV (*).
After annihilation, it will remain an area of 2 KeV.
This area will be ejected in a direction that preserves the momentum, in relation to the two other disturbances.

(*) This scenario is possible because the accuracy of measurement is: |me+ - me-| /m <
8.10^{-9}, with a confidence level (CL) of 90%.
Here, the difference is 2 KeV for teaching purposes but in reality, it is infinitesimal.

Interpretation

The scenario of the previous section, which is purely intuitive, coincides curiously with that of
an electron-positron (e-e+) annihilation.

The two areas of high and low density of spacetime could be the positron and the electron,

The movements of spacetime due to annihilation could be the two gammas of 511 KeV created
by the e+e- annihilation,

The volumes A and B disappear. In physics, the positron and electron disappear too,

The volume of the movements in spacetime corresponds to the volumes destroyed.
Our website www.mass-gravity.com explains with simplicity the
transformation of a "closed volume", i.e. mass, into waves,

Such a coincidence between the theory here described and the experimentation is disconcerting but not
sufficient to validate a theory.
We will make further deductions in the following chapter.
These conclusions confirm that the present scenario describes, word for word, an e+e- annihilation.
In other words, this confirms that particles are made of spacetime.

The Neutrino

If volumes are slightly different, the remainder could be the neutrino (or antineutrino).
Indeed, we do not have the proof that the positron has exactly the same mass as that of the electron,
but we have proof that the neutrino exists.

If the neutrino comes from an electron or positron, it must have a spin = 1/2 (spin is a quantum value
sometimes assimilated to an intrinsic momentum).
This is exactly what the experimentation proves.

If this scheme is correct, the neutrino must also have a very light charge.
However, this charge, if it exists, would be so light that it could be very hard to detect it.

Discussion about the neutrino is covered in Parts 3 and 4.