Everything around us is made out of matter. From you, to air to galactic dust, all of it! It is the very substance that forms the observable universe. That would be the base definition for normal matter- it’s anything that takes up space (volume) and has a mass. The building blocks of matter are common knowledge- atoms, made up of electrons, neutrons and protons. You may even be aware of even more fundamental particles called leptons and quarks, and their different ‘flavours’ (flavours here refers to varieties of the mentioned object, not what you use to describe ice-cream). However, there is a lesser known substance known as antimatter, which will be this article’s primary focus.
Antimatter is known to be an opposite excitation of matter particles everywhere, permeating quantum fields . More precisely, the sub-atomic antimatter particles have properties that are akin to that of matter, passing over the fact that each particle will have an exact opposite charge. We would have antiquarks and antileptons, one of which is an anti-electron (called a positron). The positron is similar to the electron in every way, other than its positive charge.
Since antimatter is so similar to matter (except for the opposite charge thing) they could combine in identical ways to form protons, anti-atoms, antimolecules, and anything, in principle, from an anti-pencil to an anti-Everest.
The relationship between matter and antimatter is a rather tricky one due to the opposite charges possessed by each particle respectively.
When both particles meet, they annihilate, releasing a huge burst of energy. In fact 1 gram of antiparticles, in a matter-antimatter annihilation should release enough energy to match that of a nuclear bomb! The thought of weaponizing such a powerful force in itself makes me fear the consequences of doing so, but the most antimatter made thus far is only 15 nanograms so I wouldn't be too worried.
We are gradually crossing over from the realm of theoretical physics to the practical world, though. Scientists have managed to create an atom that consists of both matter and antimatter. This atom is called antihydrogen, where an electron orbits a positron; that is until they both destroy each other. They currently have a lifespan of a nanosecond. It does not help that we only have the ability to create and contain only a few hundred antihydrogen atoms at a time.
- There is no device referred to as an antimatter trap. In order to review antimatter, you want to prevent it from annihilating matter. Scientists have created ways to do just that. Charged antimatter particles can be held in devices called Penning traps. They can be compared to tiny accelerators. Inside, particles spiral around because the magnetic and electric fields keep them from colliding with the walls of the trap (and consequently annihilating matter).
- Antimatter might fall up (instead of down). Antimatter and matter particles have an equivalent mass but differ in properties like charge and spin. The Standard Model predicts that gravity should have an equivalent effect on matter and antimatter; this has yet to be seen.
- Antimatter is a lot closer to you than you might think. Small amounts of antimatter continually fall upon the Earth in the form of cosmic rays, which are active particles from the cosmos. These particles approach our atmosphere at a rate ranging from one per square meter to more than 100 per square meter. There has also been evidence of antimatter production over thunderstorms. Some other antimatter sources are even closer to home. Did you know that bananas produce antimatter? That’s one positron roughly every 75 minutes.
- Antimatter has applications in modern medicine. PET (positron emission tomography) uses positrons to supply high-resolution images of the body. Positron-emitting radioactive isotopes (like those found in bananas) are attached to chemical substances like glucose that are used naturally by the body. These are injected into the bloodstream, where they're naturally weakened, releasing positrons that meet electrons within the body and annihilate. The annihilations produce gamma rays to construct images.
As mentioned before, creating antimatter was a problem, which was later solved by the invention, development, and use of particle accelerators. Even though we have the ability to create antimatter, containing it is a problem, since all containers (that we know of) are made of matter. In order to avoid this we use particle decelerators to study antimatter.
CERN houses such a machine, which is named the Antiproton Decelerator, a container which will capture and slow antiprotons to review their properties and behavior. In circular particle accelerators like the Large Hadron Collider (near Geneva, Switzerland), particles get a kick of energy each time they complete a rotation. Decelerators add reverse; rather than an energy boost, particles get a kick backward to slow their speeds.
But let’s rewind a bit. It all takes us back to this question: Why bother? Why are scientists even spending so much time and energy trying to create antimatter, when it seems to have no obvious benefit?
The truth is, it's hard to say. In the words of quantum physicist Dr Shiraz Minwalla, “There is this desire to know. All of us at some point or the other looked up at the sky and wondered, ‘What is the grand scheme of things?’ Understanding physics tells us how the world works at a very minute level. It doesn’t have a practical purpose, but it does satisfy us. And that’s part of the reason we do Science.”
The origins of antimatter is a question we’re still trying to answer. In theory, antimatter dates back to the big bang, where matter and antimatter were created in equal amounts at the big bang. They should have annihilated each other completely in the first second of the universe’s existence. The cosmos should be filled with light and little else.
And yet here we are. So are planets, stars and galaxies, as far as we can see, made solely out of matter. A reasonable answer to this mystery is that annihilation was not a whole in the first couple of seconds. Somehow, matter and antimatter managed to escape each other’s terminal grasp. Somewhere out there, in a possible mirror region of the cosmos, antimatter is still hidden, and has consolidated into anti-stars, anti-galaxies and conceivably even anti-life.
And guess what? We may never know
- Cern accelerating science. CERN. (n.d.). Retrieved September 13, 2021, from https://home.cern/science/physics/antimatter.
- What is antimatter. (n.d.). Livescience. https://www.livescience.com/32387-what-is-antimatter.html
- Ten things you might not know about antimatter. (n.d.). Symmetrymagazine. https://www.symmetrymagazine.org/article/april-2015/ten-things-you-might-not-know-about-antimatte r