Everything around us from people to trees and stars to galaxies are made up of molecules, atoms and quarks, which all together scientists call ordinary matter. But, it has a mysterious twin that is like its photo negative.
It’s called antimatter.
You can have an anti-person, an anti-tree or an anti-galaxy.
When I was researching this topic, I thought that maybe their colours would be inverted, or they’d be see-through or something like that.
But it turns out each one would be indistinguishable from their ordinary version except for one thing. If the two ever come into contact, they’ll explode with a force greater than an atomic bomb.
If an antimatter Earth fell into the Sun, the blast would outshine the light of over 2,000 galaxies.
This happens because of the parts they’re made of. Matter is made up of certain kinds of quarks, but every quark has an opposite particle.
Except for an opposite charge, they have the same properties as normal quarks. This means they can be arranged to form atoms – creating an anti-atom. Combine anti-atoms and you’ll get anti-molecules, anti-stars, and anti-galaxies.
When they encounter each other, their charges cancel each other out and the gigantic amount of energy that’s held within the mass of the objects is rapidly converted into radiation and heat. In other words, an explosion.
The reason why we are made of matter and not antimatter is one of the largest unsolved problems in modern physics.
We know that in the seconds following the big bang, huge quantities of matter and antimatter were created, and they collided. They annihilated each other in an era of colossal explosions in space.
As a result, the universe was almost over before it really started. If all the matter and antimatter annihilated each other, the universe would be empty, without stars, planets, or life.
But for unknown reasons, a tiny portion more matter than antimatter was created. It outlasted the explosions, and went on to form everything we see in the universe, from galaxies to coffee cups.
Everything in the universe today is that tiny portion of leftover matter. It’s amazing to think just how much matter must have been created in the first place.
This imbalance is called the baryon asymmetry, and if you solve it you have a Nobel Prize waiting for you.
Antimatter still occurs naturally in some extreme circumstances like cosmic rays, but it only lasts until it encounters regular matter and explodes. But in the last few decades, there’s been a new source of antimatter in the universe – human beings.
We have (incredibly) learned how to manufacture anti-hydrogen and anti-helium, by smashing together their component quarks in just the right way.
It’s currently the most expensive substance in the world, at $25 billion per gram. For reference, gold costs about $40 for the same amount.
Part of the reason of its expense is that, apart from needing a particle accelerator to make it, antimatter is incredibly difficult to store. If you put it in any container made of atoms, it will annihilate them and explode. Instead, we levitate it in a high-tech vacuum sealed chamber using electromagnetic fields.
Pretty cool, hey?