Anti-particles are particle alter-egos. When they meet they annihilate each other to give a fiery burst of energy. Just after the Big Bang the particles and antiparticles should have met and the universe should have ended but we exist. Read on to find out how.
An Universe-gobbling Mistake
What will happen if you take ten positive integers and add them up to ten negative integers? Zero, right? In the particle world, there are particles and anti-particles that destroy each other on collision and give out zero mass. The annihilation leaves nothing but energy. According to the standard model of physics, the big-bang must have created equal number of matter and anti-matter.
Following our analogy, all matter and anti-matter should then, annihilate each other to leave behind zero mass. This claim however, denies the existence of the universe itself. Since, you are reading this and you exist, the universe exists too. So we are forced to accept that our assumption is wrong. This assumption of matter and anti-matter being equal in number came from the standard model. So is our standard model of physics wrong?
This contradiction between our models and the most obvious of observations has been puzzling the physics community for quite some time. After all, they designed the standard model to account for the behavior of all the observed particles. What folly has caused the standard model to predict that the universe shouldn’t exist? How did the mistake creep in to the standard model? To answer these questions, let’s take a look at how physics understands anti-matter.
The World Of Antiparticles
Let’s begin with a friendly particle, the electron (black ball above), imagine that it has a positive charge. Now, imagine that this positive-electron (white ball above) collides with our normal electron. This would result in mutual destruction in a fiery burst of energy. This new particle is a positron, the antiparticle of electron. The positron has the same mass as the electron but opposite charge.
The case that we just made is not unique to the electron. It can be extended to all other fundamental particles. All familiar particles have an anti-particle viz. (proton, anti-proton), (neutron, anti-neutron), (neutrino, anti-neutrino), etc. Just like the electrons, all other particles, are always so excited to meet their anti-particles that they destroy each other on collision and give out energy.
Mutual annihilation on meeting might make anti-particles and particles look like arch-enemies. However, Particles and anti-particles have more similarities than differences. Anti-particles should, in theory, show all the chemical and physical properties of matter. Just like particles clump together to form all the things in our universe, the anti-particles should be able to do the same thing.
Take a hydrogen atom for instance, it is made up of a proton and an electron. Similarly, an anti-hydrogen atom consists of anti-proton and an anti-electron. CERN(European Centre for Nuclear Research) was the first to produce it synthetically. This means that anti-particles may be capable of making higher elements and an anti-universe (antiverse?). However, we haven’t observed any anti-element heavier than anti-helium till date.
This discussion has now made us capable of understanding the predictions of the standard model better.
So Much Matter
Our original question was, “If the big-bang created equal number of particles and anti-particles in the universe, how does it exist? Why didn’t everything annihilate everything else?” Presently, there are 50 billion observable galaxies made up of particles and none made up of anti-particles. The evident abundance of matter and the rarity of anti-matter contradicts our models of the universe. The ability of anti-particles to form hydrogen and helium is a promising prospect towards an antiverse. Alas! the absence of heavier anti-elements puts our hopes, of touring an antiverse, in the sink.
After all, the standard model of physics is our interpretation of how the subatomic particles behave. These particles then, combine to make up the universe that we see. Our puzzle points out that there is something wrong in our interpretations of the universe.
Find out what’s wrong and to fix it, here.