Matter — that’s all the stuff that we and everything around us are made of. Then there’s antimatter. It carries the exact same properties as matter but the opposite electric charge. It should have destroyed all matter long ago — but it hasn’t, mysteriously. Physicists are using AI to find out why.

We’re in the swimming pool. You’re happily diving around while I’m doing my lengths. Suddenly you lift your head in the air and spout a fountain of water at me. ‘Ugh,’ I exclaim, ‘you nasty little beast!’

‘You can wash my germs off with antimatter,’ you shout and dart off through the water. I chase after you. ‘What do you mean?’

‘My physics teacher said that! When matter and antimatter come together, there’s a bang and then both disappear.’

When antimatter meets matter, it gets rather explosive

‘He’s right. But it would be rather expensive to use antimatter to make your germs disappear.’

‘Yeah, I’ve never seen it in a store…’

‘That’s because there are only two places on earth where antimatter is produced in large enough amounts. And those are Fermilab in the US, and CERN in Switzerland.’

‘Whoa, then it’s rarer than gold!’

‘True. Besides, using it as a cleaning agent might have fatal consequences.’

‘Why?’

‘Because when matter and antimatter meet, it gets pretty explosive. Physicists explain that with Einstein’s formula, E=mc². The E stands for energy, m is mass, and c² is the speed of light squared. It basically means that energy and mass are the same thing.

Antimatter is some rather explosive stuff. Photo by ActionVance on Unsplash

‘Matter and antimatter have mass. And when matter and antimatter meet, their masses turn into a huge amount of energy. That could be quite explosive.’

‘Okay, then you can wash my germs off this way,’ you cry and splash a wave of water in my face. I shake my head in surprise. ‘Alright, thanks.’ Then I continue with my lengths.

You catch up with me. ‘How do we know that antimatter really exists?’

‘The theory of the Big Bang predicts it. At the beginning, there was a whole lot of energy. That energy turned into matter and antimatter particles, like a reverse explosion.

‘Then the matter and antimatter annihilated to energy again. But somehow a little bit of matter was left over. We’re made of matter, and we only exist because a small fraction of it mysteriously survived.’

The matter-antimatter asymmetry problem

‘You mean, we’re just the leftovers of lots of crazy explosions?’

‘In principle, yes. We have no idea why some matter was left over and formed the universe that we know today. And why there is almost no antimatter left in space.’

‘But if the people at Fermilab and CERN are producing antimatter, can’t they destroy us all?’

‘No, the amount of antimatter that they make is much too small. Plus, they always make sure that everything is very safe.’

‘Why do they make antimatter anyway?’

‘Because we want to find out how it works! And whether its properties are somehow different from ordinary matter. That would explain why there was matter left over after the Big Bang.

The experimental apparatus of the BASE experiment at CERN. Courtesy of the BASE collaboration

‘But despite all experimental efforts, matter and antimatter seem to be exactly the same. The only difference is that they have opposite charges. For example, a proton carries positive charge. The antiproton carries negative charge, but the exact same amount.’

‘And do people measure that charge and the other properties of antimatter?’

‘Yes. The BASE collaboration at CERN is one of the groups that is working on this problem. They refined the measurement techniques to an impressive degree. But even at that level of precision, matter and antimatter seem to have identical properties. In fact, I interned there for a couple of months when I started my career as a physicist.’

Physicists are trying to unveil one of the biggest mysteries of our time. Photo by Billy Huynh on Unsplash

‘Oh cool! But you didn’t solve the problem.’

‘No. And somehow there isn’t enough antimatter in space to solve the problem, either.’

‘There’s antimatter in space?’

‘Yes. There are cosmic rays from outer space that consist of antimatter. But they don’t contain that much of it. All in all, we’ve only found a tiny fraction of antimatter in space, in comparison to what we’d expect if there were the same amount of matter and antimatter in the universe today.’

‘So what do physicists do about that?’

‘Even more research! And developing new research tools.’

‘Like what?’

Particle physicists team up with AI to solve toughest science problems

‘Artificial intelligence, for example. It could help detect antimatter. It’s incredibly difficult to build detectors that are sensitive enough to detect antimatter particles.’

‘Why?’

‘Because a detector is made of lots of electronics. And electronics always produces noise. The detectors need to distinguish this noise from the signal that the antimatter leaves. Building in AI tremendously improves that.

‘So far, we haven’t been able to uncover any asymmetries between matter and antimatter. Maybe AI will change that.’

‘But now it’s a mystery!’

‘Indeed it is. But my revenge isn’t!’ I cry as I splash a big wave of water in your face.