According to the Big Bang theory, their should be equal parts of matter and antimatter in our Universe. Conventional wisdom states that they should have annihilated each other, resulting in radiation. If that were true, we should have a Universe filled with only radiation. However, the Universe we observe consists of both radiation and matter.  If there were any significant quantities of antimatter in our Universe, we would see radiation emitted as it interacted with matter. We do not observe this. Therefore, it is natural to ask, “What happened to all the antimatter?”

Let’s start with a simple definition of antimatter. Antimatter is the mirror image of matter. For example, if we consider an electron matter, the positron is antimatter. The positron has the same mass and structure as an electron, but the opposite charge. The electron has a negative charge, and the positron has a positive charge.

In 2010 – 2013, scientists using the Large Hadron Collider have shown glimpses of evidence that suggest antimatter decays faster than matter, but the numbers are relatively small and do not fully explain why we have a Universe of matter and radiation. In addition, there is not full agreement in the scientific community regarding the different rates of decay of matter versus antimatter.

Several theories float within the scientific community to resolve the missing antimatter issue. The currently favored theories (baryogenesis theories) employ sub-disciplines of physics and statistics to describe possible mechanisms. The baryogenesis theories start out with the same premise, namely the early universe had both baryons (an elementary particle made up of three quarks) and antibaryons (the mirror image of the baryons). At this point, the universe underwent baryogenesis. Baryogenesis is a generic term for theoretical physical processes that produce an asymmetry (inequality) between matter and antimatter. The asymmetry, per the baryogenesis theories, resulted in significant amounts of residual matter, as opposed to antimatter. The major differences between the various baryogenesis theories are in the details of the interactions between elementary particles. Baryogenesis essentially boils down to the creation of more matter than antimatter. In other words, it requires the physical laws of the universe to become asymmetrical. We need to understand what this means.

The symmetry of physical laws is widely accepted by the scientific community. What does “symmetry” mean in this context?

  • First, it means that the physical laws do not change with time. If a physical law is valid today, it continues to be valid tomorrow, and any time in the future. This is a way of saying that a time translation of a physical law will not affect its validity.
  • Second, it means that the physical laws do not change with distance. If the physical law is valid on one side of the room, it is valid on the other side of the room. Therefore, any space translation of a physical law will not affect its validity.
  • Lastly, it means that the physical laws do not change with rotation. For example, the gravitational attraction between two masses does not change when the masses rotate in space, as long as the distance between them remains fixed. Therefore, any rotational translation of a physical law will not affect its validity.

This is what we mean by the symmetry of physical laws.

Next, we will address the asymmetry of physical laws. In this context, “asymmetry” means that the symmetry of physical laws no longer applies. For example, a law of physics may be valid in a specific location, but not in another, when both locations are equivalent. Is this possible? Maybe. There has been experimental evidence that the asymmetry is possible (a violation of the fundamental symmetry of physical laws). For example, radioactive decay and high-energy particle accelerators have provided evidence that asymmetry is possible. However, the evidence is far from conclusive. Most importantly, it does not fully explain the magnitude of the resulting matter of the universe.

This casts serious doubt on the baryogenesis theories. In addition, the baryogenesis theories appear biased by our knowledge of the outcome. By making certain (questionable) assumptions, and using various scientific disciplines, they result in the answer we already know to be true. The universe consists of matter, not antimatter. Therefore, baryogenesis theories may not be an objective explanation.

Obviously, the absence of antimatter is a profound mystery of science. Future work at the Large Hadron Collider may help us resolve this mystery. Based on their current findings, we are close, but do not have the total answer yet. If there are any breakthroughs, I will post them.